Okay, let me update this thread to ask for some specific 250R info. Have just gotten a 1986 250R that was ridden for a few years and has sat for the last 10 or so. Compression is good and upon inspection it looks overall quite good. Completely stock still I am looking to make some upgrades that make sense for the northern Michigan trail riding that we do here. There are a lot of short, straight blasts on the trails, but also a lot of cornering that will require some low-end power. Top speeds will rarely be utilized so I can give a little from that end in return for the low-end. I need tips on pipes and minor replacements that will pay dividends such as K&N filter, air box mods. and sprocket changes.

Thanks,
Hillside Hawk

 

One more thing....the 250R is a legend in these threads, but top speeds aside how does this stack up either on trails or MX track against the 300/400EX and Scrambler 400/Sport 400L? Those are the quads this will be riding with so I'm looking for some heads-up. Later this summer I will provide my own first-hand insights.

 

The cheapest way for you to get some bottom end is to just change some sprockets. You say that you can sacrifice some top end. So a pair of sprockets will run you about $30 total. I believe the stock gearing on a 250r is 13/38.(someone correct me if I'm wrong) So just drop teeth on the front, or add teeth too the rear.
Also, some new rear tires are just the ticket. The 250r spins half of the time. Using that wasted power with help also.
By the way, what trails do you ride in Upper Michigan?

Chris 00' red rocket

 

on the 86-87 the stock gearing was 13-37

I would go with a good low to mid pipe such as the LRD adjustable pipe, Uni air filter (K&N is mostly for dunes, not muddy trails) a set of aftermarket reeds (Delta VForce cage if you can afford it) and maybe have the head milled a bit to bump the compression up, but don't go over 180 lbs or so if you still want to run pump gas.

Good luck

 

I just wanted to set things straight, the gearing for the 250R in 86-7 is 13/39, and was 13/38 on the 88-9. The reply by Dill was incorrect. As far as gearing goes I do serious hill climbs and woods riding and with 22" rear tires the stock gearing is great. I have tried a 12t counter and it shortens your gearing to much. Stick with 13/39, or maybe 13/40. Dave

 

well, I guess I could be wrong, but I was almost certain stock gearing on an 86-87 was 13-37 not 13-39.

as far as 22 inch rear tires go, I'd stay with 20's, a 22 inch rear tire has too much of a sidewall and tends to flex in corners.

 

I stand corrected, I visited www.macdizzy.com and looked at the trx250r micro fiche (VERY handy) and FourTraxXC is indeed correct, gearing on a stock 86-87 is 13-39, and it is 13-38 on the 88-89