Here we go! my 416 build...

Just tore it apart this afternoon and here's what were looking at....

 

Fortunately i recently got the shack back to myself... my shop is quasi outdoors so we are working in the kitchen instead!!!

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cylinder head... yuck! can't believe that spark plug worked just fine!!

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cylinder wall look surprisingly good shape, carbon/oil deposits on very upper lip, boring to the 87mm piston...

 

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and the piston... rings looked good...

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so now what to do??? from the top down...

 

1) what you think about stock cam on the 416.... trying to save some money... could always upgrade later...

2) new crf timing chain... stock tensioner ok??

3) new valves, stem seals, and guides, and i suppose springs too

4) bore for wiseco 87mm piston, 416cc

5) some heavy duty clutch and raptor lever

 

running a uncorked uni filter stock carb b/c mikuni pumper slide keeps binding open on me... xrs only header with gash in midpipe and exhaust, hammered, broke, and never repacked... i might be going back to the stock header and can since it isn't broken... front suspension self serviced and re-valved... rear never serviced, next on the list...

When I pulled my head recently, I had some carbon build-up on the piston, head, and valves after only 2,000 miles.  It was about half as thick as your photos show.  I talked to my cousin about this and he said it is caused by pump gas.  Every engine he has opened had carbon with the exception of motors that ran race gas.

You are supposed to do this kind of work over the winter! Or don't you have winter?

winter is actually the good riding season here!!!

 

here is what the head now looks like!!!

 

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i am currently having trouble finding an 87mm gasket... would love to find a metal one as part of a top end gasket kit... any ideas out there?

Check Amazon for a Cometic gasket where I got mine.

just went to wiseco site and apparently 87mm-89mm is same part number... so, i think i can a little price shopping'

FINALLY!!! got it all back together! took it for a 20 mile lap around the neighborhood!! all seems good!

Did you end up using the stock tensioner with the new crf cam chain?? Do you have a part number for the cam chain you used? I'm having trouble finding one locally for my XR4.

i did use the stock tensioner with a CRF cam chain... chain is same length but slightly thicker...

i don't have the part number... threw the package out....

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