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Crf Off Idle Bog

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Do any of you guys notice that your bike has an off idle bog. When i'm in first or second gear, and going very slow, giving it no gas, go from idle speed and crank the throttle really quick past halfway. It just bogs and goes nowhere, just checking to see if everyone elses does. The dealer says its normal, mx bikes are supposed to be ridden hard, not idled around on. Post feedback please.

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It sounds like jetting. Do a search, there are lots of posts about the bog. There is a sticky post about jetting. The CRF 250s are way to lean from the factory.

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I asked my local head mechanic and he said it was the nature of this slide carb, alot ALOT of throttle off idling for a while when rolling will make it get way too much air and go lean or even stall

maybe he was describing a diff problem but i see how he can be right.

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Do any of you guys notice that your bike has an off idle bog. [...] The dealer says its normal, mx bikes are supposed to be ridden hard, not idled around on.

your dealer is an idiot.

the keihin FCR carb, used on both the CRF and the yamaha 250F's has an accelerator pump (AP). the bog is caused by the AP introducing too little or too much fuel when you crank the throttle. in most cases it's too much fuel.

you can read up on how the AP works and how to adjust the delivery of fuel at the 250F FAQ; all of the processes for tuning are exactly the same as on your CRF.

http://www.thumperfaq.com/ap.htm

http://www.thumperfaq.com/ap_mods.htm

in general your best approach is to get an alternate leak jet, one larger than you currently have.

jim aka the wrooster

'01 wr250f

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I'm not sure what is in the '05 model, but switching the leak jet to a 55 in the '04 cleared the bog right up.

Good Luck

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I remember the good old days when you bought a 125 or 250 took it home and killed it, that was it, alittle shock adjustment and maybe a pipe and I was happy, now days you buy it (5 to 6 grand) take it home change everything on it before you ride it and hope it don't blow up that sux! (don't get me wrong I'm no super A class rider just a hard weekend rider) I have been out of it for 15yrs and got my son a bike, 2months later got me one and now I am half scared to ride the thing hard....

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Do any of you guys notice that your bike has an off idle bog. When i'm in first or second gear, and going very slow, giving it no gas, go from idle speed and crank the throttle really quick past halfway. It just bogs and goes nowhere, just checking to see if everyone elses does. The dealer says its normal, mx bikes are supposed to be ridden hard, not idled around on. Post feedback please.

my 250 x only does this when ites cold ,,,u have this happen when ites warm???

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Hey Killer,

Aint that the truth!!!

Remeber when all that was advertised in the magazines was tires, pipes and handlebars! You could do a piston in an hour, now you need a manual thats an inch thick. The manufacturers think they're doing the right thing, I don't. Now, they want to get rid of the XR, the best bike they ever had. They're advancing themselves right out of business!!

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Here is a good one for all you boggers out there. I just did the JD kit / blue needle because it is 37 degrees outside.

The bog is still there. Pulled the sub frame to test the AP squirt. I have a slight problem. THERE IS NO SQUIRT....and yes the fuel bowl is full. Bike starts and runs. We raced the damn thing like that and was told they all do that....

Comments/suggestions?

I never had a FCR apart, I will now...

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My 04 X has the bog, and gets better when warm, but never goes away. So I ordered a 55 leak jet to try. But when I tore it down, it already had a 55 from the factory. Has anyone tried any other accelerator diaphram's, or does Honda even have any other's? Does anyone know if the Yamaha one's are interchangable?

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Did everyone with the bog change the pilot jet? The JD kit does not come with it. Keep in mind as it keeps getting colder the air is more dense so you need to increase fuel to compensate for low altitude or low temperatures. Cold weather exaggerates the bog due to lean jetting.

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Pilot is a 42.

Seems there are two theories on the "bog", too much squirt or too little. The CCC mods say use a 70 leak, that is what I have. Stock was a 55 (richer squirt). The mods referenced too in this thread reduce the squirt even more than a 70. I run race fuel with a fast curve so even the squirt evaporates fast that should make my conditions rich compared to you guys running pump gas that puddles.

I had the fuel screw open to almost 3.5 turns and it was better. That is why I decided to look inside.

