I am going to be installing a Whte Bro.s after market slip on exhaust on a stock TRX 90. I'd like to keep the air box lid on. My question is what jets will I need to change and per chance do you know what sizes. Help[img]i/expressions/face-icon-small-confused.gif[/img]

 

You might not have to change them. If you do it will be only a size or two. I put a BIGGUN on my son's and I didn't change it. It ran fine and the spark plug didn't look to lean. I have since changed the bore size of the engine and had to rejet, but all in all the engine is very forgiving to the jet size. These are just my opinions, but I'm right. I think the stock size is a 80 for the jet. If you want it to really go you will need more than a pipe. Good Luck!!

 

I put a W/B R series pipe on my daughter's 90. I changed the main jet to a 90 (stock is an 80) You can get this from your local Honda dealer by getting a replacement main jet for an XR 100 (dirtbike) It cost about $4 and and takes about 15 min to change if I remember correctly. I don't think I even had to take off any plastic, just disconnect the intake an a few other small things and turn it sideways to get to the bottom of the bowl. I also put in a UNI filter, about $12. It's not nearly as cold natured now and diffinately helps on power. best $20 I spent on it. good luck. Oh, also try pulling that pink wire from the rev box. It's under the plastic on the left front. Just look for where the pink wire goes in, and pull that pin out with the wire attached. Tape the wire off with electrical tape and put a dab of silicone in the hole of the box to keep the moisture out. This way, you can just pull the silicone plug out with tweezers later and reinsert the wire if you pass it down to someone not ready for the extra speed. It doesn't rev a whole lot higher, but it is good for probably 5 mph on top end I'm guessing. I haven't clocked it, but it does make a noticable difference, even with an adult on it (I weigh about 155lbs) Good luck! Oh one more thing, I don't know if it makes too much difference, but I only run premium unleaded in it with a little octane booster. 3 years of riding and no problems with starting yet.