yamaha 70 betol

bill taylor · 30 October 2005, 00:03

I have been making adjutments to a 1999 betol engine as per clymer manual.
However, I can not get the throttle to open the last few degrees. It is not due to linkage adjustments. The problem is that the throttle cam at its maximum throw is insufficiant to fully open the throttle plates. Can anyone please help? Bill.

Hightower · 30 October 2005, 00:12

Couldn't be a worn roller or cam, could it! Only other suggestion is that somehow the lever that the roller sits on has turned on the shaft and needs re-adjusting.

bill taylor · 30 October 2005, 18:12

Thanks for reply Andy. There is a rubber sleeve over the roller. This appears to be in good condition although it does seem a bit soft which would allow the cam to sink in a bit. Do you think that its possible for the rubber to have deteriorated on an engine this age? Bill

Hightower · 30 October 2005, 19:04

Who knows Bill!

What you could do is to open the throttle fully (by hand) whilst the throttle lever is pushed fully forward (simulating WOT), you could visibly see what sort of gap you have between the roller and cam and this might be some sort of indication of what is going on. If you check out all the linkage and can't see any problems, one solution might be to replace this rubber roller with a hard plastic on (Delrin or nylon 66 is suitable I think), but you will need to have this custom made for you.

jwalker · 30 October 2005, 19:53

If it's not much it's probably not worth concerning yourself about.

http://www.rib.net/forum/showthread....throttle+plate

Go down to #9.

bill taylor · 02 November 2005, 15:00

Thanks for advice lads . I think I will try and order a new rubber from Yamaha.