Fuel System Purge

Darryl.Richman · Post by **Darryl.Richman** » Sun Oct 26, 2014 9:00 am

Welcome! Sounds like you have gotten a bike that is in great condition, which is the best way to start out. But unless the carbs have been modified, you will find that they don't have vacuum ports for you to attach your TwinMax. There are vacuum gauges you can get that you can hold against the intake side of the carbs and get a relative reading, so you can compare them side to side.

stagewex · Post by **stagewex** » Sun Oct 26, 2014 9:00 am

Greetings, I am new here (joined a few minutes ago) and just became a "vintage" owner a week ago. A little about my new to me bike... 1969 r60/2, US version. 21498 documented miles, unrestored. The previous owner had an enormous amount of work done at Max BMW last June (I have all the printed bills) but seems to have only ridden the bike a little more than 100 miles since then. And about 300 miles altogether during his 2 years of ownership. In comparison he bought a 2014 HD the same day he dropped the r60 off for service and has already put more than 3000 miles on that bike. So while he did take good care of the r60 and its needs its clear it wasn't the bike for him. At least as a rider. And the owner before him also did not ride it much. So last Sunday, the day after I took ownership and possession I took her for a 200+ mile ride after adding a bit of SeaFoam to blow out a mixture of old and some new top-off fuel. Runs fantastic but cold starting is different for me... that's another subject and topic as I apply different sequences and have it down to 1 to 4 kicks now. I went 213 miles before complete empty. I filled her with 4.2 gallons of fuel, she should have taken according to the manual 4.5... that .3 would have gotten me home. I figured that there probably was debris built up around the petcock and when I took it out that was in fact confirmed. Small sludge run although the tank is nice an red inside. This new ethanol based fuel we are forced to buy is real crappy when stored (another subject).

I could clearly see crap/debris in the micro fuel filters so I drained the tank, cleaned the filters and hoses, found a bunch of debris in the petcock and in its screen that I cleaned and today will take off the tank and flush it as well. As a just in case I have removed the carb on one side and taken it apart. It appears clean but I am going to put it in an Ultrasonic Cleaner with Simple Green and then reasemble. To go this far and not do that just didn't make sense to me although these are the first Bings I have ever worked on.

I should add that the carbs were fully rebuilt (by Phil at Max BMW) last June and the entire fuel system hose-wise had been upgraded as well. Really nice stuff. But I do not see cleaning or flushing the tank as part of the service and certainly having close to the same fuel in her for close to 2 years is not a good thing. Actually a shame that was not done at the same time.

Any pointers for me about re-assembly? I'm basically going to do one carb at a time, count how many times each jet and adjustment should be screwed in and go from there. If the bike does not run right (she was sputtering a bit which prompted this cleaning) I can always start from scratch and use a TwinMax that I have. Thanks.

ps: when I figure out how to post a picture I will of some of the junk I've found so far.

stagewex · Post by **stagewex** » Sun Oct 26, 2014 9:07 am

No, they have not been modified so... the TwinMax is too modern of a device tool to work on these carbs, too funny.
Hopefully I'll be able to dial-in the adjustments by just recording and duplicating where they were before I started this operation.

schrader7032 · Post by **schrader7032** » Sun Oct 26, 2014 9:08 am

The Bing carbs on these bikes are simpler than the ones on the /5-on bikes. You might want to consider getting the book from Bing which describes the carbs in good detail. As for settings, you could compare the settings of your carbs as you disassemble with this page:

https://www.flickr.com/search/?w=67726688@N00&q=bing

If nothing else, you could set them to the standard settings and go from there.

Darryl mentions the intake side vacuum gages...search the forum by putting EMPI in the upper left search box. Several of us have bought these devices for helping with carb balance. Barring that, you have to fall back on the old shorting techniques to get a good balance.

jrapose · Post by **jrapose** » Sun Oct 26, 2014 3:20 pm

It's called a uni-sync and it is how we used to tune old MG and Triumph cars.... you can adjust it for the amount of vacuum and then just hold it against the opening of the carburetor than by going from carb to carb you can easily see which one is pulling the heaviest it makes the adjustment very easy... Napa used to keep them in stock...everyone can order one...probably plenty of them on EBAY.

