Common cause of power loss on Nikki carbureted models
03-12-07, 11:26 AM
#1
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Common cause of power loss on Nikki carbureted models
A tune-up story from a newbie.
I got my first Rx-7 (1981 GSL) last week. When I drove it back to my house, I noticed that it was pretty sluggish. (Weak acceleration, slow throttle response). After doing a lot of searching and researching on this forum(thanks for the great information btw), I was ready to do a good tune up. This being first real tune up (not just an LOF, which I have done for all my cars) I was a bit nervous.
I changed out fluids(oil, antifreeze, transmission), filters(fuel, air, oil), plugs, cable, and distributor/rotor. The old fluids were not too bad, except the antifreeze which had some rust flakes (time to do some more forum searching, lol). I took it out on a drive and noticed a drastic change. Better acceleration but still a slow throttle response not to mention a gas smell like it was rich. So I took it back home and started to adjust the carb and once I was satisfied, I took it out again. The result was barely any backfires and better acceleration and better throttle response.
I was pretty happy with myself but I had a feeling it could do better. I started looking at the carb again and you wouldn't image what I saw: The accelerator cable was not correctly hooked up. I guess the best way I can describe it is that it was half way hooked up. I started the car, and my Rx-7 purred. I drove it again and all I can say is wow. Awesome acceleration and throttle response. It was great.
I guess the lesson of the day is: don't assume everything is hooked up.
I do have one question and I have to apologize because it is a stupid question: Is the choke valve suppose to be completely vertical when the choke is not engaged? I know, flame on, I deserve it, but the choke cable is broke and the choke valve is 75% closed. I just want to make sure.
Thanks for listening to a newbie's story!
I got my first Rx-7 (1981 GSL) last week. When I drove it back to my house, I noticed that it was pretty sluggish. (Weak acceleration, slow throttle response). After doing a lot of searching and researching on this forum(thanks for the great information btw), I was ready to do a good tune up. This being first real tune up (not just an LOF, which I have done for all my cars) I was a bit nervous.
I changed out fluids(oil, antifreeze, transmission), filters(fuel, air, oil), plugs, cable, and distributor/rotor. The old fluids were not too bad, except the antifreeze which had some rust flakes (time to do some more forum searching, lol). I took it out on a drive and noticed a drastic change. Better acceleration but still a slow throttle response not to mention a gas smell like it was rich. So I took it back home and started to adjust the carb and once I was satisfied, I took it out again. The result was barely any backfires and better acceleration and better throttle response.
I was pretty happy with myself but I had a feeling it could do better. I started looking at the carb again and you wouldn't image what I saw: The accelerator cable was not correctly hooked up. I guess the best way I can describe it is that it was half way hooked up. I started the car, and my Rx-7 purred. I drove it again and all I can say is wow. Awesome acceleration and throttle response. It was great.
I guess the lesson of the day is: don't assume everything is hooked up.
I do have one question and I have to apologize because it is a stupid question: Is the choke valve suppose to be completely vertical when the choke is not engaged? I know, flame on, I deserve it, but the choke cable is broke and the choke valve is 75% closed. I just want to make sure.
Thanks for listening to a newbie's story!
Last edited by Rx-7Doctor; 03-15-07 at 10:13 PM.
03-12-07, 11:44 AM
#2
Lives on the Forum
The choke "flap" should be fully opened when not in use. That will definitely effect the mixture levels.
Can you give a better description of how the throttle cable was? You need to make sure that you don't adjust the cable too tight, or you can damage the carb. There should be some slack in the cable, but still fully open the carb when the pedal is fully depressed.
Can you give a better description of how the throttle cable was? You need to make sure that you don't adjust the cable too tight, or you can damage the carb. There should be some slack in the cable, but still fully open the carb when the pedal is fully depressed.
03-12-07, 12:51 PM
#3
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Here is a pic that shows what was happening with my carb. I connected the cable correctly and now it runs great.
Credit for picture goes to cdrad51.
Credit for picture goes to cdrad51.
03-12-07, 04:08 PM
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That finger is used to tighten up the linkage to the throttle. I have had many say it does nothing...and have had a rotary machanic flip it back down to where yours is placed. When I had a 12a and first pulled mine up to the fork fingers I did notice a slight difference in throttle responce...so this is what i lead it to.
cheerz
cheerz
03-12-07, 09:36 PM
#5
Oh man doing that was like night and day with my 7. I didn't even realize it was disconnected. No wonder my 7 seemed so damn slow LOL. We got some good things accomplished with getting his shutter valve blocked off and getting his choke plate tepmorarely opened straight until we get more time to mess with it. It needs tuning quite a bit with the mixture and idle speed but the timing needs set right first.
Last edited by Rx-7Doctor; 03-15-07 at 07:33 PM. Reason: Streamlining for archives.
03-13-07, 05:10 AM
#6
Originally Posted by StricklyOldskool
That finger is used to tighten up the linkage to the throttle. I have had many say it does nothing...and have had a rotary machanic flip it back down to where yours is placed. When I had a 12a and first pulled mine up to the fork fingers I did notice a slight difference in throttle responce...so this is what i lead it to.
cheerz
cheerz
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03-13-07, 12:28 PM
#8
I was reading this thread and decided to pop the hood on my RX-7. Guess what? My car was suffering from the Teeter Totter syndrome too. I feel bad because this "teeter totter" thingy has been out of position for the last 4 years since I owned the car. Popped it back in place and now my RX-7 runs like a raped ape. Thank you for the help!
03-13-07, 09:10 PM
#11
Yeah I think every FB owner should check for this. I had noticed it just seemed like the scondaries just weren't doing anything, I ran seafoam through her and still nothing. The lowend actually felt better then the top end. After 4k it was just like wasted RPM. Once I hooked it back up, Bingo they are back and **** does this car fly. I can't wait to get my RB header actually on tomorrow morning
03-15-07, 01:27 PM
#15
WOW great info. im gonna go check if mine is hooked up when i get home today. i tought my car was a bit sluggish. but being its my first 7 i wasnt sure. thanks for the info keep them coming :smiley_12
03-15-07, 10:06 PM
#17
Ok got home and hooked it up i think i did it right (i have attached pics) big diffrence in throttle response WOW "BUT" now my idle went way up to like 2000 rpm and drops really slowly to 1500 rpm. what do i need to do next remember im a rx7 newb so be nice 
03-15-07, 10:10 PM
#20
Originally Posted by VPTUNING
Ok got home and hooked it up i think i did it right (i have attached pics) big diffrence in throttle response WOW "BUT" now my idle went way up to like 2000 rpm and drops really slowly to 1500 rpm. what do i need to do next remember im a rx7 newb so be nice
03-15-07, 10:39 PM
#24
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I remember when mine popped loose. It was on the dyno. The throttle hung wide open. 8500RPM before I got the key shut off....... Video on request.
Even without the benefit of the secondaries, it still pulled 96RWHP........... The inductive lead wasn't reading very well, so it barely registered. I think the 136RWHP spike was a fluke.
Even without the benefit of the secondaries, it still pulled 96RWHP........... The inductive lead wasn't reading very well, so it barely registered. I think the 136RWHP spike was a fluke.
03-15-07, 11:27 PM
#25
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Even with mech secondaries, if that nut has come off of the 'teeter-totter' the spring will jam up against it and the throttle will not open 100%.
I went through an entire autocross season before I figured that out.
I went through an entire autocross season before I figured that out.