The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: thrang on March 29, 2008, 02:19:58 PM
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Hiya all, not been on line much lately... I've been in the shed arguing with various bits of the Bimbo, but having had a wee carb problem with the RT which needed resolving. Anyway £70 got me two complete rebuild kits (seals, jets needles and o rings) and the rebuild has improved my fuel consumption by a massive 10 miles to the gallon!
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Wow, 10 MPG is a dramatic improvement ! There must have been quite a bit of leakage past the seals - did your carbs have the rubber tip
needle valves ? The mixture must have been fairly rich beforehand - how do your spark plugs look now ?
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Good grief. What was your mileage down to, and what is it up to? My bike sat for so long before I bought it that I didn't have any choice, so no dramatic discoveries like that. Good job!
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Ever since I got the RT I knew she drank more juice than the Bimbo averaging around the low 40's to the gallon but put it down to the combination of the extra weight of an RT fairing and pannier kit and the Lake Districts road conditions as the MPG on 100m plus journeys was not that much less than the Bimbo.
I guess with the way fuel has gone up in price, the Euro fascists insisting that we sell fuel in litres and my habit of tossing a tenners worth of fuel in the tank every 100 miles or so meant I was not really really taking much notice of the consumption.
Anyway come January (naturally.... since I just love working on bikes outside in winter... yeah right) I ran down to see my parents in Southport I noticed that she was down to around 35. Assuming it was knackered diaphrams I popped into Southport Superbikes bought a pair and replaced them... only that did not cure it and if anything made things worse as now the plugs were getting very sooty....
Since I used my bike most days in winter running the 4 miles each way to work and back each day I am used to having sooty plugs (lots of running on half choke) and tend to clean them pretty regularly.
Pulling the carbs apart (one at a time) both were putting it mildly not in the best of nick. The float were heavy, and the rubber tips on both were rounded enough to be knackered. The diaphragm needles were mismatched in both type and setting. The LHS was on position 4 while the RHS was on three. Internally they were full of 'sh*t'. I replaced all the seals rubber o rings and jets, put them back together and after a bit of fiddling got them set up, and balanced about right and boy what an improvement....
Just goes to show never trust what a PO tells you as I was assured that the carbs had been recently rebuilt when I got the RT this time last year....
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Hi thrang
I too live in southport, and as i am getting my bike back together am thinking new diaphragms might be next on my list. Did S/superbikes have them in stock or did you have to order them in specially? As I thought I may have to order from motoworks or such like.
thanks Steve.
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And while we`re at it......Can anybody confirm that my 1979 R65`s FLAT-TOP Bings do not have the big spring shown on many of the exploded diagrams.
This appears to sit on or in the piston/diaphragm assy,but I`m unsure if its only fitted on the later domed-top carbs.
I`m asking before I remove the tops to check the situation ?
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From what I can remember, the flat top carbs don't have the springs on top of the diaphragm.
Can't find my Bing manual quickly !
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No springs on top of the slides in the flat-top Bings.
I may be remembering this incorrectly, but I seem to remember reading on a European forum (Kleineboxer?) about some folks adding an aftermarket spring to theirs. It would take me days to find the source again... :(
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I'm thinking of replacing my floats & float needles due to the dripping carb situation. Can I do this without removing the carbs? Also, do I need to re-balance the carbs after?
Thanks, Bill Conquest ( '79 R65)
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You can replace floats and needles without removing the carbs from engine but you'l have to kneel and "kiss" the ground :)
it's a good idea to rebalance carbs after. pay atention to the level of fuel.
good luck
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Bill,
Just to clarify what scuba said about level of fuel - make sure that the floats are stopping the flow when they are parallel with the bottom of the carb.
If they are not, there is a bendable tab that presses on the needle for adjustment.
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thank You Rob, I was thinking exactly that. sorry for such "dry" info :-[
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Thanks for the info,guys - guess i'll get out there and get horizontal.. any words of wisdom on getting the pins that hold the bowls out? I've never done this!
Thanks, Bill Conquest
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Look for the side that has something that looks like a star on the metal where the pin goes in, thats the side the pin comes out.
The pin has serrations on one end.
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For the amount of time it takes to remove a carb, against how rarely the floats need changing I've always removed mine to swap out the floats.