NC30 not as fast as it used to be....what can i do?

[yellow_blackbird]

Ok so its crap at running high up in the RPM range....in 5th and 6th gear mostly....it hesitates...it pulls and then stops and then pulls again...like its misfiring or something i dont know.... i can get to 120 in 5th but once im in 6th i cant go anywhere else...it just doesnt want to pull...

it used to pull to over 135 indicated...i never got it to the limiter in 6th it gets better after an oil and filter change but gets worse over time after.

its a 1989 with later adjustable forks...
its got standard gearing and NEW chain and sprockets on...
standard not blowing exhaust system with a stubby can
120 front 122 rear jetting - i know its running wrong because its over fueling....Change down a size or 2?
the brakes are not binding on

Could it be that the HT leads need replacing? (they might be original 20 year old ones!) if so what ones?
it was serviced Oil + filter (c@strol GPS) 3k miles ago (just about)

the spark plugs however have been in for 8000 miles is that a bit too much for them?

the throttle cables are a bit looser as of late.....could it be them?

should i change / clean the airfilter again??

and the valves havent been checked or adjusted since ive owned it....it makes no odd noises and starts from warm easy enough, it will also start from cold....Very cold takes it a while thanks to my streatched choke cable....

and other ideas as to why its running a bit naff?

i got some of that orange STP octane boose stuff and it says it helps restore lost power...i thought it was worth a shot...

[viper_biker]

I think you answered your own question. Try 118f/120r jets, new plugs and air filter, adjust the chain, check the cleances and adjust accordingly and you'll be on for a winner.

[yellow_blackbird]

It burbles a bit too much and after ive ridden it hard it can backfire on its own if im too throttle happy.... also the exhaust is full of soot and what not...

so less will be more on the jetting front you reckon?

what about HT leads? do they ever need changing? if so why??? do they 'fail' after a certain ammount of time...like wear out gradually?

[Gazzahh]

Soot in the exhaust pipe and backfiring? I had the same problem and it was a split diaphram on the rear cylinders carbs one side ran weak the other rich poor performance aswell.

[yellow_blackbird]

well its not like its totally full of soot, i can just see theres soot stuck to the inside of the exhaust...its always been like this even when the bike ren better in the past.

[wullvfr]

i think like viper say's try smaller jets and see if that makes a difference.

definately seems like it's running rich!!!!

as for the leads,i would just check and see what kind of spark you are getting,if it looks healthy enough then i wouldn't worry about that.

have you ever cleaned the carbs or balanced them?


william

[britaxcooper]

mine redlines at 120! off topic but perhaps mines got the wrong gearing

[yellow_blackbird]

nope never had the carbs balanced....

according to the haynes the spark plugs need changing at 8000 miles.....

looks like i need a new set then!

[wullvfr]

depends on how the well they are sparking,if it's healthy and the electrode gap os fine then they will be working fine.
if it ain't broke don't fix it,if you know what i mean.just thinking about saving the pennies

the plugs are not cheap,so i would make sure they are definately not sparking as well as they should be


william

[Sligeach]

i can get to 120 in 5th
it used to pull to over 135 indicated...i never got it to the limiter in 6th :.

is the speed limit not 80