Rotary Snowmobile (12A)
07-27-12, 08:51 PM
#1
Rotary Snowmobile (12A)
Has anyone seen a Carb 12A in a snowmobile?Well, if not im thinking of building one.
I currently have a 1999 Polaris 700XC that is in need of a rebuild. I have some time on my hands and Im looking for a small project. My main concerns:
DriveTrain - I Found out the drive-train for the stock 700 has held up 220+ Hp. I feel confident that the drive pulleys should be fine.
Power- Im looking for ~200Hp from the 12A. i know that this will mean bridged Primaries and secondaries. One plus is exhaust will be free flowing, no emissions lol.
Heat - Cooling the 12A is going to be one of the hardest tasks, as i don't think the stock Radiator will cool the ~1100CC engine
E-Shaft to Eccentric Clutch - Im thinking im going to use a custom hub adapter from the E-shaft to clutch. Im trying to use the stock clutch assembly and adapt it to the Shaft.
Starting- I dont think a hand pull will work. Maybe a AC start up like on the snow blowers? Im stuck here lol.
RPM - Im looking to increase the Stock 7k Red line to 10k. Im guessing that Ceramic seals would be best for this, whereas; the RA classics/Black would be a secondary option (Its not turbo, but i dont think you can tune a snowmobile as well as a car lol) as longevity for a snowmobile is 6k where as 20-30k with the 12A on hard seals would still be a huge increase in longevity.
Electric Power - Getting power for the spark, starter, lights, sensors. Ill have to do more research on the stator for the 700XC (if there is not started used or it is externally powered)
Please shoot me any ideas you have. This is just the brain storming stage i want to have a full plan so the build can go smooth.
I currently have a 1999 Polaris 700XC that is in need of a rebuild. I have some time on my hands and Im looking for a small project. My main concerns:
DriveTrain - I Found out the drive-train for the stock 700 has held up 220+ Hp. I feel confident that the drive pulleys should be fine.
Power- Im looking for ~200Hp from the 12A. i know that this will mean bridged Primaries and secondaries. One plus is exhaust will be free flowing, no emissions lol.
Heat - Cooling the 12A is going to be one of the hardest tasks, as i don't think the stock Radiator will cool the ~1100CC engine
E-Shaft to Eccentric Clutch - Im thinking im going to use a custom hub adapter from the E-shaft to clutch. Im trying to use the stock clutch assembly and adapt it to the Shaft.
Starting- I dont think a hand pull will work. Maybe a AC start up like on the snow blowers? Im stuck here lol.
RPM - Im looking to increase the Stock 7k Red line to 10k. Im guessing that Ceramic seals would be best for this, whereas; the RA classics/Black would be a secondary option (Its not turbo, but i dont think you can tune a snowmobile as well as a car lol) as longevity for a snowmobile is 6k where as 20-30k with the 12A on hard seals would still be a huge increase in longevity.
Electric Power - Getting power for the spark, starter, lights, sensors. Ill have to do more research on the stator for the 700XC (if there is not started used or it is externally powered)
Please shoot me any ideas you have. This is just the brain storming stage i want to have a full plan so the build can go smooth.
07-27-12, 10:14 PM
#2
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If you are talking about a sno mo rad then it is way to small , I tried using a bike rad on my rotary build and it just couldn't do it , the little engine would just overwhelm it in 5 minutes especially if you are giving the throttle a bit . There are those that don't agree with me and that is fine but that was one of the biggest reasons that rotary bikes and snowmobile failed in the marketplace and of course some of the reason was just because they were so different . Even in cold weather the coolant still needs to travel rapidly from rad to engine and back to rad when the thermo is open and no you shouldn't run without a thermo . JMO 
Gerald m. EDIT Why can't you use a battery and starter you will be a tired dude starting that thing by hand .
Gerald m. EDIT Why can't you use a battery and starter you will be a tired dude starting that thing by hand .
Last edited by gerald m; 07-27-12 at 10:20 PM.
07-28-12, 12:28 PM
#3
I was afraid that the rad wouldn't be able to cool engine. Any ideas on how to cool this thing?
I was thinking an AC powered starter to save on weight but if it ever died or I stopped it restarting it would be a problem. But that brings us to the recharging problem. I'm not sure if the stator will recharge a small battery. Given the stator is designed for a light and two plugs.
