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R75/6-not starting

Y

yrfuneralmytrial

Guest
Hey guys, in the "can't leave well enough alone" department comes super-noob...me. A friend (good mechanic) and I did some work on the R75 yesterday.
Valve adjustments, fitted new throttle cables, new brake and clutch cables (for new euro bars). I cleaned the black paint off the valve covers while they were off. Tonight, I put the valve covers back on, top off the motor oil and hit the starter button. The bike starts immediately but at really high revs. I kill the engine. Ponder a bit and remember showing my friend the friction screw device. I make sure it's not too tight and go a bit far and it comes out. I screw it back in. I hit the starter again...no go. Plenty of battery, just no starting. I'm heading back out to the garage but wanted to post. Throttle cable(s) askew? Did I do something taboo to the friction screw? Sometimes I want to kick my own ass. Thanks.
 
I wish I could cop to that but no...it fires away just like normal...just not fulling starting. Like it's not getting fuel. But I can't see it high-revvin' one second and then nothing if it were a fuel-delivery issue.
 
Actually, you can kick your own ass. Fill an old boot with sand, tie a rope to the laces, hang it from a rafter in your garage,......you get the idea.

A runaway open throttle is a terrible thing. Extremely un-nerving. If the electric start rolls but the motor doesn't fire, I'd look for spark at the plugs first. I always carry a spare, used spark plug. Remove a plug wire from either side, put the spare plug in the end of the wire, lay it on the head, roll the starter and look for spark in the gap. If no spark, you might want to fiddle with the kill switch while rolling the starter. Compression, fuel, and spark are the essential elements. One has taken a vacation from your bike.
 
I've got spark on both sides. Took the new plugs out, they're not wet...no discernable gas smell on them or in the cyclinders. I went out this morning...same thing. Fired up, revving really high. Killed it. Back to not starting. Where's that boot and sand? I would think binded throttle cable(s) but it would likely start and rev high every time right? The friction screw is not essential to anything is it? Just a cool old BMW perk right?
 
When you did the valve adjustment you just needed to adjust it a tiny bit, right?

If you had to do a major change, it indicates you did not have the piston on the correct stroke.
 
Aha clues.
Assuming that you DO have the fuel taps on and fuel in the tank make sure that the throttle cables are in fact moving the throttles. Even if they aren't working, it SHOULD start (if cold) just using the enrichener (choke) and no throttle.
 
Also, the throttle cables should have 1mm slack in them with the idle screws turned in one turn after touching the tab that they touch.
 
"When you did the valve adjustment you just needed to adjust it a tiny bit, right?"
-Correct.

"Oh, petcocks ON and gas in tank too, just to cover everything!"
-Yep.

Cables "seem" to be doing their thing correctly.

----

FWIW: Bike started, ran, idled etc... perfectly before you know....I got a hold of it.

If the cables were binded, it would still start right? It would just rev high each time started right? This is a HIGH rev!!!

I keep feeling like it's something to do with this friction screw which of course means it has nothing to do with the friction screw. Friction is right.:D
 
nealart said:
You should be able to start your bike with the friction screw in your sock drawer.
Click to expand...

+1. Loosen that up until there is almost no friction. Maybe you have it in a position that locks the throttle open, excessively. But, in the time to type "I keep feeling like it's something to do with this friction screw which of course means it has nothing to do with the friction screw." you should have been able to loosen it, get a feel of the response, and try starting the bike again.

I enjoy your logic in that sentence, though. Sounds like me.
 
Firstly, thanks for the feedback. I appreciate it. I took the friction screw out (put it in my sock drawer). Oddly, it started briefly without the high revs but soon died and resumed not starting. I had the screw loose (not holding throttle) to begin with but odd. All taps are on, I've given a little throttle, I've given none. I even sang "I've Got A Feeling" by the Beatles which usually works in any scenario for me. Not this time. I'll get my buddy Dave over tonight and subliminally challenge him to fix it.
 
So, when you look at your carbs with the throttle off, the cables are ever so slightly slack, right?

And then while still looking at the carbs, and twisting the throttle you can see both cables pull up on the mechanism - correct?

One more thing - be sure the choke lever is pushed all the way down and that when you do so, the levers at the carb are moved all the way to stop.
 
By the way, thanks for taking the black off of your peanut head rocker covers. I saw your bike here and on advrider.com and that was buggin' me, such a beautiful bike...
 
Paint is off:clap Well, I took off the top of the throttle housing and disconnected the new throttle cables. The bike started ride up and idled perfectly. So, they're either too short or I've got to route them differently. Small problem at least. I'll figure it out from here (I think).
 
Sounds good.

That little sprocket has to be in the right position.

Should be a mark on the sprocket and one on the twist grip notches if I remember right.
 
Man, I had a helluva time getting the cables in place and the throttle cap back on. I thought that would be the easy part. I adjusted the throttle cables evenly at the carbs to get a bit more wire at the throttle end. Finally got it all together and functioning properly (I think). I'll do a neighborhood test run tomorrow to make sure the brakes, clutch and throttle are functioning safely.

Question: how's everybody making these Napoleon style mirrors work with the long clutch lever? Hacking the ball-end off? Not crazy about that idea.
 
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