I have a 1986 TRX250R that 's "completely stock". "No air box mods, stock bore, carburator Etc." I bought an ESR pipe, silencer and some Delta Force Carbon Reeds for it recently. What jetting would everybody recogmend for this setup? Will I only need to change the Main jet? or will the pilot and needle need changes as well? ATV run @ or near sea level in Calif.

Thanks............ Rude Dog

 

You bought the pipe/silencer and reeds and now you need to get an air filter to finish. Get either a Uni or a K&N (my preference), get rid of the snorkel, and drill many holes of at least 1/2" in the lid (or just toss it).

Stock 86, main jet is .150, put needle in 3rd clip (middle). With the mods you have made, you will need to increase the main jet size at least 3, up to a .158. Keep in mind, you may need to go larger, may need to go smaller.

Now, warm it up and do a plug check. You want a plug that is light brown/tan color. If it's white, go larger main and check again until you get tan. Black or oily, go smaller.

Your pilot jet may need changing also. If you have a sputtering off the line, pilot is too large. Really crisp and responsive, most likely good. You can do a plug check for that also.

 

trapperb 1:

I don't have time right now for the air box mods as I'll be leaving on a trip next week. What I'm really looking now is jetting suggestions based on a "stock" air box setup with the pipe and reeds. When I get back and I have more time I'll work on getting a K & N filter, pre-filter and running without an air box lid, and then re-jet for that setup. Do you have an idea of what jetting to run based on what I noted above?

More help/suggestions from more people would be MUCH appreciated!!!!

Thanks, Rude Dog

 

Rudedog,
I'd start with the .158 main jet. Leave whatever pilot jet is there.
You can just take the lid off the air box, that'll help.
With the .158, if it runs "good" and you have the lid off, try the .160. Still good, try .162.
If it sputters at high revs, go to .155. Still sputters try .152.
Main jets only cost about $4 at Honda dealers, should be about the same price any shop.
Get the .155, .158, .160, .162. Should cover you for now.
Good luck and have some fun![img]i/expressions/face-icon-small-happy.gif[/img]

 

Trapperb 1:

I picked up 4 sizes of Main Jets yesterday. I'll experiment with them and hopefully figure out the right size.

Thanks, Rude Dog

 

you need to go with the airbox suggestion. so far, you have opened air (with new cage), and opened exuast (with new pipe), but that does you no good if you aren't getting any air to these new parts. I would reccomend the K&N, but at least drill the holes, or better yet toss the air box lid so you can allow the new mods to work their magic..........[img]i/expressions/face-icon-small-wink.gif[/img]