I was thinking an AC powered starter to save on weight but if it ever died or I stopped it restarting it would be a problem. But that brings us to the recharging problem. I'm not sure if the stator will recharge a small battery. Given the stator is designed for a light and two plugs.
08-01-12, 12:30 PM
#4
A stock clutch won't last long turning much above 8,000 rpm's. i run a Micro-belmont on my sand rail and have turned it as high as 10,800 rpm's but not for long. The sno-mo racers i know cringe when i talk about the high r's. Not a pretty sight when a clutch comes apart. I'm running roughly 180 hp on a 12a and then adding nitrous to wake it up.
I'll be running mine for a demo race at the Rochester Nh fairgrounds on 8/26 if you want to take a peek.
I'll be running mine for a demo race at the Rochester Nh fairgrounds on 8/26 if you want to take a peek.
08-01-12, 03:31 PM
#5
I got 6+ years out of a stock core 12a in my car. Turning 9200 every pass for many seasons. 7800-8200 now that I got the clutch working right. BTW, I didn't think a rotary had a red line?
So you can see my adapter:
Video of the car running (click on the image)
Sand Drag Central • View topic - Some times you just have to say screw it!
So you can see my adapter:
Video of the car running (click on the image)
Sand Drag Central • View topic - Some times you just have to say screw it!
Last edited by chainreaction; 08-01-12 at 03:37 PM. Reason: added info and links
08-01-12, 11:12 PM
#6
I see. I was planing on using my sock eccentric clutch and machining an adapter from the E-shaft to the drive belt. I was under the impression that the clutch automatically engaged at 10k. I could be wrong as i don't know anything about sleds lol.
I believe in building an engine to suit your needs. I planned on rebuilding the 12a and building it for a safe 10k every time pass. I see it like this - a sled needs a rebuild about every 6-8k miles (top end) a high powered 12A BP with the correct seals, bearings, springs should last 30k. the longevity would be 4-5 times that of a normal sled engine.
I believe in building an engine to suit your needs. I planned on rebuilding the 12a and building it for a safe 10k every time pass. I see it like this - a sled needs a rebuild about every 6-8k miles (top end) a high powered 12A BP with the correct seals, bearings, springs should last 30k. the longevity would be 4-5 times that of a normal sled engine.
08-02-12, 07:53 PM
#7
The primary clutch engages depending on the weights and springs you choose to put in the primary clutch.
You can set it to engage at say 3,000 rpm's and adjust the secondary clutch to allow it to rev up to say 8,000 rpms and shift up to maintain those rpm's from there. Engagement is controlled by the primary, rpms' is controlled by the secondary.
I kept part of the bellhousing to allow the use of the stock starter, went with an ultralight weight aluminum flexplate, but also requires a 12v car battery.
You can set it to engage at say 3,000 rpm's and adjust the secondary clutch to allow it to rev up to say 8,000 rpms and shift up to maintain those rpm's from there. Engagement is controlled by the primary, rpms' is controlled by the secondary.
I kept part of the bellhousing to allow the use of the stock starter, went with an ultralight weight aluminum flexplate, but also requires a 12v car battery.
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08-03-12, 12:12 AM
#8
The primary clutch engages depending on the weights and springs you choose to put in the primary clutch.
You can set it to engage at say 3,000 rpm's and adjust the secondary clutch to allow it to rev up to say 8,000 rpms and shift up to maintain those rpm's from there. Engagement is controlled by the primary, rpms' is controlled by the secondary.
I kept part of the bellhousing to allow the use of the stock starter, went with an ultralight weight aluminum flexplate, but also requires a 12v car battery.
You can set it to engage at say 3,000 rpm's and adjust the secondary clutch to allow it to rev up to say 8,000 rpms and shift up to maintain those rpm's from there. Engagement is controlled by the primary, rpms' is controlled by the secondary.
I kept part of the bellhousing to allow the use of the stock starter, went with an ultralight weight aluminum flexplate, but also requires a 12v car battery.
The 13B has so much more reliability (i feel) and much better power potential for this type of build. Only problem i can think of is EFI. I don't want to run ( or spend thousands) on stand alones for spark ad fuel control. I don't really want to run an ECU too for fear of shorting out (like most limp mode ECUs). The 13b carb would be the best bet.
Now, for ports i have Judge ITO's agressive street port, i would then add a small eyebrow to it and join the secondaries or leave the 5 & 6 ports and just widen them?set the RPMs for 9k.
