Was Hard Starting... now couple more questions..

schrader7032 · Post by **schrader7032** » Fri Apr 03, 2009 1:34 pm

Sounds like you need to increase your idle speed and/or go through a carb synch process. For a newly rebuilt motor, you should be sure that you're running a tad rich just to avoid getting too hot with a lean setting.

As for valves, they shouldn't be making that kind of noise. Have you gone through the torque and retorque process as the head gaskets settle in? Not sure about the R51/3, but you also need to check the end float on the rocker arms. There should be no excess up and down movement on the rocker arms...you should just see a squeezing of oil film where the rockers meet the blocks.

Kurt in S.A.

Darryl.Richman · Post by **Darryl.Richman** » Fri Apr 03, 2009 4:46 pm

Peter, I'm having a Tech Day at my house in Santa Cruz tomorrow. You should come by and I'm sure you'll find people to talk to about how your bike runs.

zwinakis7515 · Post by **zwinakis7515** » Fri Apr 03, 2009 6:46 pm

As for the rattli-ness, I re-torqued the head bolts before I adjusted the valves so I don't think it's that.. I only hear it when the engine is under load. Not on decelleration.

Allan.Atherton · Post by **Allan.Atherton** » Sat Apr 04, 2009 10:08 am

... wondering about valve-train noise. It sounds a little "rattley" upon acceleration, like the sound of an engine pinging on crappy gas. Since the motor has ridiculously low compression, that can't be the case. Should the valve-train be pretty silent? ... I re-torqued the head bolts before I adjusted the valves so I don't think it's that.. I only hear it when the engine is under load. Not on decelleration. If the timing is too advanced, the motor will knock and ping. Maybe at Darryl's they will use a strobe light to check the timing.

Bruce Frey · Post by **Bruce Frey** » Sun Apr 05, 2009 3:51 am

If you have uneven performance and hear ratling, it could be the slides in your carbs. They wear over time (causing air leaks) and there can be enough play so that they can be heard.....and can be mistaken for valve noise.

If that is the problem, this company in Canada can resleeve the bores. They have a good reputation.....or of course you could replace the carbs.

http://www.tritonmachining.ca/

Bruce

zwinakis7515 · Post by **zwinakis7515** » Sun Apr 05, 2009 6:21 pm

Thanks guys.. I'll get it sorted the best I can and then persuade someone with a bunch of history with these bikes to take my bike for a spin. That's probably the best way to get to the bottom of these subtle issues. Thanks again, Peter Z

AntonLargiader · Post by **AntonLargiader** » Mon Apr 06, 2009 5:58 am

If you have a 'canter' in the idle, three beats and a skip, it probably means you have a bad idle mix adjustment on one carb. I've seen that on several slide carb bikes including our R51/3. Simple fix.

VBMWMO · Post by **VBMWMO** » Mon Feb 15, 2010 2:52 pm

Was having hard starting problems. Set Magneto, set/checked static timing (was within differential limits), adjusted the valves, adjusted/balanced carbs, changed oil/trans oil.... Now starts first kick every time.. Couple more newbie questions though. The idle is super low.. but it is a little "gallopy", not perfectly regular. Is that normal for a recently rebuilt R51/3? Also I am wondering about valve-train noise. It sounds a little "rattley" upon acceleration, like the sound of an engine pinging on crappy gas. Since the motor has ridiculously low compression, that can't be the case. Should the valve-train be pretty silent? The motor was rebuilt about 3K miles ago so I hope it's not a bad wrist-pin or bearing.. Finally, are any of you in the Bay Area? I'd love for a very knowledgeable person to take a spin on my bike and see if they think it is as it should be... Thanks, Peter Z
(Redwood City, CA)

Vintage BMW Motorcycle Owners