Hard starting and......

[Travis Bikel]

1976 R75/6. It takes 3-4 tries of 5 sec duration to get the bike started. The voltage at the battery (after the bike is running) @ 2k rpm is 13.3 v. My understanding is that it should be at least 14v. Battery, starter relay and voltage regulator are less than 3 months old. Where do I start ?

[Bobmws]

Basic tune up. Valves, timing, carbs, plugs, coils.......

[20774]

13.3v at 2K doesn't sound too bad...should get higher as you get 3K and over. What type of riding do you do? Maybe you're taking short trips and the battery is not being topped off...could use a battery tender maybe.

Is this a new problem or has it behaved this way for a while? What about the choke...does it make any difference? Maybe the choke is not fully engaging.

What's you're starting drill, especially with the throttle? Typically, you should leave the throttle alone as opening it only leans out the mixture by adding more air. On my /7, I usually crank for a couple of seconds and then I blip the throttle open maybe 1/4 and it usually fires at that point.

[m_stock10506]

Tight valves make for difficult starting.

[lmo1131]

It takes 3-4 tries of 5 sec duration to get the bike started.

If your battery can sustain that load, it isn't the battery.

Basic tune up. Valves, timing, carbs, plugs, coils.......

+1

[doktortim]

Do verify basics. Valve lash, compression balance and spark energy and timing. When all that is good and the symptom remains, then go inside the carbs for complete cleaning, and make sure the tiny holes in the enricher discs are free and clear and those gaskets are not warped and leaking.

With full enrichers engaged if it doesn't fire right up, something is not right.

[Travis Bikel]

Do verify basics. Valve lash, compression balance and spark energy and timing. When all that is good and the symptom remains, then go inside the carbs for complete cleaning, and make sure the tiny holes in the enricher discs are free and clear and those gaskets are not warped and leaking.

With full enrichers engaged if it doesn't fire right up, something is not right.

No kidding. Neglected to say that 3000 miles ago: carbs and "chokes" were overhauled, rings and a valve job, have adjusted valves twice , new throttle and choke cables, new plugs. Bike has Boyer Microdigital ignition.

[20774]

Interesting...Boyer ignition. When you've had the bike running, have you checked the timing? Nominally, at idle you'll see the S-mark in the timing window...usually not critical, but it needs to be somewhere in the ballpark to start...that's a problem you're having. At what RPM does the full advance mark show up in the timing window? Should be around 3K. Generally, this is really more important as that's where you spend most of your time. But if the full advance is off, could be the idle mark is off...that would be a starting problem.

[Stan_R80/7]

Before the carburetors were synchronized, my '78 had similar symptoms. I used the spark plug shorting technique which showed one cylinder was carrying all the load. After getting the cylinders sharing the load by adjusting the idle and mixture, the cold start choke worked better. The cold engine starts now after ~ 4 revolutions with a slight amount of throttle. It's not quite where I would like, but the improvement was significant. Good luck!

[Travis Bikel]

Interesting...Boyer ignition. When you've had the bike running, have you checked the timing? Nominally, at idle you'll see the S-mark in the timing window...usually not critical, but it needs to be somewhere in the ballpark to start...that's a problem you're having. At what RPM does the full advance mark show up in the timing window? Should be around 3K. Generally, this is really more important as that's where you spend most of your time. But if the full advance is off, could be the idle mark is off...that would be a starting problem.

I've checked the timing twice since valve job, etc. Instructions from Boyer say full advance @ 4k. I found the problem, actually by accident : After checking the output of the voltage regulator I shut the bike off and went back inside my apt. for a bit. When I returned to the bike I turned the ignition on and ..... nothing, none of the lights came on neutral, charge ,etc. I banged on the seat with my fist and the lights came on. When I replaced the starter relay I replaced all the female connectors going to it. Found one of the connectors not securely crimped. After replacing it, and checking the others the bike fired up in a second or less and the voltage regulator put out 14.35 volts. Thanks for your help.

[PeoriaMac]

OK, I've gotta ask. Was the seat banging a technique for fixing the bike that's worked in the past...or was combined with a number of curse words followed by "that BMW"?

Mac

[brittrunyon]

OK, I've gotta ask. Was the seat banging a technique for fixing the bike that's worked in the past...or was combined with a number of curse words followed by "that BMW"?

Mac