85r motor swap question

[trikeguy2014]

So I wanted to give my 85r it's time to shine, I just finished up a motor swap taking my 86 trx 250r motor carb setup and putting it on my 85 atc 250r. They both ran good before the swapping but my trx is a really fresh motor from BDT racing. The 86 trx had a 38mm keihin and my 85r is still on its stock round slide. Both have full fmf systems. When I got my trike finished I took it for its test ride and something just isn't quite right. It's idling kinda high and stuttering showing a lean symptoms (I believe). I just wanted to make sure the electronics are not different causing my problem before I begin attempting any jetting. I did a short ride so I would not do any damage if the electronics are the problem. And everything plug up the same so I did no custom anything.
Any help would be great because if I need to do a swap back before trike fest comes as it's fast approaching and I don't want to leave number 27 at home!

And no I haven't put my trx back with the 85 motor I wanted to see how it went before it got put back together

[Eric250R]

Intake boot in good shape ? Any cracks that could cause a small air leak ?

[BOB MARLIN]

I'm running a BDT trx motor in my 85R. There was no change in the electronics. I think you have something else going on.

[yaegerb]

Stuttering where? On idle? If not, what throttle position? Need specifics on what's exactly going on.

[trikeguy2014]

Yeah intake boots everything is in good shape, I'll give it a good once over again and make sure. Could it just be running a tad lean from being a different pipe and intake boot etc?

[yaegerb]

It could be running lean for multiple reasons. Intake leak, failed seals, wrong jets. I would spray carb cleaner over intake joints while it's running to see if it dies. The I would do a pressure test. What jets in carb? Any port work, head work? Different reeds?

[trikeguy2014]

High idle some stuttering from about half on to full throttle... Engine ran perfect when it was in my trx, I just pulled it out and did the swap. I just wanted to be sure it wasn't anything electrically different that would cause it the problem

[trikeguy2014]

Reed assembly and carb throttle and cable everything came off straight from my trx.

[yaegerb]

Have you checked for intake leaks and/or pressure tested the motor?

[trikeguy2014]

I'll spray some carb cleaner around all the intake joints and see if it dies or not.

[yaegerb]

So essentially you put an 86 trx motor and 38 mm carb on your 85 250r? it was running perfect in the trx? What airbox were you using on the trx vs now on the ATC?

[trikeguy2014]

Yeah that's all I did, both setups were on air boxes with lids and full fmf systems. The engine carb reeds was all from my trx

[yaegerb]

All things being equal; if it was running good before it should be running good now. Double check intake leaks, and electrical comnections.

[trikeguy2014]

Still no luck looks like this wknd I'll be switching back to my 85 motor, I still believe it's something electrically, jetting can't be that far off. I'm having eratic idle, doesn't die but sometimes idles high sometimes it's fine. also it just stutters a lean sound and just doesn't have much power. I don't know what else to do.

[atc300r]

Try putting the trx coil on the atc.