R65LS - idle rising when ridden

[Inveloveritas]

Hi all
Newbie here, thanks for having me.
I’m having issues with my R65LS. I have rebuilt the carbs a year ago fully with all new parts and towards the end of last year put new floats, float pins and float needles with gaskets to solve a leaky float bowl. I did both of them at this time.
Recently, I’d been having trouble starting her and getting her to run properly, backfiring and then once running the idle speed keeps going up and up till they are absolutely racing.
So, when the float bowl overflowed I pulled them both off again and they were about 8mm deep with hard (like concrete) sediment in the bottom of both float bowls. I cleaned them both out, reset the right hand float and then calibrated the carbs again using my CarbMate. The idle was absolutely perfect and the bike running perfectly. I took it for a ride this morning for 15 minutes and it ran better than its run for ages, possibly ever. BUT the idle keep rising while running, getting faster and faster as it warmed up.
The only thing I missed mentioning is that when I did the carb synch yesterday, the left hand exhaust was much cooler than the right, much cooler. I burnt my hand on the right one but could touch the left.
Are these two things linked ?
I haven’t changed the throttle cable when I brought it back to life a year or so ago but I have a new one of thoughts are that might help. But I’m floundering here. The bike is running perfectly except this but it actually makes it quite dangerous to ride around town like this.
Thanks in anticipation
Sean

[barryh]

8mm of sediment only 1 year after a rebuild is to say the least unusual. I would be inclined to strip the carbs again and make sure everything is clean. Then start with base settings of half a tun out on the mixture screws and 1 turn or less on the throttle stops. Adjust the idle speed down after a good long run when the engine is fully warmed up, then adjust the mixture setting for maximum idle speed followed by resetting idle speed if necessary with the throttle stops. Carb balance is the least of your problems so that's the last thing to check with your CarbMate.

The objective is always minimum possible throttle stop setting for the desired idle speed. Never use mixture screw settings to reduce idle speed

[Inveloveritas]

Thanks Barry.
Just to double check, the mixture screw is the one under the body next to the vacuum port and the throttle screws are on the top with the cable going into it ? Is that correct ?
Sean

[barryh]

Correct.

[SteveD]

Thanks Barry.
Just to double check, the mixture screw is the one under the body next to the vacuum port and the throttle screws are on the top with the cable going into it ? Is that correct ?
Sean

6. bing labelled.jpg (122.62 KiB) Viewed 748 times

[Inveloveritas]

Thanks Fellas. Appreciate the help.

[SteveD]

If you have junk in the bowls and hard cold starting, is the jet in the corner of the bowls clear? It meters to the "choke" on start up.
Barry mentioned it already, but the warm up pre tune is vital otherwise you will get a high idle.

https://youtu.be/Wpd27HTGCv8?si=IpAhejcN59JNqjDr

[Inveloveritas]

Thanks Steve
Yeah, so those jets were clear when I blew through them with brake cleaner.

Back onto the earlier point. I take the bike out (it’s now riding perfectly by the way except the high idle when it’s really warm) and get it up to temp. I then drop the idle mix screw to 1/2 turn out and the throttle stop screw out to 1 full turn.

I then fettle the idle with throttle stop screw until it idles nicely. That right ? From memory my idle mix screw was 1 1/2 turns out.

Thanks
Sean

[SteveD]

The bing chart says 0.5 turns out.
On a warm engine, set the mixture screws to their highest idle.
Ensure there is a little freeplay on the throttle cables...2mm usually plenty. Use the throttle adjust screws to set the idle.

BING bmw jetting chart_cv_carbs.pdf.png (273.69 KiB) Viewed 692 times

[Inveloveritas]

Super helpful !!! Last (stupid) question. Do I reset all the screws while the engine is running or when it’s stopped ? Thanks.