How does this sound so far?
Sold by the time I found it
09-28-12, 12:54 PM
#10
Just a little bump. I was talking to a rotary friend about the build and he brought up a good point. With a 13B (EFI or carb) he felt that the low end torque would be much less then the current motor in the sled now. That means off the line would be much slower where as the top end would be greatly increased. For trail riding and short stretches the pick up on the sled would be reduced, moreover, this build would be mainly for lake riding.
Any input guys, maybe some porting advice that wouldn't harm the low end like a HBP but still keep my 200+ HP and torque. I know it's been done before.
Any input guys, maybe some porting advice that wouldn't harm the low end like a HBP but still keep my 200+ HP and torque. I know it's been done before.
09-28-12, 01:28 PM
#11
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sled motors dont have a ton of torque, they are 2 strokes and make power in the upper range only, 3000 is a conservative engagement point, my xcr 440 (97 factory cross country sled) engaged well over 4000 from the factory, your 13b will make much more power all over the place, the clutch setup will be a challenge to get 1) aligned, and 2) weighted to use the power of the engine.
As for cooling look into different model years, some ran rads under the tunnels, and others ran them under the floorboard, maybe going with a combination of the 2 will net enough cooling, scrapers could also be added to throw more snow into the tunnel to help cool when running on hard pact snow. Even adding a long track tunnel for the additional rad space would be an idea worth checking out.
In the end yes it can make more power than a sled in a similar rev range, but your front end is going to be so heavy (thing wet weight on fast sleds is under 500lbs) that its going to be hard to drive comfortably, noise will be an issue. Unless this is being built as a specific use sled (grass drags, ice drags etc) its likely not the most practical use of an engine.
As for cooling look into different model years, some ran rads under the tunnels, and others ran them under the floorboard, maybe going with a combination of the 2 will net enough cooling, scrapers could also be added to throw more snow into the tunnel to help cool when running on hard pact snow. Even adding a long track tunnel for the additional rad space would be an idea worth checking out.
In the end yes it can make more power than a sled in a similar rev range, but your front end is going to be so heavy (thing wet weight on fast sleds is under 500lbs) that its going to be hard to drive comfortably, noise will be an issue. Unless this is being built as a specific use sled (grass drags, ice drags etc) its likely not the most practical use of an engine.
09-28-12, 01:30 PM
#12
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Just a little bump. I was talking to a rotary friend about the build and he brought up a good point. With a 13B (EFI or carb) he felt that the low end torque would be much less then the current motor in the sled now. That means off the line would be much slower where as the top end would be greatly increased. For trail riding and short stretches the pick up on the sled would be reduced, moreover, this build would be mainly for lake riding.
Any input guys, maybe some porting advice that wouldn't harm the low end like a HBP but still keep my 200+ HP and torque. I know it's been done before.
Any input guys, maybe some porting advice that wouldn't harm the low end like a HBP but still keep my 200+ HP and torque. I know it's been done before.
A 200 hp 13b will tear the friggin track right of that machine . remember you are only moving 4 or 5 hundred pounds not a car that is 1500 to 2000 pounds. Properly set up with the proper clutching and gearing it would be fine .. Gerald m.
09-28-12, 01:48 PM
#13
sled motors dont have a ton of torque, they are 2 strokes and make power in the upper range only, 3000 is a conservative engagement point, my xcr 440 (97 factory cross country sled) engaged well over 4000 from the factory, your 13b will make much more power all over the place, the clutch setup will be a challenge to get 1) aligned, and 2) weighted to use the power of the engine.
As for cooling look into different model years, some ran rads under the tunnels, and others ran them under the floorboard, maybe going with a combination of the 2 will net enough cooling, scrapers could also be added to throw more snow into the tunnel to help cool when running on hard pact snow. Even adding a long track tunnel for the additional rad space would be an idea worth checking out.
In the end yes it can make more power than a sled in a similar rev range, but your front end is going to be so heavy (thing wet weight on fast sleds is under 500lbs) that its going to be hard to drive comfortably, noise will be an issue. Unless this is being built as a specific use sled (grass drags, ice drags etc) its likely not the most practical use of an engine.
As for cooling look into different model years, some ran rads under the tunnels, and others ran them under the floorboard, maybe going with a combination of the 2 will net enough cooling, scrapers could also be added to throw more snow into the tunnel to help cool when running on hard pact snow. Even adding a long track tunnel for the additional rad space would be an idea worth checking out.
