doesn't idle?

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motorizedmatt

New Member
Aug 31, 2010
37
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0
Orange County CA
Hi guys,

Looking for a little help here. I riding my mb to work and home everyday, approximately 12 miles total. On the way home today it started running really wierd, wouldn't idle ( I had to rev it so it wouldn't die) and had poor power all around. I made it home, barely and I pull the plug and it looks like it's running super lean. It has good spark but I can't figure out why it is running crappy.

I threw on a different carb I had and it still runs bad, and won't idle.

Can anyone shed any light on this? I already checked and everything is tight with no air leaks, just can't figure this problem out.
 
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matthurd

New Member
Dec 13, 2010
817
2
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manchester NH
have you tried adjusting your idle screw and the other screw (think it's the air screw?)

that's the problem i was having before, another member told me to check that and it started running great.
 
2door

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
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Littleton, Colorado
How did you confirm you have no air leaks? Your symptoms are consistent with air entering somewhere it's not supposed to. If you're sure the intake/carburetor/ manifold to cylinder is not the problem then you need to start looking at your crankshaft seals. There is one behind the magneto rotor (magnet) and on the other side behind the small gear. If you see evidence of oil inside either right or left cover, its a good bet one of the crank seals is defective. Get back to us with what you find.
Tom
 
GearNut

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
Taking note that you say the spark plug looks like the engine is running lean.....If the carb is getting enough fuel to it, and the intake manifold has no air leaks, check the float height in the carb. It may be too low, even though you changed the carb out that is no guarantee that everything inside it is adjusted correctly. Also you can check the head gasket, cylinder base gasket, and crankshaft seals for leaks.
 
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motorizedmatt

New Member
Aug 31, 2010
37
0
0
Orange County CA
matthurd said:
have you tried adjusting your idle screw and the other screw (think it's the air screw?)

that's the problem i was having before, another member told me to check that and it started running great.
Click to expand...
It couldnt be that it started happening while I was riding, and it would die as soon as I let off the throttle if it was messed up
 
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motorizedmatt

New Member
Aug 31, 2010
37
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Orange County CA
Hammond Egger said:
How many miles are on it. Is the screen petcock filter inside the tank still on it? Do you have a filter outside the tank?
Click to expand...
It has 150 miles on it. The filter still is on on the inside, but I don't have an outside one.

2door said:
How did you confirm you have no air leaks? Your symptoms are consistent with air entering somewhere it's not supposed to. If you're sure the intake/carburetor/ manifold to cylinder is not the problem then you need to start looking at your crankshaft seals. There is one behind the magneto rotor (magnet) and on the other side behind the small gear. If you see evidence of oil inside either right or left cover, its a good bet one of the crank seals is defective. Get back to us with what you find.
Tom
Click to expand...
I checked the crackshaft seals and they are 100% dry.

GearNut said:
Taking note that you say the spark plug looks like the engine is running lean.....If the carb is getting enough fuel to it, and the intake manifold has no air leaks, check the float height in the carb. It may be too low, even though you changed the carb out that is no guarantee that everything inside it is adjusted correctly. Also you can check the head gasket, cylinder base gasket, and crankshaft seals for leaks.
Click to expand...

checked the carb and it looks good, and the float is fine. Around the head gasket is can see alittle bit of brown (hard to see because I have a black motor) and when I stick a flashlight up there it looks like i can see when the bolts attach the bottom side of the lock light right above the head gasket (kinda hard to explain).
 
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motorizedmatt

New Member
Aug 31, 2010
37
0
0
Orange County CA
I just pulled the cylinder head off and there was alittle oil on the outside of the head gasket, but more conceringly I discovered a gouge in the wall of the cylinder. See picture below, is this something to be concered about? It is definately feelable with your finger.

 
2door

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
It would sure concern me. Could be a broken ring or the engine has injested something unfriendly. What you are experiencing is sever compression loss through that groove. Sorry about my earlier optimistic diagnosis. Let us know what you find, please.
Tom
 
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motorizedmatt

New Member
Aug 31, 2010
37
0
0
Orange County CA
2door said:
The cylinder. The part that the piston moves up and down in. It will come off easily with the head bolts/nuts removed. It could be stuck on the gasket but with a little urging it'll come right off.
Tom
Click to expand...
i got it up but its kind of hooked on the piston do i just pull it up hard? i looked down in there and it doesn't really look like anything is messed up but its hard to tell. Not sure what its supposed to look like this is the first time I had to open one of these things up.
 
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Hammond Egger

New Member
Oct 23, 2010
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Tucson, AZ
The gouge is something to be concerned about but here is where I was headed. Even if you rinsed the tank out it takes about 100 miles to shake loose the paint chips inside it and clog up the screen filter. I would remove the petcock, take the screen filter off and dispose of it and get an aftermarket filter for outside the tank.
 
GearNut

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
Before worrying about upgrading the fuel filter (which in my opinion is mandatory), let's figure out what came loose inside the engine and grooved the cylinder.
As things look now, the engine will need at least a new cylinder and piston/ rings, but what came loose inside it? That needs to be addressed too.
With only 150 miles on it, I am hoping that the engine can be warrantied.
 
Goat Herder

Goat Herder

Gutter Rider
Apr 28, 2008
6,237
20
38
N.M.
Hammond Egger said:
The gouge is something to be concerned about but here is where I was headed. Even if you rinsed the tank out it takes about 100 miles to shake loose the paint chips inside it and clog up the screen filter. I would remove the petcock, take the screen filter off and dispose of it and get an aftermarket filter for outside the tank.
Click to expand...
The only prob I ran into with what you are saying is the stock petcock has too small of passages in it. Least mine did . I had to find a different pet cock with bigger passages inside so's it would not keep plugging up.

http://motorbicycling.com/f34/your-bike-losing-power-top-speed-24880.html
 
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