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mc 21 power valve


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planb100

 
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mc 21 power valve

Sun Apr 07, 2013 3:12 am » Post: #1 » Download Post

im doing a top end on my mc21 and never done anything usually send it in to get what ever it needs done but im learning now to save money.... I am having trouble taking off the power valve how do you take off this center bolt? any input would be much appreciated thanks


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Middo
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Sun Apr 07, 2013 3:46 am » Post: #2 » Download Post

Left hand thread.......
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planb100

 
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Sun Apr 07, 2013 3:51 am » Post: #3 » Download Post

ya thought so from what i been reading but it doesnt loosen or tighten it just keeps turning and turning
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TuckerBag

 
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Sun Apr 07, 2013 4:00 am » Post: #4 » Download Post

What I am GUESSING has probably happened here is that the thread has been stripped by someone over tightening the nut when trying to undo it, not realising that it is a LH thread.

So, if you can get a wedge or claw hammer or something(?) in behind the bracket and apply a force outwards on the bracket away from the barrel as you turn the nut clockwise, it MAY (not definite) start to take up on what thread is still left and start to undo.

Otherwise it may be time to think about using a grinder or similar Sad

Hopefully someone can suggest a more professional method.
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Dave Ett
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Mon Apr 08, 2013 7:24 pm » Post: #5 » Download Post

I suspect Tuckerbag is right on this one, and the thread has been stripped.

As he says, you should be able to lever the nut onto good thread, or in a worst case lever the entire assembly out of the head - I promise you the power valve is not held in by anything other than friction once you have removed the bolts from the cable carrier (two of them, one shown in your picture)

I've patented the claw hammer technique, so royalties will be due if it works for you, and a complete denial if you break your barrel! Wink

You may be able to get a nut breaker on there, or possibly a dremel to slice it apart. I doubt the shaft is damaged as it is made of very hard metal whereas the nut is relatively soft. Fingers crossed all you'll need is a new nut from Honda...
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greggo
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Mon Apr 08, 2013 11:19 pm » Post: #6 » Download Post

Isn't there a sacrificial C-clip in there? So resistance might be significant until that gives way (but it is supposed to be sacrificial and damaged on removal.)
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Andy
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Tue Apr 09, 2013 12:26 am » Post: #7 » Download Post

The "E-clip" Greggo refers to is only to stop lateral movement of the shaft, sandwiched between the barrel and the oil seal. It clips to the shaft, but doesn't locate the shaft into the barrel. Any resistance you feel when trying to pull the shaft out is either the oil seal sticking, or more likely carbon build up on the RC Valve flaps and shaft.

Unfortunately we have seen a large number of shafts with stripped threads, where you would normally expect to see the nut stripped. Be prepared to buy a new/good used shaft. All MC21 shafts are the same.
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planb100

 
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Tue Apr 09, 2013 1:34 am » Post: #8 » Download Post

Ouch I guess I'm a have to try and source one...honestly I'm just trying to remove it so I could tighten that peskey cylinder nut behind It I mean I was able to take it off but tightening it to the exact same way it was is gonna be hard with that power valve in the way especially since it was a pain to take it off.... If I'm able to tighten the cylinder bolt and leave the shaft the way it is should I consider it a problem and replace it right away or can I just leave It as is since its intact the same way as when it was running ? I'm pretty sure it's been like that for a while

Trying to get my first top end rebuild right Smile
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Andy
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Tue Apr 09, 2013 4:12 pm » Post: #9 » Download Post

To be blunt, if you're "trying to get my first top end rebuild right", then you should replace the defective part(s).

The RC Valves should be removed and cleaned frequently, as dirty (and consequently, sticking) RC Valves are the number one cause of burned out PGM units. If you don't replace the shaft and/or nut (if you're very lucky, it will just be the nut) now, then not only will [a] you just make life hard for yourself when you next need to clean the RC Valves during preventative maintenance, but also [b] suspect you won't even bother doing it at all!

Do the job properly while it's all apart. It will only be expensive in the end, else!
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planb100

 
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Wed Apr 10, 2013 3:09 am » Post: #10 » Download Post

just took it out took forever but once i got that bolt out everything slid right off there was carbon build up in there but not bad unfortunately the screw was stripped and also the shaft has to what appears stripped threads as well


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StephenRC45
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Wed Apr 10, 2013 4:46 am » Post: #11 » Download Post

You'll be needing a new shaft, nut and E clip then. Well worth keeping on top of.
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planb100

 
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Wed Apr 10, 2013 5:14 am » Post: #12 » Download Post

the clip and seal is on its way =) and just ordered the nut.... as for the shaft i was told that it maybe rethreaded the guy is gonna take a look at it if cant im a just be buying another one
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