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Post by bigmac on Oct 21, 2013 18:18:58 GMT -5
I ordered a new cylinder head but the valve stems are shorter than the ones on my original head. My original head has 69mm valve stems and the new one has 64mm stems for some reason. This is a problem because the rocker arms will not work with these shorter valves.
Would getting rocker arms that work with 64mm valve stems be the correct solution or would other engine parts need changing as well?
Is there any difference between the two lengths in terms of engine performance? If not, then why would they make valve stems different lengths? It's a huge headache.
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Post by buford1488 on Oct 21, 2013 18:46:56 GMT -5
it's commen..just change the rockers you will be fine..................no big deal....
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Post by bigmac on Oct 21, 2013 20:40:38 GMT -5
I think you're right.
I compared the two heads just now and size wise, they appear to be identical to each other. The camshaft sits at the same height in both heads so I don't think the camshaft chain and/or crankshaft will have issues with the shorter valves.
By the way, this is a completely stock 50cc in case anyone wants to know.
Seems everywhere I look, the valve stems and rocker arms are either 64mm or not specified. In my case, the seller didn't specify and I ended up with the 64mm. I found only one seller on ebay with rocker arms for 69mm valve stems and wants $120 for them. Wow, are these rocker arms rare or something?
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Post by buford1488 on Oct 22, 2013 4:53:50 GMT -5
Camshaft retaining frame and rocker arm assembly Camshaft holder frame complete with new rocker arms, adjusters, shafts, etc. Only $29.  ! scrappydogscooters.com |
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Post by bigmac on Oct 22, 2013 16:19:25 GMT -5
Ended up getting 64mm valve stem compatible rocker arms on ebay for $19. with free shipping. There was a cheaper seller in China, but I don't feel like waiting 1 to 2 weeks. Weather here is mild during the day and cold at night now but soon will be cold all the time so I want to get this thing finished. Guess my 69mm rocker arms can be cleaned, oiled, and stored away for any possible future use. |
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Post by bigmac on Nov 2, 2013 0:29:39 GMT -5
The shorter valve stems worked with the new rocker arms. I prefer the longer stems though. It's easier to set the valve clearances when the stems stick out of the cylinder head more. Had to bend the feeler gauge some to slip it in.
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