• Welcome, Guest! We hope you enjoy the excellent technical knowledge, event information and discussions that the BMW MOA forum provides. Some forum content will be hidden from you if you remain logged out. If you want to view all content, please click the 'Log in' button above and enter your BMW MOA username and password.

    If you are not an MOA member, why not take the time to join the club, so you can enjoy posting on the forum, the BMW Owners News magazine, and all of the discounts and benefits the BMW MOA offers?

/6 cylinder temp

skotlyc

New member
Hello all. After spending all winter completely rebuilding my 75 r60/6, I'm finally getting a chance to get it out and ride it with the nice weather. I am noticing however my right cylinder is running just a tad hotter than you left. According to my IR gun,by 10 degrees. Is this OK? My spark plug isn't white and other than a little bluing on the right header, I wouldn't know the difference. Both header pipes are discoloring, the right slightly darker... they are cheap MAC aftermarket. Whatdya think?
 
My wild guess would be that the right cylinder is running leaner than the left. I've seen this before on a 600 with type 53 Bing carbs. The best answer would be to send them to Bing for a re-build. You could get a kit and try it yourself as well. Y'know, soak 'em and blow out every passage with Gumout and/or compressed air. Be careful, there is a tiny accelerator pump built into the main jet stack. The other guy I knew who had this issue installed the Mikuni conversion. His bike had set for 30 years with rotten fuel in the system, so those carbs were hopelessly blocked up internally.
 
I'm not sure 10 degrees is much to be concerned about. Might just be that the new "toy" is providing you something to worry about. Be sure the carbs are balanced by the best method you know of and that should be about as far as you need to go. I wouldn't worry about something so minor.
 
I am not sure anything to worry about. Get some hundreds (thousands?) of miles on it, carefully watching things as you go. Be sure carbs are correctly adjusted. If you did a rebuild, rings, ect., it simply could be break in that is a little tighter on right side.

If is sounds OK and rides OK with no visible issues, ride!!!

Be sure to re-adjust everything (valves, carbs, etc.) after a few hundred miles.
 
I didn't think it was a huge deal... it runs way to well for me to be concerned too much.
Well then, why post?
One pipe blueing more than the other always indicates an issue, which is one cylinder running hotter than the other. Plain and simple.
 
Well then, why post?
One pipe blueing more than the other always indicates an issue, which is one cylinder running hotter than the other. Plain and simple.

Not necessarily true. There are a lot of factors that affect the "blueing" of the exhaust pipes.

Not saying that there isn't a problem, but to me, highly unlikely. There needs to be some break-in done to let all the wear surfaces to smooth out and seat with each other.
 
I have also messed around with an IR gun with the bikes . With the R80 the temperature difference between cylinders has been close to 10 degrees , sometimes a little less ; usually right around 300 degrees by the time I get the bike into the back yard , and get the gun . Can't remember which side was hotter , because I did not find the difference meaningful . Which way the wind is blowing or if you are aiming at exactly the same spot are variables too difficult to resolve . Aimed right above the exhaust nuts , between fins . Would be even more difficult while in motion .
 
Hmmm...EGT or exhaust gas temperature probes?? Has that been done on an Airhead before?

Now back your regularly scheduled thread... :stick
 
Well then, why post?
One pipe blueing more than the other always indicates an issue, which is one cylinder running hotter than the other. Plain and simple.

With aftermarket products, (say made in China) is it possible the quality of plating may vary enough to cause the difference in bluing at the same temp.
 
With aftermarket products, (say made in China) is it possible the quality of plating may vary enough to cause the difference in bluing at the same temp.

The bluing of the header is what we might call a "heat affected zone". The quality of the plating would more likely affect the appearance of the heat affected zone. Example: the heat zone on the header of my 1988RS is a light brown rusty color all the way from where it starts to bend leaving the head to the crossover pipe. On my /5, it is a deep blue in the same area. For what ever reason, the 1000 cc motor has cooked the plating down to nothing. Both are original headers and both have considerable miles on them.

With respect to the original post, the spark plug coloring will ultimately tell. I'm not sure I would give it much worry if the motor runs well otherwise. The type 53 mechanical Bing carburetors can be pretty fussy and inconsistent in my experience.
 
I wouldn't worry about it to much to be honest.... I've got a 74" R60/6 that's been in the family since new and it always had the right side discolor quicker then the left, one thing to keep in mind is where the crank case vent goes.... but a difference of ten degrees is not an issue. I was actually thinking about placing an EGT probe temp system on my bike (like they use on GA aircraft for quality). But decided against it as I want to keep it original and I didn't want to start worrying about 'false imagined problems", I might do it on my 75/5 project though.
 
10F is not significant overall. if it was 40F or above, there may be a reason. i put an old military aircraft dual CHT gauge in the vent hole on my 81 R100RT just for fun (and it looks way cool to match the large oil pressure gauge on the other side). i was running 40F or greater on one side. turned out that side had the choke cable end sitting on top of the choke ferrule making that side RICHER! yes, richer equating to hotter. once i slipped the cable back down, the cylinder temps evened out.

for the most part, they run the same but i notice that a sidewind will cause the downwind side to run hotter. also noticed that idling 5-10 minutes doesn't really overheat the cylinder as there seems to be enough dissipation to keep things in stasis. yes, you can FEEL heat rising off the cylinders but the actual temp doesn't rise that much over running down the road.

-dan
 
also noticed that idling 5-10 minutes doesn't really overheat the cylinder as there seems to be enough dissipation to keep things in stasis. yes, you can FEEL heat rising off the cylinders but the actual temp doesn't rise that much over running down the road.

Interesting to hear that...I've always been conscious of idling too long. One time, I was stuck at an intersection at a 2-lane cross road trying to cut across the near lane to get into the opposite lane. I became concerned about the length of idle time (maybe 2 minutes) so I decided to get into the flow of traffic the wrong direction so that I could find a spot to do a turnaround.
 
I agree with Kurt. Being a Shriner and riding my bike in parades, I noticed the oil temperature sometimes rising well over 300 degrees, up from the normal 220 or so, after idling for more than a few minutes on my old R100RT. I've pulled out of parades sometimes to let the engine cool off to prevent damage.
 
Always thought running rich is running cool. Lean equals hot. I too will go outa my way to avoid putting around or sitting still. Same for an unsafe intersection. Keep it moving sir. My S runs on the third slide notch and after checking for many years and maybe going to the second notch for a while, or switching to 150 mains, I just ride it fagettabout it. FWIW, which isn't much.
 
Never been a pilot, but I thought I'd heard that on the general aviation aircraft like the Cessna 172, you increase the mixture at idle to get max exhaust gas temperature and then went back "one notch" lean. So, being too rich did create more heat. Probably all washed up there... :dunno
 
when i had the one side running rich, i'd pulled off the exhaust pipes and valve covers as part of deep winter maintenance. the hot, rich side exhaust was sooty black, the cooler lean side tan inside the exhaust. additionally, the hot rich side was so much hotter it had scorched oil brown staining under the valve train whereas the lean side was perfectly clean. this all surprised me too.
 
Back
Top