The bike had a tad of jet lag since we got it from the previous owner who said it was the best jetted bike he ever rode... Not.

We tried the race fuel and that helped the snap some, next uncorked the can, better power but still lagged. I just put in the JD kit. And a "R" silencer. Junior said it pulls real nice up top like never before but the jet lag is more pronounced.

Upon pulling the carb 😢

I filled the bowl on the bench and tested the squirt, NONE. I noticed the little arm was going on "unloader" (against the spring) , a pressure build up. Cars with a holley carb will do that. I pulled the diaphram cover, looks OK???. I sprayed brake clean (with the red wand) into the passage that leads to the brass nozzle, most of it backed up...no spray. URG!!! I removed the Float bowl next. Sprayed the same and it came out the float bowl outlet and the bleed jet. I then sprayed the carb body hole that leads to the nozzle..A second passed and then a spray... Something must of had it blocked some place. It is together and now squirts about 3 inches+ for almost a second or so.

Tomorrow will tell when I fire her up. I would have tried but I spend 20 minutes getting the hot start back in... I have not found the trick for that part yet..

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Hey Bodyman,

Good luck & Keep us posted on your test ride. As I was reading your post I remembered seeing a couple pieces of dirt(like small rocks) in my carb when I put the JD kit in. I have no idea how they got there cause my bike was never apart and the rocks were in that plug on the bottem of my carb. Maybe we all should pull the plug out once in awhile and clean/check it.

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Mine had dirt in the bowl too. I'm going to put an inline fuel filter on. My pump had lots of squirt, but the way it dies, I think the problem is not enough fuel. It doesn't spit or blubber like too much would.

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😢 Well 😢😢

Did the fire up and test. Failed.

In Neutral, A flick of the throttle wide open will stall the bike with a cough.

1 st gear at a fast walking pace, flick it wide open, What I have is a bog then a blubber as it pulls, once it revs out it clears and flys. Junior said he never had the gurgle/blubber but always the bog. When it is cold the bog is real bad as it gets hot it is a tad better.

IMO the bog is there from the AP or Pilot and the gurgle may be a tad rich in the middle ????

I am only searching,as it is a pain to take the carb off and on to make these changes. I have to but want to get in the correct direction.

I plan on going with the 55 leak and maybe a larger pilot, after work I will give it a shot.

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Well for you bog followers.

Semi Success 95%

JD kit red needle #5, 158 main, 55 leak, 45 pilot, 2 1/4 turns on the screw. I also messed with the AP adj screw. Actually went in a half turn. Squirt seemed fuller faster. Still under 1 second. I would need video to time it better.

Air temperature has dropped 20 degrees since noon also 30 vs 49. There is a slight crackle at a fast crack of the throttle in nuetral and at a crawling pace. The good news is this bike now lofts the wheel at will even with the crackle. The more Junior rode it up an down the yard the better it sounded as ir heated up.

Hope this sends someone in the correct direction. I'm not done be we can ride it this way.

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Finally, answers that actually HELP... I've been having NO sucess and after taking the carb of I think I might be wearing the rubber boot that connects the airbox to the carb down - not good. I'll do my part and try to see what's up - thanks for the info.

Wow- I just checked it out right now since it was already apart from me trying to play around with the carb last time.... Absolutely NO squirt whatsoever - NOTHING in the intake chamber. Hmm... this probably should have been something I checked to begin with... Keep ya'll posted - oh, and make sure you check yours too, just in case...

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Well for you bog followers.

Semi Success 95%

JD kit red needle #5, 158 main, 55 leak, 45 pilot, 2 1/4 turns on the screw. I also messed with the AP adj screw. Actually went in a half turn. Squirt seemed fuller faster. Still under 1 second. I would need video to time it better.

Air temperature has dropped 20 degrees since noon also 30 vs 49. There is a slight crackle at a fast crack of the throttle in nuetral and at a crawling pace. The good news is this bike now lofts the wheel at will even with the crackle. The more Junior rode it up an down the yard the better it sounded as ir heated up.

Hope this sends someone in the correct direction. I'm not done be we can ride it this way.

Any 100% sucess yet?

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