stripped threads

Technical Help Forum

stripped threads

NstyDevil 07-04-2008, 1:53 PM
well, it happened to me now, i've seen posts where a person's threads on the cylinder head from bolting the cylinder head cover down get stripped due to the soft metal.

i have searched or attempted to search the forums for information on this, but can't locate anything.

i was thinking of shimming up the threads with a toothpick or two as an emergency measure until i can properly fix it.

what is the proper fix? replace the cylinder head? use a thread fixing thingy?

__________________

'80 CX500 Deluxe
approx 80k on the odometer

Re: stripped threads

Shep 07-04-2008, 2:33 PM

NstyDevil wrote:
well, it happened to me now, i've seen posts where a person's threads on the cylinder head from bolting the cylinder head cover down get stripped due to the soft metal. i have searched or attempted to search the forums for information on this, but can't locate anything. i was thinking of shimming up the threads with a toothpick or two as an emergency measure until i can properly fix it. what is the proper fix? replace the cylinder head? use a thread fixing thingy?

The correct device you requires is a,"Thread watchamacallit"<grin>.

OK.It's a Heli-coil kit,

UK

http://tinyurl.com/6xysjc

The Heli coil thread kit you need is a Metric M6 1.0mm fine thread kit.This is the most common thread size used on the bikes so it will come in useful as some later date as well should another of these threads go as they can do with age and previous misuse.

Note:If you are going to do the job without taking the heads off then you MUST secure the area around where you work with rags/Masking tape etc to make sure absolutely NO swarf or metal can get down into the engine/orrifices otherwise you can ruin the engine and you must make sure you fully clean masked area of any swarf/metal as well before you remove the masking/rags.

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Re: stripped threads

NstyDevil 07-04-2008, 2:42 PM
thanks shep. add it to the list of tools i want to get to properly fix up this bike at anytime.

will the toothpick idea work in a pinch though? it's not sealing properly, and i'm leaking a small amount of that goopy stuff in the engine all over my pants.

__________________

'80 CX500 Deluxe
approx 80k on the odometer

Re: stripped threads

NstyDevil 07-18-2008, 11:49 AM
Update:

threads are totally gone.

tried everything to get the threaded bolt to hold.

finally decided after a couple days of having my left leg soaked in oil, that it's safest to hang up the keys for a while, until i can fix it right.

I have a friend who is a sponsor in a lot of the motorcycle races here in canada, and he's going to take the head to the mechanics he knows in the races and get them to tap the head with a slightly larger sized thread and i can match it with a slightly larger bolt size.

__________________

'80 CX500 Deluxe
approx 80k on the odometer

Re: stripped threads

hakko808 07-18-2008, 12:51 PM
That is pretty much what a helicoil does expect instead of a larger bolt it is a sleeve allowing use of the existing bolt. If you are going through the trouble of taking the head off any decent machine shop can handle it, usually for about the price of a kit, although wiht the kit you have the tools and extra pieces to do more if you need.

Re: stripped threads

LRCXed 07-18-2008, 1:04 PM
If your clean and careful, the job can be done with the head still on. Just wrap rags around it and vacuum it clean when your done.
Or even hold the vacuum up to it while you drill and tap the new threads!

If your going to do something, do it right, don't do it half as@*d.
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Re: stripped threads

Shep 07-18-2008, 4:31 PM
I would advise against tapping it to take a larger bolt as the Head Cover bolts are already quite small and there's not alot of meat around the holes.You will most likely end up ruining a good head.They should be heli-coiled which doesn't take much meat out of the hole and allows the heli-coil insert to screw in and re-use the original bolts which in themselves are hard to replace as they are CX/GL specific AFAIK.

I've just had to heli-coil a bottom bolt on one of my CX engines I serviced.I double mask to make absolutely certain no swarf can get into the engine,

This is the1st masking

Then a secondary one,

Before de-masking I make sure I remove all swarf from the worked area and off myself as I want nothing falling into the engine

It's not as hard as you think so long as you take care.
Wearing safety goggles.
Mask up/Drill slight oversize hole(6.3mm or 1/4! drill for M6 heli-coil).
Clean drilled hole out(Cotton buds/Carb brake cleaner/Air blower)
Insert heli-coil then use the supplied snapper tool(it just breaks the tang at the bottom of the heli-coil).
Job done.

Get out your Yellow pages as local engineering company suppliers/Bolt suppliers usually have them.As you are uin the USA they may supply a 1/4" version.You should be able to get away with this if you cannot get an M6 metric version.

HTH :)

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Re: stripped threads

I'm going to GL 07-18-2008, 6:07 PM
I agree 100%! I will never again make the mistake of going to oversized threads!

A properly done heicoil job will last a very long time and allows the use/re-use of the correct hardware. If you just take your time, you'll find it to be a simple job.

1982 GL500 "When the going gets weird, the weird turn pro" - Hunter S. Thompson

Re: stripped threads

larryb22 07-18-2008, 6:54 PM

Another thing you might consider when drilling and tapping for a Heli-coil is also putting grease on the drill bit and tap. The grease should hold most of the junk.

Larry

1971 Moto Guzzi Ambassador. SW Michigan.

Re: stripped threads

Shep 07-18-2008, 8:25 PM

larryb22 wrote:
Another thing you might consider when drilling and tapping for a Heli-coil is also putting grease on the drill bit and tap. The grease should hold most of the junk.

Larry

Damn.I should have remembered that!! I did 6 years on metal work as well!! Doh!!

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Re: stripped threads

NstyDevil 07-21-2008, 5:04 AM
thanks for all the tips and suggestions guys, my friend delivered the head to one of the top motorcycle mechanics at a recent race at Mosport Speedway, and I got it back last night. He did the heli-coil thing to it, and the screw goes in nice and smooth now and appears to hold pretty good once it's all the way in.

So now comes the fun part, putting it back on, and hopefully i won't get the coolant leak from the top tubes, etc....

__________________

'80 CX500 Deluxe
approx 80k on the odometer

Re: stripped threads

Willj 07-21-2008, 9:14 AM
Man was I a little surprised when that valve cover bolt gave way. Things were going so well and then snap!! I ended up going to a machine shop to have them drill the hole and do the heli-coil thing. 90.00 mistake...or lesson learned the hard way.

Re: stripped threads

NstyDevil 07-22-2008, 9:21 AM
bike is back on the road... took me only an hour to take the head off, and 4 hours to put it back on again, but running nice now.

__________________

'80 CX500 Deluxe
approx 80k on the odometer

Re: stripped threads

LRCXed 07-22-2008, 9:58 AM
Make sure you re torque the head a couple times. These head gasket settle very quickly after the motor is run. It only takes e few miles to loosen them a little.

If your going to do something, do it right, don't do it half as@*d.
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Re: stripped threads

Shep 07-24-2008, 6:14 PM

LRCXed wrote:
Make sure you re torque the head a couple times. These head gasket settle very quickly after the motor is run. It only takes e few miles to loosen them a little.

Damn right.Cost me a head gasket one time.Lesson learnt!!

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Re: stripped threads

NstyDevil 07-25-2008, 6:02 AM
i was planning on doing that anyway, just to be sure.

__________________

'80 CX500 Deluxe
approx 80k on the odometer