headache

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aarcher30

New Member
Sep 18, 2014
44
0
0
masontown, pa
China girl 66/80cc on cruiser, 200 miles or so 40:1 mc-1 oil which is 50:1 recommend. bike rode fine up until next morning I went to go for a ride and the clutch wouldn't catch but every other grab and only slightly. took off clutch cover and a dark gas oil mix dumped out now what? rebuild or buy new. I do have anothe engine that the mounting bolts are snapped off In?
 

KCvale

Well-Known Member
Feb 28, 2010
3,966
57
48
Phoenix,AZ
Blew a seal.
Fixable, but it's 50/50 if it's worth it or not, some cheap engines will always be crap.
 

crassius

Well-Known Member
Sep 30, 2012
4,032
158
63
USA
first, clean it out - then make sure it wasn't just from carb overflow dripping on clutch
 

Kioshk

Active Member
Oct 21, 2012
1,152
10
38
Connecticut
I've never went this deep into my motors
Well, if you want a reliable happy ride, now's a good time to start!

The only practical way of fixing that seal is to split the case. You MIGHT be able to extract it after only removing the crank's beveled-gear, but I sure have never had luck doing it that way. In any case, if it's as you described, you'll need to buy a new seal...they come in pairs, and it'll put you back about $10. You'll also probably need new bottom-end cylinder and case gaskets ... another $15? If you don't have the proprietary gear-puller, that's another $10 delivered. Assuming you're not too mechanically inclined up to this point, you'll also need proper tools...$$$. I think the investment's worth it, but as a beginner, you'd better get used to the headaches of becoming an expert...I think it's worth it.
 

MotorBicycleRacing

Well-Known Member
Jul 28, 2010
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SoCal Baby!!!
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The only practical way of fixing that seal is to split the case.
You MIGHT be able to extract it after only removing the crank's beveled-gear, but I sure have never had luck doing it that way. In any case, if it's as you described, you'll need to buy a new seal...they come in pairs, and it'll put you back about $10.
There is absolutely no need to split the case to install a seal on these motors!

You can buy seals individually at $3 from many places.
The right side bevel gear side seal is the thick one. The thinner one goes on the magneto side behind the magnet.

You will also need the gear puller tool.

Use a sharp pointed tool to extract the old seal.
Use a socket that is a bit smaller than the diameter of the seal
to push it straight into the case.
Lube the seal with oil.
Check the shaft that it has no sharp edges that may damage the seal.

Might be easier to replace if you pull the clutch off.

Do you have mechanic tools in metric?
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
If fuel is "literally dumping out" your problem isn't a crankshaft seal. I'd start looking at a stuck float valve in the carburetor, a leak from the fuel tank/petcock/fuel line.

I bad seal will not allow that much fuel to get into the clutch area.

You can clean up the clutch with Brake Clean, a spray solvent and dry it with compressed air.

If crank seals need replacing they aren't difficult t do but I'd make very sure where the fuel is coming from before getting into that job.

Tom
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
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Littleton, Colorado
I'm almost positive it's the crankcase seal behind the beveled-gear, I don't have money at the time just a parts motor
Crankshaft seals are not reusable. You can't use the seals from a "Parts motor". You won't get one out without damaging it.

Seals are cheap.

Tom
 

aarcher30

New Member
Sep 18, 2014
44
0
0
masontown, pa
ya that's part of the reason I got a new motor, the studs weren't coming out. I did clamp my engine at that time with 1/8th in metal, conformed around the engine and bolted, ran for 300 miles until I lost the woodruff key, th at half moon peice.