if i put sythetic oil in my clutch housing with it stop the lag that causing the grear box to crash when its cold

 

I would assume you are talking about the primary? 3 things will improve this. While synthetic will flow better I doubt you would see the diff. ATF would work best. The clutch needs to be adjusted to spec an the hardest one of all is, especially with 07 and up is to have the primary chain set to 5/8, or a touch more freeplay. The problem is the auto tensioner likes 3/8-1/2" most of the time. The chain adjustment really changes how it shifts up and down with almost metric smoothness. Every time I've had the primary apart, the first ride is amazing, then the auto tensioner does it's thing and by the time I get home it's back to it's stiff clunky self.
Ron

 

I assume you are talking about cold oil clutch drag. The best oil I have found for this is Redline MTL which is a 70w80 GL4 lubricant with no moly and a pour point like 5w30 motor oil. Try that and a good clutch adjustment to get full disk seperation when you pull the clutch lever. If you have a Sportster try the Redline MT90.

You can find the redline at www.myoilshop.com

 

Just thought I'd further explain the chain tension thing as many reading that would think WTF has that got to do with it. This effects clutch action at operating temps. What happens is , even though there is clutch separtation, the chain pulls on the clutch hup which puts considerable pressure on the clutch hub bearing. This in turn creates some rotational forces on the primary shaft similar to a slightly dragging clutch. When a shift is done the primary and secondary shafts need to change speeds but the drag from the bearing offers extra resistance to speed change on the primary shaft and the result is more pressure needed on the toe to make the gear change. More pressure makes a louder shift clunk. Due to the large components involved in the clutch and trans and inertia of these components it can never be totally eliminated, but with the right components and fluids it can be substantially reduced. For anyone who experiences their bike shifts better in the first few miles and then seems to get stiffer when hot, the source is the chain tension, as it gets tighter with heat. This is one area where the HD auto tensioner could cause less than stellar operation between tension and shift harmony.
Ron
Ron