Other 760 exhaust bolt size reducer

[bach6177]

What is everyone using to reduce the bolt size on a 760 cylinder to fit a b pipe manifold?


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[x2mafia]

8x1.25 timecert

 

[37]

Go with steel Time-Serts in 8x1.25. If you use stainless inserts with stainless bolts, you risk them galling together and creating headaches when you go to pull everything apart. I usually use red or blue Loctite to install the inserts even though they're a good mechanical fit. You'll need the full Time-Sert kit to install. Don't expect the inserts to work alone.

If you ride in saltwater, assemble them with good marine grease (Yamalube Marine Grease works great) and reduce your torque values ~20% to compensate for the friction reduced by the grease. Assembling with grease is a good practice regardless. Disassembly is easier and risk of galling is near zero.

 

[bach6177]

Thanks for the help guys


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[rowsto]

Drill the holes in your manifold to 10mm

 

[96superjet]

Just picked up a 760 short block and getting ready to deal with this same decision. Simply enlarge the bolt holes on the exhaust manifold and use M10 bolts or go the time cert route.

I'm 99% freshwater riding but just want something simple and not problematic.


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[yamanube]

I'd go with inserts, some day you might want to go back to a 61x cylinder or you might want to sell it and it seems 61x manifolds sell easier.

 

[JetManiac]

You will not be happy trying to get m10 bolts into the top middle 2 spots on a bpipe manifold. M8 bolts are hard enough to fit and tighten.

 

[96superjet]

Sounds like time certs it is then.


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[96superjet]

OK, so now I watched this time sert video and have more questions.

1. Can you just thread the time serts in or do you have to chamfer the top part of the hole with their tool?
2. Do you need their install tool or can you spin them in by hand?

https://www.youtube.com/shared?ci=mrkDlx_Kp_o



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[bach6177]

My last factory pipe manifold was drilled out for m10 and the two top bolts were impossible to get tight. Also kinda kills resale of a manifold that was drilled, no 701 guys will want it.


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[TheBuzzard]

just put helicoils in the top 2 inner holes and leave the rest 10mm. its very easy to just use a tiny sleeve on the 8mm bolt if it ever needs to go back on a 61x cyl. very short pieces of 3/8" copper tubing works perfect. its only required to center the manifold correctly.

 

[augustaf]

Sounds like time certs it is then.


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You might consider M8-1.25 Helicoil inserts in this application- cheaper, easier and have been working well and holding up for me for 20 years on 62T cylinders. - M10-1.25 holes in the cylinder are just right for these inserts, no drilling, no chamfering needed.

 

[Christian_83]

I did a lot of research about thread repair and found an engineering site that claimed helicoils to be superior to timesert. I bought a set of both and did my own research and test. The helicoil was stronger than the timesert (if done correctly)
But is the M10 holes for the 760 exhaust 10x1.25mm ? (does it fit the outer sleeve threads on the timesert?) or would you have to tap the timesert threads?

 

[Christian_83]

Post#15
http://www.x-h2o.com/index.php?threads/pos-predator-pump-inserts.174790/#post-1862005

 

[JetManiac]

I did a lot of research about thread repair and found an engineering site that claimed helicoils to be superior to timesert. I bought a set of both and did my own research and test. The helicoil was stronger than the timesert (if done correctly)
But is the M10 holes for the 760 exhaust 10x1.25mm ? (does it fit the outer sleeve threads on the timesert?) or would you have to tap the timesert threads?

Yes 62t cylinders (701 and 760) are m10x1.25. The m8x1.25 helicoils screw right in w/o modification to the cylinder, so you can always pull helicoil out and be back to stock.

 

[96superjet]

Sounds like time certs it is then.

OK... revised my decision. Helicoils it is then.

I suspect I should throughly clean/chase the bolt hole threads with a tap or wire brush and hit them with break fluid cleaner. Insert the helicoils with blue thread locker and then bolt up my manifold.

On a side note, who's got a good deal on an ADA head (non girdled). Looking to do a budget build for a Blaster.


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[Christian_83]

No never insert helicoil with thread locker one of the benefits with helicoil is that its a spring, that can spread the load better and also easy to get out with the correct tool, if you want to replace the hell coil.
BTW the ORG helicoil have diffrent helicons, one with thread locker that i used for my mid shaft. The middle spring is hexagon, really nice coils.

 

[96superjet]

Hate to beat this horse to death, but...

Looking at the myriad of spring style inserts which are available and have more questions.

text on http://www.stanleyengineeredfastening.com that tangless seems to be the way to go.

Tanged vs Tangless:
"They eliminate the need for tang break-off and tang retrieval and allow for non-destructive insert removal. Tangless inserts are easily adjusted and easily removed after installation."

Free Running vs Screw Locking:
"Free-running inserts automatically adjust themselves, radially and axially, to any expansion or contraction of the parent material."
"Screw-lock inserts permit repeated assembly and disassembly yet will not relax their grip on the screw even in tough metals such as cast iron, alloy steel, titanium, etc."

Material type:
"Available in Stainless Steel, Gall Resistant and with Primer Free II."

I'm torn on what to pick. Suggestions...

 

[yamanube]

Sell that 760 cylinder and get a 61x cylinder.