QUICK question for Motoman 393

Motoman, I was looking at your site, specifically the BK mod section, and I have a quick question.

The screw that you install, do you have to turn it in so that it pushes the black cam looking thing?

From the picture it looks like it only stops it from rotating too far. But it also looks like it only rotates counter clockwise, and it won't contact the screw that you installed.

Am I not seeing it correctly?



It rotates clockwise, pushing the pump actuating rod, which attaches to the [edit]right[/edit] of the black plastic cam's pivot, down, depressing the pump diaphragm, operating the pump.

So, yes, the screw serves as a stop for the cam, turn it in and the pump stroke is shortened.

Hopes this helps.

[ November 20, 2001: Message edited by: Hick ]

Exactly! That's all it does.

I truly apologize for being a dumb a$$, but I'm still a little confused. After reading the 2 posts from above, I went and looked at the pictures on Motoman's site. How can the black cam rotate clockwise since it's already pushed up against the "timing screw" at the top right.

I can see (from the picture) it rotating ccw and pulling the rod up. Unless, in this picture, it's already at the end of its rotation. However, if this is the case, then how does the screw that was installed for the mod come into play?

I guess what I'm wondering is, does the picture show what it should look like when you are done, or did he back the screw out to take the picture?

Thanks a bunch for your time and understanding, I again am sorry for being confused.


What you can’t see from the pic is how the thing operates. The cam is not operated directly from the throttle pulley. It is spring loaded, the timing screw is operated directly by the pulley.

So when the slide is lifted the arm that the timing screw is threaded through moves to the right allowing the spring to push the black cam thingy clockwise, operating the pump until the other face of the cam bumps into the BK screw.

[ November 20, 2001: Message edited by: Hick ]

Thank you Hick, that makes more sense.

I think that I'm going to try it.


Well sorry for the late response...I have been rebuilding my suspension since 7am this morning! It looks like everyone has answered your questions. Take the black dust cover off and twist the throttle a few times and you can see how it works! The BK mod acts sort of like a throttle stop if you will. Just give it a try it is easy to do and you will understand it better when you take the carb off! After rebuilding my front forks and shock the past 3 days, I have realized that carb/engine work is much easier IMO (probably because I have more experience with it). Later,


Thank you, Garrett.

I'm going to give it a try. I'll let you all know how it works.


Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now