G
Gravity
Guest
I'm in the rebuild process with my carbs and am officially, thoroughly confused. I suspect the engine on my '78 GS750 might not be the original, and the jetting and float height on my carbs doesn't match the resources I've found around this site.
My main jets are 105 (100 is stock), pilot jets are 17.5 (15 is stock), and needle valve seats are 2.3 (not sure on stock number). The weirdest thing is what (on paper) would seem to be a very low fuel level - the float height is set at about 27.5 mm, where 22 - 24 is stock and the highest setting for the VM26, on the GS750B, seems to be 26mm. There's always the possibility the needle valves are just longer, aftermarket units and the fuel level will be fine. The bike ran when I got it, but not super well, and the airbox was a total mess and the intake boot o-rings weren't in great shape either. Maybe the PO was just adding fuel with the bigger jets to balance the extra air...? SO on to my questions:
Should I start from square one and get the "proper" jets and set everything based on a 1978 GS750E? Or because I don't know what all has been done, would you recommend keeping things how they are and just use the clear tube method to set my fuel level to about 3mm as that seems to be the happy place for pre-80s 750s? This is my first encounter with carburetors, so I don't want to get everything to the point where I'm ready to tune just to have to tear it back down and replace a bunch of stuff.
My main jets are 105 (100 is stock), pilot jets are 17.5 (15 is stock), and needle valve seats are 2.3 (not sure on stock number). The weirdest thing is what (on paper) would seem to be a very low fuel level - the float height is set at about 27.5 mm, where 22 - 24 is stock and the highest setting for the VM26, on the GS750B, seems to be 26mm. There's always the possibility the needle valves are just longer, aftermarket units and the fuel level will be fine. The bike ran when I got it, but not super well, and the airbox was a total mess and the intake boot o-rings weren't in great shape either. Maybe the PO was just adding fuel with the bigger jets to balance the extra air...? SO on to my questions:
Should I start from square one and get the "proper" jets and set everything based on a 1978 GS750E? Or because I don't know what all has been done, would you recommend keeping things how they are and just use the clear tube method to set my fuel level to about 3mm as that seems to be the happy place for pre-80s 750s? This is my first encounter with carburetors, so I don't want to get everything to the point where I'm ready to tune just to have to tear it back down and replace a bunch of stuff.
