Hi guys changed engines on my nc35 after blowing my last one up! Fitted the new engine and started first time but it seems to have a problem! When cruising about 70 the bike seems really lapse i suppose it seems to not want to go as it should and when i go to blip the throttle to change down there is nothing there i have to hold the throttle open for a few seconds before the revs pick up. All the wiring is existing so cant see there being a problem with it and it also sounds a bit like a bag of nails. Anyone got any ideas what i can check??

mattydrvf wrote: Anyone got any ideas what i can check??

The credentials of the seller?

Does it have the snorkel and rubber flap in V of the frame attached in front of the carbs?

Did it come with carbs and did you use those? Checked all the settings and stuff?

The seller i would deam as creditable as it was abrmotor from this very site! Yes the carbs came with the engine and have been balanced by a honda mechanic but didnt realise i had this problem for a few weeks!

With the rubber flap are you saying it could be blocking the snorkle or something else just so i know what im looking for

Just make sure its in place preventing turbulent air from being channelled down the snorkel. It will have trouble going high speed if the snorkel and flap are not in place.

Check if you don't know for sure what air filter and jetting you are running in those carbs... you never know. Is it a rev problem or just once speed goes past 70mph? Does it run perfectly otherwise and at other revs/speeds?

Also it could be fuel starvation due to not enough fuel being supplied fast enough at those speeds.

Need more details.

When i got the engine it had been used as a race engine i think and had a bolt in the cylinder to block the vacum off so i have removed the bolt and fitted a new connector and vacum hose i have also changed the plugs. It seems fine on idle and at low speeds its mainly when you open it up. Just realized the carbs were my original ones from the old engine sorry forgot.

Again, need to be more specific... by 'open it up', do you mean when revs are high or only when speed is high? By the way, how did you manage to blow up your other motor?

I managed to blow my engine up due to my pure stupidity! I carried out a shim change last year and dropped a shim into the engine. It took me four hours to get it back out and then decided to block all the holes up with tissue. When it came to manually turning the engine to do the other cylinders i didnt realise the engine ate a tissue. Put it all back together without realising and after about 50 miles the tissue clogged up the oil filter/ pump etc and starved the engine of oil and resulting in snapped conrod and a smashed block oops!! Had a guy from kawaski shop and he said its from 5 thousands revs upwards but i think this is only when the engine is loaded if i sit there in neutral and rev it its fine all the way up!!

Sorry to hear about your mistake with the tissues man. Did you lose a rod through the engine casings? Shit that must have made a noise eh? Did the oil pressure light not come on?

Are you running all stock induction (air filter, snorkel, rubber flap etc) ? If you can man, get your carbs apart and tell us what is in there- main jet sizes, washers under the needles and float heights. You never know what you'll find in there...