The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: Happy Eeyore on March 06, 2026, 08:14:22 AM
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A puzzlement: New dual endura last coils, new plugs, new plug wires, new points, new condenser, valves spot on, cleaned carbs, parts match recommended Bing standards, Needles set at lower setting, new diaphragms, bean can clean and happy, timing set, points set, advance happens, idles pretty good but still missfires at higher speeds. 32,000 miles. Have not yet checked compression, gauge coming, The other puzzlement is that the right exhaust is about 80 degrees hotter than the left exhaust. I can idle the bike with either just the left or right cylinder firing using a drop idle setting. What say you oh long of tooth, and vast R65 experience?, Electrical or fuel?
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The exhaust temperature measurements would suggest a mixture difference between the two carbs. Is that temperature measurement after running at speed or extended idling ?
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I would adjust the needles to the setting that Bing recommends .
Check the float adjustment .
Check the fuel line where it enters and exits the airbox I had mine kink and restricted fuel flow .
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Shame oh Shame but confession about not checking the basics is good. It was bad fuel.. Dumped the tank sloshing it side to side and added sea foam about 2 oz per gal and the missing cleared right up. It has been so long since I got bad fuel I did not even consider the possibility. Rebalanced the carbs. Temps are about equal. Running sweet now. Burn this after you read it so my shame will not linger.
It is starting to warm up here in North Georgia and we have wonderful roads in all directions dirt or paved, well sort of paved sometimes,.
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Just read this, what part of N. GA? I live in WNC north of Asheville. Maybe we can sneak a ride in sometime.
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I have chased this missing at high speed for a couple of weeks and thought I had solved it several different times. Thought it was bad fuel. Thought it was the bean can. Well for certain it was starved for fuel. I did a fuel flow and was getting about a gallon every 25 minutes which is way too low. Today I drained the tank and took out the pet cock and cleaned the junk off the two screens and now she runs like a champ. Inside of the fuel tank looks very good. Probably the first time the pet cock has been off. So if you run into this problem check the fuel volume flow rate and save yourself the chase.
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Did you have flakes on tank liner in the filters?
Two of my LS's have a screen in the tank that goes over the tubes on the fuel tap .
That are available from after market parts sites .
I had high speed miss after installing an inline filter, too restrictive .
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I have chased this missing at high speed for a couple of weeks and thought I had solved it several different times. Thought it was bad fuel. Thought it was the bean can. Well for certain it was starved for fuel. I did a fuel flow and was getting about a gallon every 25 minutes which is way too low. Today I drained the tank and took out the pet cock and cleaned the junk off the two screens and now she runs like a champ. Inside of the fuel tank looks very good. Probably the first time the pet cock has been off. So if you run into this problem check the fuel volume flow rate and save yourself the chase.
Did you have flakes on tank liner in the filters?
Two of my LS's have a screen in the tank that goes over the tubes on the fuel tap .
That are available from after market parts sites .
I had high speed miss after installing an inline filter, too restrictive .
My plan is to check the screens or just replace the petcock one iI get the LS back from some maintance and the Siebenrock 860 kit install.
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Bob, no rust showing in the tank. The crud on the screens was rust looking but it was some very small paint flakes I think. Gooey crud is the official analysis. The crud was about halfway up the pipe which was why the miss would come and go depending on the gas level. There were two screens , one large one covered the two straws in the tank and there was one downstream of the valve stuck up inside and it had to be hooked with a dental pick to pull it out. Both were partlally covered with crud. . I have a small in line filter after the petcock and I have a new one coming but it looks clean.
I read in Snowbum's complete history of western civilization that flow rates should be about 8 gals an hour. I was less than half of that. I had a DR650 and the first thing you do is take out the strainer because it always plugs. But I did not even know the R65 had strainers until I took it apart.
If the problem ever returns I will take out the strainers and just run with the in line filter.
Live and learn, then get old and forget then get to learn again.