herrmnnn wrote:
Can you explain how to adjust the accelerator pump timing? From your explanation on your site it looks like mine is coming on too soon but I couldn't find a description of how to actually adjust it.
Depends a bit on the carb you have, there are lots of different ones.
On the FCR I fitted I went with MxRobs recommeded merge AP spring and leak jet and its fine, as anticipated.
My 650 Berg FCR has no adjustable/replaceable leak jets but it has a tab on the carb that could be drilled and tapped to fit a set screw to make the stroke of the plunger variable. The way it worked out was that the washers = the thickness of the plastic cover and the exposed thread of the screw = AP stroke, or the gap between the end of the screw and the plastic lever. Easily adjustable anytime on the Berg, not sure but should be OK to access on a DR too. The carb I got for my DR did not have the 'meat' in the carb body to fit a screw like this however.
The MKI carb I fitted to my 501 has an external plunger and a collar was fitted to that for a similar result, known as the BK mod I think.
Its under the rubber sleeve on the AP shaft. Not the best pic, but probably not the carb you have.
You can also get aftermarket externally adjustable leak jets that replace the AP bowel or complete float bowel. These can foul the starter on a DR though, depends.
The logic with the FCR's AP is apparently that the carb was originally developed for road racing 750/1000 fours which don't generate the intake vacuum like a big single. The bigger the cylinder, the more vacuum and the less AP squirt required. And jetting with it connected can complicate things, so jet without it connected, and then when steady state response is right, bring in the AP to manage lean stumbles and get some 'snap'.
But if you have a replaceable leak jet, the #35 works as per MxRob.
Steve
