The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: Luke D. on March 18, 2015, 05:51:54 PM
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Good day all. After working on the bike during the winter, she does not want to stay running. All I did over the winter was change the valve cover gaskets, take off the air pulse system, and pull the bowls off to make sure everything down there was okay. I got it fired up no problemo, went and throw some race gas in it and when I got to the station she died. Got home no problem and tried to adjust the idle a little bit. Will run for a short time then idle down and die. Could you help me with the procedure as to how to adjust the idle up and make it run synced up? Thank you all for your time. Have a great day.
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Sounds like you may have debris in the carb causing problems .
The first thing would do, is to remove the float bowls and blow through the small metering jet, that feeds the cavity that the small diameter brass tube fits into .
You may want to remove the carbs and use carb cleaner to clear the drilled passageways in the carb body .
I had numerous problems with my '82 LS, clogging the ports and passageways, the auto parts store sold me vacuum hose, instead of fuel line, it was mismarked by the manufacturer . >:(
If your fuel line is old, may be a good time to replace it .
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Thank you Bob Roller for your input. If some of the ports are clogged would the bike run fine when using the throttle and just not stay running?
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The Bing CV carbs can be a bit tricky, especially getting the idle to where you want it. BTW, to keep oil pumping to the timing chain chest, idle speed should be between 800-1100 rpm.
Here's an easy suggestion: Take the bike for a good warm-up ride. Maybe 20+ miles depending on ambient air temps.
Back off the Idle Adjust Screws to where they are just off the lever. Note the position of the Idle Mixture Screws. Mark that screw slot position with a pencil so you can always return to your original location.
Adjust both screws to where the idle is to your specification. Turn no more than a screwdriver's blade thickness. Blip the throttle and allow the engine speed to settle. Too high? Go the other direction. Shoot for that 800 number, minimum.
Go for another ride and take along your screwdriver. If the idle needs to be a bit higher, use the Idle Adjust Screws to adjust.
This is all dependent on your carbs being clean and free flowing.
Be advised that the valve lash, bean can advance weights and timing also play a part in getting your idle to its happy place.
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Montmil, thank you for you help. What about the little brass screw on the bottom of the carb? Its next to the little (brown on mine) vaccum hose. At the beamer meet up here at the Minnesota State Fair, on of the really smart air head guy helped me even out the carbs and made it run right(right rpm and not dieing). He adjusted the top (idle screw?) and then the bottom brass screw. Thanks again.
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It is also important to know that your valve clearance is correct before you go about synching the carbs and setting the idle speed. It is possible / likely that you have some debris clogging the idle jet, which would cause the engine to not idle and stay running unless you keep twisting the throttle to pump some gas in to the intake stream. If you removed the carb(s) it might be that you didn't get the carb back onto the rubber boot securely and/or you have an air leak between the carb and the cylinder head.
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The adjustment screw on the bottom of the carb is the idle mixture screw which weakens the mixture when you turn it in and richens the mixture when you turn it out. There is a base setting which is usually 1/2 turn out from being turned in until it gently seats. Besides making sure the carbs are clean you should check the float levels are correct.
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There is a base setting which is usually 1/2 turn out from being turned in until it gently seats
small detail, but on the US bikes the base setting is further out. Something like 1 to 1-1/2 turns.
I remember wondering why my bike idled like crap at the base setting and required so much extra juice... it was because we're jetted leaner than the European bikes.
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Sorry its taken awhile to say thanks to all of your help. I finally had a chance to get the carbs apart and cleaned up. It idles just fine now (once I got it to the right setting) But now once it warms up and I go above 3000 RPMs and pull the clutch (shift/slowing down) it will stay at 3000. I read that it may be the bean can stuck on advance, or the carbs are not synced up, a couple other things. My grandpa let me borrow his carb sync tool and that is my next step. I have a question about when you are syncing the carbs what do you adjust to make the sync up? The idle screw, air/fuel mixture screw? I did put the air/fuel mixture screw to about 1- 1 1/4 turns from bottom. (Thank you Luca) Also after the engine has been rev'd up for awhile (freeway/highway) when I put the clutch in it goes down to the idle set and sometimes dies, but when I am at lower speeds (in town) it idles just fine. Could that be because the carbs are not synced? Thank you all again for your help with my issues. You are all a great help. Have a great day.