In the end yes it can make more power than a sled in a similar rev range, but your front end is going to be so heavy (thing wet weight on fast sleds is under 500lbs) that its going to be hard to drive comfortably, noise will be an issue. Unless this is being built as a specific use sled (grass drags, ice drags etc) its likely not the most practical use of an engine.
I completely agree on noise, and i accept that i will need ear muffs lol. My whole sled now is 495lbs whereas my friends 700 weighs in at 640ish. I'm thinking if i can keep it around 650-700 the weight shouldn't be to bad.
That was my thinking as well. I joined a Polaris forum and talked to a few people who have 200+ hp on the stock drive train, so that kind of put that issue to ease for me. If anything i would assume that torque would be the killer for the drive-train.
09-28-12, 03:59 PM
#14
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Right now it has the factory 700CC, and it moves! I hit 135 on a frozen lake. If i can get the right setup without spend thousands of dollars and 4 years on it i think it would be a great toy to have in the winter.
I completely agree on noise, and i accept that i will need ear muffs lol. My whole sled now is 495lbs whereas my friends 700 weighs in at 640ish. I'm thinking if i can keep it around 650-700 the weight shouldn't be to bad.
That was my thinking as well. I joined a Polaris forum and talked to a few people who have 200+ hp on the stock drive train, so that kind of put that issue to ease for me. If anything i would assume that torque would be the killer for the drive-train.
I completely agree on noise, and i accept that i will need ear muffs lol. My whole sled now is 495lbs whereas my friends 700 weighs in at 640ish. I'm thinking if i can keep it around 650-700 the weight shouldn't be to bad.
That was my thinking as well. I joined a Polaris forum and talked to a few people who have 200+ hp on the stock drive train, so that kind of put that issue to ease for me. If anything i would assume that torque would be the killer for the drive-train.
As far as cooling I use a rad from a old courier 1/4 ton truck and find it does a fine job . in the winter I feel it would be an easy job to cool the little engine providing the ( PROPER ) thermostat etc. is used I would keep the snow away and just use the free air to cool with maybe a little fan on rad to induce air flow .
I do agree with Dale Birch in that you will have a fairly heavy front end The little engine ready to run should weigh in at around 170 pounds . a forum friend of mine CHAINREACTION runs a sand car with some type of heavy duty sno mo clutch with very good results . he frequents my build thread and he does have a thread on this forum . very knowledgeable when it comes to driving things with a belt drive . You could always run three skis in front if you need more foot print for the weight ratio . Good luck
Gerald m.
09-29-12, 12:17 PM
#15
You will want to take a look at the snowmobile noise laws where you intend to run it. In Maine and NH, you would get a ticket before it was ever unloaded. Both states require factory stock exhausts on all sleds now, only exception being at an organized, licensed competition. Most sled exhaust dumps under the sled to help in deadening the noise. My car measures at 60+Db measured from 300' away with stock porting, 2" open headers with minimal silencers on it.
Here you can hear the noise over a muffled 400ci small block
Good Pass video by YorkRace - Photobucket
Here you can hear the noise over a muffled 400ci small block
Good Pass video by YorkRace - Photobucket
10-16-12, 11:47 PM
#16
Arctic Cat Sachs actually made a 295 cc and a 303 cc Lynx and Panther too. Evinrude had a 500cc version about 45 hp The 295 cc was the better of the two cat designs. If you run a sled up at 8000 it won't last only a few seasons racing on the ice, only weekends not 7 days a week. These are all one rotor engines.
12a weighs in at about 200 lbs I shipped one once. I ve been in sleds my whole life and rotaries since 2005 racing, my suggestion would be to
get a sled with a rotary engine and then decide if you still want to put a two rotor 12a on it.
12a weighs in at about 200 lbs I shipped one once. I ve been in sleds my whole life and rotaries since 2005 racing, my suggestion would be to
get a sled with a rotary engine and then decide if you still want to put a two rotor 12a on it.
10-19-12, 05:30 PM
#17
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With with all due respect to all I don't think most of the members on this thread understand where ryan123 is coming from .. He wants to build a sno machine with a 12a rotary not a sachs or anything else and is asking for imput in that direction .
Oval RX7 you must have been weighing your crate as well to make a 200 pound package the 12a only comes in at 165 -170 ready to rip.
