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03 WR250 rev limiter

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I need some help here guys. I've done a search and found plenty in the archives on the rev limiter, but nothing as specific as I am looking for.

I have an 03 WR250 that has all the free mods and uncorked the stock exhaust. I have been real happy with it and never, hit the rev limiter..... even in first.

A while ago I added a Dr D. to the system and as soon as I took it for a spin noticed the bike would miss at 3/4 throttle in first and second (I marked the grip just to gauge exactly where it started missing).

I just took the bike to the dealer so they could do it correctly, told them it missed badly when it got to 3/4 throttle, they put the Dr D. back on leaned out the main jet and added a 42 leak and took the bike for a spin, said it ran great. When I got it home it is exactly the same.

Is it possible the bike hits the rev limiter that much quicker?

How do I know if it is the rev limiter or just badly tuned?

I thought OK if the bike hits the rev limiter at 7500 RPM in neutral (I read this somewhere in the artchives) then I tried revving the bike in first and I didn't even notice it stutter a bit. I had to stop because I was afraid of grenading the thing.

Any suggestions would sure help.

Bob

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Yes sure have.

It's wild, if I ride the bike it rips, pulling hard from lower, but "feels" like I am only getting to 10K RPM, but with the stock pipe (baffle removed) it keeps on pulling....like I said I have NEVER hit the limiter with the stock exhaust.

Anyone else that installed a Dr.D? maybe you can give me some insight.

Bob

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Maybe it's not the rev limiter you're hitting. Maybe you need to put a larger main jet in which is common after putting an aftermarket pipe on. It might be cutting out at high rpm's because it's too lean.

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That makes far more sense to me. The wierd thing is the dealer leaned it out and said the MJ was large (I had a 185 he replaced it with a 175). But even when I had the 185 it still acted the same.

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Where are you in NC? I've got the same bike. I bought the JD jet kit, red needle 4th clip, 180 main, YZ pipe, and it runs great. Let me know, I'm sure we can figure it out.

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I'm in Hickory,

I have the JD jet kit but had the same problem with it installed, so I went back to the standard needle, just to see if it helped, figuring one thing at a time was the best way to go.

Do you ever hit the rev limiter with your YZ pipe?

PM me if you are close.

Bob

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That makes far more sense to me. The wierd thing is the dealer leaned it out and said the MJ was large (I had a 185 he replaced it with a 175). But even when I had the 185 it still acted the same.

Definately lean.

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Yes sure have.

It's wild, if I ride the bike it rips, pulling hard from lower, but "feels" like I am only getting to 10K RPM, but with the stock pipe (baffle removed) it keeps on pulling....like I said I have NEVER hit the limiter with the stock exhaust.

Anyone else that installed a Dr.D? maybe you can give me some insight.

Bob

What do you mean when you say "Dr. D" did you add a pipe? or the Dr. D hotstart lever?

If you piped it you definatelly need to go up a few jet sizes on the main jet, (2 steps should get you in the ballpark).

If you added the Dr D hotstart lever, that's a simple cable operated plunger that when pushed, adds more air to help aid hot starting the engine, maybe the plunger is not fully seated in the bore, and it's acting like it's always "open" (allowing too much air).

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I have the DR.D as well and a similar problem. In my case the grey wire is cut and the cutout is intermittent.

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Contrary to what is typically said you probably do not need a bigger main - in fact you need to go leaner. When an exhaust is working as a tuned pipe and shockwaving it will create a stronger pulse in the venturi of the carb and pull more fuel in.

I have had my bike on a dyno after fitting Hotcams and the Akrapovik - had to go to a 165 (from a 175) to get rid of a rich (12:1) AFR at high rpm. Yes we had a 4 gas analysis set up. However the midrange and peak torque is lean on WOT so now have to adjust the cam timing a little to alter the valve overlap and look at putting a different main air jet in (bigger to lean out the top end without affecting the mid). Hard to do on a WR as the MAJ is CAST. I am really surprised given all the mods done that nobody on a WR has had to alter the MAJ. I wonder how many people can tell the difference between a missfire at 10-11K and the revlimiter for real at 13K????

Guy

What have you done with the cam timing?

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Wow. Thanks for the responses. Yes it is the Dr D. pipe, and it is definately lean now, (popping on decel.)

I know I do NOT know the difference between a miss and the rev limiter, but why am I hitting it so early at 3/4 throttle.

How does a dealership tell the difference when they tune a bike, as to whether it is the rev limiter or missing, is there a big difference?

I haven't done anything with the CAM timing, why? (I have a feeling I'm about to get deeper in a hole)

Thanks

Bob

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To give you guys an idea of what it feels like to ride the bike now....it feels like I am short shifting out of 1st and 2nd.

Maybe that helps, but it feels that obvious.

Bob

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STRIPES123 - What do you mean "the cutout is intermittent".

Do you think yours is hitting the rev limiter?

Bob

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STRIPES123 - What do you mean "the cutout is intermittent".

Do you think yours is hitting the rev limiter?

Bob

Dunno, it just feels like the rev limiter comes in early on occasion. I supermoto race the bike almost exclusively and have a real good sense of where on the track I need to shift. What happens is that I will be in the meat of the powerband at WOT and it falls on it's face (deceleration). I have changed the main jet many times but the problem still exists. Again, it's intermittent and almost exclusively occurs after several laps when the bike is good and hot.

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No that is different to what I am experiencing, I really believe that it may be fuel starvation not the rev limiter.

This is dying at 3/4 throttle then will pickup then die then pickup again, by which time I am expecting the whole thing to go BOOM! so I change and try my luck with 2nd same thing.

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Well it depends how hard you hit the rev limiter! In 1st and 2nd it can feel like a brick wall. In 3rd and above it should appear more like an ignition missfire.

What does it do on full throttle?

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