Low end bog on cr125

Casper250

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#1
I just bought a 2001 cr125 and the bike has a low end bog. From just off idle to maybe a quater throttle, there is definatly a hesitation but once it gets the revs up, it has normal crisp throttle responce.

When i got the bike, there was a fair amout of oil from the tailpipe dripped all over the back hub, brake and rim. Either the guy i bought the bike from was a little heavy with the 2-stroke oil, or didn't like to rev the bike. I pulled the plug and put a new one in and still the bog is there. I also ran the bike hard for about 10 minutes and the oil from the tailpipe has slowed, but it still drips out.

I was wondering if this bog is a carburator issue or is this bog just the nature of the beast on a 125cc?
 

marcusgunby

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#2
The 2001 doesnt have much bottom but good jetting helps alot-do a search and it should throw up a few threads on this topic, i ended up with a 40 pilot and a 2169 needle i think.
 

shnalln

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#3
Sounds like you're alittle lean on your pilot...mess with your airscrew before you tear into it too deep...Eric Gore has a good general jetting info page on his web site...helped me alot. Good luck!
 

Casper250

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#4
Originally posted by marcusgunby
The 2001 doesnt have much bottom but good jetting helps alot-do a search and it should throw up a few threads on this topic, i ended up with a 40 pilot and a 2169 needle i think.
Thanks!!! this seemed to do the trick. I put the needle in the middle clip for now. I also bought a 350 main and a 360 main when i ordered the pilot and needle. I didn't write down the numbers for the jets and thought that some one metioned a 350 or 360 main. Do i need to mess around with the main jet at all or needle position?

Also, when my jetting is all set up, do i need i mess around with it as the weather changes? My last bike, a 2000 kx250, i never had to touch the jetting from the day i bought it and it ran fine even in the snow of winter.
 
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#5
if the bog you are experiencing is in 0 to 1/4 throttle openings only, do not touch the needle jet, jet needle or main jet. You want to go richer on the pilot jet.
 
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#6
Hey guys, what makes you think that his bike is lean?? If it is dripping oil that suggests a rich condition not a lean one. If it was lean most of the time it would surge and not just bog like a rich pilot would do. Also, i think the main is a 360 stock. It is on the 2000 any ways. Do a throttle chop test and check out the color of the plug, if it is mocha tan then don't get any leaner or richer on the main. You can mess around with the needle bit, it will give you a good idea of which is lean and which is rich and put the clip where it feels best. The pilot can usually be dropped two sizes from stock. The stock i believe is a 50. Order in a 45 and a 40. Keep the one in that feels the best and then mess with the air screw for best throttle response. That should take care of all of your jetting problems.

Good Luck!
 

shnalln

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#7
"If the engine is slow to respond and bogs (engine makes a booooowah sound) then the carb jetting is too lean. You can verify lean
jetting by engaging the carb's choke to the halfway position."

This comes directly from Eric Gorre's website, the quick link to his site is right here on the side of these threads. Do yourself a favor and check it out. As far his bike spooging goes then yea, that would indicate that his mains are rich. But his low end circuits are saying that they're lean.
 
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#8
This may sound stupid but take a peice of paper and tape it to the end of your silencer (with it repacked) and ride from 0 1/4 throttle for a little bit. If there is any spooge it is rich.
 
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#9
yeah, but the bike could be lean on the pilot but rich on the main or needle... Notice he said that he had noticed spooge dripping when he got it. It wasn't dripping after he got it. So for example, if the last owner was riding it in mid rps's all the time and the needle is rich, you just got yourself nicely soaked silencer packing and a spooge dripping exhaust...

Eric

PS most of the time, a bog means a lean condition. You can easily tell if a bike is running rich by the weird rough sound of the engine. you can really hear it loading up.
 

NO HAND

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#10
Originally posted by ericlachance
yeah, but the bike could be lean on the pilot but rich on the main or needle...
Also, this is a very common scenario with Hondas lately. My 03cr250 was 2 steps too lean on the pilot and 2 steps too rich on the main.
 

Casper250

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#12
Originally posted by ericlachance
yeah, but the bike could be lean on the pilot but rich on the main or needle... Notice he said that he had noticed spooge dripping when he got it. It wasn't dripping after he got it. So for example, if the last owner was riding it in mid rps's all the time and the needle is rich, you just got yourself nicely soaked silencer packing and a spooge dripping exhaust...

I thought that the oil from the exhaust wold stop after i rode it for a while so that all the oil in the exhaust would come out. After i changed the pilot, the bike ran great but the oil drip from the silencer is still there. I don't know what the stock main jet is but i bought a 350 and a 360 main to play with. I haven't had a chance to take out my bike since i rode it the one time after changing the pilot and needle so i haven't touched the main or the air screw. So is changing the main jet now where i should be looking to get ride of the oil drip?
 
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#13
depends, hows throttle response at 0 to 1/4 throttle opening? and from 1/4 to 1/2? 1/2 to 3/4? and 3/4 to wot? do a plug chop on at wot to check the condition of the main jet.

What type of riding do you do? trails, mx... And do you usualy ride at wot, 1/2 throttle or do you ride it in very low rpm's? Also, change the packing in the silencer, if it's dripping, It's soaked with spooge.
 
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#14
MX Rider 031 where abouts in Saskatchewan are you, I'm always kepping my eyes and ears open for tracks across the prov. let me know. I'm in Melfort,1 hour south/East of P.A. just a couple farmer field mx tracks here
 

Casper250

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#15
I mosty ride sand or MX tracks so i'm in the upper RPMs most of the time. The bike runs great at low revs now but it's still a little querky. If i run at low to mid RPMs for a little while and then i run it at WOT, it has sort of a delay like it's clearing out a gas build up. It only happends every once in a while and i havent had a chance to mess with it. From what it sounds like from people telling me, my main might be a little rich. Does this sound right?