QUICK question for Motoman 393

7 replies to this topic
  • john.hilton@cape.k12.de.u

Posted November 20, 2001 - 08:58 AM


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?


  • Hick

Posted November 20, 2001 - 04:50 PM


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 ]

  • thumpy

Posted November 20, 2001 - 06:11 PM


Exactly! That's all it does.

  • john.hilton@cape.k12.de.u

Posted November 20, 2001 - 06:27 PM


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.


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  • Hick

Posted November 20, 2001 - 09:31 PM


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 ]

  • john.hilton@cape.k12.de.u

Posted November 21, 2001 - 01:57 PM


Thank you Hick, that makes more sense.
I think that I'm going to try it.

  • motoman393

Posted November 21, 2001 - 07:20 PM


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,


  • john.hilton@cape.k12.de.u

Posted November 22, 2001 - 08:35 AM


Thank you, Garrett.

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


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