66cc Engine won't Idle

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BeaverRat

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Jun 27, 2011
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I found the air leak!!! It is HUGE... Anyway, it is located at the gasket that splits the engine in half the long way (I think it's called the crankcase center gasket?). I pressure tested it and it leaked very badly in this one spot. I put 5 PSI into it, and it all drained in less than a second... Its supposed to hold 5 PSI for a couple minutes ha ha. How do I get to this gasket?

I removed the head and cyllinder, and then un-screwed all the screws that hold the two halves togetcher, but it still wont come apart...

Thanks
 
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MarkSumpter

MarkSumpter

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Nov 27, 2010
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BeaverRat said:
I found the air leak!!! It is HUGE... Anyway, it is located at the gasket that splits the engine in half the long way (I think it's called the crankcase center gasket?). I pressure tested it and it leaked very badly in this one spot. I put 5 PSI into it, and it all drained in less than a second... Its supposed to hold 5 PSI for a couple minutes ha ha. How do I get to this gasket?

I removed the head and cyllinder, and then un-screwed all the screws that hold the two halves togetcher, but it still wont come apart...

Thanks
Click to expand...

Good to hear you found the leak Beaver my opinion is that using the method I posted on pressure testing is the only way to find all of the air leaks on an engine.

You will have to remove the clutch assembly (Make sure you remove it as a complete assembly and not try to remove the ring gear and pressure plate in separate pieces because there are like 60 small ball bearings that are a bite to put back in place), pinion gear (that drives the clutch ring gear) and the coil and magnet to split the crankcase. I would personally coat a new gasket with Indian Head Shellac Gasket sealer and then reassemble both halves of the crankcase. While you are at it you might want to call your local IBT warehouse and get a set of double rim seals for the crankshaft. The china seals are kind of cheapos and IBT can hook you up with far better seals for your engine.

I think Norm has a thread somewhere on complete engine tear down and reassembly and if I remember correctly he also has a part number for the crank seals.
 
MarkSumpter

MarkSumpter

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Nov 27, 2010
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GearNut said:
http://motorbicycling.com/f39/bicycle-engine-tear-down-391.html

I also recommend getting or making a new cylinder base gasket.
Bicycle Engine Gaskets Seals - Motorized Bike Engine Gaskets - Bicycle Engine Se Bicycle Engine Kit - Gas Powered Bicycle - Bike Motor Kit - Bicycle Engines - Grubee - Beach Cruisers - Bikeberry - BikeBerry.com
Click to expand...
Right you are GearNut I neglected to say that and on the same note I never use the gaskets from the dealers. I have a good source for felpro material and use .015" for crankcase gaskets .025 for cylinder base gaskets (which actually advance the port and intake timing slightly and give better top end) and .015 for the head gasket and seal everything with Indian Head Shellac sealer. Some people rag me for it but my engines never leak and run like striped a*@ apes...

BeaverRat said:
Do I need a special tool to remove the clutch assembly?
Click to expand...
No just follow the instructions in the post gearnut linked that I couldn't find....
 
MarkSumpter

MarkSumpter

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Nov 27, 2010
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BeaverRat said:
And you have to remove those to remove the clutch, and ultametly SPLITthe crankcase...
Click to expand...
*fixed* Yes these all need to be removed as well as the keys in the keyways to separate the 2 halves of the crankcase.

Normans tutorial on tear down goes in depth on the full procedure and is well worth the read if you are thinking on doing it yourself for the first time.
 
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