My Valve Adjustment Story So Far: Could Use Some Advice?

[Colonel Nikolai]

I was hand tightening this bolt and after 3.5 turns it was a little sticky. Tried backing it out and backing it in a few times. Tried a few different bolts in this spot. Still a little sticky. Eased it a bit with an Allen just to see if this was a little hangup and BOOM. Blew it.

What can I do now? It's the bolt over the #2 cylinder intake.

[JetdocX]

Heli-Coil.

[Colonel Nikolai]

Heli-Coil.

Thank God. I was worried this meant "source a new valve head". I feel really stupid for doing this but MAN I was hardly using any force at all

[Colonel Nikolai]

When I look at the picture again it looks like I just overtightened it. But the head didn't look very sunk and I was not using much force at all. *sigh*

[Colonel Nikolai]

After doing some research, I'm thinking of working with a machine shop to do the helicoil work. With the the engine at an angle and all it seems very easy to get the drilling angle wrong which would put me where I was when I started.

I've also read that fine threaded helicoils in aluminium are very problematic since there just isn't enough material to hold onto. This implies a different bolt, which might also have to be custom machined.

Some folks on the pro drag racing circuit say they will cut helicoils into brand new heads just so they don't run into the problems I just did since the helicoils are stronger than the originals.

Any thoughts?

[Bixxer Bob]

I made many many aircraft modification kits of various types in aluminium in the 1980s and we ALWAYS installed helicoils as part of the manufacturing process - the raw aluminium is simply not up to repeated use -  so I'm not surprised that the drag race guys do the same.   I guess the automotive industry don't due to cost and that the odd failure doesn't usually end in a smoking hole in the ground.

In this case I would definitely use a (good) machine shop - but be sure they do this sort of stuff all the time rather than let them experiment on your head.  Ask them what they plan to do and how.  If they're any good they'll be only to happy to explain it to you.  If they're vague, walk away.

I've not heard of troubles with fine thread helicoils; that's not to say they don't exist, but I suspect the probs are largely of their complainant's own making.  Helicoil designers wouldn't produce a product that was flawed from the outset if used properly.

[Colonel Nikolai]

In this case I would definitely use a (good) machine shop - but be sure they do this sort of stuff all the time rather than let them experiment on your head.  Ask them what they plan to do and how.  If they're any good they'll be only to happy to explain it to you.  If they're vague, walk away.

Good points. Curve-ball for you: rented a mechanic's bay in a machine shop this month so I could access their tools and environment and I suppose expertise. And I bought the right size helicoil too, tonight. So I'm thinking of starting there. The guy in the bay next to me said he'd done a good deal of them in steel but never aluminum. So now I'm wondering...

[Birdy68]

make sure there is some free play in the cable at the twist grip end there is an adjuster there at the twist grip...

:?
Yeah - there was NO free play - even with the adjuster fully twisted in.

So I pulled the carbs again and saw that the piston in the carb on Cyl.#1 was 5 mm higher than the other two! It wasn't seating down correctly.

So I dismantled the carb cover and found a perforated O ring on the vacuum seal and the fact the the teflon washer was not seating correctly on the needle head. So I made the corrections and could fix the piston to seat down fully.

Reinstalled and....

make sure the cable is setting into the ferrule at the carbs properly ...

:oops:  Yup - noticed this was my hic-up!
That 90 degree cable tubing was not sitting down in it's ferrule!!!

Something soooo small and on the surface!?!
It really goes to show that it could make sense - from time to time - to simply take a step back, mug of tea with some biscuits and view things over...

All is working well now!


@ Col:
Ooooh - sorry to hear you have other 'issues'! Hope it gets fixed easily.

Cheers all,
Birdy

btw - pre-ordered the 800XC - will be available around March-April next year!
Still keeping my Steamer though - it shares the same Birth Year as my son  :lol:

[Bixxer Bob]

It's hard to call CN, if access to the damaged hole is good then you should be ok.  I'm not familar with where it is.

"The chances of it going wrong is equal to the square of the difficulty divided by the inverse of the operator's experience" or something like that....

The key is to not dive straight in. Get a lump of aluminium  (it can be any old casing casting etc as long as it's got some depth) and practice until you are sure you have it cracked.  10 or 20 wasted helicoils are still cheaper than a scrap head.  Duplicate what you are up against as best you can so drill a hole the root dia of the original thread, if you can tap that size you can do that, then drill with the oversize helicoil drill then tap with the helicoil tap.  Lastly, fit the helicoil. Practice until you've got it.

Lubricate the drills and taps with a drop of paraffin; paraffin is a good lube for aluminium.  I think you call that kerosene...

Oh, and if  I was really worried about doing a difficult fix, I'd opt for using a hand drill if I could get in with it.  You have much more control over what's happening - even with the revs wound down on a battery drill, things can go wrong pretty rapidly :shock:

When it comes to the tapping, if it's difficult to get the tap wrench aligned properly so the tap goes in square to the hole try making up something like this:



You can support the tap in alignment with the hole using the drilled bar while turning the tap with a vice wrench or similar.  Again practice first till you'er happy.  Good luck!!

[Mustang]

It's hard to call CN, if access to the damaged hole is good then you should be ok.  I'm not familar with where it is.

it's in the cam caps , thats where the bolt holes for the valve cover are .

be very careful cuz if you screw up you will need a new cam cap/bearing which are only available with an entire cyl. head. they are the bearing surface for the cam, and are line bored with the head at time of manufacture of the head .

a heli coil should be fine as the valve cover bolts are only torqued to 7nm
the thread size for the valve cover bolt is M6x1.0 mm
a word of caution though when you do it .............remove the cam cap and repair it off the engine  for two reasons

1. you won't accidentally drill into the camshaft , and DO NOT drill all the way thru (remember it's a bearing cap)

2. you won't get any aluminum swarf into the engine by doing it on the bench

3. you will have much better success of repair done off the bike

[Bixxer Bob]

That helps!!

As I said,  Im not familiar with where that bolt goes, I thought it was on the head somewhere.

Repair on the bench is much easier and safer!!!

[iansoady]

Given the potential for things to go very wrong here, I would be tempted to glue a bit of studding into the remains of the threaded hole with JB weld or similar then make up a sleeve nut to go on top. It's only holding the cam cover on after all, and a little bit of silicone (stress the little) on the gasket should hold the oil in.

Personally I'd rather have a slight oil weep than run the risk of having to buy a new head.

But then I do try to find the easy way out.

[Colonel Nikolai]

Thanks you guys! Everyone! You are amazing. But I'm starting to go back on myself after reading all this and take it to a machine shop again.

I'll try with a piece of practice aluminum with a half dozen or so coils. If I find myself fumbling around after that, I will definitely abort the mission and try a machine shop. And yeah, I have to take the cam cap off, since it's #2 anyway. *sigh*. It's good to know that since if it was 1 or 3 I might have tried to do it in-situ. :shock:

I think I need a hug or something. I'm a scared, quivering little thing after this ordeal.

On a more positive note: I checked the valves on the steamer in the stable: all 12 within spec: intakes sitting low at .102 so I will keep an eye on 'er.

[Colonel Nikolai]

After checking the valves on my steamer, putting her all back together again. Ran her up to hot and let her cool down again. I see a little bit of weep on the right side (of the photo) gasket. I skipped using the recommended gasket sealer as Mustang does. Guess I'll have to opener up again and use that junk.  :x

[Bixxer Bob]

So did you do the helicoil yourself or did you pass it over? :)