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The initial step in syncing the twin Bings, and a very important one, is to have the engine at full operating temperature. With the temps in MN right now, that could mean a ride of 20-25 miles depending on ambient temps.
Best to have your garage prepped for the syncing drill prior to your warm up ride. The engine must be at normal op temps. Have a fan handy to blow some cooling air across the engine if you spend more than 5-7 minutes doing the manometer work. Avoid overheating. Stop if you must to allow a short cool down.
Carb cables should have about 2mm of freeplay at the carb's cable adjust screws and lock nuts. This is important. The idle adjust screws -those on the top of the carbs- should be just off the throttle levers. Not touching but just clear.
With the manometer lines attached to the vacuum take off points on the bottom of the carbs, adjust the idle air mixture screws -those on the bottom of the carb body- to equal readings on the manometer. Get the idle up to a minimum, balanced rpm -where the engine is not stumbling- using only the idle air screws. You want to keep oil squirting -and that's exactly what it does- on the timing chain and gears. Blip the throttle occasionally after each adjustment and permit the idle to re-establish itself.
After vacuum levels are equal, you can use the idle speed screws up top to set a slightly faster idle, if desired.
Balancing the throttle cables is another step but only after you have balanced the Bings.
Keep us posted on your efforts and success.
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I have a question about when you are syncing the carbs what do you adjust to make the sync up?The idle screw, air/fuel mixture screw?I did put the air/fuel mixture screw to about 1- 1 1/4 turns from bottom. (Thank you Luca)Also after the engine has been rev'd up for awhile (freeway/highway) when I put the clutch in it goes down to the idle set and sometimes dies, but when I am at lower speeds (in town) it idles just fine. Could that be because the carbs are not synced?
Your sync tool generally won't respond to changes in idle mixture screws and they should be set separately. The base setting for turns out will depend on what size idle jets are fitted. Euro bikes have 45's and US bikes I think have 40's so that would explain the need for more turns out but I'm surprised it's as much as 1 - 1 1/4 turns.
As far as the idle hang up is concerned it's nearly always carb related rather than a sticking advance so eliminate carbs as the cause first before diving in to the bean can.
If the mixture screws happen to be set grossly too rich or grossly too weak it will reduce the idle speed and the throttle stops then have to be screwed further in to compensate and bring the idle speed back up. These are the conditions that cause carb related idle hang up because the throttle plate is now open further than it should be at idle which starts to flow mixture from the transition ports. Therefore in tuning the carbs the object is always to achieve the correct idle speed using the minimum possible idle stop screw setting. And that means you should always set the mixture screws first. From 1 1/4 turns out I'd be inclined to try turning them in until the idle speed starts to fall or stumble and then out again only as far as is needed to restore a smooth idle. Any further out will be richer than necessary at least when the engine is fully warmed up.
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Good day all, hope you are all having great days. Alrighty here is the scoop, I have an old Manometer (grandpas tools :) ) so I took my bike for about a 10-15 mile ride on the way home from work. Temp was about 60ish maybe a little more. I got back and hooked up the manometer and the carbs a tad bit off (inch or so on the meter). Well first I checked to make sure there was a little bit of play in the throttle cables (Montmil) that was good. I adjusted the idle screws (on top) so they were just off the throttle piece. It would not start. I turned the idle screws down a bit (enough to get the bike to idle). Then I hooked up the meter and they were kind of close, the right side (sitting on bike) was at 4 and the left side was at 6. I made the low side richer but the meter did not show any change. I believe Berry said that the meter would not change based on the idle mixture being changed. ( I could be mistaken) So I put the mixture screws (bottom) back to the book setting (3/4 turn from bottomed) and that did not work so I put them up to 1 turn from bottom. Now I am just lost on how this is supposed to work. Do I set the idle mixture (bottom) to the book/ 1-1.5 turns first or do I set the idle (top) first and then adjust the mixture (bottom)? I am really confused on all of this stuff. Thank you guys for all your help, and im sure if I knew anything about carbs it would help but Im at a loss. Again thank you guys lots and lots. Have a great evening.
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Hey, Luke- The Idle Air Mixture screws are the first item of business. Also, the US-sold Airheads were jetted leaner than the Euro models due to US Bubmint's clean air regs; so try 1,25-1,50 turns out on the Idle Air screws. Also, take them out and make sure they are clear n' clean. Rubber o-rings can be problematic if they are buggered up.