I would not get too carried away with cleaning the inside of the tank.... I would use a good quality floor cleaner... and if it is a real problem you could always slush the tank with Glyptol to reseal it..

Joel (old autoshop teacher)

jrapose · Post by **jrapose** » Sun Oct 26, 2014 3:32 pm

If you have electronic ignition, MZ-B or Powerdynamo or anyone elses.... NEVER EVER pull a plug wire... The system will produce a spark, plug or not...and it has to go somewhere... it will go into the controller and cause serious damage... I have only had two units returned for service and both had been the victim of this. (honest owners) By the way I give extra credit to honesty... and I have only been stung once...( and it was hard....., but with any sort of business I think that is amazingly good)

If you have electronic ignition you must ground the plug... or the plug wire...to prevent damage. Much easier to use a Uni-sync

Joel

Darryl.Richman · Post by **Darryl.Richman** » Sun Oct 26, 2014 6:21 pm

Joel, about Glyptol... I have heard (warning... second hand information ahead) that it is good for sealing electrical pieces and even the insides of cases. But I have also read that it is soluble in ethanol, and thus may not be good in a fuel tank with our "modern" fuels.

jrapose · Post by **jrapose** » Sun Oct 26, 2014 7:45 pm

What we used Glyptol for was to seal the inside of engines to aid in the return flow of oil...worked well, we often ordered it as Electrical Motor Winding paint... which I think was it's major purpose... I had not thought about ethanol problems as that was not around at the time...... I am sure Eastwood sells a product for lining fuel tanks.... I know it is a common practice with home built aircraft...we used to call that stuff Slushing coumpound.....to me it looked like paper cement... and smelled as bad... sure the aircraft folks would have an upgraded compound that resists ethanol....

stagewex · Post by **stagewex** » Mon Oct 27, 2014 9:11 am

Thanks for the suggestions guys. I was just going to just use a little gas and swish the tank around a bit. I do not have any flaking going on so don't want to take a chance and disrupt any of the tank lining at this point. The lining looks great. I think the debris is from the gas and it's interaction with the rubber fuel hose. This bike was barely ridden and just stored in a hot garage all summer. I come to that conclusion because the debris in the in-line filters was too big to pass through the screen in the petcock. The petcock and what little came out of the tank is mini-granular. The stuff between the petcock and the (and in the) fuel one filters almost looks like the type of bacteria that sometimes grows in diesel fuel if you know what I mean. I'm doing the carbs as an "well I'm here anyway" project.

Already finished one carb: disassemble, cleaning in Ultrasonic Cleaner (Simple Green), hand polished, reassembled and just put it back on the bike. Looks stunning if you can find beauty in an inanimate object.

Two (2) Related Questions:
1) do you guys turn your petcock off and let the carb drain dry when you turn it off? Or maybe just when you are not going to use her for awhile?

2) previous owner recommended using High Test/93 Octane. Manual says use Regular (not octane listing). Of course that 1969 regular. What do you guys think?

What's the deal with replying so that your post continues in the same historical order?

schrader7032 · Post by **schrader7032** » Mon Oct 27, 2014 9:56 am

I think the general recommendation for petcock use is to turn it off when the bike is not in use. I consider it unwise to totally rely on the float to shut the fuel flow off 100% of the time. Shutting the petcock off is the best method.

Another thing that most recommend is to shut off the petcock when you near your final destination, say after finishing a local run for the day or when you're heading to a gas station for refueling. Do this about a block or so before engine shut down. If you have clear fuel filters you can even see the fuel level drop in them as the fuel is consumed in the bowl. The idea is that once stopped, the engine heat tends to expand the fuel in the bowl and it can spill out or flood the cylinder. This is especially troublesome at fuel stops. While tickling the carbs for starting is essentially flooding the carb, doing that in conjunction with this heat-related fuel expansion can make restarting difficult. BTDT.

The R60/2 is a relatively low compression bike, 7.5:1. You can probably get away with the lowest grade of gas. That said, you don't want any pinging, so if you run regular and you hear the telltale sounds of pinging, bump to the next grade of gas. If you end up needing the highest octane to avoid pinging, you probably have combustion chamber deposits which artificially increase the compression ratio.

As for the posting order, I think that is the way the forum is set up...you can change it from oldest first to newest first using the feature at the bottom of the page.

Vintage BMW Motorcycle Owners