melville wrote:
The drag can make that much difference? Surprised.
With the VWs that make most of my motor experience, a lotta endplay will advance the ignition when the clutch is disengaged. Idle speed will pick up. Definitely not a factor on an Airhead.
No need to be surprised really, when you think about it. At idle, the speed of the engine is pretty delicately balanced, the engine is producing just precisely enough power to idle at whatever speed it's set at. If the power output goes up, the speed will increase to match... if it goes down, the speed will similarly decrease. By the same token, any change in the load on the crankshaft will similarly affect the speed. Of course, this is true at any power output but, when the engine is at idle, the only load it needs to overcome is the friction load of the engine so even a slight change can represent an appreciable proportion of the overall load.
melville wrote:
The drag can make that much difference? Surprised.
With the VWs that make most of my motor experience, a lotta endplay will advance the ignition when the clutch is disengaged. Idle speed will pick up. Definitely not a factor on an Airhead.
No need to be surprised really, when you think about it. At idle, the speed of the engine is pretty delicately balanced, the engine is producing just precisely enough power to idle at whatever speed it's set at. If the power output goes up, the speed will increase to match... if it goes down, the speed will similarly decrease. By the same token, any change in the load on the crankshaft will similarly affect the speed. Of course, this is true at any power output but, when the engine is at idle, the only load it needs to overcome is the friction load of the engine so even a slight change can represent an appreciable proportion of the overall load.
Rob
Also, if the idle speed is already set too low it would make a more noticeable drop in speed.
hi to all , to my knowledge ( which isnt much ) kurt in S.A is correct . ! you have to much endfloat in your crankshaft that's if everything else is ok ! had a 90/6 a very long time ago and had the same problem when you pulled the clutch lever in the revs would drop and when we re-shimmed the crank all was well again . well thats my 2cents worth over and out !
I just stumbled upon this thread. I too am having the same RPM dip on a R75/5 with a completely rebuilt motor (new crank bearings, it was re-shimmed and everything), rebuilt Trans, lightened flywheel, new clutch, etc...
I'm pretty sure we put the bigger clutch on because of the 20% Siebenrock power upgrade piston kit.
Do you think that could be the cause of this?
My handlebar clutch play is good.
I wouldn't mind the problem though it seems that I need to increase my idle a bit so I do not stall out when I engage the clutch as I down shift and find neutral coming up to traffic lights (bike is warmed up).
I could live with it if it didn't effect the stalling. as of now, i have 250 miles on the bike and I'm chasing idle speeds to find one in which I won't stall.
The clutch feels a bit stiff compared to my R100S so I was going to adjust the arm on the tranny a bit more and hope that helps the slight RPM dip.
Just sounding off here to see if anybody has other suggestions or what the progress of "aharrett' is a year later.
You did well to find this thread JJ.
Someone else had this problem a while back and I thought it was resolved to be something too do with the thickness of a new friction plate.
I tried to search for that thread with no luck.
I forgot to mention that we went with the heavier duty clutch because of the power upgrade and the 5speed transmission. Maybe that was a mistake and could be the cause of all this.
I did ignore it, and it is still present but much less noticable. Quite likely it has always been like it is now - it's only the episode from last year that makes me pay attention. So what have I done? Nothing except put about 5000 miles on a new clutch friction plate.
