2v Valve Shimming

Yes, BUT if the bike is an SS you have to take most of the bike apart to get the rear head off.

 

Don't know about the Multi but on a 916 you need £100 worth of gaskets to remove/replace the heads, so despite it being a right faff messing with the rear cyl exhaust valve shims (916) it is still preferable to removing the heads.

I have MBP collets in both my bikes and rarely need to change a shim, in fact since I've had the MBP collets I've never had a valve go out of spec (by that I mean the spec that a dealer would use) so I've only altered them to get them spot on as I'm being finicky.

I always remove the belts though because if you want to set the closer clearances tight, you can't feel drag except by turning the cam with your hand.

 

This thread is about the 2v air-cooled models; removing and replacing the heads is not too difficult or expensive. You seem to have veered away into talking about the watercooled 4v models @Dukedesmo where the considerations are entirely different.

 

Maybe I have missed something, but even if it's an SS with the access challenges (rear shock out...) then you can always check the clearances with the heads on, and then decide whether enough needs changing (e.g. closers) to justify taking heads off.

 

Absolutely.
Check with the heads on, and if they are near enough leave them alone.
If they need re-shimming, take the heads off and clean up the valve seats, then do the shimming job properly.
IMHO.

 

If the bikes already been run will that carbon already of been burned away , why will there be carbon between the valve and seat after being used in the road ?
Do they suffer with hanging valves ?

 

Veered indeed, but I was thinking that maybe a multi also uses head gaskets of some type?

I know the SS/Monster doesn't but I still wouldn't be removing the heads for routine valve servicing, far too much unnecessary work IMO.

 

One thing that may not have been mentioned is if you need to change the closer shims/remove or replace collets then care is needed when levering down the closer rocker as if your lever tool is makeshift and slips (ie using a screwdriver/similar) then the closer shim and the collets if now loose can ping off the valve with some speed, if the opening rocker is off to the side then these can disappear off into the distance. You can have the opening rocker just above the closer shim to stop it flying off the valve as a means of helping avoiding this. If you have pucka tool for levering the closer rocker then this may not be as much of a problem.. PS they may be launched with enough force to put an eye out if peering intently at the valve while attempting to remove or insert collets.

 

It is true that modern engines accumulate less carbon in the combustion chambers than older engines did. A correctly-tuned engine used at full throttle a lot may have no carbon on the valve seats at all. But if the mixture is a bit rich, or a bit of oil is getting up past the piston rings, and the engine often runs while cold or idling, there might well be some carbon (or that biscuit-coloured crud which forms on piston crowns). If you don't look, you won't know.

 

A tip for you. Once you have pushed down the closing rocker, slip a 10mm or 3/8" Allen key between the far end of the rocker and the base of the cam box. When you release the pressure the spring will jam it there keeping the rocker in the fully open position, making it easy to remove/replace closer shim and half-rings

 

Good tip, I use a piece of nylon bar 10mm.

 

All good advice............

.....but I prefer pushrods :wink:

 

After having spent yesterday afternoon tinkering with a 2-stroke, I have to say they have their plus points too.

I've heard it said that anything more than 2 strokes is a wank...

 

I must be a rotary then ...... continuous motion .....