I'm wondering about Grandpa's "old" manometer. Can you confirm it is functional? You should definitely see changes in vacuum readings on the manometer with even the slightest movement of the Idle Air screws.
Leave the Idle Adjust screws off the butterfly arms until the mixture adjustments match.
There may be some carb disassembly and cleaning in your future...
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Morning all, thank you Montmil for responding so quick. Frist off no I can not tell if the manometer is working. The silver stuff goes up and down very rapidly (vacuum from the cylinder firing, I think) and it seemed to do little changes when adjusting the idle mixture screw(bottom) but they would not equal out. The closer I got to equal the crappier the bike ran. I might be doing something wrong though (most likely). :) So the next thing are the idle adjust screws (top). If I don't have some kind of preset if you will on the butterflies it wont run. By the way why do they call them butterflies :-?? I will try and take the mixture screws out to see if they are clean before I try this next and then I will adjust them out to 1.25-1.5 turns. Thank you again for all of your help. Have a great day.
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As I said above your sync tool won't respond properly to changes in idle mixture screws. It will however respond to the smallest adjustment of the throttle stop screws.
To begin with I would put the mixture screws back to the book setting. I have to say I've never seen as much as 1.5 turns out for an R65 regardless of the size of the idle jet but do whatever the book says. Then use the sync tool to balance the carbs using the throttle stop screws at idle. Once you have them balanced at idle do them again with a small throttle opening of 2-3000 RPM using the cable adjusters on the top of the carbs to make sure both carbs are opening up together.
That should give you a reasonably smooth running engine and you can then go back and fine tune the mixture screws by ear if necessary. I generally turn the mixture screws in from the book setting until you hear the first indication of the revs dropping off and then turn them back out again only enough to restore the idle speed.
The other method is to turn them in until the revs drop and the out again until the revs drop noting the mixture screw settings for each position so that you can then set them in the middle of the two extremes.
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As I said above your sync tool won't respond properly to changes in idle mixture screws. It will however respond to the smallest adjustment of the throttle stop screws...
Gonna have to call you on that statement, Barry.
My $5.00 yardstick manometer filled with BMW 7.5 fork oil is quite sensitive to the positions of the Idle Mixture screws. I use the bottom screws to get my vacuum balance and idle set correctly before doing anything else.
US-sold Airheads are set leaner and do require the greater turns out of the mix screw that the Euro bikes. Using the tighter settings will have 'murican owners chasing their tail.
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Good day Berry, thank you for your quick response. Sorry if I am not understanding but are you and Montmil saying the opposite thing? You are saying to adjust the mixture screw (bottom) to the book setting and then hook up the meter and equal them out with the idle "speed" screw (top). Correct? And I think Montmil is saying to set the mixture screw (bottom) first, back the idle "speed" screw (top) all of the way out. Hook up the meter and equal them out with the mixture screw (bottom). Then adjust the idle after that. I think I am missing something :-/. Sorry if you guys are saying the same thing and im just not getting it. This carb stuff is waaaaaaaay over my head. :) I understand what they do and how they do it but I have never really worked with them. Thank you both/all for your help with my bike. Have a great day everyone.
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Luke, I was trying not to make this more complicated than it needs to be. I agree with Monte that ideally idle mixture should be set first but to do that you have to have the engine running reasonably well with the idle reasonably balanced otherwise it's simply not going to work. You inevitably end up doing the whole thing several times in order to home in on the best settings. That's why I suggested setting the mixture screws to the book setting and doing the idle and throttle cable balance first before going back to fine tune the idle mixture. If this fine tuning results in the need for an idle speed correction then you have to do the vacuum balance again with the throttle stop screws and cable adjusters.
If I'm reading Monte correctly, where we differ is that a manometer can be used to set the idle mixture because within normal limits the mixture screws have no impact or at best very little impact on engine vacuum.
Short of using a proper gas analyser setting the idle mixtures spot on is very difficult and that is good reason to not differ wildly from the book settings. I find the shorting method works well for me as an additional check that the idle mixtures are the same side to side but we are getting too complicated before you have the engine running reasonably well.
How does everyone else set their idle mixture ?
