Page 2 of 2 FirstFirst 1 2
Results 16 to 26 of 26

Thread: R75/7 Carb adjustment

  1. #16
    Registered User
    Join Date
    Dec 2012
    Posts
    1,159
    Quote Originally Posted by DennisDarrow View Post
    I really DO NOT understand the need to diminish other folks' advice, knowledge and recommendations; but each to their own needs.

    Yes, it is understood quite well about the learning capabilities of various types of individuals and the various styles of completing various
    "hands on" tasks. There are MANY ways to skin that particular cat. Next year will be the 40th year of the /6 750 and above engines that are equiped with carbs that have the capability of using vacuum guage equipment to adjust and synchronize. The method that YOU insist that all MUST use is a valid and real method that has been used on small engines of all types, cylinder configuration/number, and level of displacement. It is valid and real. All that I am trying to point out is that there are MANY ways to accomplish a task and NONE is wrong........

    No one is suggesting to bring in some kind of device to move air over the engine that is in a decible range that will drown out what the engine is doing. Here on our farm we have several "fans" that are in the 3' to 4' range that move LOTS of air. There is no way that they "drown" out the subtle sounds that are required to adjust the idle and sync by feel, touch, sight, and sound. WHAT is important is the need to keep that engine cool while one "learns" the various methods required to tune carbs or engines. Again, there is NO right nor wrong about this "tuning" business. It's just what works best for YOU, the situation, and machine...........God bless..........Dennis
    To quote Ronald Reagan, "There you go again!"

  2. #17
    Registered User
    Join Date
    May 2008
    Location
    B.P., MN
    Posts
    836
    Talking about Dels, I gave up vacuum gauges, mercury sticks, water stacks and the like and simply went back to basics, as a member suggested couple years back. First very important that all air connections carb to cylinder head are air leak free. Any air leak will effect the mix. Cracked hoses and the like. I seal the cable to carb tops too with a wrap of silicone self sticking tape. Hopefully no air into mix except through the carb.

    Next all jets and carb internals, stock as per manufacturer. figure that's what the engine guys came up with. Assuming valves are in adjustment, valves guides are good, rings are good, timing is spec, electrics are spec, valve seats are spec, and that's a lot to assume, move on to owner's manual.

    Next check carb slides are exact same height check with the click method, check cables properly seated in their ends with no binding either end, this exact slide height is where the engine operates on the main jet over 3K rpm, same height?, very smooth. For idle adjustment start at owner's manual settings and as stated by others, I use the ear and hand since we don't don't idle down the road.

    Two cents

  3. #18
    Registered User
    Join Date
    Dec 2012
    Posts
    1,159
    I think that we need to find someone who will sell expensive BMW Divining rods. Not only can they find underground water lines/streams, but they could double as carb adjustment tools. Just sit on the bike while it is running and the rod will "jiggle" on the side that the carb need the adjustment.

    Sell them with a fancy name and people will buy them! Some people just can't resist buying something!

  4. #19
    '92 R100GS '81 R100/t brittrunyon's Avatar
    Join Date
    Sep 2009
    Location
    Ojo Caliente, New Mexico
    Posts
    407
    [QUOTE=20774;892741
    That's just me![/QUOTE]

    +1
    1992 R100 GS, 2007 F 650 GS

    Big Bend Ride video at http://brittrunyon.com/
    More riding videos @ http://vimeo.com/user2721333/videos

  5. #20
    Registered User blackbeauty's Avatar
    Join Date
    Oct 2005
    Location
    Canton, GA
    Posts
    30


    I'm going to pea everyone off by saying there was great advice from everyone. Grounding out one cyclinder is not recommend with electronic ignition, it is ok with older models with points and condenser. I didn't see this point stressed. I use my ear and then go back and use a home made vacuum gauge to double check, but the sound is the final conclusion. I do use a fan regardless, and it generates very little noise, plus I live in the South where temps are not ideal without a fan most the year. If I were more experienced and quicker to do the adjustment in 3 minutes for each carb I wouldn't need a fan either. When I stop at a red light it's usually a 3-5 min wait. In the heat of summer with traffic heavy I sometimes turn off the engine. But this also causes a lack of escape if some one is greasing their lips in a mirror approaching unnoticed.

  6. #21
    P Monk
    Join Date
    May 2005
    Location
    Port Neches, Texas
    Posts
    723

    just my preferred method

    I prefer my carbs be in sync at 3 to 4 thousand rpms. I like both carbs to lift at the same time. But how many miles do you cover at idle? Get them as close as you can at idle, but I will always do the final setting at operating speed. You will need manometer, carb tune, twin max or whatever to set them at operating speed.
    P. Monk
    74 R90/6 (also know by bride as the Black Hole). 09 R1200 GS. My wife, 1953 model who has survived aplastic anemia and a bone marrow transplant.

