Just fired up my MC18 for the first time after fitting it into a superkart frame, notice that the lower cylinder exhaust is not getting as hot as the top cylinder exhaust, I would have thought they would run at the same temp?.
I have updated from CDI PGM to PGM2.
I have changed coils and spark plugs but still the same.
Engine does seem to have lost any power but I have only bench tested the engine and not circuit tested yet, I see no point until I have sorted this issue first.
Has any one come across this problem in the past?.

Forgot to mention I am using premix 45:1 and removed the oil pump,
was not too sure what to do with the two small oil pipe's so just folded them in half and secured with a cable tie ,would not have thought this modifacation is causing the issue?.

I have never come across this problem. But I will put in my 2 cents anyway.

The MC18 runs a ratio of about 30:1 when the oil pump is being used. So I would tend to want to run that ratio,.. at least initially.
You say:
"Engine does seem to have lost any power", but I guess thats just a typo and is supposed to be,
"Engine doesn't seem to have lost any power", yes?

I assume that the "cold" pipe is still pretty hot. I also assume that you are now running two pickups for the PGM-II, and have good spark on both cylinders.
So perhaps the difference is due to the carburation being quite lean for the hot side and quite rich for the cold side? Try a plug chop when you get it mobile maybe?
Or maybe the "cold" side has a blown base gasket, main seal, or leaky reeds or something like that.
Perhaps a compression test might show a lower compression on the "cold" side?

But you state that "the engine doesn't seem to have lost any power" (assuming typo), so maybe I have got it all wrong?
Perhaps it could be something to do with the way the water flows through the cylinders and heads? From memory, the orientation of the head gaskets can alter the water flow slightly? Maybe it has something to do with the water pump?

Just throwing ideas out there. Hope it helps, or at least triggers someone else to add their thoughts.
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[color=#808080][size=9]Yes,.. I too know how to waste Time and Money,...

Also, just want to check that the oil path into the carbs is definitely blocked,.. so no air is getting in via the oil path.
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[color=#808080][size=9]Yes,.. I too know how to waste Time and Money,...

Yes typo error, just cant spell . It should have read that
"Engine doesn't seem to have lost any power".

Yes the cooler of the 2 pipes will get warm/hot to the touch but you cant touch the other pipe without taking skin off your fingers and also exhaust gases are cooler than the other pipe but not so much smoke.
Have tried changing spark plugs and coils, if this is what you meant by chopping. but no differance.
yes there are two pickups and a good spark on both plugs, but what is interesting is that when you drop off one pickup both spark plugs fail to spark ???.
I have the radiator fixed to the rear of the kart and the cooling system has good flow as both top and bottom hose's get hot.

Anyway thanks very much for your input, I will do some more checks and if i find out what the problem is I will post on here .

Just checked out your blog mate.
when are you at Hampton downs next, would nice to check out your bike.

i see you have tried different front sprockets, do you have any spare one's?.



i am looking into running a 14 tooth 420 pitch instead of 520,but cant find anything unless i have it made which will cost the earth, it's just because i have an assortment of axle sprockets that are 420 pitch,and also they would be lighter.

Hi mate.
I have also shifter kart and the pitch that they use is 428.
You will find easy in the web 2 piece 428 sprockets for the thickness of your rear axle. http://sharkshifter.com/zc/index.php?main_page=index&cPath=96
The front sprocket with 428 pitch for the NSR engine is an other story. J T sprockets site has drawings with dimensions,check out if any others bike sprocket is compatible. If not,there is a way to make the sprocket that you want but this must be the last choice.
For the chain,the shifter karts use non o-ring and the best chain which can handle their power is DID-428NZ.
Check here the chains specs http://www.didchain.com/chainSpecs.html
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Owner of : Honda NSR250 MC28 95sp colours / Honda NSR250 MC18 R6K SP / Honda RS250 NF5 89 in boxes / Honda C50 12V cub / Honda C50 12V super cub Japanese version /Yamaha XT600 89 benetton

yes sorry i ment 428 pitch.
and thanks for the info
happy racing

Make shore the carbs are set right with the adjuster in the middle I had this went to far and the other zaust got hotter

I won't be at Hampton Downs or Taupo until late Spring/Summer now.
I only have 1x15 tooth and 1x16 tooth front sprockets (both 520), so no, I do not have any spares.
I know a guy who is fully into karts so will ask him and get back to you about a suitable (14 tooth) 428 sprocket.

Somehow I think Marcus127 may have found your problem - Make sure the two carbs are balanced; the two throttle slides must be aligned with each other to give even throttle settings for both cylinders. As he says, there is a balance adjuster screw in between the two carbs.
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[color=#808080][size=9]Yes,.. I too know how to waste Time and Money,...

Oh, and a "plug chop" is a way to see how rich/lean the mixture is at full throttle near max revs.
Just google "plug chop". I never bother to take the hacksaw to the spark plug though, as some recommend.
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[color=#808080][size=9]Yes,.. I too know how to waste Time and Money,...

I have been doing a bit looking on here and found that my main jets are too small for premix at 30:1, main jets are stock at 135 in both carbs, you can change them between 170 to 185 as per the HRC jet kit and improve the emulsion tubes by drilling extra holes. HRC kits and JHA are as rare as rocking horse manure and if any one has any please let me know. But to start I will change one thing at a time, starting with the main jets and checking the carb balance too.
cheers