I don't believe there should be any problem cooling the little engine , and if set up proper you can make the clutches cut in and top out at what ever rpm you want .. As far as drive belts go I bought belts from $120.00 down to $38.00 and found out that I needed to break them in proper or they wouldn't last 1 mile . so far now that the clutch is tuned a bit on my grass drag bike the 58.00 MAX 1065M3 belt with thicker sides for more traction on the pulleys seems to be real tough and has maybe 20 miles of hard acceleration up and down . you will also find if you engage your clutch at to high of rpm will result in smoke time depending on what clutches you use .
I run my 13b around 3000 for primary engagement and then the spring weight in the secondary holds your top end rpm and also controls the upshift . So its size of weights and spring size for engagement on primary and size of spring on secondary to control upshift and hold your rpm . The engine should hit top end almost immediately and the secondary should control it . HAVE I GOT THAT RIGHT DARRYL ?
If you are looking to race you will find that you will need to work the final drive for speed . I needed to loose 2 teeth on my primary sprocket on the final drive so I could engage hard and not slip my belt , for warp speed a couple extra teeth and ease into it a bit on the start and it gets to the point for me that I can't see proper anymore and that is to darn fast. JMO Gerald m.
Oval RX7 you must have been weighing your crate as well to make a 200 pound package the 12a only comes in at 165 -170 ready to rip.
I don't believe there should be any problem cooling the little engine , and if set up proper you can make the clutches cut in and top out at what ever rpm you want .. As far as drive belts go I bought belts from $120.00 down to $38.00 and found out that I needed to break them in proper or they wouldn't last 1 mile . so far now that the clutch is tuned a bit on my grass drag bike the 58.00 MAX 1065M3 belt with thicker sides for more traction on the pulleys seems to be real tough and has maybe 20 miles of hard acceleration up and down . you will also find if you engage your clutch at to high of rpm will result in smoke time depending on what clutches you use .
I run my 13b around 3000 for primary engagement and then the spring weight in the secondary holds your top end rpm and also controls the upshift . So its size of weights and spring size for engagement on primary and size of spring on secondary to control upshift and hold your rpm . The engine should hit top end almost immediately and the secondary should control it . HAVE I GOT THAT RIGHT DARRYL ?
If you are looking to race you will find that you will need to work the final drive for speed . I needed to loose 2 teeth on my primary sprocket on the final drive so I could engage hard and not slip my belt , for warp speed a couple extra teeth and ease into it a bit on the start and it gets to the point for me that I can't see proper anymore and that is to darn fast. JMO
Gerald m.
10-28-12, 08:18 PM
#18
With with all due respect to all I don't think most of the members on this thread understand where ryan123 is coming from .. He wants to build a sno machine with a 12a rotary not a sachs or anything else and is asking for imput in that direction .
Oval RX7 you must have been weighing your crate as well to make a 200 pound package the 12a only comes in at 165 -170 ready to rip.
I don't believe there should be any problem cooling the little engine , and if set up proper you can make the clutches cut in and top out at what ever rpm you want .. As far as drive belts go I bought belts from $120.00 down to $38.00 and found out that I needed to break them in proper or they wouldn't last 1 mile . so far now that the clutch is tuned a bit on my grass drag bike the 58.00 MAX 1065M3 belt with thicker sides for more traction on the pulleys seems to be real tough and has maybe 20 miles of hard acceleration up and down . you will also find if you engage your clutch at to high of rpm will result in smoke time depending on what clutches you use .
I run my 13b around 3000 for primary engagement and then the spring weight in the secondary holds your top end rpm and also controls the upshift . So its size of weights and spring size for engagement on primary and size of spring on secondary to control upshift and hold your rpm . The engine should hit top end almost immediately and the secondary should control it . HAVE I GOT THAT RIGHT DARRYL ?
If you are looking to race you will find that you will need to work the final drive for speed . I needed to loose 2 teeth on my primary sprocket on the final drive so I could engage hard and not slip my belt , for warp speed a couple extra teeth and ease into it a bit on the start and it gets to the point for me that I can't see proper anymore and that is to darn fast. JMO Gerald m.
Oval RX7 you must have been weighing your crate as well to make a 200 pound package the 12a only comes in at 165 -170 ready to rip.
