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Boyesen accelerator pump cover

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does it work?

scott,

we have this cool search feature... which returns, for example:

http://www.thumpertalk.com/forum/showthread.php?t=225219

and

http://www.thumpertalk.com/forum/showthread.php?t=221049

and

http://www.thumpertalk.com/forum/showthread.php?t=219920

and

http://www.thumpertalk.com/forum/showthread.php?t=219796

but before you spend ANY money, read this thread:

http://www.thumpertalk.com/forum/showthread.php?t=214185

and the entirety of the 250F FAQ.

i say this because the problem you are trying to fix can usually be solved for less than $90.

a lot less.

like $80 less.

jim aka the wrooster

'01 wr250f

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Does anybody have any actual, as opposed to merely anecdotal evidence regarding this product?

i say this because the problem you are trying to fix can usually be solved for less than $90. a lot less. like $80 less.

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Does anybody have any actual, as opposed to merely anecdotal evidence regarding this product?

did you actually read through the first and second links i posted above? :)

jim aka the wrooster

'01 wr250f

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scott,

we have this cool search feature...

Point being this really does help us from talking about the same things over and over and over, may help keep the same questions from popping up again and again. :)

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i say this because the problem you are trying to fix can usually be solved for less than $90.

a lot less.

like $80 less.

jim aka the wrooster

'01 wr250f

I'm not disputing the validity of tuning the ap circuit etc... but I find it hard to believe that when I bring this up to my local shop the guys swear up and down that the "bog" is just the way it is and Yamaha has stated that you "can't really do anything about it" :)

Just yesterday I asked one of the mechanics if he had ever tuned it ap circuit or changed his leak jet in order to cure the bog and he gave me the canned answer.... :)

Oh well, as soon as I don't have to freeze my nutz off to do it, I'm following the faq and tuning my ap... :p

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So the guys at your local shop know everything there is to know about these motors? I would say that they need to join this forum and learn a thing or two. Several members including myself have asked this same question about the bog, we all got the same answer and we were able to fix the problem with help from the members HERE, not at the local dealership.

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So the guys at your local shop know everything there is to know about these motors?

Nah, if I thought that I would have said -

"I'm not disputing the validity of tuning the ap circuit etc... but I find it hard to believe that when I bring this up to my local shop the guys swear up and down that the "bog" is just the way it is and Yamaha has stated that you "can't really do anything about it", since they know everything about YZ250F motors..."

But I didn't... :)

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Does anybody have any actual, as opposed to merely anecdotal evidence regarding this product?

just to follow up this question,

read James_Dean's post about halfway down this thread:

http://www.thumpertalk.com/forum/showthread.php?t=229662

summary... $12 leak jet = $98 boyeson cover.

ps: you won't read that in any MX magazine, will ya! :)

jim aka the wrooster

'01 wr250f

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Even though it is a nice "static" comparison, it still does not answer my question... :)

I have subsequently learned that many racers use the product, or similarly modified covers, because of the more efficient pump charge cycle time, as opposed to stock. This is especially important when getting through a tricky rhythym section or successive jumps (dynamic), as opposed to putting down the trails.

just to follow up this question,

read James_Dean's post about halfway down this thread:

http://www.thumpertalk.com/forum/showthread.php?t=229662

summary... $12 leak jet = $98 boyeson cover.

ps: you won't read that in any MX magazine, will ya! :)

jim aka the wrooster

'01 wr250f

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Even though it is a nice "static" comparison, it still does not answer my question... :)

I have subsequently learned that many racers use the product, or similarly modified covers, because of the more efficient pump charge cycle time, as opposed to stock. This is especially important when getting through a tricky rhythym section or successive jumps (dynamic), as opposed to putting down the trails.

I reccomend you go waste your $90 on that piece of crap then if you know so much more than us "putters" :)

My bike runs perfect with the #40 leak jet and a little a.p. timing adjustment.

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That's really good for you, glad to hear it...

I recommend that learn how to use the spell-checker.

