Oil Leak from Carb Manifold at Head

[Johnwhatsisname]

I have a small but irritating oil leak that is coming from the outermost bolt on the carb manifold, front cylinders and back cylinders. It seems like the bolt holes are impinging on an oil gallery. I see from the part numbers of the bolts that these two bolts are in fact supposed to be 16mm long whilst the other six are 20mm. I guess in the past that these have been swapped around (easy to do) and the longer bolt has breached the oil gallery.
Does anyone have any suggestions on fixing this? I was thinking of putting some PTFE tape on the appropriate length bolts when I reassemble.
I have to take the head off anyway as the water spigot at the top has corroded and needs to be replaced.
Thanks in advance. John

 

[maleko89]

Hi John, those two bolts are shorter and do penetrate an oil pocket. The manual says to use sealant. I use an ultra black sealant to keep the area dry.

Mark

 

[Jack Hammer]

Ultra Black here too. PTFE is not a good idea with hexes as it increases torque needed therefore easy to round off the bolt head.

 

[Johnwhatsisname]

Thanks for the replies. Is "Ultra Black" a brand name. Could you be more specific as to what it is so I can get an equivalent here in South Africa?

 

[Jack Hammer]

A variation of black RTV silicone. As long as you use silicone resistant to oil you are fine. Use what you can find locally.

 

[Johnwhatsisname]

Is this the Permatex product?

 

[Jack Hammer]

Yes.

 

[maleko89]

Yamabond 4 or 5 would work too.

 

[MaxMidnight]

Any silicon sealer will do the job but don't use too much - just a light smear around the manifold hole top and bottom.

 

[one2dmax]

Very normal and nothing was damaged. Just need to silicon it up. Let it drain out completely first and then dry the location so the silicon will stick. See screenshot from the Yamaha service bulletin.

 

[Johnwhatsisname]

Great thank you. That mystery sorted.
Now, how to undo the the camshaft sprockets. Can I turn the crank/camshafts in order to access the bolts? I'm sure this has already been posted but I am not sure how to search the Gen1 threads. Could someone point me in the right direction

 

[Fire-medic]

http://vmoa.net/VMX12-Service-Manual01.pdf
Print out a copy & use a loose-leaf binder.

 

[one2dmax]

I would not normally remove the sprockets to remove and replace. Watch our youtube video on setting the cams.

 

[Johnwhatsisname]

one2dmax: Are you able to offer some advice on this?
I have had my heads cleaned up with a brass spigot pipe for the coolant. As the valves clearance have now all been set, I am reluctant to remove the cams and would rather break the chains. Are you able to recommend a tool for this? Thanks

 

[one2dmax]

I don't ever both breaking the chain though the new chains from yamaha come with a link to squeeze once you install it. I think we've used an RK chain breaker tool before on them.
Again, I think it's best to remove the cams and slide them back in with the chain intact (but you have to have the chains on the crankshaft before you put the halves together too). Taking the cams in/out will not change the shimming.

 

[Johnwhatsisname]

Thanks for the input