R27 Cold Start Nightmare

[Worleybird89]

Starting my '62 R-27 is like buying a lottery ticket. I can occasionally get it to fire on the first 1 to 3 kicks, but if it starts and dies after a few seconds, I cannot get it to start again. If it does keep running, I can stop it and restart it over and over again. The battery is good, and I get a good spark at the spark plug. This week, I completely disassembled the Bing 1/26/68 carburetor, cleaned it thoroughly, and put it all back together. It fired right up and ran better than ever. I stopped it and restarted several times, no problem. The carb didn't even leak! It previously leaked like a sieve as soon as the engine turned off. The sun came out today, so I decided to go for a quick ride. It started on the second or third kick, but stopped before I got to the throttle. Same as before, after that, nothing I did would get it to start again. I tried removing the spark plug and blasting with compressed air (assuming it is flooded) and verified I still get a spark. Each time I do this, the engine might fire for 1 or 2 cycles, but won't start. I'll start looking for a new spark plug to see if that makes a difference. Is it possible that a bad plug just floods too easily?

Background and history: My dad bought this bike in 2015 and had Vech at Bench Mark Works do the majority of the restoration. He didn't ride it as much as he thought he would, and when I casually asked him to let me know before ever considering selling it, we quickly came to deal. He brought it to me from Cali last Spring (2023). We had a little trouble getting it running when he got here, but after replacing fuel lines and tightening up a few screws/nuts on the carb to slow the leaking, we had a blast riding it around my rural neighborhood for the next few days. The bike has not been registered since the restoration, so my goal was to keep riding it to work out any kinks, then get it inspected, titled and registered in Texas. Fast forward a few weeks, and the bike stranded me about a mile from my house. I got busy after that and gave up on it for a few months. Thinking it was ignition related, I dug into the headlight bucket and pulled the generator cover to see why I could not get it to fire. Only, I could. I was getting a pretty decent spark, so I put it all back together and it started right up. A week later, it would not start again. I know enough to deduce if there is spark but the engine doesn't fire, it must not be getting fuel, so that's when I decided to clean the carb. The float is good, but it is the old style with the metal needle in the center. The idle mixture adjustment is near the recommended starting point of 1 1/2 turns from closed. I put it back to exactly where it was when I took it apart (where Vech set it upon restoration). When I can get it running, this bike is a blast to ride, and I'd like to ride it a lot, but until I can figure out how to get it to start consistently, that just isn't going to happen. To my knowledge, the closest shop that knows anything about vintage BMW bikes is Austin Moto Works, 2 hours away from me. They are not currently accepting anything in the shop and have a wait list to start accepting appointments in January. I've tinkered with all kinds of engines all of my life, from two stroke model engines, to lawn mowers, dirt bikes, and all the way up to small block Chevy 350s, with success, so I am at a loss why this one is giving me such a challenge.

Thanks for any and all advice!

[schrader7032]

Could it be electrical? The R27 is a battery-coil bike, meaning it's just like your older car or say a 1971 R75/5. The coil must be good, the connections must be good, and the battery must be good. Maybe you have some corrosion in the electrical circuit.

[Worleybird89]

That was my thinking when I opened up the headlight bucket and generator cover. But I can consistently get the spark plug to spark when removed from the cylinder head and held against the cylinder to ground. I haven't gone so far as checking resistance on the coils yet, because it sparks. I've heard of R27 coils acting up when they get hot, but running for a few seconds would not do that. When it has started, I've ridden it for up to 10 or 15 minutes, up and down the street, and except for the time it stranded me, I've been able to restart it while warm.

Just ordered a carb rebuild kit from Bing.

[r67boxer]

I've got a '58 R26. When I purchased it the PO gave me one bit of advice. With the ignition off turn on the fuel tap, prime with the tickler (hold button down for several seconds), kick it over two or three times with the throttle just on a little bit and then again with the ignition on. Should start immediately. If I don't follow this procedure it can take many kicks to get it started or not at all.

Kevin

[Halexb]

I had similar experiences getting my Dad's R50/2 running after a couple dozen years in storage.
Carb overhauls, fuel lines, plugs, valve adj, wires, clean tank, change oils (of course)... on and on.
Major prob was kick starting only provided 1 thump. I made a paddock starter and engine would roll over much easier.
Tickling the carbs made the biggest improvement.
No more paddock starting needed.
Now I just need to fix my sciatica probs and I can get to riding again.
Good luck. Sounds like yer on the right track.

