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September 1st, 2004, 05:01 AM   #1
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rocker cover thread stripped....not happy!!!!

Hi all

have just had the frustration of finding that the thread in the head for the rocker cover bolt which goes through the exhaust rocker pin is stripped.

have just had new rocker bearings put in by dealer after i removed the rocker cover myself.

when putting back on had difficulty as the pin was not set straight. thought i was careful, went for a ride, and found oil leaking. thought hadn't let silicon set long enough, so removed rocker cover, cleaned, re-siliconed, and then couldn't get bloody bolt to torque down!!!

what are the options???can it be rethreaded???hoping don't need new head!!!!!

ARRRRRRRRRGGGGGHHHHHHHH!!!!!!!!!!!!!!!

Have fun (I'm not right now!)
Jeff
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September 1st, 2004, 08:39 AM   #2
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A 1/4" x 20 SAE thread may be tapped into the stripped hole as opposed to installing a metric insert. Said option removes very little additional material.

Hope this helps.

Best Regards,
Dale
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September 3rd, 2004, 01:49 AM   #3
eon
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Hi Jeff,
This reply is a bit late sorry, I had the same thing happen to me - I think (I've just had a couple of rums after work) anyway as I screwed the bolt in, it got damaged by the rocker pin which in turn ruined the thread. I found that the hole was deeper than the thread so I tapped it out a bit more and used a longer bolt that I pinched off an old SR500 I had lying around, hope it helps.

Ian
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September 5th, 2004, 03:04 AM   #4
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Ian

thanks for reply(and Dale!)

actually tried that the other night, but had trouble getting the bolt through the upper part of the thread, and unfortunately the lower part ended up stripped too.

in the end put a heli-coil in.

after thinking about it, options were to pull head off or whole motor out of bike. since pulling head off would have required a new head gasket and 2 hours of driving to get one, i pulled the whole motor out, drilled, heli-coiled, and bolted it all back together.

then i did a valve adjustent - how quick and easy is that with motor on the bench!!!!!!took about 2 minutes!

did 2 tanks of juice this avo and it looks OK. i know i'll be more careful next time!!

Have fun
Jeff
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September 5th, 2004, 04:48 PM   #5
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Originally Posted by LINEAWEAVER
A 1/4" x 20 SAE thread may be tapped into the stripped hole as opposed to installing a metric insert.
That's a bit rough, isn't it? It makes it really easy to stuff up reassembly in the future by getting the bolts mixed up. I realise sometimes there is no other option but usually if you see mixed threads on a machine you should start looking for other "dodgies" that might have also been done.

Generally springlike coil inserts (Helicoil, Loc-coil, etc) are stronger than the original thread if you can get the coil and bolt engaged into the metal at least 2 times the bolt diameter. Coils are good in that the OD of the coil is not too much bigger than the original bolt so you can fit them in thin areas, but they need special taps to cut the new thread. They can be a real nightmare if you don't break the insertion tang off cleanly and straight as the thread will pick up next time you try to remove the bolt.

For high strength areas you can get thread inserts (Keysert, Locinsert etc), in Grade 8 steel or stainless if necessary. Can be a problem in tight spots as the outer thread is one or two standard tap sizes bigger than the bolt. As the bolt thread is pre-machined, no problems with threads picking up.
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September 5th, 2004, 09:40 PM   #6
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Originally Posted by Brad
Originally Posted by LINEAWEAVER
A 1/4" x 20 SAE thread may be tapped into the stripped hole as opposed to installing a metric insert.
That's a bit rough, isn't it? It makes it really easy to stuff up reassembly in the future by getting the bolts mixed up. I realise sometimes there is no other option but usually if you see mixed threads on a machine you should start looking for other "dodgies" that might have also been done.

Generally springlike coil inserts (Helicoil, Loc-coil, etc) are stronger than the original thread if you can get the coil and bolt engaged into the metal at least 2 times the bolt diameter. Coils are good in that the OD of the coil is not too much bigger than the original bolt so you can fit them in thin areas, but they need special taps to cut the new thread. They can be a real nightmare if you don't break the insertion tang off cleanly and straight as the thread will pick up next time you try to remove the bolt.

For high strength areas you can get thread inserts (Keysert, Locinsert etc), in Grade 8 steel or stainless if necessary. Can be a problem in tight spots as the outer thread is one or two standard tap sizes bigger than the bolt. As the bolt thread is pre-machined, no problems with threads picking up.
Hi Brad,
Often is the case that the installation of a threaded insert will further weaken an already questionable area by requiring a substantial amount of material be removed in order to accommodate said insert.

Since a coarse thread has a higher grip capacity than that of a similar size finer piece (ie .250 x 20 tpi SAE vs 6mm x 1mm tpi Metric) and given the 1/4 x 20 SAE thread is a mere few thousands of an inch in diameter larger than that of the OEM 6mm such an upgrade to 1/4 x 20 in my opinion is a far superior alternative to that of insert installation albeit best when all screw holes in the cover are addressed. (Which is indeed protocol)

In addition it works wonders regarding the sealing of potential mating surface leaks.


kind Regards,
Dale

Ps
I perform said upgrade on many engines each and every year simply as a precautionary measure. As for "stuffing up reassembly" and / or other "dodgies" it is also of my opinion that one should always be on the alert. :P
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September 5th, 2004, 09:55 PM   #7
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Originally Posted by JJW501
Ian

thanks for reply(and Dale!)

actually tried that the other night, but had trouble getting the bolt through the upper part of the thread, and unfortunately the lower part ended up stripped too.

in the end put a heli-coil in.

after thinking about it, options were to pull head off or whole motor out of bike. since pulling head off would have required a new head gasket and 2 hours of driving to get one, i pulled the whole motor out, drilled, heli-coiled, and bolted it all back together.

then i did a valve adjustent - how quick and easy is that with motor on the bench!!!!!!took about 2 minutes!

did 2 tanks of juice this avo and it looks OK. i know i'll be more careful next time!!

Have fun
Jeff
Hi Jeff,
When installing 1/4 x 20 screws into the rocker cover one must enlarge the pilot holes to 1/4 inch.

Just the same, happy to learn it all worked out in the end.

kind Regards,
Dale
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