07 RM250 Stuttering

[cr1mnl]

Hi All,

I have recently purchased an 07 250. Its set up for trail riding and has IMS 12L tank, 10oz FWW, 18" Rear wheel and a V-force 3 Reed Block.

I'm loving the bike so far it handles like a dream and pulls way harder than my old 01 KX125.

Only problem I have so far is when you roll the throttle on just a fraction say 1/8th and hold it there it stutters badly.

It runs fine when you are accelerating and you don't really notice at all when you are in the bush because i'm always just grabbing handfuls of throttle or hard on the brakes but its when i'm riding to the bush from my house that I notice it the most. You cant just ride along at a constant speed. You have to just squirt it then coast ,squirt coast etc etc

I live in Fiji the bike came over from New Zealand so the climate here is alot hotter say 10-15 deg Celsius so i am guessing it maybe running a little rich.

Any thoughts? I'm going to pull the carb off this week and check what jetting its running and try dropping the needle one clip and see what happens

Other than that small problem it pulls hard in all gears right off the bottom when you crack it wide open

[mihylo33]

Sounds a lean to me.... but you are on the right track.

[zig06]

Try reinstalling the stock reed block, that VForce is messing with your stock jetting.

[Doctor DK]

Try reinstalling the stock reed block, that VForce is messing with your stock jetting.

Do You think the v-force has petals that are too stiff,or is it, that its the thickness of the spacer itself,,,sometimes, I can feel that on My RM,,but, it has never hampered My racing performance...the only time I feel, What He is talking about, is after the RM is all rapped out, and, ran out of gears, while I am looking for another gear, down a long, straight road.......mine sounds more like a blubber,instead ,of a, stutter.....it almost sounds like a normal two-stroke thing,,, My bike runs great,but, for the hell of it, I am going to put the stock reed block back in, and see what happens,,,but, His problem, could easily be a jetting problem,,,, thanks for the advice.........Dr.D..

[cr1mnl]

yeah thanks for the advice. I am running the v force without the reed spacer so I will try switching back to the stock cage which has carbon reeds fitted and see if that makes a difference. At the same time i will check the jetting as well to see what it is currently running

[zig06]

Do You think the v-force has petals that are too stiff,or is it, that its the thickness of the spacer itself,,,sometimes, I can feel that on My RM,,but, it has never hampered My racing performance...the only time I feel, What He is talking about, is after the RM is all rapped out, and, ran out of gears, while I am looking for another gear, down a long, straight road.......mine sounds more like a blubber,instead ,of a, stutter.....it almost sounds like a normal two-stroke thing,,, My bike runs great,but, for the hell of it, I am going to put the stock reed block back in, and see what happens,,,but, His problem, could easily be a jetting problem,,,, thanks for the advice.........Dr.D..

I wouldn't say that the pedals are too stiff or not, it's the change in air flow between the vForce and the stock cage that's messing with the jetting. Like when ever I install a RAD valve I just about always plan on going down 3 sizes on the pilot and 2 down on the main. The improved flow puts a hard pull (lower vacuum signal) on the carb and that pulls more fuel than what it really needs.

[cr1mnl]

mmmmm could well be the problem. It seems to be using a sh1t load of fuel as well. I am getting the same economy as my riding buddy thats on a CR500.

[Doctor DK]

I wouldn't say that the pedals are too stiff or not, it's the change in air flow between the vForce and the stock cage that's messing with the jetting. Like when ever I install a RAD valve I just about always plan on going down 3 sizes on the pilot and 2 down on the main. The improved flow puts a hard pull (lower vacuum signal) on the carb and that pulls more fuel than what it really needs.

Are You sure about the shape of the spacer,or, the thickness of it,,,,,,what's a RAD valve,,,,,, it seems like to Me, that whenever I put on a set of boyseen,or,v-force reeds, I always got a harder hit,, which means to Me that the reeds added a stronger,and, quicker seal,, but,, that's a good point that You brought up,,about, changing the jetting,, every bike that I ever had,,as soon as I got it, I put aftermarket reeds on it,,then I jetted it,,,,,,,so, I don't know about jetting changes, after a reed change,,,Mihylo, mentioned something about fiberglass reeds,, maybe, He's got something there......good diagnosis............have a good one............Dr.D..