I finally get my J-SPEC motor all together, go to start it, and she just cranks...i check spark, i'm good...i check fuel, i'm good...i check compression, i'm fucked......front rotor gave me 20 psi, 20 psi, 80 psi and the rear rotor gave me 0, 0, 0......great...did this happen to anyone else or do i just have bad luck?...any suggestions on what i should do? the place i bought it has a "guaranteed startup" warranty, so i guess i'm gonna have to take it all apart, take off all my toys and get a new one...i will compression test this one before it leaves the shop...

 

yep thats about the only thing you can do. NOw if you really want something that is going to last and is reliable then get one that has a good core and rebuild that sucker! I should have done it however my jspec has been a good work horse. What you may want to do if you have time and just a bit of money is see if you can get that jspec like half off or something and then with the money they give you back, by a rebuild kit from RA or Mazda and rebuild it but if you need it quick then yeah just get another jspec.

edit: also watch out for the 720cc primaries as it may give you hot start issues, as it did to mine. In that case 550/890cc injectors support the same hp as the 720/720 combo.

 

Sorry to head about that after you put all that stuff on to thats horrble. It seems alot of people have this luck with JDM motors. I have 100PSI on my jdm motor guess I am lucky.

 

At least you have a warranty, JSPECs are sometimes hit-or-miss unfortunately from what I've heard. I guess just call the people you bought it from, get another, and hope for the best.

 

They used to give a month warenty on jspec motors and guerenty compreshion. Your only wori then was a month motor :-) Now you only get it starts and we dont warenty seals. Umm ok seals not warenty you do know thats all there is in a 13b right?

 

what ???? Anyways when I got my jspec the first motor had no compression in the rear, so I returned it and got a new one, then I on the second one, I tried to plug the oil injector holes with bolts but they were a bit too long and bend the housings... Beautiful housings ruined. Anyways supposedly the guy checks them in japan before he puts it in the container, but by the time they get here and actually sell them, the seals get stuck and they dont seal good.. I found this to be partially true.. I had the second one for a bit before I started fukin with it... it had 80-80 comp when I first got it, after putting wd40 in the exhaust ports and spining the motor for many times, the compression shot up to 110 front and 105 or so in the rear... but definately the best thing to do is buy a jspec and rebuild it..... thats what I did. They make the best cores..

 

I must have also been lucky. I purchased 2 motors (one 87 and one 89) from japanstarmotor.com. Both came in longblock form with transmissions. Company claimed the 89 motor had low compression, but they offered me both motors, trannies and accessories for 1000 dollars Shipped to my door. I couldn't pass up the deal, almost a too good to be true deal. I got the motors, and the 89 had a blown rear rotor, but the front rotor and housing were perfect.. Used that motor for parts and sold the rest. The s4 motor was as if it was freshly rebuilt. The only reason i got the motors was to use them as a core for a rebuild. The rotor bearings and stationary gear bearings look brand new, The side seals fell out of the rotor when i pulled the front rotor, and they stuck to the intermediate plate.. That's how freshly rebuilt the motor was. I almost wish i hadn't taken it apart. The motor actually ended up having s5 housings and plates, with s4 rotors in it. So it was a custom done motor.


I had very good luck, but then again, i didn't ever intend to drop in a J spec without rebuilding.

-Justin

 

The Japaneese junk yard scroungers are enjoying the fruits of your efforts right now, PLease contact them again to go pull a JUNKYARD engine to install.

 

maybe you should try injecting oil in the plug holes and cranking it, or something before giving up.

 

you think this will work?

 

what do you have to lose?

 

Alot of times even on brand new engins when rotarys situp the apex seals stick and you put oil in the holse and put plugs back in and crank will free them if it is indeed this.

 

well the engine spins fine, she spins beautifully...just no compression

 

If they are stuck it will spin just fine actualy faster just wont have compreshion

 

put diesel with some ATF in the motor and let it sit for a couple days rotating by hand a little here and there, sometimes that works to free up the apex seals. This is the fastest and most effective way of de-carboning the engine. If this doesn't work chase that warranty!!! I once bought a JDM engine and had the company send me 3 engines before I actually got a good one, make them pay shipping too!!

 

I bought a jspec also and it had no compression in the rear chamber. Tried all the tricks, now I have a complete builder core! too bad it was crap inside. Good luck on this though.

 

Exactly how much oil should I use?

 

OK! After the use of Gunk Motor Flush, i got the front rotor up to 120, 120, 120.....perfect compression....still not getting anything in the rear tho....lettin it sit over nite, i'll try in the morning...this is my last resort....pray for me guys!!!

 

ok...nothing in the rear rotor, so i'm gonna take it apart and clean out all the carbon build up. i hard that if i just take off the rear cover, i have to rebuild the whole thing because the seals warp? is this true, can i just take off the rear cover, clean it out, free up the apex seals and put it all back together?

 

Does this warping apply to the front rotor to? Is it a good idea to rebuild one rotor if the other looks good?

 

Who says the seals warp? ARe you talking about the apex seals? No the apex seals do not warp, they are hard pieces of steal.... ALthough you should just go ahead and replace the apex seals, and waterseals since you are pulling the motor apart. As for price concern, you are looking at maybe 350 if you only do the apex seals and water seals. It includes the RA 2 piece 2mm seals and OEM coolant seals. Other than that, the more things you replace the better of you are... HAve fun with the rebuild...

 

but my question is do i have to do the whole engine, or can i just do the rear rotor, if the front is perfect?

 

although not recomended, but yes you can do just one rootr.

 

I figured he ment warped from overheating and if you pull it down that it will not seal again.

I got 75psi on my front rotor and 100psi on rear on 87 13bt. I am guessing carbon as well being rear rotor looks so good but who knows.

 

When you take tension off the stack you run the large risk that the front 3 sets of water seals will flex or break, and not reseal when retensioned. And you almost certainly will tear up the old ones on the rear when you pull it off. Plus, you're likely going to find a rotor and housing eaten up from apex seal damage, so it's going to need to come completely apart any way you look at it.

Wouldnt it be a bitch to do a "half rebuild" and get it installed only to find out that you now have a coolant seal leak and have to pull it all back out and apart?