Making a 2-stroke good on tight trails?

Dropping a tooth ot two on the front sprocket sound like the best bet. A RMX is built for the bush/trails etc... so gearing should be no problem if stock.

If the bike has a low speed bog I would look at your jetting. An adjusted air screw and a changed clip on the needle is a free power mod!

With more riding experience in general and tight woods specifically - we don't know how much you have - your speed will pick up as you gain confidence, and as a consequence should be using less clutch.

Until then it would not hurt to lower the gearing one or two teeth in the rear; the front is already as small as one should go at 13T. The chain will need an extra link and master with the o-rings of the same brand/model; try to bum one off of a friend or shop.

A few years back I had a 52T on the back of my RMX, but found I spent too much time in the upper gears, and went back to stock. Last spring I tried it again but soon discovered it resulted in exiting tight corners/turns with too much RPM, lifted the front end and lessened control - stock was better as it forces you to use lower engine speed and hence less rotational mass effect for easier control.

Do raise your forks in the clamps until the caps almost touch the handlbars. If you are 5'-9" or taller then buy Ceet's tall foam so you can scoot forward in the cockpit. Taller bars do help, as does a new upper tripple clamp to move the perches forward, albeit the latter would be a difficult to impossible find these days new - try e-bay; the RM250 of the same years had similar dimensions/components.

An added flywheel weight would improve steady low-RPM plonking. If you do use Steahly's then buy an IMS/Moose/MSR shift lever because it needs to bent out to clear the ignition cover with the added spacer.

If the carb is a stock Mikuni and it runs cleanly, then congradulations: you're doing better than most.

Top clamp: http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2432341909&category=35587

If the bike has a low speed bog I would look at your jetting. An adjusted air screw and a changed clip on the needle is a free power mod!

Click to expand...

And a new pilot jet is less than $10. If the bike doesn't idle, the jetting could be off. The pilot jet and idle mix screw (air screw) regulate the a/f mixture at low throttle. It's crucial that these jets are correct if you want good low end power and throttle response.

The RMX has an adjustable preload on the powervalve. Could be yours is way off. If it is opening too quickly (or stuck open), the bike may exhibit some of the symptoms you describe. I had a '90 model and rode tight woods with no problem. The jetting was a little bit difficult, but if I remember correctly, I ran a 350 main with the clip in the 2nd notch (from the top) on the needle. Mine had aftermarket exhaust and cylinder base and head gaskets from the same year RM250 (thinner gaskets which raised compression). I do not remember the pilot jet I used, but I do remeber that it was on the lean side and would barely idle. One size up and it blubbered at low throttle. I decided it was better to deal with a bad idle than a blubber off the bottom. Gearing was 13/50.

It could also be time for a new top end?

lwsmithjr>>> A new top end was my line of thought too... or another mechanical problem, such as the powervalve, or even a bad crank seal.. that'll give you a lean bog down low for sure. Just some stuff to check into.

Those were great bikes,I had one and loved it.Since then I've had a string of RM's I have used for Hare Scrambles and Enduros.You've been getting some good advice here.

First,I'd make sure the compression in the engine is within specs,then you're not chasing other problems that are really a worn top-end.If thats ok,then I'd make sure the powervalve is at the stock adjustment.Now it's time for jetting.Get someone experienced to help you,those bikes could be made to run very crisp,top to bottom.Just don't start chasing jetting without knowing your compression is good,your air filter clean,and premix fresh.The stock exhaust and muffler sucked,I'd run an FMF Gnarly or ProCircuit Platinum 2,and jet from there.

The gearing is a personal preference, but a couple years ago I noticed the GNCC Pro's would actually gear their bikes a litlle UP ! Sure,they're way faster than me,but with a properly tuned motor,their bikes already tuned for a lot of low end via pipes,jetting,etc., you can make the motor pull by short shifting and have a much less tiring experience.Too low can make your bike wheelie prone,and you'll not even use first and sometimes second,because the bike just wants to stand up.

For instance,stock RM gearing is 13/49,Team Suzuki Off-road usually runs 14/48 or 49.I went to 14/49 and completely love the way it works.Good luck with your bike,and while you're working on it check every nut and bolt,especially the engine mount bolts.Loose or gone engine mount bolt = cracked frame. Doug

P.S.-I love my flywheel weight,a Steahly 8oz. I wouldn't buy one though until you get the jetting and gearing where you want them first. Doug