I don't believe there should be any problem cooling the little engine , and if set up proper you can make the clutches cut in and top out at what ever rpm you want .. As far as drive belts go I bought belts from $120.00 down to $38.00 and found out that I needed to break them in proper or they wouldn't last 1 mile . so far now that the clutch is tuned a bit on my grass drag bike the 58.00 MAX 1065M3 belt with thicker sides for more traction on the pulleys seems to be real tough and has maybe 20 miles of hard acceleration up and down . you will also find if you engage your clutch at to high of rpm will result in smoke time depending on what clutches you use .
I run my 13b around 3000 for primary engagement and then the spring weight in the secondary holds your top end rpm and also controls the upshift . So its size of weights and spring size for engagement on primary and size of spring on secondary to control upshift and hold your rpm . The engine should hit top end almost immediately and the secondary should control it . HAVE I GOT THAT RIGHT DARRYL ?
If you are looking to race you will find that you will need to work the final drive for speed . I needed to loose 2 teeth on my primary sprocket on the final drive so I could engage hard and not slip my belt , for warp speed a couple extra teeth and ease into it a bit on the start and it gets to the point for me that I can't see proper anymore and that is to darn fast. JMO
Gerald m.I have a full engen harness for a S5 and ECU so all i would need is an engine and custom parts. My friend Lui AKA FD3S freak on the forum, said that the low end would suffer greatly, and i think that is a valid point. Any ideas on ports, timing or MAYBE forced induction?
10-29-12, 10:53 AM
#19
Gerald, you learned well. You are right on!
I weighed my 12a without fluids, the water pump, intake or flywheel and came in at 198# on our bath scale.
I have run a wide variety of belts from stock Bearcat (0627-014), kevlar Bearcat (42X4900), stock Polaris and kevlar Polaris. I currently run a Gates kevlar-Polaris spec (44-4810). With my clutch engaging at 4200 I have been getting 70-80 passes or 1 full racing season out of a belt, with my fastest passes being the last 3 before I replaced it!
We put alot of effort into getting the lowest possible launch ratio.
".....this change should take us from an effective launch gear ration of 13.67:1 to 17.62:1. ....since we were only shifting about 1/2 way through the secondary clutch, we changed the drive sprocket from a 14 tooth to a 12 tooth, driven sprocket is a 72 tooth."
I weighed my 12a without fluids, the water pump, intake or flywheel and came in at 198# on our bath scale.
I have run a wide variety of belts from stock Bearcat (0627-014), kevlar Bearcat (42X4900), stock Polaris and kevlar Polaris. I currently run a Gates kevlar-Polaris spec (44-4810). With my clutch engaging at 4200 I have been getting 70-80 passes or 1 full racing season out of a belt, with my fastest passes being the last 3 before I replaced it!
We put alot of effort into getting the lowest possible launch ratio.
".....this change should take us from an effective launch gear ration of 13.67:1 to 17.62:1. ....since we were only shifting about 1/2 way through the secondary clutch, we changed the drive sprocket from a 14 tooth to a 12 tooth, driven sprocket is a 72 tooth."
10-29-12, 06:06 PM
#20
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final drive
Darryl I noticed after I got the drive belt kinda close and going down in the primary pulley all the way the acceleration seems to increase as you go down the track right to the end , not just increasing speed but increasing energy as it goes , I don't know if that makes sense on not .
That is what I needed to do on the primary sprocket also down 3 teeth from 16 to 13 but only 48 on the rear but then you are running 130 or 140 ponies more than I. If I had anymore go on grass without a rear wheelie bar I would be in trouble , quite a feeling when you can feel the front wheel tapping on the ground .
Any way Ryan 123 the reason I am discussing this on your thread is to give you a couple of different options to over come the lesser low end torque , half track is where the dragon really turns on with energy my engine it is quite low end compared to most guys little engine builds ..As far as porting and the rest I have never done any engine work . There are lots of guys on the forum that could help you along but most want to know your serious before they will open up much . I know the deeper I got into my build the more good help I got .
have a good one .. Gerald m.
That is what I needed to do on the primary sprocket also down 3 teeth from 16 to 13 but only 48 on the rear but then you are running 130 or 140 ponies more than I. If I had anymore go on grass without a rear wheelie bar I would be in trouble , quite a feeling when you can feel the front wheel tapping on the ground .