  7. #22
    Administrator 20774's Avatar
    Join Date
    Sep 2005
    Location
    San Antonio, TX
    Posts
    14,960
    Quote Originally Posted by blackbeauty View Post
    Grounding out one cyclinder is not recommend with electronic ignition, it is ok with older models with points and condenser. I didn't see this point stressed.
    What is NOT recommended for the electronic ignition is to lift the spark plug cap off the cylinder while the engine is running. And it's probably not good to do even with points/condenser. It was acceptable to do with the pre 1970 /2 bikes because most were magneto ignition and they had a safety gap which allowed the spark to find a path to ground. That is the key to any of the ignition systems...the spark must have a way to get to ground otherwise that excess energy stays in the system and can cause harm...especially to sensitive electronic ignitions.

    Personally, I don't see anything wrong with plug shorting on an electronic ignition. The reason is your are providing that path to ground through the screwdriver. This does not effect the ignition. I've done it multiple times on my /7 with Dyna III ignition system.

    Now, if a person has trepidations doing this and they're not crisp in the movement of the screwdriver shaft on and off the shorting extension while at the same time touching the engine fins, then maybe a different method of synching should be considered.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  8. #23
    Administrator 20774's Avatar
    Join Date
    Sep 2005
    Location
    San Antonio, TX
    Posts
    14,960
    Quote Originally Posted by dpmonk View Post
    I prefer my carbs be in sync at 3 to 4 thousand rpms. I like both carbs to lift at the same time. But how many miles do you cover at idle? Get them as close as you can at idle, but I will always do the final setting at operating speed. You will need manometer, carb tune, twin max or whatever to set them at operating speed.
    This is something to consider however, the point where the difference is vacuum can more easily be felt is just off idle. You could end up with some hesitation as you transition from say a stop light and pull away.

    But remember there are three adjustments to the carb synch - idle mixture, vacuum just off idle, and cable tension. They each affect different aspects of the carb operation. By adjusting the carb at 3 to 4K RPMs, you're effectively only checking that you have the same cable tension and/or that the slides have been moved to a common point such that each cylinder is pulling the same. You wouldn't necessarily have affected or helped the operation off idle.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  9. #24
    P Monk
    Join Date
    May 2005
    Location
    Port Neches, Texas
    Posts
    723

    Kurt, we are in agreement

    Didn't intend to say that idle and simultaneous lift off of the slides are not important, however I still believe that sync at the rpm the bike operates at 80%+ of the time is important, and that can only be checked with a vacuum gauge of some kind. If adjusting the sync at operating speed causes stumbling because one of the carbs is not being opened at the same time, then there is another problem to deal with.

    I had a similar problem with the 90/6 with timing. If I set the points so I was perfect at idle it would start great and was good at low speed, however i was not close on timing at speed. Had new timing chain installed. New points (several of them) and still couldn't get it exactly right. My solution finally was to install the Alpha ignition. For the first time the old bike's timing is perfect at full advance. It is smoother and more powerful than I could ever get it with the points. Now the old beast is perfectly happy cruising at 80mph. A lot of my carb issues were solved. Should have said perceived carb issues.
    P. Monk
    74 R90/6 (also know by bride as the Black Hole). 09 R1200 GS. My wife, 1953 model who has survived aplastic anemia and a bone marrow transplant.

  10. #25
    Administrator 20774's Avatar
    Join Date
    Sep 2005
    Location
    San Antonio, TX
    Posts
    14,960
    The Alpha ignition can take care of a host of issues, especially if they're tied to a worn out advance unit. Since the Alpha is crank-fired (I think that's correct), that's better than the stock firings off of the camshaft.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  11. #26
    #4869 DennisDarrow's Avatar
    Join Date
    Jan 2006
    Location
    Sugar Valley, Ga
    Posts
    1,282
    Quote Originally Posted by dpmonk View Post
    Didn't intend to say that idle and simultaneous lift off of the slides are not important, however I still believe that sync at the rpm the bike operates at 80%+ of the time is important, and that can only be checked with a vacuum gauge of some kind. If adjusting the sync at operating speed causes stumbling because one of the carbs is not being opened at the same time, then there is another problem to deal with.
    .
    Right there with you on the sync at operating speed..........What is it doing at 4K??.......Make sure you have a really good fan on in front of the cylinders, If stumbling at speed or hesitation with a roll-on, it's time to check out the diaghrams.......pardon spelling...Using a surface pro 3 and often the spell check is really hard to use......God bless.....Dennis

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •