Cold Starting Tips Wanted

[technothrill]

Hi folks.

I've got the 79 R65 up here in San Francisco, it's new home, and am having some issues with cold starting on these chilly misty evenings in Western Addition.

The carbs were previously tuned for SoCal running, needle position 2, jet sizes are as follows:

Pilot 45
Main 140
Needle: 2.66

Traveling at high altitude on the trip up here the bike was seriously under-powered and wanting to die, so I changed to needle position 3, which drastically improved things and that's where it remains.

With full choke/enricher, bike starts then dies with a sputter before I have time to go to half-choke. It's tough to start after that unless I let it sit for a bit.

What's happening here? Too much fuel getting into the carbs? Is my starting technique rusty (bike started first try in SoCal)

Should I go back to needle position 2? Clymer says 3, BMW manual says 2

Flat top 32mm carbs.

[Bob_Roller]

You should go back to the stock settings and parts on the carbs .

The bike is originally set up for sea level elevation and temps in the 50's F. can't remember the exact temp .

If you post the carb numbers, they're located at the front of the carb on a vertical flange , should be something like : 32/64/325 .

There's a left and right carb, so the very last digit will be different on the carbs .

I can post what Bing says how the carbs came out of the factory, settings and parts .

Who knows what previous owner(s) may have done to the bike since it left the dealer over three decades ago .

[raymr]

Do you hold the throttle open while starting? I get instant cold starts with full choke and and throttle turned about 1/4.

[Barry]

With full choke/enricher, bike starts then dies with a sputter before I have time to go to half-choke. It's tough to start after that unless I let it sit for a bit.

What's happening here? Too much fuel getting into the carbs?

I does sounds to me like too much fuel.  

Will it start with no choke ?  

If not try full choke and just dab the starter momentarily with no real attempt to make the thing run. That will pull some fuel through the carbs. Now push the choke right off and try to start as normal. In 5 - 10 Deg C temperatures it works for me with flat top bings. The only time I can use full choke is when the temperature is close to freezing and even then it will not run for more than a few revolutions unless I move the choke lever to off as fast as my hand will move. With the lever mounted on the air filter house you'll know how difficult that is particulary if you start with the clutch pulled in as I always do.

Not sure what temperature you are experiencing but my choke lever has not been touched since March as I don't need any choke at all at 10 Deg C or above. Fires up instantly on the button and I catch it with a touch of throttle and hold the revs for a few seconds before pulling away. At 15 Deg C or above I can start and pull away pretty much instantly.

There seems to be some variation in the way different models of Bings work on choke so I realise that not all airheads will behave like this. I know the original BMW handbook advises starting with full choke regardless of temperature but you have to discover what works for you.

[Air4Life]

Since when is San Francisco considered high altitude?  I didn't think the city was any higher than 1000 feet above sea level.  I would think that if you are experiencing significant changes from so. cal. you were probably running marginally, at best back there.  

[Bob_Roller]

He changed needle settings at higher altitude during his trip . If the needle is set lean to compensate for density altitude, the carb is too lean for his present situation, which is close to sea level .

Plus, if you're not the original owner of the bike, or know it's history, you have no idea what  other owners may have 'adjusted' settings/parts wise in the past, so you really don't know what you're working with .

You need a base line to start from .

That's why I asked for the carb numbers, members here have given their carb numbers on previously owned bikes they had, only to find out that the carbs they had were never put on R65's from the factory .

[donbmw]

I would  also set the carbs back to stock settings. I have been all over this country on my 1982 R65 carbs set the way it was bought new. The only time I had any high altitude problems was on Pikes Peak.  

[Ed Miller]

Do you hold the throttle open while starting? I get instant cold starts with full choke and and throttle turned about 1/4.

Mine is close but different:  I start with full choke and no throttle, then when it does catch I give it a little bit of throttle and rev it a little.  Then it will run on full choke for a minute while I get my helmet on or what ever.  Half choke once I'm rolling, then off when I hit the road, though if I need to stop I'll have to keep it running with the throttle for the first few miles.  It was 32 this morning and I couldn't get my lazy butt out the door to ride my bicycle so I rode the R65.  It started fine, unlike me.

[Bob_Roller]

Ed, it was 80 F. this morning when I left for work at 0510 .

My starting routine is the same as Ed .

[technothrill]

You should go back to the stock settings and parts on the carbs .

The bike is originally set up for sea level elevation and temps in the 50's F. can't remember the exact temp .

If you post the carb numbers, they're located at the front of the carb on a vertical flange , should be something like : 32/64/325 .
.

Thanks for that. So far as I know, I'm running stock jetting (see first post). I'll run down in a minute and check the numbers for your cross reference.

What's not clear is what the recommended needle position is. Manual says 2. I was running 2 in SoCal, no issues. Ran like shit at elavation so I lifted it to 3. Now at near sea-level in San Fran, I should probably go back.

[technothrill]

Since when is San Francisco considered high altitude?  I didn't think the city was any higher than 1000 feet above sea level.  I would think that if you are experiencing significant changes from so. cal. you were probably running marginally, at best back there.  

I'm not experiencing significant changes from So Cal except that I'm running one needle position richer (3) from my high altitude trip, and it's freaking cold here in the night and mornings.

[technothrill]

With full choke/enricher, bike starts then dies with a sputter before I have time to go to half-choke. It's tough to start after that unless I let it sit for a bit.

What's happening here? Too much fuel getting into the carbs?

I does sounds to me like too much fuel.  

Will it start with no choke ?  

If not try full choke and just dab the starter momentarily with no real attempt to make the thing run. That will pull some fuel through the carbs. Now push the choke right off and try to start as normal. In 5 - 10 Deg C temperatures it works for me with flat top bings.

Yes, it sure behaves like it's choking (har har) on fuel.

When ice cold (not sure of the temps here but they sure aren't sunny SoCal) she won't start without choke.

Bike behaves the same as yours in that if I don't back off on the choke immediately, it'll die.

Situation is complicated by the fact that the left hard choke cable, the short one, broke and the little toothed gear was lost. Cables are no longer available from BMW. I have a spare but am missing the gear that fits into the choke lever. So, I have a wire sticking up from the left carb that I have to quickly jam down, along with operating the lever for the right side. Makes starting all the more of a complicated choreography.

I think I'll put the carbs back to needle position 2 and get those numbers to reference Bing recommendations for jet sizes and needle position.

Thanks for all the tips yall.

[Bob_Roller]

So, you've got multiple 'factors' going on here .

I'd say get the needle back to the recommended position, get the 'choke' mechanism back together again and I don't think you'll have any real issues .

Just as a side note, my '81 R65 developed hard starting issues below 55 F. about 10 years ago, the same time they started adding 10% ethanol to the fuel supply, getting away from MTBE which was used before .

My problem turned out to be a weak ignition coil (low primary circuit resistance), when the fuel went to the alcohol mix, it became harder to start due to the alcohol is harder to get vaporized than gas alone at lower temps  .

[technothrill]

So, you've got multiple 'factors' going on here .

I'd say get the needle back to the recommended position, get the 'choke' mechanism back together again and I don't think you'll have any real issues .

Just as a side note, my '81 R65 developed hard starting issues below 55 F. about 10 years ago, the same time they started adding 10% ethanol to the fuel supply, getting away from MTBE which was used before .

My problem turned out to be a weak ignition coil (low primary circuit resistance), when the fuel went to the alcohol mix, it became harder to start due to the alcohol is harder to get vaporized than gas alone at lower temps  .

Interesting note Bob, re MTBE. I've been running premium octain fuel. Tested resistance in the coils some weeks ago and they seemed okay (don't recall the values but an electrical guru was overlooking). I do have questions about spark plugs, caps. Running 5 ohm caps right now though some recommend Zero ohm.

Yes, repair choke cables: anyone have a spare little toothed gear for those?

Question remains: What is the stock recommended needle position? 2 or 3?

Thanks Bob!

[Bob_Roller]

Post those carb numbers and I can get you the answer when I get home from work today .

The needle clip positions are numbered from the top groove, just to remove any possible errors in how they are numbered .

On your parts problem, we have a member here not active in some time now, lamont, he is an eBay seller lamontsanfurd, real name Larry Chabira, dismantles airhead BMW's and Guzzi's, he's located in Austin, Texas .

I have done business with him and I think Monti has purchased an R65 from him stands behind what he sells, if something isn't right with a part, he will do whatever it takes to make it right .