Any way Ryan 123 the reason I am discussing this on your thread is to give you a couple of different options to over come the lesser low end torque , half track is where the dragon really turns on with energy my engine it is quite low end compared to most guys little engine builds ..As far as porting and the rest I have never done any engine work . There are lots of guys on the forum that could help you along but most want to know your serious before they will open up much . I know the deeper I got into my build the more good help I got .
have a good one .. Gerald m.
10-31-12, 11:04 AM
#21
I agree Gerald. My car rolls off the starting line and then seems to accelerate exponentially as it goes down the track. By 100' the steering gets light and by 200' it is pulling real hard. I find it hard to let off after 300' as it is still accelerating so hard. It would appear that once the primary clutch has fully locked up and shifted out, things get fun!
My cars prior owner still holds the "C/Pro-buggy" national record with an Autocraft VW motor he ran 3.93 seconds at 79.56 mph. While I have run a best of 4.596 at 74.92 mph with my little rotary in the same car. A bit off on the et, but right there on the mph. I know my ET and MPH are viable numbers as I have run at his home track in Michigan with the car and ran identical numbers as I had been running at my home track in Maine.
We have been having fun with Jordan's snowmobile powered drag bike. we have been putting it on a diet and getting the weight better balanced. replaced a bent secondary clutch and now have a bike that has run a 4.65 at 73 mph and likes to carry the front tires. Bike is 350# and the 600cc Ski-Doo motor is making roughly 115 hp. With the lower weight, the bike snaps your head hard when the primary engages! You have to lean into the launch and really hold on!
My cars prior owner still holds the "C/Pro-buggy" national record with an Autocraft VW motor he ran 3.93 seconds at 79.56 mph. While I have run a best of 4.596 at 74.92 mph with my little rotary in the same car. A bit off on the et, but right there on the mph. I know my ET and MPH are viable numbers as I have run at his home track in Michigan with the car and ran identical numbers as I had been running at my home track in Maine.
We have been having fun with Jordan's snowmobile powered drag bike. we have been putting it on a diet and getting the weight better balanced. replaced a bent secondary clutch and now have a bike that has run a 4.65 at 73 mph and likes to carry the front tires. Bike is 350# and the 600cc Ski-Doo motor is making roughly 115 hp. With the lower weight, the bike snaps your head hard when the primary engages! You have to lean into the launch and really hold on!
Last edited by chainreaction; 10-31-12 at 11:06 AM.
10-31-12, 12:44 PM
#22
biggest problem is going to be building the adapter to run the drivetrain/clutch and then figuring out whether the transmission will hold the power. i would just run a streetported 4 port block, ditch the bridge idea as a 4 port can get you close to 200whp without the notchy low end. that would also require upgraded intake, carb and custom tuned exhaust.
then the cooling will be the next hurdle, needing a radiator near the size of a factory car but can get by without about 35% less surface area since it will be in sub zero conditions and won't need as much radiator efficiency to cool the engine.
and large bore 2 strokes have plenty of torque... just not as linear as 4 strokes. my brother had an '86 CR500, you couldn't keep the front end down even if you idled it, tapped the throttle and sat on the bars in ANY gear. it was more finicky than 600cc 4 strokers with newer technology. he eventually had to sell it, even us seasoned riders could barely handle that bike.
alternately you could just find a cheaper engine and throw it in there. bought my ultra 150 1200cc triple 2 stroke jet ski for $800 with trailer. engine puts out 145 horses out of the gate with no modification. the engine isn't all that huge either, just would need an external water pump system.
then the cooling will be the next hurdle, needing a radiator near the size of a factory car but can get by without about 35% less surface area since it will be in sub zero conditions and won't need as much radiator efficiency to cool the engine.
and large bore 2 strokes have plenty of torque... just not as linear as 4 strokes. my brother had an '86 CR500, you couldn't keep the front end down even if you idled it, tapped the throttle and sat on the bars in ANY gear. it was more finicky than 600cc 4 strokers with newer technology. he eventually had to sell it, even us seasoned riders could barely handle that bike.
alternately you could just find a cheaper engine and throw it in there. bought my ultra 150 1200cc triple 2 stroke jet ski for $800 with trailer. engine puts out 145 horses out of the gate with no modification. the engine isn't all that huge either, just would need an external water pump system.
Last edited by RotaryEvolution; 10-31-12 at 01:02 PM.
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12a, 1999, 700, evinrude, exhaust, experiment, high, motor, polaris, pro, restarting, rotary, rotory, snowmobile, sunk
