Topic: Helicoils Part II

[Phoenix]

As Dion said, "This is my story. It's s.ad but true.  I started a pevious thread concerning helicoiling all the holes in the top of the head.  I have assemled and taken apart the towers and rockers three times now and try to get 7 pounds of torque.  All the holes have helicoils.  I installed the towers and cam caps.  Most everything holds torque except... the bolt on the number one cap.  It gets somewhat tight and then spins.  Now I can't tighten it without spinning and it spins when I try to take it out. Tried to pry up the head as I unscrewed it but you can't get on the head.  Dare I leave it as is?  The season is half over.  I'm almost read to J&B the bolt head to the cup.  Any ideas out there.

Sugestion.  Make a sign:

If it ain't broke, don't fix it!

[PeWe]

The thread for helicoil must be bad if bolt is not possible to tighten.

Correct tap used for helicoil?


That hole can use thread insert like a Time-sert. If a Time-sert start to come out, there is a next size, Big-sert.

There are also self threading inserts by Wurth.
I bought chinese copies that work fine.

But those cannot be used were the knock pins sit.

Too wide, not possible to drill wider than the 8mm knock pin that must sit tight in head aligning cam tower correct

[rotortiller]

Maybe a twinsert is needed.

[Kelly E]

Maybe a twinsert is needed.

Yep, they are much thicker and hopefully will work.

[bryanj]

Also a thing called keensert which has hardened locking pins to stop it comming out

[simon#42]

Worth do something called a timesert , they work well .

[madmtnmotors]

Maybe a twinsert is needed.

Yep, they are much thicker and hopefully will work.

Also a thing called keensert which has hardened locking pins to stop it comming out

Worth do something called a timesert , they work well .

Those cannot be used were the knock pins sit. Too wide, not possible to drill wider than the 8mm knock pin that must sit tight in head aligning cam tower correct

Most everything holds torque except... the bolt on the number one cap.

The cam cap bolts are where the knock (alignment) pins reside. I'm with PeWe on this one, pretty sure helicoil is all that will fit at that location.

[PeWe]

I should try time-sert. They fit helicoil std tap.
But if the thread are really bad, JB Weld to help the time-sert.

In worst case fill hole with JB Weld to glue the thread insert in place.

Or let it harden, drill and tap for time-sert.
Cam holder as drill jig. Possible to drill 6mm drill thru cam holder bolt holes. I have done 6.5mm too.

The easier to get hole aligned, thread too.
Fasten time-sert with loctite 272.

It might be possible to use helicoil too in the new hole in JB Weld.

I tighten max 9Nm, 6.7 ft lbs with a good torque wrench. A small one with 1/4" sockets. Mine cover 2.5-25Nm.

I do not trust my 1/2" socket, 10-60Nm under 20Nm. Too long for small threads.

This should be possible to fix without taking off the head.
Clean surfaces. Good to have a liter Acetone
Not for nails version

[Phoenix]

With everything holding torque except the bolt on the number one cam cap.  Do you think I can go with it.  When putting the bolt in, it was somewhat tight until it was snugged down.  At that point it began to spin not letting me tighten it or remove it.  Don't know how to get it out.  Nothing to pry on.  Was thinking of putting a dab of J&B to hold it.  Do you think that would work.

[Don R]

 I've taken them apart that were running and had stripped threads. Not a good idea but it might last until the end of the riding season. Another idea is to take it apart and lift on the entire rocker stand while trying to loosen the bolt.

[madmtnmotors]

With everything holding torque except the bolt on the number one cam cap.  Do you think I can go with it.  When putting the bolt in, it was somewhat tight until it was snugged down.  At that point it began to spin not letting me tighten it or remove it.  Don't know how to get it out.  Nothing to pry on.  Was thinking of putting a dab of J&B to hold it.  Do you think that would work.

Wow, really grasping at straws. I doubt you would get anyone here to agree to that being any kind of acceptable solution. De-Nile ain't just a river in Egypt...

Remove the cam sprocket bolts and slip the sprocket off the cam sprocket shoulder, then remove all the other cam caps along with the middle bolts for the cam towers. Remove all of the rocker arms while you're at it and you will now have a little bit of free play to lift up on the cam tower while trying to remove the offending bolt. If you still can't get it then I would suggest grinding the head off the bolt so you can finish disassembly for a proper repair.

EZPZ 

[Geoff Hastings]

No way try running the engine with that stripped thread. Annoying I know but, I’d remove all the previously fitted good bolts leaving only the stripped one. Then hopefully the valve spring pressure will help the bolt come out but if not apply some upward pressure on the camshaft while you turn the cam cap bolt. Don’t go down the route of JB weld no matter how good you think it is, either use a timesert type repair or admit defeat and get it filled with weld and start again.

[Phoenix]

Ok.  You're all right.  Just getting frustrated after having it apart twice.  Don't tell anybody I even suggested that/

[HondaMan]

I just finished rebuilding an otherwise-nice 750K2 engine that had a "cam" installed by someone a long time ago, which got the bike parked, apparently.
It took all 8 cam-bearing bolts/studs new Helicoils (4 already were Helicoiled, but badly done, even twisted sideways in the holes) and sealing it shut under the #2 bearing's bolt-hole as someone had broken the bottom right out of the head. Then 2 more of the cam bearing hold-down bolts (there are 4) were stripped out, too. So, when the "rebuilder" attempted to ride it, the vales likely clattered and kept changing their valve lash all by themselves, which explains why all the rocker locknuts were almost round from many, many adjustments being done to them.

It takes a little patience, but it can be fixed. One of the cam-bearing bolts would not unscrew when I started, so after loosening the cam as MadMtn describes above I gently pried upward on the bearing while turning (with cam removed) to help me get that one out. Everything torqued back to spec numbers afterward, using 8mm-long Helicoil inserts.

...Then I had to Helicoil even more, of the cam-cover hold-down screws...I think that mechanic was either a gorilla, or had too much beer to help him out.