very hot cylinder head

Pietro · Post by **Pietro** » Mon Apr 25, 2011 9:10 pm

Hi all,
77 RS here, with a temp problem.....Right cylinder head gets extremely hot in comparison to the left 30 min ride I can still lay my hand on the left valve cover, not so on the right....any ideas on where to start looking for problems ? Oil passage plugged up possibly ?, ring problems, cylinder wall problems ??
Thanks in advance
Pete

schrader7032 · Post by **schrader7032** » Tue Apr 26, 2011 3:55 am

Check your plugs; you might find that the right plug is very white as compared to the left. I would first look at the carbs...most likely you're running quite lean on the right side.

Bruce Frey · Post by **Bruce Frey** » Tue Apr 26, 2011 9:07 pm

If you can lay your hand on the valve cover on a warmed up bike I think the problem cylinder is the "cold" one, not the "hot" one, which sounds normal.

Bruce

Pietro · Post by **Pietro** » Thu Apr 28, 2011 7:03 pm

OK pulled both plugs last night.....left side had whiteish electrodes.....right side....gas soaked and black.....
I dialed the carb mixture back to 1 1/4 turns (starting setting) replaced the plug and restarted the engine....ran for 5 min...turned it off....both heads are now close to the same temp.....but....sigh.....while running it sounded like the timing was off a bit.....
today....bought a timing light and compression gauge.....more as it happens......
Thanks for the replies.....please keep the suggestions coming...
Pete

schrader7032 · Post by **schrader7032** » Thu Apr 28, 2011 7:24 pm

You will need to synch the carbs so that each is pulling an even weight for running the engine. Just changing the carb mixture setting might tell you something, but you will need to run through the steps to make each side equal. The BMW twin motor is like having two independent engines running. They each must be optimized but also in such a way to work well with the other in order to make the engine perform at its best.

joe28 · Post by **joe28** » Fri Apr 29, 2011 9:46 am

Here's a tip a old bike mechainc taught me years ago when he worked for Honda on the inline 4s.
He take the air cleaner snorkel off the carbs.
He's set the idle by slipping a drill bit between the slide and the base and adjusting the idle screw until the carbs were just touching the drill, (all the slides were then the same height and should pull the same amount of air in).
Then he'd turn the throttle to 1/2, lock it in place with a vise grip, but I've used tape, weights taped to the tube, anything to "hold it there".
Again adjust the slide to base of carb using drill bits or???? but make sure they are all the same height, (adjust by using the cable adjuster on this one).
Go to 3/4 and check, adjust if nessary.
back to 1/2 to check.
Turn your mixture screws in and count the turns.
Average it out and set both to that.
Now you can fire it up.
If it's idles low/high, turn EACH adjuster screw the same amount.
If you have to, turn each idle speed screw the SAME amount.
This has worked well for me over the years, but I check it with my HVAC air flow meter just for sheets and giggles, most times it's really close, (the meter will also tell you the condition of your engine, if the intake valves are outta adjustment or the rings worn, the air flow will be less).
Joe
Just my 2 cents worth!

Pietro · Post by **Pietro** » Fri Apr 29, 2011 9:36 pm

Kurt, Joe.....thank you both.....should have added that I ordered the vac gauge...book suggests 1 1/4 turn as a starting point....use the vac gauge to dial that in....
weather was a bit unsettled here yesterday on the East Coast.....so tomorrow is a play day.....hope to get the critter running right as there is a club meeting and breakfast Sunday....
Will let you know what I find.....Like the drill bit idea Joe...thanks.....
Pete

Bruce Frey · Post by **Bruce Frey** » Fri Apr 29, 2011 11:24 pm

Check the float on the carb that is running rich before trying to tune the carbs.

Bruce

Pietro · Post by **Pietro** » Sat Apr 30, 2011 6:01 pm

Checked the timing this morning.....dead on....as is the advance.....
Heads are running close to the same temps....after moving the mix screw back to starting point of 1 1/4 truns....
Vac guage gets here will fine tune the carbs.....was actually able to ride for an hour or so today....damn that felt great.....
Bruce...you were correct on the float.....letting in to much fuel.....reset it as well......
Guess next time I ask for specific work to be done, I'll add...please test drive after work is completed......sigh....
Thanks again all.....will let you know how far out the carbs really are when the guage gets here
Pete

Vintage BMW Motorcycle Owners

very hot cylinder head

very hot cylinder head

Check your plugs; you might

If you can lay your hand on

OK pulled both plugs last

You will need to synch the

Here's a tip a old bike

Thanks guys

Check the float on the carb

update