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Old 12-31-2011, 04:53 PM
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DaveC DaveC is offline
Motorized Bicycle Elite Member
Join Date: Jul 2010
Location: Boise, ID
Posts: 967
Default Re: what did you do to your motor bike today?

Yeah, I know exactaly what went wrong. The holes are not tapped to the bottom I think to cut labor costs on the motor. I went to Harbor Freight and got a metric tap set and ALL the holes were shallow tapped, usually to only half their depth. HF tap set was under $12 and a good investment. This practice also is the reason the head capscrews can sometimes bottom out and give false torque readings.

I discovered this when I tried to bolt on a Pirate Cycles CNS carb intake and the bolts stuck out 1/4" before they stopped going in. Got the tapset and finished tapping the hole and did all the rest.

I had another bastard part, the head studs were of a slightly smaller size. Not a metric and not SAE. The threads going into the block were fine thread and the nut end was a coarse thread. I discovered the different size from standard when I tried to put the SBP headstuds in and they would not go in. Tapped the holes with an 8mm tap and they worked fine.
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