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Discussion Starter · #1 ·
My cx500E 1982 is having problems with left cylinder smoking and fouling plug (L/C sitting on bike).



Jobs carried out so far in relation to this problem,



1.New plugs and caps, also switiched coils round.



2. Carb, cleaned twice then cleaned again using Larry's book. Used ultrasonic cleaner, new parts used all over apart from floats.



3. New valve stem seals.



Compression tests done with engine warm throttle open = L/C 125 R/C 120, Leakdown test on L/C took it up to 150.



History of bike, 33000 miles. Ive owned it for 2 years and probaly only put about 1000 miles on it. Normally I don't get to ride at all during winter.











The plug on the right belongs to the left cylinder.

The only conclusion I can come to possible stuck oil ring?



Not sure if Ive missed anything, so if any of you guys can diagnose what the problem could be before the summer finishes in the UK, it would be a bonus!!



nig
 

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hi Nigel,is the smoke blue or white?looking at the plug ,blue

first immpression,your rings are fine,you are running very rich due to float level in that carb.connect a clear tube to your overflow,run up along side the carb body....level is?



mixture screws are how far out?



have you any air leaks being compensated by mixture screw settings?



im only guessing mate,as you have covered a lot already
 

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nig



It looks like you've done a fair amount of work trying to solve this problem.



Are you using any oil? If so, how much? I see that you haven't ridden the bike too much so this may be hard to tell.



Did you notice any difference with new valve seals? Were the old ones hard and brittle?



What is the color of the smoke? Blue or black? Blue is oil, black running too rich.
 

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lol,Dan, me and you have had too many black eyes.lmao
 

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Discussion Starter · #5 ·
Hi Bandit. I beleive its blue smoke, however its interresting you mentioned float leval. This is one thing I did not do when I redid the carbs, I always struggle to understand where I should have the float resting on FNV. However I did do the clear tube to check leval, and this appeared just below the mating surfaces.



Mix screws out 2.5 turns, and no I havent checked for leaks.



Dan, cant say wheather its using oil, not tested this year for road, wanted to sort this problem first.



The stem seals when they came off seemed fine, and no difference at all with new ones fitted.



While I suggested above it was blue smoke, it smells strongly of petrol and where ive got the bike sitting 2 ft from a fence, you can see black carbon sticking to the fence from that cylinder.



nig
 

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Nigel,first a question...to you and anyone.left hand silencer smoking equates to left or right pot?from the h-box that is.



and Nigel,did you mean 1000 miles in 2 years,500 in one year average 40 something a month?
 

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Discussion Starter · #7 ·
Bandit, that sounds like a teachers question, im assuming Its coming from left pot because of spark plug colour.



Mileage, 2 young kids, long hours at work, 6 day week, bike not going so well, I think i død well to get upto 40 av month!
 

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............While I suggested above it was blue smoke, it smells strongly of petrol and where ive got the bike sitting 2 ft from a fence, you can see black carbon sticking to the fence from that cylinder.



nig




You're running rich! WAY RICH! Pull that carb and check the float level!
 

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Did you put new air cut-off valves in the carbs?



Is the rubber plug that goes in the idle jet tower in place and does it fit tightly in the tower?



A hole or damage in the air cut-off diaphragm can cause a rich condition, as will missing or loose fitting rubber plugs in the idle jet tower.
 

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Is the suspect cylinder firing properly and evenly?



As far as reading the plugs goes, the fellers above are correct.



However, there is a wild card on this one.



If spark is weak or inconsistent the plug will read as rich due to incomplete combustion.



If the cylinder idles smoothly it will be the carb as stated above though, especially if you can get it to run on the bad pot alone.
 

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Is the suspect cylinder firing properly and evenly?



As far as reading the plugs goes, the fellers above are correct.



However, there is a wild card on this one.



If spark is weak or inconsistent the plug will read as rich due to incomplete combustion.



If the cylinder idles smoothly it will be the carb as stated above though, especially if you can get it to run on the bad pot alone.
good point.

nig states above that the float levels are equal,just below the seam,so we have to assumn that they are correct.

i wonder if,when he cleaned the carbs all the jets went back into there correct homes.would that cause the rich issue...
 

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I remember reading a post from Larry (and he may to confirm) but it is possible that the idle mixture screws do not have to be 'identical'...maybe its as simple as that?
 

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Hello fellows,

Well, I have to put my two cents in on this one. That being said, You show two plugs, one darker then the other,

this could be because the plug on the dark side is now get as hot of a spark as the other side. Now the

h-box is some what a mixer, as far as the exhaust go. In real life, smoke should be come out both sides.

If all this is true? When I put my carb. back to together I put my air jets, I did not remore the stops,

ome and half turns out, with the stops pointing toward the front of the bike. When the engine started I

enrichen both air jets, up against the bracket, as far as I could go, about 1 and 3/4 out. I adjusted

the idle to about 1100 rpm. using the black idle adjustment. It run perfect. This might not be perfect for

every bike but 2 and 1/2 turns out seams like a little to much. Like I say my two cents. Happy Motorcycling.

OLDBIE
 

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All good info.Here's a bit more of interest.



Confirmed using an Exhaust gas analyzer at my local MOT station.



When one cylinder is firing the exhaust gasses mainly come out of the opposite side muffler with a small percentage of unburnt fuel from the none firing one and vice versa.



When both are firing some exhaust gasses from both cylinders come out of both exhausts at once because of the collector box having two cylinders firing into it and mixing them but it's design affecting the flow.As the analyzer was an emission control device there was no way of knowing what the percentages were just if they were correct combustion and within our legal limits when both are firing
 

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Nigel,first a question...to you and anyone.left hand silencer smoking equates to left or right pot?from the h-box that is.
i knew id heard it somewhere on the old forum,when something is amiss.



When one cylinder is firing the exhaust gasses mainly come out of the opposite side muffler with a small percentage of unburnt fuel from the none firing one and vice versa

thanks shep
 

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Discussion Starter · #18 ·
Hi Guys, Thanks for all the replys. I will try and answer the questions you asked, and hopefully we may resolve this problem.



Anyways,



New cut-off valves fitted, others in a bad way.



Rubber plugs, 1 was ok, the other binned and used the end off a bic pen with a very little superglue to keep in place. A beer to the guy who can tell me which side of the carb thats on!!



If I pull the spark plug and wire brush the carbon off, the bike starts no problem and will idle for ten minutes or more before the left cylinder starts to miss.



As far as the spark on that plug is concerned, if ive just cleaned the plug good spark. If I remove plug after carbon fouled, weak spark tracking up side of plug.



Jets, I could of made a mistake but I was following Larrys book and thought I got it right, but will check.



Mix screws, have ajusted L/C. couldn't really get change the engine note/idle in any way.



Just a couple of more details. I did another compression test with the engine running at op temp, totaly different results from original test.



L/C now = 110 R/C =140



Also when removing plug from left cylinder, and shining a light into cylinder the top of piston appears to be wet!!



Thanks so much for all your replys.



I will pull carbs again and recheck items above



nig
 

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Worse case scenario is a blown Piston ring,possibly the oil ring.I have a spare engine in my garage with one I suspect




Because of their design this would be a really big job but still doable at home as I've re-built all my engines from the crank up
 

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Is the suspect cylinder firing properly and evenly?





If spark is weak or inconsistent the plug will read as rich due to incomplete combustion.



If the cylinder idles smoothly it will be the carb as stated above though, especially if you can get it to run on the bad pot alone.
mmmm, CXP,maybe not such a wild card now mate,considering the above post
 
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