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05-11-2004 | 01:31 AM

#22

ziggy12345

Tech Master

Joined: Jun 2003

Posts: 1,596

From: West Midlands, UK

Quote:

Originally posted by NitroOB4You
Ok...well...now Im totally confused...although what you two say seems to make more sense than what I had heard in another forum. I was told that the Pixi is over shimmed????...I mean...
it is good with no shims for 30% and that to run a lower % , one would have to have the head button machined down. I can say, as for right now, it is running great. Although I have only run 8 tanks worth so far...despite beautiful weather, I have been sick all week and havn't had desire to do anything

Hi the Pixy IS OVERSHIMMED! The head clearance is around 0.020"with NO SHIMMS. this will be good for 20-30% Nitro.

The only way to check is to measure it.
Take out the plug and insert a piece of solder.
Turn over the motor fully so that the piston flattens the end of the solder
Measure the flat spot with a vernier or a micrometer

It should be 0.018" for 16% Fuel or 0.022 for 30% fuel.

If the head clearance is too big the motor will overheat as the fuel burning happens after the piston has gone over the top (advanced timing).

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