Help required! Cam cap Failure!

[Storm Trooper]

Think this has to be a first! Serviced the bike over the winter, done the valve clearances, changed shims and all put back together as per workshop manual with correct torques. 1000 miles later and on Sun night after coming off the boat at Troon, rattle, rattle rattle. Recovery home. Knew it wasn't CCT's, as manuals were fitted 7 years ago when I got the bike, so strip down last night revealed this!!!

Advice, help or miracle required please.



Is it possible to replace with another cap if found to fit with similar wear, as I know the originals are all machine matched at manufacture. Is there a possible fix to this, or is it a new head if I can find one as they are like hens teeth.

Worst case scenario is the expense of a 2nd hand engine or even bike to get the head, as my bike is totally sorted other than this effin failure!!! I am totally gutted with the prospect that I may not get it sorted!

Any help, advise, or if anybody has a spare head they would be willing to sell, with matched cams and caps, would be appreciated so much I cant put into words.



Many Thanks

Nigel

[lloydie]

Front or rear head ?
They are matched to the heads and my thoughts would be new head .
I have both heads spare :-)

[Storm Trooper]

Lloydie,

It is the Front head Exhaust cap, so a front cylinder head would be required. Are you in a position to help a very depressed storm owner?

Cheers

[lloydie]

I am :-) tho I'm at work

[AMCQ46]

I have never seen that before......... it kind of hints that it was not assembled correctly when you did the shims, if not I don't know how it could fail.

you are correct that they are line bored as a matched pair, so it will be a risk if you just put an other cap on it at random............. but the worst that can happen is that you need a new head if it is too tight or too slack.............and you already need a new head!!!!!!!! so might be worth a try

[Storm Trooper]

I cant understand the failure either as I checked and double checked everything when I put back together after shim replacement over the winter. All the rest are ok.

Been trawling the forums and speaking to a lot of specialists today, and the consensus is that there is no fix to the problem. The caps and the head are machined as one at factory so therefore need to be matched to provide the correct tolerances. Also the fact that the cam has probably been moving will mean the seat on the cylinder head will not be true now either. Only solution is a replacement head and they are like hens teeth due to the number of CCT failures.

A couple of engines on Ebay. One really really tatty at £275 and the other really clean at £700 quid so both those are a no go.

Will wait and see what comes up.

[kitsun]

what about getting a completely new head assembly from Partzilla? USD519 + USD100 shipping?

http://www.partzilla.com/parts/search/H ... parts.html

k

[AMCQ46]

that's totally sh1t mate. if you were closer I would have loaned you my spare engine till you find one, but it could only be a loan as I still plan to do some work on it.

sounds like you have to follow up with Lloydie on the heads he has spare. you could also try and get a rear head machined to fit the CCT on the other side

[tony.mon]

Hold on.....calm down......
In the past I have successfully mixed and matched caps several times, with no noticeable issues.

Sure, it's best to use the ones that are line-bored to the head, but the tolerances are very close; you might need to try a couple to see which one fits best, but that's all there is to it.

As long as the cam doesn't move up and down, or side to side, but still goes round, no probs.

I've got loads spare, if you want I'll ship three up and you can see which one fits best, then return the unused ones.
But if someone local has some spares, try those, it'll be quicker.

Panic over, nothing to see here, move along, move along.....

[bigtwinthing]

Hold on.....calm down......
In the past I have successfully mixed and matched caps several times, with no noticeable issues.

Sure, it's best to use the ones that are line-bored to the head, but the tolerances are very close; you might need to try a couple to see which one fits best, but that's all there is to it.

As long as the cam doesn't move up and down, or side to side, but still goes round, no probs.

I've got loads spare, if you want I'll ship three up and you can see which one fits best, then return the unused ones.
But if someone local has some spares, try those, it'll be quicker.

Panic over, nothing to see here, move along, move along.....

Tony would fitting plasigauge work and then measure the amount its squashed, and make sure that the caps have minimal clearance? ( just a thought no piss taking pls)

[Storm Trooper]

Tony,

That would be much appreciated. I would test and see what tolerance is like and return any or all of them if not suitable.

Cheers

Nigel

[tony.mon]

Tony would fitting plasigauge work and then measure the amount its squashed, and make sure that the caps have minimal clearance? ( just a thought no piss taking pls)

Plastigauge will work perfectly.
Never bothered with Plastigauge myself, just tried to move the cams after clamping down- if you can feel any movement it's too much, and fit the cam without the chain and see if it revolves sweetly, if so, job is, as they say, a goodun.

The oil pumped at high pressure between cap and cam prevents any metal-to-metal contact, you rarely see any wear marks on the caps or cams anyway, unless manuals have been set too tightly or the engine has been run very low on oil, and oil pressure has failed.

[bigtwinthing]

Tony would fitting plasigauge work and then measure the amount its squashed, and make sure that the caps have minimal clearance? ( just a thought no piss taking pls)

Plastigauge will work perfectly.
Never bothered with Plastigauge myself, just tried to move the cams after clamping down- if you can feel any movement it's too much, and fit the cam without the chain and see if it revolves sweetly, if so, job is, as they say, a goodun.

The oil pumped at high pressure between cap and cam prevents any metal-to-metal contact, you rarely see any wear marks on the caps or cams anyway, unless manuals have been set too tightly or the engine has been run very low on oil, and oil pressure has failed.

Cheers i hope i never have to try that however. I take it just ensure the caps are torqued to correct figure

[tony.mon]

The caps have little dowels, that can snag when fitting. If they aren't pushed fully home before tightening the bolts then the pressure from tightening a bolt will cause a failure.

It's easy to do.

[VTRDark]

I take it just ensure the caps are torqued to correct figure

Be careful with torquing used bolts up to exactly the specified torque as in the manual as you can strip the thread You will find that after many times of being removed and then tightened back up that the bolts stretch. I tend to do them up either by feel or just under the specified torque to allow for any stretched bolts. The important thing is that they are all done up evenly and consistently. Even a half turn tightened on the rachet can make difference to valve clearances.

(:-})