85r motor swap question

[RIDE-RED 250r]

Your '86 TRX CDI should not plug into your '85 ATC harness. So I am guessing you are running your ATC CDI?? Are you running the coil from your TRX as well or are you running the ATC CDI?

What you are describing sure sounds like a fuel mixture issue to me, whether it be a jetting issue you need to dial in or as suggested, you may have an air leak somewhere that you haven't found yet.

You shouldn't have any issues plugging on your 86 TRX engine harness to your '85 ATC chassis harness, or running your '85 coil. If your '85 engine ran fine too, then I would say electrical is probably not your problem.

The ATC pipes are different than the TRX pipes and may require different jetting specs to dial in right. But having said that, I would expect the differences to somewhat small.

[trikeguy2014]

some pictures for you guys, I just unplugged the 4 wires coming from the stator. the plugs and wire colors were the same from both motors like you guys said. so maybe it is just my jetting???

[yaegerb]

The only way your jetting will be off is from either the airbox, pipe, or you have an airleak some where. This isn't rocket science. If it worked on your trx, the only variables that changed was the length of your expansion chamber, your airbox (which you said was an identical setup), an airleak has now developed or your electrical system has an issue.

What did the ATC run like before you pulled the motor?

[fieldy]

What does the motor do when it idles and you use the choke some? Does that change the idle speed?

[trikeguy2014]

Yeah your right it shouldn't be, both ran boxes with lids shape is obviously slightly different. Pipes shape is quite a bit different but both are fmf. I'll do some more looking this weekend, work is always in the way, and try to get this figured out, if not I guess I'll swap back motors for now.

Thanks for all information, any more just post it, any suggestions are better than none

Atc ran good and trx ran good (when something isn't broke don't fix it) ("bordom I guess")

[trikeguy2014]

Haven't tried choke yet, never thought about seeing if it changed anything. I'll give it a try and see


Also this hasn't been brought up but I use same gas and oil in both so that's not it if someone is thinking it, klotz r50 40:1

[fieldy]

Just a possibility that you have gotten a piece of dirt in the carb. I would try to blow air through the carb or use a carb cleaner with a straw first. I had this happen before. Then if it still revs, i wouldnt mess around, do a pressure test. Maybe the intake leaks since you may have put some pressure on it swapping things. If it tries to idle really high pull the choke out so it stops running. Check throttle cable too.

[trikeguy2014]

I'm going to eliminate jetting and intake off my list. I sprayed starter fluid all over the intake boots and it didn't effect anything at its idle at all. I went up on main jet in several steps. First size or to helped slightly but not even close to what it should be. It did seem to help idle as it idles normal, not sure why, but it still will not hit power band very hard and just stutters at half throttle on.

[yaegerb]

I'm going to eliminate jetting and intake off my list. I sprayed starter fluid all over the intake boots and it didn't effect anything at its idle at all. I went up on main jet in several steps. First size or to helped slightly but not even close to what it should be. It did seem to help idle as it idles normal, not sure why, but it still will not hit power band very hard and just stutters at half throttle on.

Main jet increase will not help your idle circuit. So either you imagined your idle was rough or something else has changed since you dropped it in. Above you mention that both pipes are FMF which doesn't matter. The length of your expansion chamber and carburetor jetting go hand in hand. So if it's not an airleak, it's either jetting because of the different pipe or an electrical issue (but you said the ATC motor ran fine).

[trikeguy2014]

All time let down today, I tried jetting up thought it was lean like I said that didn't help. So today I decided to put the main jet from trx back in it. Still terrible so I pulled air box lid off. Great! Ran clean tons of power a light blue smoke everything seemed great. Then it started acting really weird started to try and die so I killed it. Now it will hardly kick over (I didn't try hard but defiantly not right) my perfect running trx 250r that had about 10 hours since it was gone through powder coated and chromed is done. Explain that???? Guess it's time to get that 85 motor back in

[RIDE-RED 250r]

Sorry to hear that. The only person who can explain that is you, and the only way you will be able to explain it is to start the autopsy on the engine.

Get your '85 mill back in, go to TF and enjoy yourself. Once you get back, start digging into that engine. Please post up what you find, pics would be great too. I myself am curious to know what happened.

[trikeguy2014]

That's the plan... I'll definatly post back when I get some answers, I don't even want to see inside that motor now, maybe ripping it up at trike fest will get me in the mood to break the engine down and see what went on

[fieldy]

If you could look at the spark plug first then take it and have the 250 pressure tested before disassembly. I am also interested in why all the sudden you had trouble and how many hard hours were on the newly rebuilt TRX motor.
To remove an airbox lid and garage/yard run it and a overheats/semi-sieze? Thats....yeah let us know. Maybe those guys who built it will work with you on the repair since you are their customer.
If the pressure test is good, then its gonna get interesting! Have a good trikefest!

[trikeguy2014]

I put a few hours on my trx just taking it real easy, probably more than I needed, but I wanted to take the extra precaution on it. I had 2 trips to haspin, several rides around the house and farm on the trx after the break in, I'm guessing around 8 hours of actual hard riding on it. It ran great, no leaks no problems out of it till the swap. Like I said I'll post back after it gets pulled apart. I did get swapped back and we should be good to go for trikefest, least I hope

[trikeguy2014]

Also spark plug was good color, about perfect when pulled it after it cooled down. The next day I was able to roll it over by hand, so hopefully I got it shut down without extensive damage.