I reccomend you go waste your $90 on that piece of crap then if you know so much more than us "putters" :)

My bike runs perfect with the #40 leak jet and a little a.p. timing adjustment.

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Before discounting what the guys here have to say, ask yourself a few questions...

Who befefits financially from the sale of a Boyesen cover?

Have you ever found the magazines to describe an item as a waste of money, especially when it's from a big long-term advertiser like Boyesen?

Why would a mechanic want to spend time rejetting the bike with a $5 jet, when he can spend only a few minutes installing a $90 cover?

Why would you want to spend $90 on a cover when you can spend $15 on jets and an hour rejetting and adjusting? This obviously depends on your time/money ratio, just like the mechanic.

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Before discounting what the guys here have to say, ask yourself a few questions...

Who befefits financially from the sale of a Boyesen cover?

Have you ever found the magazines to describe an item as a waste of money, especially when it's from a big long-term advertiser like Boyesen?

Why would a mechanic want to spend time rejetting the bike with a $5 jet, when he can spend only a few minutes installing a $90 cover?

Why would you want to spend $90 on a cover when you can spend $15 on jets and an hour rejetting and adjusting? This obviously depends on your time/money ratio, just like the mechanic.

It takes 5 minutes to put a leak jet in. And you are right, as with most things in life there is an easy way out. I chose to do the research and use the leak jet method. I don't have $80 to throw down the drain. And about your comment about the mechanic using the Boysen product instead of spending time rejetting....any good mechanic should know how to jet a bike. I'm not saying the Boysen is bad purchase, just not money well spent IMO.

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I made the same post 2-3 months back about the Boysen cover. Wrooster hooked me up with the links, and I read and decided not to buy one because basicly my bike runs fine, no bog whatsoever. I was just curious about all of the full page advertisements in the MX mags. So... a month or so ago, one of my riding pals got one given to him by the dealer who sponser him (on his 450,which I have ridden and raced several times). I could tell absolutly no difference (all be it I am a vet C class rider)and neither could he(and he is a pro ). I'm not spending my money on one unless someone shows me otherwise. So that is my experience with it, hope it was helpful. :)

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Yes the bogg can be cured. I had a 2002 Yz250f and had a powernow and #80 leak jet and it was gone. Now I have a 2005 Yz250F and I have a powernow, powernow plus and a P-38 ( same as the boysen cover) and my bogg is not complete gone but I am now putting in a #70 leak jet ( stock size is still in) and I am completley sure my bogg will be next to nothing like my 02 was. And on my 02 there was NO bogg anywhere. I will post my results with my powernow, powernow plus, P-38 and my new jetting changes as soon as they come in and the whole day at the track is spent working on it. Roost ya later.

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Yes the bogg can be cured. I had a 2002 Yz250f and had a powernow and #80 leak jet and it was gone. Now I have a 2005 Yz250F and I have a powernow, powernow plus and a P-38 ( same as the boysen cover) and my bogg is not complete gone but I am now putting in a #70 leak jet ( stock size is still in) and I am completley sure my bogg will be next to nothing like my 02 was. And on my 02 there was NO bogg anywhere. I will post my results with my powernow, powernow plus, P-38 and my new jetting changes as soon as they come in and the whole day at the track is spent working on it. Roost ya later.

Wow, I'm suprised your '02 didn't bog with that large of a leak jet. When I first got mine I tried the power now to help woth the bog, didn't help much. I then tried a series of jet changes (this was before the #40 leak jet was the common fix) and nothing helped. After the #40 leak jet and timimg my a.p. the bog was completely gone. I guess this further proves that every bike is different.

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From what I am reading over on the 450 forum, the Boyesen cover refills faster than the stock AP cover, and squirts slighlty longer. What people are doing is using the 40 leak jet to get the squirt duration right, then if they need to blip the throttle several times in succession, (like when going over the whoops), they add the Boyesen cover so the AP can refill quickly enough to provide a consistent squirt.

Since I ride in the woods, and never would need to glide across the top of the whoops, I'll be saving my $90. But I can see where it could be useful at the track for the racers.

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