Hey guys I have been trying to figure out why my RM 250 was bogging when I'm not on the throttle all the time... I rebuilt the top end and it still has the same problem (I thought the compression was low). I've cleaned the carb numerous times (i believe it has a 160 main jet), and the other day when i was cleaning the air filter took it for a quick spin around the block. It runs fine without the air filter, what gives? My air filter is a brand new uni too so I dont get it... Could that mean my bike is running too rich, but a 160 main jet is kind of small isnt it? The previous owner ran race fuel, but I dont see the need when its the stock piston. Do you guys think it could only be setup to run on race fuel? I really can't think of anything else it could possibly be. :bang:
Weird bogging problem!
- Thread starter 1998RM250
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OriginalRider
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- Nov 23, 2008
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Try adjusting the air screw go all the way in then 1 1/2 turns out.Try setting the needle pos at 2nd notch from the top.You should be ripping then!
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- #5
yeah thats what i need to do, because running $10/gal race fuel is kinda crazy on a stock piston I think. Only thing is the screw onthe top of the carb, it looks likes some weird allen wrench but has a nipple looking thing in the middle so you can't fit one on there.
OriginalRider
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- Nov 23, 2008
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Look on the left side not the top.
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- #7
oh yeah i tried messin with the air screw, didnt seem to do much. To my understanding to adjust the needle i need to take the top of my carb off where
the cable goes down into the slide, and i cant figure out how to get that screw out.
thanks for the advice, I've been tryin to get this thing running right forever... hate to get stuck in the woods!
the cable goes down into the slide, and i cant figure out how to get that screw out.
thanks for the advice, I've been tryin to get this thing running right forever... hate to get stuck in the woods!
OriginalRider
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- Nov 23, 2008
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Sorry i miss understood you.Yes there should be two alien keys i have the 89 rm250 and mine were alien keys until i swapped it for a lt500 because the choke didn't work.Every check your reeds?1998RM250 said:
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- #9
I'll have to take the carb off again and check it out, btw its a 2007 RM 250 and I've got the V-force delta reeds. The bike doesnt seem THAT fast to me, but it lifts the front tire through all 5 gears when its not bogging. 1st gear is the worst for some reason, it clears up through the higher gears when I stay on it.
OriginalRider
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- Nov 23, 2008
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You have to jet it with the reeds.try a 170 main.
Those screws are security torx screws, special bits for sure! Before you go jumping on changing the main, fix the beginning of the jetting. I would not run the engine with out an air filter, the engine can draw a lot of things into it! If your air screw is ineffective, you need to determine if its rich or lean, listen to the engine, or look at the plug. You have to dial in the pilot first! Vintage Bob
OriginalRider
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- Nov 23, 2008
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If it has a stock piston i doubt it.foxforks is real good he helped me out alot.
Where on Earth did that come from? We were talking jetting, yes? BUT, since you brought it up, an improperly ported engine may never be able to jet cleanly, and may never come off idle cleanly. Vintage Bobsr5bidder said:
whenfoxforks-ruled said:
actually no, Bob, I thought the thread was about the engine not running propperly (bogging) just thought I'd throw that out there, because Idiots normally just break out the rattle can and paint the plastics to ruin bikes, but you never know when something is second hand, and so many times everyone jumps on the jetting wagon, I'll try harder in the future to not think outside of the box. :nod:
If I ever catch the bozo that has cases of black paint, and shoots it right over the dirt! My biggest fear with used bikes, has some fool been at the ports, and worse the cases. CC them if I knew the correct volume? Shiny exhaust or intake? I have whats supposed to be a 97 cr250 engine, its got a sleeve and a piston from a 96? Good thing it came with another clean cylinder. If the previous owners ran long on the rebuilds, the bore can no longer be round enough for good compression, ovaled bore. A new top end will still run crappy. Vintage Bob
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- #17
I brought the head down to the dealer when I had it apart, its all stock and in decent shape. The bike was ridden by an AMA pro rider, but when I seen it had such a small main jet i was supprized? Tuning this thing looks like its turning into a pita, I'm going to try some 110 fuel if I can find it around here and see how it runs on that since thats what the previous owner ran. If that doesn't solve the issue where can I get one of those security torx bits? I wonder why they put those on there? I really want to go riding today, this sucks!
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- #20
Hmm so even the 93/110 vp race fuel mix won't cut it... I was also wondering, how do I know its getting good enough spark? It kinda like bogs and cuts out, Maybe clean the pickups on the coil might help? It's killin me seeing all these other two strokes run right when I know this bike will rip when setup. If its higher compression it would have like a wiseco kit or something right? The head is all stock down to the oem piston...
I never understood the fuel mixing thing. If you got barrels of the actual mix, another story. Oxygenated race fuels come 2 ways, ether(the only way for real throttle response in the dirt) and alcohol(better off drinking it or using it for food!). So you take some, and mix with pump fuel(lots of water in it). Ether and alcohol makes for an odd mixture. And if any of the fuels has lead in it, it does crazy things to the oxygen levels! Try the vp straight? I believe your problem is elsewhere. It seems you have entered the circle of denial? Vintage Bob
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- #23
I'm just trying to figure out if its jetted for 110, would running it on 93 cause that problem? I just put new rings in it a few weeks ago because it has been doing the same thing for awhile now and thought that was the problem. At this point I just don't know where else to look for the problem, and I don't want to spend endless dollars at the dealer with them playing guessing games as well.
EDIT: okay well I'm an idiot, I cleaned the filter a few hours before I rode yesterday and i thought it was dry. Today I felt it and its still like damp with water, watch it run okay when it drys completely.
EDIT: okay well I'm an idiot, I cleaned the filter a few hours before I rode yesterday and i thought it was dry. Today I felt it and its still like damp with water, watch it run okay when it drys completely.
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OriginalRider
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- Nov 23, 2008
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My rm250 was doing the samething about 2 weeks ago but the bog was only there when i was just about in power band took the slide out and the clip was off completely.I doubt that 93 would cause any problems i went from reg pump to 91 oct without changing jets.I never ran vp and never will.
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- #25
Thanks, I'm just going to have to find the torx bit to get the carb apart. The thing just wont rev, even in neutral it bogs when u try to rev it... Once your on the trail and get into like 3rd gear and open it up its fine, 1st and 2nd gear just bog and are useless. This is my 3rd RM 250 and I've never seen one run this way...
