I have set my idle at around 1100rpm. Once the engine warms up, the rpms become erratic. When I stop at the traffic lights, they reach as high as 3000rmp with the throttle closed. If I apply the front brake and let out the clutch slowly, the rpms go back down to 1100rpms, but when I pull in the clutch the rpms start to increase again. I have checked to make sure that the cables are not frayed and have no sharp turns causing them to bind. I have read that these symptoms are an indication that my electronic ignition unit could be sticking in advance position? My question is: If this is the problem, can it be unstuck? or do you have to replace the unit?
1985 BMW R65, Electronic Ignition sticking.?
- Thread starter Geoffa
- Start date
Thanks for your reply,
I have just been out to recheck the clamp tightness, and they are ok. This year I replaced the rubber sleeves which connect carb to cylinder, I also replaced the floats and float needle.
a better check would be ... spray carb cleaner on the area.. and if there is a leak , the rpm will change
chiefswallow
Banned
Or use a propane torch (not lit), works great for pinpointing the leak (if there is one).
Hi Cheifswallow and Jamie, Just checked for airleaks using propane torch (not lit) and found no change in idle speed when applying propane to intake area.
Bike has been sitting in shed for the past month, but started immediately today. Idle speed @ 1100 rpm and sounds great. As soon as I go for a reasonably long ride, and the engine warms up, the surging starts.
My first experience of this was 3-4 months ago. I drove down the 401 highway to Mississauga, and it started. Then it was ok for 2-3 weeks then it starts to surge again. And now it seems to do it all the time (when engine hot).
chiefswallow
Banned
Yikes. I have no experience with machines of your vintage, maybe try Ted at Rosey Toes?? Good luck, sounds tricky
Tripletrouble
Well-known member
Does it have a mechanical advance/retard? Maybe lubricating the mechanism or replacing the springs will help if it does.
Not sure how the electronic ignition works. The older models have points, along with a mechanical advance/retard system. I have read that it is quite easy to convert back to points, but taking this route would be a last resort.
Thanks guys for all your input. I guess I need to do a lot more reading, to find out how the electronic ignition works.
Thanks guys for all your input. I guess I need to do a lot more reading, to find out how the electronic ignition works.
Tripletrouble
Well-known member
Normally the electronic ignition units have a built in advance and eliminate the mechanical set up completely. Is it a Boyer-Bransden unit?
I have a 87 BMW R80. I very much doubt that timing advance could cause that much of an increase in idle speed. A few hundred rpms, maybe. If you have a timing light it is easy to check the ignition advance.
What you have not stated so far is whether you have physically pushed the throttle plates back to their resting position by hand, at the carbs, when it is idling high. It definitely appears that the throttle plates are staying open slightly.
What you have not stated so far is whether you have physically pushed the throttle plates back to their resting position by hand, at the carbs, when it is idling high. It definitely appears that the throttle plates are staying open slightly.
The last time I rode the bike it was surging pretty bad. my focus was getting home without damaging my gearbox. Once I reached home, I checked to make sure that the cables were sliding freely and the throttle plates were seating and they were. I failed to do what you suggested. I should have pulled the bike over on the hard shoulder when it was surging, and made sure the throttle plates were seated properly. I decided to place my BMW in the shed until a solution was found. I had my insurance transfered to my other bike. I will have to get the bike on the road again and perform this check before I do anything else. Thanks georg for your input, and to all the other knowledgable guys who answered this post.
