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CRF 450R - 05 - Engine Blog

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Anyone out there ever had the following problem? I've noticed that if I'm in first gear on something that's slow and technical, and I need to jump the front wheel up and over something, and I give the throttle a little twist, but very quickly, I get an engine blog, like it's getting to much fuel to quickly or something and stalls. This doesn't happen if you just rev the motor normally, only on a quick twist......Is this just a trade mark of 4 strokes, or is there something wrong?

PS- My valves are fine, I check and shim them myself, carb is clean, correct jets and settings for our altitude.

I've had this bike for nearly a year now, and love it to pieces, but I could never get my CR250 to blog like this. I don't know, 4 strokes are superb today, but maybe it's time to go back to a 2 smoker.

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Do a search in the jetting forum. It's your jetting & Accelerator pump adjustment. You'll more than likely have to adjust you fuel screw, AP timing and possibly have to rejet and change the AP leak jet.

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This happens to me only when I have my quite insert in my exhaust, take it out and it's gone..... Hummmmmmm. Sounds like it may be jetting like Redbeard said.

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I'd go with Redbeard on this one. This "blog" as you put it can be pump timing, or a lean or rich "blog". I personally experienced a rich "blog" and the Boyesen pump cover only made it worse after trial and error. With some needle adjustment and pilot fine tuning, your "blog" should get better. Check your plug after you experience the "blog" to get steered in the right direction. If it's dark and sooty, try leaning out your slow circuit some. :banghead:

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I'd go with Redbeard on this one. This "blog" as you put it can be pump timing, or a lean or rich "blog". I personally experienced a rich "blog" and the Boyesen pump cover only made it worse after trial and error. With some needle adjustment and pilot fine tuning, your "blog" should get better. Check your plug after you experience the "blog" to get steered in the right direction. If it's dark and sooty, try leaning out your slow circuit some. :banghead:

I knew someone would have to big up the ball and run with it. :banghead:

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The first thing I would do is tweak the fuel screw leaner. Although these bikes start and run fine when they are too rich, they will definitely have a noticeable "blog" that goes away when it's leaner.

If that doesn't get you where you need to be, swap the pilot for a smaller/or bigger one.

If it isn't one of those two things, you're going to need to play with the accelerator pump.

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Chu No Dat! :banghead:

Are ya chokin' down what I'm spewing out, Bra?

Had any run-ins with the Dog, lately? I might have to use my vacation to come over and ride with you, and hopefully I can run into Leland and knock the crap out of him just for fun! :banghead:

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Mi casa e su casa. I think you'd like our ridiculously huge, jump-ridden, hard-packed, neglectedly maintained, supercross track here! Next month David Bailey and Team WBR Suzuki are coming down to do a 2-day camp and the boys will be racing that sunday as well. I can't wait to see them in action! :banghead: AND they're raffling off Ryan Sipes and Richie Owen's 250F's. . .

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Mi casa e su casa. I think you'd like our ridiculously huge, jump-ridden, hard-packed, neglectedly maintained, supercross track here! Next month David Bailey and Team WBR Suzuki are coming down to do a 2-day camp and the boys will be racing that sunday as well. I can't wait to see them in action! :banghead: AND they're raffling off Ryan Sipes and Richie Owen's 250F's. . .

That sounds sweet!

What island are you on? I've been wanting to do that two-wheel adventure thing since I read the article about MC doing it. I wonder if I can get the ole' lady to wear coconut shells? 🤣

It's too bad those WBR bikes are yellow with steel frames, but a free bike is a free bike. :banghead:

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My KTM Duke had a similar problem. Playing with the fuel screw fixed it. Don't be afraid to mess with it. just count the turns in to full stop, then back it out to the original setting and adjust from there. If you can't fix it at least you can go back to the original setting by recounting screw turns to the starting position.

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Thinking about going back to a smoker myself. I am seeing Yellow these days.

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