The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: jamestnewsonr65 on April 23, 2016, 04:16:05 PM
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After getting the bike out for a couple of days last week I've noticed the revs seem to stay a little high when changing gear and they seem to be slow in falling once the throttle is released.
I think it could be down to how my cables are routed and wondered if anyone has a pic/diagram of correct routing.
For info purposes: the carbs have been rebuilt and work great, bike idles fine at 900/1000, coils have been replaced for dynacoils with new leads and plugs previously.
Thanks in advance.
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What year is your bike? Does it have the "cable splitter" cylindrical shaped cable assemblies on the throttle & choke cables (only 1 cable up at the choke/throttle mechanism on the handlebars, with cylindrical shape cable splitters under the tank that take that 1 cable end from the bars and activates (2) cables on its back end, one for each carb)... Earlier models have separate throttle cables all the way to the handlebar
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An 83 should have a splitter or did the later models eventually go back to individual cables ?
You should be able to visibly confirm at the carbs if the cables are not allowing the throttles to close as soon as the twist grip is released. If they are slow to close I wonder if the splitter is more likely to be the cause of a cable problem rather than the routing. I have individual cables which pass either side in front of the headstock and back through the front down tube aperture above the top rail and then either side of the tank to the carbs. There are no cables ties to restrict movement.
Your idle speed is not high other wise for me carb settings would be the number 1 suspect cause.
Which leaves the possibility of sticking advance weights.
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Barry's right the 83 has the cable splitters under the tank.
Everything works as it should and the carbs have been working great up until now. If it were the carb set up what would be the problem? Sticking throttle return spring or something?
The ignition and advance weights etc in the bean can are the only thing which hasn't really been changed on the bike. If it were these is there anything to look for or any upgrade/replacement which works well?
Thanks.
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Carb related idle hangup is an idle speed/mixture tuning issue. Usually idle speed set too high in combination with incorrect mixture setting. Doesn't sound like that's your problem.
As mentioned earlier if it's a mechanical issue down to cables or return spring you should be able to see that just by looking at it as you close the throttle. Return springs don't usually cause a problem as if anything the springs are stronger than needed.
There is an oval shaped inspection cover on the side of the bean through which you can lubricate the advance mechanism. Might be worth a try before diving into a strip down of the bean can.
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I'll give the lubrication a go and see if that helps next time I'm out.
I'm waiting on a new oil pressure sensor as the current one has developed a leak. Will report back on whether the lubing of the bean can fixes anything.
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The bean can lubing should be done with a very light oil or spay lubricant. I've used silicone lubricant that I also use on sewing machines/fly rods, etc.
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I was wondering what type of oil to use. I assumed that it wasn't something heavy which would clog it up.
Is there any trick to doing this or is it case of spray a little in the hole?
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So, I gave the advance mechanism a bit of lubrication and at the same time adjusted the cable tolerances on the choke and throttle. I also had a look at the timing and adjusted it after taking the bean can off for lubrication.
The bike seems much better now and idles lower again which is great. Also the engine returns to near idle revs when accelerating and pulling the clutch in. Before it would just return very slowly to idle if at all.
I now however have another problem which is fairly annoying. It seems that the charging circuit is not working at all !!
I charged the battery last saturday, used the bike 3 times this week to go to work (about 32 miles a day) and the battery indication is showing in the red. Would this indicate that I need to replace the bean can???
The charging light comes on at idle and goes off when revved as it should, but I have noticed it has been flickering slightly when ive been on the bike in say 3rd or 4th gear at about 40 - 50mph.
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Check the brushes. Worn down to nubs, they may not be consistently making full contact on the rotor.
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James,
I have similar issues and already rebuilt the carbus, replaced the springs on the carbus, and tried to optimise the cable routing, without much difference.
Both accelerator + clutch are sub-optimal in my opinion.
Is your conclusion that it was a lubrification issue? Any procedures on the forum on how to service and/or change the clutch and throttle cables?
Good luck with the charging circuit!
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@Einar, I would say that the lubrication did fix the issue I was having in combination with checking the tolerances on the cables and carbs.
Also checking the timing probably helped too. My bike used to pop and bang when throttling off, but now runs alot smoother than before I adjusted everything. After the lubrication I also seem to have a more consistent lower idle.
It is probably all down to adjusting everything.
@Montmill. Is there a particular way to check the bushes or is it just a visual check? Is there a way to measure the voltage?
The electrical system is really the only thing which has not been overhauled on the bike really.
Thanks for the help.
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@Montmill. Is there a particular way to check the bushes or is it just a visual check? Is there a way to measure the voltage?
The electrical system is really the only thing which has not been overhauled on the bike really.
First, disconnect the battery's negative (-) cable, then remove the engine's front cover. Use a small screwdriver or pick to lift up and out the snail springs that apply pressure to the brushes and ultimately to the rotor's slip rings. Carefully withdraw the brushes, noting which one goes where.
A new brush will measure 17mm in length. When the brushes wear beyond usefulness, the snail springs hang up on their holders and can no longer apply the required pressure. Time for new brushes.
To check voltage going to the battery, use the throttle lock screw to hold revs at approx 2K rpm and take a charging voltage reading at the battery's POS and NEG terminals.
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Do not overlook the return springs on the carburetors.
The choke spring caused me a headache because the choke was not closing fully and I set the carbs with a partial choke. After a couple km ride, the choke closed from vibration and the bike ran awfully ...
I also discovered that the throttle spring is actually needed for a proper idle. Don't ask me how I know this one. >:(
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Yeah I always check my choke closes by pushing down on the returns just to make sure.
My only issue now is my charging!
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I had a look at the bushes and springs today. They don't look too bad, but I'm going to replace them as a precaution and see what voltage I get after replacing them.
I'm not sure where the wear limit is on these if any, but they looked to be ok.