Flipping head around for spark plug clearance?

M

Motakitty

Member
Can I flip the head around I a 66cc flying horse motor? I have an internal cdi and I just replaced the plug wire with the sbp wire but it's too short but if I flip the head around it'll work fine. I also would like to see how the top of the piston looks too.
 
Yes, you can flip the head. If you do the whole cylinder, you have to turn the piston too, since the rings could snag on a port.
 
You can flip the head but it's not good for compression with the fins facing down...


J/k... it'll run the same regardless of the head's orientation, these will even bolt on sideways, but not good for cooling... I saw some guy selling one on ebay with the head sideways before, needless to say none 9f us bought it...
 
It will run the same with the head turned either way, but the engine will run a little cooler with the spark plug towards the rear (so there are more cooling fins in the front over the exhaust). ;)
 
amazing how often I've seen that sideways head over the years - seems some folks just don't pay much attention when they work on these
 
I never thought about sideways. Now I want to build a reverse jug, sideways head motor just to be funny. No joke I just finished what turned out to be a 're install for a customer that had the carburetor on upside down. And that wasn't the worst part of the build......
 
The crown of the piston is the same front and rear, turning the head 180° would make no difference in clearance. I am wondering why you would think you need more clearance? Unless your spark plug is a really long reach, then it would be protruding into the combustion chamber, and that would not be a good thing. If your plug has a 1/2" reach, you're OK.
 
Ducati250Single said:
The crown of the piston is the same front and rear, turning the head 180° would make no difference in clearance. I am wondering why you would think you need more clearance? Unless your spark plug is a really long reach, then it would be protruding into the combustion chamber, and that would not be a good thing. If your plug has a 1/2" reach, you're OK.
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By "clearance" the OP was talking about spark plug to bike frame clearance. Not piston to plug.

Often rotating the slant plug type cylinder head will allow mounting the engine without the plug contacting or being too close to the frame. This is especially useful when motorizing smaller bikes like a 24".

Tom
 
Ducati250Single said:
2door thank you for pointing that out...I feel somewhat foolish. The slant plug head might be the only way to go with some frames.
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No harm done, Ducati. Thanks for offering help. It's why we're here. And I certainly wasn't talking down to you. I didn't mean for it to sound that way. :)

Tom
 
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