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Good day everyone. I know you guys wanted an update on my carb syncing and stuff so here is the dealio. On Tuesday nights we have a get together of bikes at one of the pubs here in Duluth. So I toddled over there to see what I could see. Sure enough there were a couple of Beemer guys there, perfect. I talked to a couple of them and told them my issues, well my motorcycle issues. :) So the older gent went to his bike pulled out a couple of tools and started syncing the carbs. He had me hold the bike at idle and he adjusted the mixture screw (bottom) and them he tightened up the throttle cables because they were a tab uneven. Then he messed with the idle speed (top) and got it to purr like a kitten. It did not hop around and it sat there and idled just about perfectly. I stayed the for a while and bought both gents a drink (root beer) for their help and talked for a while. When it was time to leave I fired the bike up and it would not stay running(idling). Both gents were gone so I headed home and let the bike be. I headed down to the cities this weekend with it, made some idle speed adjustments (to try and get it to idle) and it wont work. My left (sitting on the bike) carb was not flat (angled to the side a bit) so I fixed that thinking that may be part of the issue but it did not help. Once the bike warms up it will idle (most of the time). when I first bring it out to ride it wont. Now maybe you are thinking that the bike is cold and therefor wont idle without the choke. It is stored in my room (basement) every night. So I am still at a loss with this but will continue to work on it till she works, and of course will keep all you lovely folks updated as I chug along. Thanks again for everyone's help and hope you have a great day.
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My Airheads live in a Texas garage where indoor temps can get rather toasty. Even so, the bikes require a few minutes running on the enrichener circuit before they'll idle properly. A couple minutes riding and gradually pulling off the "choke" gets both of us happy.
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My bikes are like Monte's. Need enrichment on for a couple of minutes before they will idle. After carb work set everything to the basic settings then go for a ride about 30 minutes then set carbs.
Don
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Hey everyone! Thank you Montmil and donbmw for the help/input. I have some new stuff going on. Once the bike warms up it will idle kind of fine but it was starting to die so I gave it some gas and it started popping. Now last week when the gent adjusted my carbs and got them sync'd my left (sitting on bike) carb was not level. This weekend I leveled the carb. Could that have mess up the sync because the carbs were set for a not so correct carb? I hope this makes sence because I know im not the best at explaining things. Thanks for all of your help. Have a great night/day.
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Now last week when the gent adjusted my carbs and got them sync'd my left (sitting on bike) carb was not level.This weekend I leveled the carb.Could that have mess up the sync because the carbs were set for a not so correct carb?
No, a slight imclination of the carb won't have any materiall effect on the carb tuning. Folks are divided on whether the carbs should be dead level or inclined in at the top slightly to provide a smoother throttle cable run.
If it idles ok when fully warm then there is not much amiss. At any time before it's fully warmed up you can't necessarily expect it to idle or run smoothyly at very low revs without holding it on the throttle. Even in the middle of summer mine won't idle unassted until it's done 3 miles and then it idles at 800 RPM instead of 1000 RPM. That is as it should be if the idle mixture is set correctly i.e. not too rich.
If you change the carbs settings so that it does idle nicely before it's fully warmed up it will then idle too fast when it is fully warm.
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Good day all, I know its been awhile. I am still having issues with my bike idleing but I had an idea. Since the US models had the that funky air stuff that comes out the front of the jugs and goes into the air box. So our (US) bikes have one jet (size wise). The European bikes do not have this air system so they must have a different size jets. If I take the extra air stuff off my bike (US) do I need to change the jet sizes? The bike is idleing at first start up just fine but once she warms up it will idle and die. I have to keep the clutch in and the throttle on. I did hook up a colortune spark plug. It is kinda clear so you can see what color the spark is. My left side is the correct blue (with alittle throttle) the right side however, I cant seem to get the right color. Also the spark is on the outside of the plug instead of inside the cylider. Still trying to figure that one out. I thought you guys would like to know my (slow slow slow) progress. My real question is about the jets? Thanks all, have a great day/night.
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No experience with emissions plumbing but if I had it on my bike I'd remove it without question. Don't know if it requires a jetting change but I doubt it will. In any case that would have no impact on the ability to set a good idle mixture.
If you are still experiencing the idle speed falling away when hot then I'd go back to the first basic step in carb tuning which is to ensure the float levels are correct as everything else is a waste of time until that is confirmed. Bing floats are known to be sinkers when they get old so it might be worth weighing both of them to make sure they are the same weight and not too heavy. Last time I had the same symptoms of idle speed falling off it was one float that was 15 or 16 grams and close to a sinker.