[Worleybird89]

I've got a '58 R26. When I purchased it the PO gave me one bit of advice. With the ignition off turn on the fuel tap, prime the with the tickler (hold button down for several seconds), kick it over two or three times with the throttle just on a little bit and then again with the ignition on. Should start immediately. If I don't follow this procedure it can take many kicks to get it started or not at all.

Kevin

Gave this a try this evening. Didn't even fire. Turned the Idle speed screw in another half turn in attempt to get a little faster idle with no throttle but never got it to fire. Removed the plug to check. It's damp, but does not seem to be enough to be flooded. Spark seems weak. Plugged the battery into the charger and will try again in an hour or so. I'm working on getting some replacement/backup ignition parts (coil, condenser, points, plugs, etc.) as well as a carb rebuild kit.

[Bob Allan]

I'd pretty much go along with what's been said here. I start my R26 in a similar manner to r67.
My bike's been back on the road for about a year now & I had a host of similar problems to yours.
Make sure the carby's clean & go through the electrical connections, loosening, retightening & then checking every one.
Substitute components if you can to see what happens.
And persevere.
One strange problem I initially had was a lack of power. The best way I can describe it is the sensation of a multi cylinder engine with one cylinder not firing. No noises or stuttering, just a significant lack of power. Obviously with the one cylinder engine it isn't that. It came good in its own sweet time.
They're temperamental little bastards.

[VintageJim]

I just finished a 1+ year nut and bolt restoration of my 1956 R26 and when doing the initial startup a few weeks ago had a similar problem with difficulty starting and gas occasionally flooding out of the tickler. I had sent the carb to Bing for rebuilding so was puzzled at why the float was not sealing off the gas and the engine was flooding. But when it would start it actually ran pretty good without gas leaking out the tickler. Then I found the problem!! I removed the top cover over the float and found that the float moved like it should and shut of the gas flow like it should. But when I installed the top float cover the gas started coming out the tickler. On further inspection I found the tickler rod was a little too long and when I put on the cover it would push down the float and cause the flooding! I shaved about 1/8" off the tickler rod and now everything is perfect and the bike starts and runs perfectly! I called the fellow at Bing to tell him the story and he had never seen this before. After his rebuild he checks with the cover off to visually inspect the float function and then drains the carb, installs the cover, and sends them out. He has never seen the tickler rod too long but it must have been from a different bike or carb.
If all else fails, I would definitely do this easy check of float function!
Jim

[Worleybird89]

I just finished a 1+ year nut and bolt restoration of my 1956 R26 and when doing the initial startup a few weeks ago had a similar problem with difficulty starting and gas occasionally flooding out of the tickler. I had sent the carb to Bing for rebuilding so was puzzled at why the float was not sealing off the gas and the engine was flooding. But when it would start it actually ran pretty good without gas leaking out the tickler. Then I found the problem!! I removed the top cover over the float and found that the float moved like it should and shut of the gas flow like it should. But when I installed the top float cover the gas started coming out the tickler. On further inspection I found the tickler rod was a little too long and when I put on the cover it would push down the float and cause the flooding! I shaved about 1/8" off the tickler rod and now everything is perfect and the bike starts and runs perfectly! I called the fellow at Bing to tell him the story and he had never seen this before. After his rebuild he checks with the cover off to visually inspect the float function and then drains the carb, installs the cover, and sends them out. He has never seen the tickler rod too long but it must have been from a different bike or carb.
If all else fails, I would definitely do this easy check of float function!
Jim

I've read about that happening with several of the old style bing carbs. That's not it on this one. Expecting the carb rebuild kit from Bing any day now.

[Worleybird89]

Update! It was a beautiful day in my part of Texas today, so after hanging the Christmas lights, I decided to try one possible resolution. I recently ordered four new spark plugs (two for R60, one for R27, and one spare). Popped that new plug in, gas on, two tickles, and she fired right up, first kick! I played with the idle mixture a bit, but was not getting the response I was expecting. Left it on the rich side, with a faster than normal idle, and went for a ride. One peculiar thing that occurred, that has never happened before, a few times at a stop sign, which I downshift into, the idle was crazy high, then would fall off eventually. Almost like there was a buildup of gas going through the carb. It did not do this every time. More like every third or fourth time I came to a stop. I suspect I just need to do the carb rebuild and start from scratch on that end. After having my fun, I was not able to start it back up warm. I think I flooded it. I'll pull the plug and see what it looks like. I'm now wondering if something with the coil or condenser can cause a plug to go bad? There were not very many miles on the old one.