CHINESE BASKET CASE 91 GLOW

A fellow club member sent in this  "good deal" chinese 91 glow engine after it suddenly stopped shortly after flying it.

This is how we recieved the engine.

Ummm I think the con-rod is not meant to be that shape, 

Oh dear, Oh well I wonder how that happened??

I suspect that it wasn't just a case of the typical "top qualtity" Chinese materials but also a somewhat poor design may have had something to do with it as well. The big end journal on the crank measured up at a stunning 7.00mm diameter and a whopping 6.00mm length. Fairly sure thats just not going to cut it, well maybe it did?  luckily the rod didn't completely disintergrate into the hand grenade department but as it is I think we can salvage the engine.

So having decided to fix the engine we started with a new, redesigned crankshaft to avoid a repeat of the original design's failure.

 

Now we have a proper bearing journal that measures up at 8.50mm diameter by 10.00mm long. We've also through drill the journal for lightening and balance and modified the flywheel design for strength and weight distribution which also helped accomodate the increased big end journal size.

 Here's the start of the reassembly with an empty crankcase, cleaned and new bearings coming.

Now it's onto the new con-rod.

Crankcase reassembled with the new crankshaft and new bearings.

Now we just need to reassemble the piston back onto the rod and refit the liner to the case.

Now for the test run.

 

Another happy ending.