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250 EXC F Bogging

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14K views 10 replies 8 participants last post by  peterg  
S
#1 ·
I know this one's been done to death in TBM and probably on here as well, but can I have some experienced advice please.

A pal of mine has an 08' 250 EXC F which has always bogged down when he opens it up too quickly and over time it has got worse and worse. When I had an 07 version of this bike, I had an accelerator pump mod done at my local dealers and I fitted a different sized leak jet (an 80 I think).

Can anyone on here tell me what he should ask the dealer to do to sort this out once and for all - he very nearly hurt himself badly on Saturday, because the bike bogged down and stalled 2 metres from the crest of a very steep bank which resulted in a lot of tumbling and the bike landing across his leg - could've been nasty!

Have I covered it in the first paragraph or is there more to do?

Cheers,


Mike
 
S
#8 ·
Hi Kev

I've only just seen this reply - thanks as always!

I'll pick a week when he's not about to get it over to you - I'll give you some warning too.

I haven't forgotten to keep you posted on the 400's oil usage either - I've just not used it enough recently to know how much its getting through. Interestingly, I did replace the rear of the airbox housing last week and its completely sorted the crap problem in the box after each ride. I think the bike must have thrown a chain with its first owner and he'd neatly run a Stanley blade around the damage leaving it looking factory produced that way. I looked under the new models at the KTM dealers near me and saw the difference immediately (£12.00 and about 2 hours of faffing about to fit it!).

Cheers,

Mike
 
#9 ·
Stoaty

I have just got hold of a 2008 250f. Went out on it as soon as I got it, and couldn't believe how crap it was at bottom end. I would open it up and nothing would happen!

Drastic action was on the cards.

I took on board all the help from this site and various pm,s.

I changed the leak jet to an adjustable Boysen jet, but changing to a 50 size leak jet will do.

Change the following:


1 a OBEKP main needle
2. 175 main jet
3. Do the O ring mod on the acc pump linkage.
4. Make sure you have 1mm of the acc rod protruding into acc pump housing, then check when you open throttle that fuel is squirted into engine for approx 1 second.
5. Remove air mixture screw and make sure an O ring is on the needle.

I have done all of the above, and a bit of fine tuning and 99% of the bog has gone. It's transformed the bike.:D:D:D
 
S
#10 ·
Bogging

Thanks Peterg

I'm planning to send it to KIY, as he's got one of these bikes too and is willing to do the mods with the benefit of experience and a decent pair of hands (I've got 2 left ones).

Yours message seems to follow the popular theme that I picked up on another thread, which has worked for plenty of folks so I guess that what KIY will do to it.

It's not mine, but it needs doing and my pal will be gratetful for it being sorted.

Thanks for the reply - I'll PM KIY

Mike
 
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