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What the max a VF250 head can be decked ?

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bkmartin

New member
Took my heads to machine shop to true up after blowing head gasket on the #5 cylinder . They cut .020 off the head. My question is how much clearance is needed between valves and piston. Not able to find that information. Thanks
 
When they shaved that much off the head , how did they check camshaft bore alignment after this procedure ????
 
I am not seeing any connection between a cylinder head of an over head cam shaft motor being shaved and the clearances between the cam shaft journals and their bearings? What am I missing?
 
I guess you need to draw a picture.----Likely the ends needed 0.015 " shaved off and very little in the center.----Thus the bearings are no longer aligned.----So easy to have the shop check this !!!
 
The cam shaft bearings and cam shaft caps are on the opposite side of the shaved surface.

Cam shaft area is completely untouched I would imagine.

 
I assume it was shaved because it was WARPED.----So now one surface is flat and cam journals are still WARPED and out of line.
 
Easier ways to repair one damaged spot on a head.----Every aluminum outboard head I have taken off has been warped.-----Perhaps the OP will post the reason for taking off 0.020" ----And post results of checking cam bearing journals.
 
Interesting. No mention from Yamaha of checking cam bearing journals for warpage. Only the block side of the head.
 
Far as taking off the .020 that what the shop said it took to clean the head up. There is wapage on the cam bearing journals around .008 on the rear side of the head. The sad part about this is he took .020 off of the other head too. Now I’m got 2 heads to replace .
 
bkmartin said:
Took my heads to machine shop to true up after blowing head gasket on the #5 cylinder . They cut .020 off the head. My question is how much clearance is needed between valves and piston. Not able to find that information. Thanks
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I'm not a big fan of decking marine engines! Not unless you plan to use very high octane fuel. I've seen many detonate.
Good luck!
 
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