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Re: 1975 R90 Idle Speed
Posted: Mon Oct 11, 2010 9:45 pm
by Ray from Indiana
With the info you've given us I would guess this is what has happened:
1. You tried to tune the carbs before the engine was fully warmed.
2. The tried to sync the carbs/set the idle
3. Set the Bings too lean
...just speculatin here
Re: 1975 R90 Idle Speed
Posted: Mon Oct 11, 2010 9:56 pm
by Jean
The pistons (In the carbs) may not be returning to the full-idle position either...maybe there is something causing them to stick in the bore.
Assuming...You have Bings?
Re: 1975 R90 Idle Speed
Posted: Mon Oct 11, 2010 10:33 pm
by dwerbil
Jean wrote:The pistons (In the carbs) may not be returning to the full-idle position either...maybe there is something causing them to stick in the bore.
Assuming...You have Bings?
Brad, last I recall, your throttle cables did not have proper slack............they were too tight, me thinks.
Re: 1975 R90 Idle Speed
Posted: Tue Oct 12, 2010 9:00 am
by bbelk
dwerbil wrote:Brad, last I recall, your throttle cables did not have proper slack............they were too tight, me thinks.
You are right - I can tell this when I turn lock to lock and the engine revs. However, with the bars straight, I do have the proper play and the engine does not speed back up once I slow it down.
Do they sell longer cables? I have USA bars and bar backs.
Re: 1975 R90 Idle Speed
Posted: Tue Oct 12, 2010 9:57 am
by dwerbil
Probably do for your set up. Best to take them off and have them with you to compare if you get them locally.
Cable Routing?
Posted: Tue Oct 12, 2010 10:10 am
by Ken in Oklahoma
bbelk wrote:You are right - I can tell this when I turn lock to lock and the engine revs. However, with the bars straight, I do have the proper play and the engine does not speed back up once I slow it down.
Do they sell longer cables? I have USA bars and bar backs.
Aside from your charging concerns, I'm wondering about your cable routing. If bar backs are a factor and if you can't get longer cables, how about rethinking the cable routing? Even if you do it like BMW did it back in the day, BMW wouldn't have been fighting with cables that were a tad too short. Maybe you could find a way to route them where they don't go through that 'funnel' between the two side plates connecting the steering stem to the frame. I haven't tried it but I'm wondering if the cables would route well on the outside of the plates, with zip ties holding them in place.
Ken
Re: 1975 R90 Idle Speed
Posted: Tue Oct 12, 2010 1:07 pm
by chasbmw
It would be a bit difficult to do that elegant full lock U turn, with your feet off the ground, if you suddenly go onto full revs!
I would really sort out your cable routing/lengths as a safety issue.
Charles
Re: 1975 R90 Idle Speed
Posted: Tue Oct 12, 2010 1:09 pm
by dwerbil
Last I noticed on Brad's bike, the routing was as good as it was going to get considering the 'short' cables.
Re: 1975 R90 Idle Speed
Posted: Tue Oct 12, 2010 3:26 pm
by Jean
Interesting to get in on this discussion. I've been pondering installing some slightly WIDER but about the same flatness bars on MY R100s to have a bit more leverage (I'm feeling my age!) and clearance from the tank bag.
Cable length is a concern...I'm using normal S-bars with bar-backs now and the cables seem to be about at the end of their useful length. I'd sure like another inch or so on each bar end, but think it'll involve a big cable-change job.
Guess I better get on the weight bench!!
Re: 1975 R90 Idle Speed
Posted: Tue Oct 12, 2010 5:39 pm
by bbelk
chasbmw wrote:It would be a bit difficult to do that elegant full lock U turn, with your feet off the ground, if you suddenly go onto full revs!
I would really sort out your cable routing/lengths as a safety issue.
Charles
Its more like bumping up to a fast idle. As a geocacher, I make U-Turns all the time - and I never put my feet down, that would be poor form.