VFr 400 nc30 Backfiring :(

[Paragon]

Hey all

I got myself vfr 400 nc30 but it needed a total motor rebuild, after getting the motor rebuild and we put everything on and connected all the wires , we started it up , but it sounded dead low revs and was back firing in the low revs 2but once the revs got abit higher it sounded more like a vfr *note* we did not replace the sparkplugs

i would just like to know what you think it might be ? sparkplugs ?
Thanks

[Paragon]

Changed the sparkplugs ,still backfiring and struggles to go from 1000rmp to 2000 but once it gets over that it rides smooth until 8000rmp then it feels like the bike is sputtering ,once you get past that the bike feels dead.. i was wondering if it can be cam timing ? anyone able to help me

[CMSMJ1]

so - has it ever worked?

Do you have the full airbox and the carbs setup as standard?

Is the speedo plugged in?

[Paragon]

Hey , yes everything is still standard ,after driving the bike for about 10 minutes i got of to feel the pipes , the back 2 where warm , and the front 2 was ice cold. So what i'm thinking is that the front cam timing might be out

[bikemonkey]

Might be carbs?

[Paragon]

Hey, i have 2 sets of carbs... the bike still does the same

[Morespeedvicar]

Are the front plugs sparking? I'd a thought you'd have to get the front cam timing out by quite alot for to not run at all, which would prob end up with bent valves.
Cheers
Ian

[Neosophist]

Are the front plugs sparking? I'd a thought you'd have to get the front cam timing out by quite alot for to not run at all, which would prob end up with bent valves.
Cheers
Ian

cam timing is easy to check so re-check

check for spart first, they share the same coil.

try swapping front / rear plugs see if the problem moves.

[Paragon]

Thanks for the reply's. When we did the cam timing we turned the motor manually and it did not hit the top, so im sure it did not hit a valve, i will check the spark today and maybe try and get another CDI somewhere :)

[Paragon]

No luck, the back 2 cylinders seem to fire , but not the front we are really struggeing to get the front cam timing right front 2 cylinders have spark , but when i took out the spark plugs they wernt even dirty!