I just bought a 86 TRX250R with FMF fatty pipe and silencer, bosen reeds.
It seems to have a really narrow powerband in 1st , 2nd and 3rd. It was just rebuild. New rings. What things should I look at first. Seem worse whenb cold. Would it be a jetting problem or reed. it seem to pull good in 4-6th.
Also do they tend to make alot of noise at ilde when they are cold.
How hard is the convertion to 400ex plastic. Is the a kit or do you just make it fit.

Thanks

 

It may be the jetting from what you described. Try dropping your needle jet down one notch below where it is right now. 86 is dead center (3rd position) stock. After that, take it for a run and check your plug to see if it's running too lean or rich. Might as well just the main at 3/4+ throttle also

 

Watch out mine did the same not long ago and just when i was thinking this isnt right i better check the plug it went bang and my piston left via the exaust,
The problem was it went lean due to a leaking crank seal. if you lower the needle ie raise the clip this would make it leaner not good.

Check your plug first if it is to light richen it up and work your way back to rich wont blow it up. also check the size of your main jet
as if you just bought it it might have anything in there i think im on a 172 main at the moment but i ride mostly at sea level and have a few mods.

Let us know how you get on[img]i/expressions/face-icon-small-smile.gif[/img]

 

You need to have a little bit more detail.... In 1st-3rd does it sputter? or does it seem to flat out? Like PIMP said you should check your plug to see what color it is. It should be a paper bag brown to a tanish color. Also if you gap your plug at 0.020 it should help out some also. I dout it is the reeds. As for the noise issue. I couldnt imagine why it would be louder when its cold??

 

yeah, if anything it would be louder when it was warmer if there was a crack somewhere or loose bolt near the intake etc

weird

 

I adjusted the needle up and removed the air box lid. Runs good now. The plug looks good. Had a friend listen to it said the noise was normal. Any info on the 400ex plastic conversion. I am thinking of getting it ported and polished adding a cool head and a new piston. What kind of piston's do you recommend. What compression ratio is the max for 93 octane gas. Any thing else you think I should do. Are the bosen reed an Ok brand. I do mosting trail ride, but I want it to freak in the dune when I go also.

Thanks for the info so far

 

No idea on the plastic conversion. Good to hear your quad is running good now. On compression, I think about 11:1 is usually the way to go for pump gas.
ProX and Wiseco Pro Lite's seem to be the most popular pistons these days for the TRX, I haven't heard anything about Nik's or the others so I hope
someone else can input on this. Usually the best choice is the Wiseco Pro Lite, a few companies shave pistons to make them lighter which increases horsepower and revving speed. Nac's does this and so does Trinity Racing. Reed's I would look into G3 Power Curve Reed's for your TRX. They are just insane...I've gone 14 sizes up on my main running them and one clip down on my needle and I am still lean after installing them! Plus they are adjustable.
They come for low-midrange power and with a simple screw adjustment can set them for mid-top range which is awesome. The accleration after you put them in is just crazy it pulls so hard, and since they have long pedals and require a 12mm torque spacer, it gets power to the ground real quick...