Topic: Additional studs for a bored out engine?

[imjustheretodelivermail]

Picked up this engine from a guy that said it had a 836 kit installed. I didn’t really believe him at the time but I saw these extra studs and can not seem to find a similar set up online anywhere. Does anyone know what is going on here? It looks like it would be a pretty intensive job to add those and I don’t see any bored out engine with them online at all so I was hoping someone on here could shed some light on the subject. I don’t know much about performance mods for these bikes so forgive me if this is a silly question. Also, please ignore the paint, I’m in the process of stripping and polishing the entire thing.

[Don R]

 In the day there weren't any valve springs especially made for our bikes. The ones you could get were really stiff and could strip out the 6mm bolts holding the cam holders to the head. Those additional bolts pressed down on the cam towers to add a little down pressure.

[gschuld]

The seller was likely right. Or at least the engine has a modified cover meant for a modified engine.

George

[paul_cb836]

Cycle X still sell them.

[Don R]

 I got one this week too! I will make use of it.  One engine I have had oversize cam tower and head hold down bolts, probably the PO stripped the cylinder head and that was the easy fix.

[MRieck]

You can replace the 4, 6mmbolts that go across the head with CBX exhaust studs. Much better clamping.

[PeWe]

You can replace the 4, 6mmbolts that go across the head with CBX exhaust studs. Much better clamping.

How much can these studs be tightened?

[Alan F.]

The 6mm bolts got what 10 inch/lbs?

[PeWe]

It depends on the fasteners class. (And the thread depth that must cope with it too)
Shiny  class 8.8  9.9Nm (7.7 ft lb) as stock seems to be.
The black ones slightly more.

Then the stiffer M6 class like 10.9  15Nm/11 ft lb.

So if the CBX ex studs are 10.9 the alu threads in cylinder block might withstand a little more since they are rather deep. But I should be too worried to tighten 15Nm.
Stiffer stud will also flex less.

I ordered a batch of various shiny allen head M6 class 10.9 some years ago.

It would be perfect  with fasteners there that can be tightened as the cyl studs, 20-22 ft lb.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.fastenermart.com/files/metric_tighten_torques.pdf&ved=2ahUKEwj7x5DNhp_0AhUXzYsKHSweBbwQFnoECBQQAQ&usg=AOvVaw2cP2K5Y1Kq0i4rYLZknaJ2