JA wrote:

>.014 total axial wrist pin clearance is a very large amount for a high RPM 30 cc engine.
>This would mean that there needs to be .024" to .029" total axial clearance in the bottom
>end to ensure that the connecting rod is guided only in the top end. Large axial clearances
>such as these are not desirable for roller assemblies designed to carry only radial loads!
>Large clearances at both the top & bottom connecting rod ends will require large crankshaft
>end play amounts.

>Large axial movement of the connecting rod & the crankshaft CANNOT be tolerated in a high
>RPM engine!

As always, your observations are appreciated.

> 30 cc engine

I really wish CY would answer the 36mm marine cylinder call and step up to the plate with
some "real" big blocks. They already have 35mm and 36mm pistons but show no interest in
making marine cylinders in these sizes. Instead, they claim they are going ahead with a 46cc
bruiser (42mm bore X 33mm stroke). Go figure.

www.davesmotors.com/s.nl/it.A/id.1102/.f

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I should have listed a brief history about the engine I took pics of. Approx. 2 gallons of
premix burned. The biggie is the multiple times I overheated it (to the point of refusing
to run) while playing around with different cooling designs.

Here are the measurements for the lower end of con rod
- lower bearing to counterweight = 0.020 inch
- side of rod to counterweight = 0.080+ inch

There is another CY-F273 engine that has been run less and abused less as well. Just for fun,
I will measure it to see how it compares.

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unclecrash: No intent to get off topic here but these are relative issues. Please let us know
what you find out on your hybrid build - I don't do 'em (not yet anyway) but they still
fascinate!