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Removing the Pulse Air Injection System will not require a jetting change. This entire POS plumbing came about due to California enacting their oft times bizzare enviro laws. As an example, one spin off is that lawnmower manufacturers have to produce special Cali units that are sold out there. To avoid the possibility of some of their motorcycles running into legal issues if being resold in California, BMW Motoradd made ALL their products with the bathroom plumbing.
Both my R65s have been through rehab treatments. Your exhaust valves and seats will thank you. Here's a DIY article with a list of the bits needed:
http://www.ibmwr.org/r-tech/airheads/plug_fresh_air.shtml
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Good day all, Thank you Berry and Montmil for the information and help. Montmil, I took off the pulse air system and plugged all of the holes with the correct items that were in the link you sent me earlier in this thread. I was super excited to get it out but must not have tightened everything down enough because about a mile from my house one of the exhaust plugs fell out. >:( I had bought the two oil drain plugs for it and they looked great. Lost the darn plug. >:( found the crush washer though. ;D I ended up taking the part that originally went in there and found a bolt that fit the hole and welded the bolt in and then tightened that on with the crush washer. Works great and it has not fallen out. :) Berry, thank you for your input too. I will open up the carbs and check them out. I did notice that when I opened them earlier this year one of them was brownish looking. I had the carbs gone though a couple of years ago by the BMW mechanic that worked on it when my uncle bought it back in 82 :o Pretty cool. It ran flawless after that and now..... not so much. I will check that out the floats though. I'll have to find something to weigh them with though. Do you by chance know how much a float is supposed to weigh? I will check my books when I get home. Thanks again for all your help. Have a great day eh.
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Last year I installed new float sourced from Motobins and weighed them on super accurate lab scales at 12.495 Grams. Call it 12.5 grams. That was lighter than I expected as 13 grams is reckoned to be the standard weight.
You can run floats at 13 grams 14 grams 15 grams or even in a pinch at 16 grams but you are definitely on the slippery slope beyond 15 grams. Allowances have to be made for the extra weight because The method of setting floats parallel or setting fuel level measured in a float bowl at 24mm is fundamentally flawed for anything other than new floats or floats known to weigh the same as new.
The actual operational fuel level which has an impact on the mixture is close to the top front edge of the bowl due to displacement of the fuel by the submerged part of the floats, castings and jets. Because of differences in buoyancy, setting float levels by depth of fuel in the bowl will give different operational fuel levels depending on float weight just like old Archimedes in the bath.
To give a specific example:
You have one new float weighing 12.5 grams adjusted to give 24mm of fuel in the float bowl.
You have another old float weighing 15 Grams adjusted to give 24mm of fuel in the float bowl.
Place the new float in the float bowl and it will displace the 24mm of fuel increasing the level to within a few mm of the top edge of the bowl.
Place the old float in the other bowl and because of it's reduced buoyancy it will displace more fuel increasing the operational level by several mm beyond the level that the new float did. When the bowl is then offered up to the carb the difference is increased even further and that difference in fuel level will have a big impact on mixture strength .
I’m not saying you can’t use old floats that weigh more than new ones. Even at 16 grams they do not sink and produce an incontinent carb (at 17+ Grams they do). What I am saying is you can’t judge the operational fuel level by measuring the depth of fuel in the bowl at the normal figure. The 24mm often quoted is only valid for new floats and would need to be substantially reduced for heavier floats. If using the parallel method then old floats have to ne set lower than parallel by several mm.
To set up old floats by the depth of fuel in the bowl method, as an approximation I reduce the 24mm figure by 1mm for every additional gram that the float weighed above new ones. So I would adjust a 16 gram float to give to 19.5mmmm in the bowl.
What I concluded after a fair bit of experimentation with floats is that to stand a chance of getting them right you either have to fit new floats or you have to accurately weigh them and then make allowances in setting them up. I really don't see any other option particularly as a pair of old floats are not likely to weigh the same as each other.
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I had that same high rev in neutral idle problem too when I bought it but it came right pretty quick by adjusting the idle stop screws so the cylinders are firing equally, often noticed by listening to the exhausts from behind the bike. There's a great article in the FAQ section on this forum titled Carb Tuning By Ear I think
If you haven't already, have a play around with the idle mixture screws too and you'll learn how to balance your carbs after doing a tune up. I found that 1100rpm suits my high mileage '85 R65 to get a steady idle...