Jetting my 1982 R65

[georgesgiralt]

Hello !
I bought this bike new 28 years ago (it sat a couple of years in the dealer's showroom).
I used it for 14 years all day, then put it aside. This year I returned it to the road. But there is no more 97 RON leaded fuel as specified by BMW.
And in France, 95 unleaded is being phased out and replaced by 95-E10 with around 10 % ethanol in it.
So I rebuild my carbs (they needed it !), changing everything rubber, putting new springs, new jets, new needles and ensuring all air holes are clean and up to spec, checked ignition put a new coil to replace my creaked gray one, new plug wires, new plugs, checked valve clearance , new oils new air filter, etc...
At first I started with factory European settings : 2,64 for jet needle, 4th position of the needle and 145 main jet. At first, I decided to set for 95 unleaded.
The bike has a pronounced hole if I fully open the throttle at 3500 RPM in 5th gear. It sets back to 3000 then start to flight.
So I tried to put the needle one step leaner to no avail (it was worse)
Then I started to reduce the main jet (after returning the needle to the 4th position) 142 at first, then 140. The setback is still here (even if maybe less pronounced) and there is another one at around 5000 RPM.
I though I had to increase size of the needle jet to 2,66 but it is the same.
I tried to put the stiffer springs of the post 1983 R65 but is is also no good.
The bike handles good in town and transitioning from idle to 1/4 throttle but could perform better above this. I still can get around top speed in 5th (the RPM goes as high as 7200) so maximum jet flow is sufficient.
So I ask for your help and advice because I want this fine bike run as when she was younger  
P.S. I have a complete set of main jets from 135 to 148, 2,64 and 2,66 needle jets and retained the standard idle jet : 45 (which is also new)

[Barry]

....I decided to set for 95 unleaded. So I tried to put the needle one step leaner to no avail (it was worse)

I'm puzzled why you would make significant changes to the carbs for running on 95 unleaded.  Mine runs fine on standard jetting with 95 unleaded. There may be issues with pinging but I'll come back to that later.

If the bike ran fine before for 14 years my first inclination would be to return to whatever jetting you had then and work from there as 95 unleaded will have little impact except a very slight leaning of the mixture.

For now though to address the symptoms you describe it suggests a need to raise the needle because it sounds like you are lean in transition from the idle circuits to the needle in other words the transition to the tapered part of the needle is happening too late.  If you were already on position 4 with a 2.64 needle jet then there was no option but to go to a 2.66 and perhaps position 3 on the needle. But if you are saying you already tried that then I think the problem may be else where. Perhaps diaphragms ? Are you sure they are fitted the right way around ? The vacuum hole in the underside of the slide should be oriented towards the cylinder head.


95 unleaded may cause some pinging at 2500 - 3000 rpm under heavy load. Initially I had to retard ignition timing by 2 deg to eliminate this but have since returned to stock timing together with a fuel additive. I don't think you should get into this issue though until the carbs are working correctly.

[montmil]

My '81 R65 experienced a similar performance drop off where the engine would simply fail to 'pull' while in 5th gear. I replaced the diaphragms with Bing OEM and the issue went away.

How old are the diaphragms in your carbs? I never did spot a hole or tear in mine but new bits solved all issues.

We have ethanol in our gasoline, too. Up to 10% by volume. So far, no problems with the carb's rubber O-rings. I do change out fuel lines annually just as a precaution. I also run 87 octane regular gas in both the R65s but use the 'hi-test' in the R100S.

[georgesgiralt]

Barry,
At first, I used exactly the same part as original (I just put new parts into the carbs but same size). I experienced the hole in the acceleration between 3500 ~ 4000. So I thought I had to change the settings to correct this.
As for the diaphragms, they came out of BMW (I can check the part numbers in the invoice) and where changed with the other carbs parts I can't state how old they are because the dealer had them in stock.
I should give another try to the 2.66 needle jet and position 3 of the needle. Maybe I've overlooked something when I've done this test.
What would you suggest as the main jet to go with this ? The 145 original or smaller ?
I've to admit this takes a long time to test and I'm a bit tired....
Anyway, thanks for your help !

[Barry]

The size of the main jet can have an effect at those revs but only if it's  many sizes too small. I'd use the 145 main jet just to be sure it's not part of the problem.

Carb problems can be frustrating.  A flat spot at those revs is usually the result of the needle not lifting high enough. And that can be caused either by too low a needle position or by something related to the vacuum above diaphragm not lifting the needle as high as it should.

[k_enn]

<snip>We have ethanol in our gasoline, too. Up to 10% by volume. So far, no problems with the carb's rubber O-rings. I do change out fuel lines annually just as a precaution. I also run 87 octane regular gas in both the R65s but use the 'hi-test' in the R100S.

I have heard from sources that work on small engines (e.g., lawnmower, snowblower, leaf blower, etc) that high test - 95 octane - gasoline has less ethanol than regular - 87 octane - gasoline.  Supposedly, this is because the addition of ethanol lowers the octane.  

Anyone know if high test has less ethanol or is this just another urban legend?  You can't tell by the labeling at the pumps here - they all say "up to 10% ethanol"  which could allow for less ethanol in high test.  

[Bob_Roller]

Where did you get the replacement rubber parts for the carbs ?

A few members here have gotten non-OEM diaphragms from Motobins and the rubber was too thick and non-compliant and carb response was affected by these parts .

Just a thought, I'm not familiar with spare parts suppliers in the European community .

[georgesgiralt]

To test for the content of ethanol is easy.
Pour in a measuring jug an exact amount of gasoline to test.
Add to this an exact amount of water.
Shake very well.
Measure the volume. the decrease of the total volume is the amount of ethanol.
Why ? Because if ethanol mix with gasoline it has a very strong affinity with water. By shaking you cause the ethanol to bond with the water instead of the gasoline....
This is the main reason they had to increase the tolerated amount of water in ethanol compounded gasoline as in pure gasoline. Ethanol absorb the moist in the air above it....
I've ordered new diaphragms and will test two settings with the new diaphragms :
2.64 needle jet and 'th position of needle, 145 main jet and
2,66 needle jet and 3 rd position of needle with 138 main jet as per 1983 R65 settings; will report when done... Which could be in a fortnight or more.
Thanks for your help.

[Barry]

I have heard from sources that work on small engines (e.g., lawnmower, snowblower, leaf blower, etc) that high test - 95 octane - gasoline has less ethanol than regular - 87 octane - gasoline.Supposedly, this is because the addition of ethanol lowers the octane.

Anyone know if high test has less ethanol or is this just another urban legend?  

I've heard the same thing about our 5% ethanol in the UK and for the same reason that ethanol increases octane.  We have no way of knowing for sure because there is no requirement to display ethanol content at the pumps and they don't ever do it.  We only know that the content can be anywhere between 0 and 5 %. The average person in the UK has no clue that our fuel contains ethanol and that it lowers the calorific value. The whole thing has been very underhand.

In Europe I believe there is the beginning of a political change of mood on producing ethanol from food crops so I'm hoping that means we won't end up with 10% which had seemed to be on the cards.

[georgesgiralt]

Hello !
I'm afraid that you're mistaken !
95-E10 is *already* planned ! It's deployment *everywhere* in Europe (including UK) has already begun ! France is quite totally converted, as is Belgium.
The only country it is fought against is Germany because a lot of Mercedes and BMW owner complain about it (it has too much water in it and is so marginally 95 that they have destroyed some engines with it, especially the old ones) And that is fun because it is said to be "green" gasoline.... And Germany is one of the greenest European countries.