Primary Chain Adjustment

I searched old threads but didn't see an answer to this question.
The manual calls for a total of 3/8" of slack ( up+ down) in the primary chain.
But how hard should I push on chain with my thumb to get this.
With the primary cover off I can see quite a difference in movement between a modest and a firm push on the chain.
I can imagine if adjusting through the access hole my ability to put a lot of presure on the chain is pretty limited.

So just reach in and lift up and push down with finger tip until feeling a bit of pressure is OK?

TIA

Bob

Yep

andychain said:

Yep

Click to expand...

+1.
It is set at the TIGEST point :!:

Bernhard said:

andychain said:

Yep

Click to expand...

+1.
It is set at the TIGEST point :!:

Click to expand...

Good point, Bernhard; normal response is to merely check the chain tension without verifying any tight spots. Pull the spark plugs and roll the engine through a few revolutions using the rear wheel (in gear, of course) to make damn sure the chain never goes guitar-string tight anywhere. You're better off to have the chain too loose than too tight. Your bearings will thank you!

Thanks guys.

if its got tight spots, better throw it over your shoulder. Too tight a chain can come off when racing. Saw that happen once. and the g/box exploded during the next race or so.

The ~3/8+" chain slack should be just gravity slack in lower run and just lift weight of upper run chain. Fill so links about mid way in lube level, chain will flop beyond your finger and gravity check or measured slack. There is little to no downside to over loose 1' chain but there sure can be with just one over tight event so best is set on conservative side to check on full road heat then creep up on it and note slack when cold for next simple finger eye flip setting. If you are finding noticeable looser or tighter 1' chain on rotation consider crank or more likely main shaft bent. Runing w/o cover a bit will help reveal if over slack & or wobbles to deal with now or later. Supposed to pull primary back with drive chain then adjust gearbox forward to take slack out of mounts and bearings then set drive chain but don't seem that big a deal.