Another smokey, slugish NSR

[blamchez]

Hi all,

My NSR is slugish above 5000 revs. it starts ok but is very smokey, even more than usual. Could this be the power valve sticking? if so, how can I rectify this?

could it been losing compression? are there any ways of checking this?

Im trying to fix it up ready for sale, so any advice would be greatly appreciated.
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50cc honda ---> CG125 ---> 125cc jap scooter ---> NSR125 ---> NC30 ---> CB500 ---> ZX7R

[hazza]

if its really smokey and sluggish i would put my money on the crank seals, check your gearbox levels to make sure
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3 Honda NC50's(Sold)-->'72 Puch Maxi S (Sold, want it back!)--> '90 Yamaha RXS 100 (Stolen)--> '87 Honda Cub 90(Sold) --> '95 Kawasaki Eliminator (Sold) --> '98 Bandit 600 (Sold) -->'07 SV650S (Current)

[blamchez]

the oil level and color is fine, what should i be looking for?
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50cc honda ---> CG125 ---> 125cc jap scooter ---> NSR125 ---> NC30 ---> CB500 ---> ZX7R

[alains]

dowload my file https://www.geneva-racing.com/~alains/NSRtips.doc
then bottom page 9 look sequence of valves working . i wont be surprised if your valves close between 2000 & 7000 rpm
warm your engine 10 mn , put tank on it's stand , then check
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the worst day fishing is better than the best day working

[blamchez]

i have checked the sequence of the r/c valves and it is all as it should be.

what i havent mentioned before is that the engine really struggles to rev over 6000 and makes a noise like its hollow or miss firing from 4500... its hard to describe.
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50cc honda ---> CG125 ---> 125cc jap scooter ---> NSR125 ---> NC30 ---> CB500 ---> ZX7R

[alains]

it shouldnt do that . when you've got good fuel line and good sparks , even with a bad compression it should fire . i suggest a good cleaning of tank (tap) , carb and air box filter then fit a new plug . prior of that take off your exhaust and look how much carbon is at the exhaust port , it's a problem when your engine is full of carbon (time to change rings and carbon cleaning)
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the worst day fishing is better than the best day working

[blamchez]