Carb Mods??
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- Settled in member
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- Joined: Thu Jun 19, 2008 12:29 pm
- Bike owned: NC30
- Location: Bristol
Carb Mods??
Hi,
I'm hoping you guys might be able to give me a bit of advice or an opinion.
The bike is currently in bits as I've decided to take the plunge and have a go at the valve clearances - whilst doing this I thought what if.....
I understand that swopping the main jets for 118 front/120 rear, adding an extra 0.5 washer under the needles and drilling the slides out to 2.5mm will all help improve the performance of the bike - the only mod it has at the moment is a slip on can and less one tooth on the front sprocket!
Is any of this worth doing and would you suggest it for a fairly standard road bike??
I don't really want to be in the position of changing all this stuff to then find the bike is running rough.....
Any help appreciated
Cheers
I'm hoping you guys might be able to give me a bit of advice or an opinion.
The bike is currently in bits as I've decided to take the plunge and have a go at the valve clearances - whilst doing this I thought what if.....
I understand that swopping the main jets for 118 front/120 rear, adding an extra 0.5 washer under the needles and drilling the slides out to 2.5mm will all help improve the performance of the bike - the only mod it has at the moment is a slip on can and less one tooth on the front sprocket!
Is any of this worth doing and would you suggest it for a fairly standard road bike??
I don't really want to be in the position of changing all this stuff to then find the bike is running rough.....
Any help appreciated
Cheers

- CMSMJ1
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Re: Carb Mods??
I'd leave it for now and if you were going to change anything then do it one at a time and make sure you know exactly why you are doing it.
Not all bikes take well to random mods. If it runs well then leave it be.
You won't get any power gain realistically as you need more air into the motor for that. You can only make sure that it runs as well as it can and is basically not wasting the power due to bad set up.
get it back to together, ride it and if you think it needs something and you are sure...then do it, one at a time.
Not all bikes take well to random mods. If it runs well then leave it be.
You won't get any power gain realistically as you need more air into the motor for that. You can only make sure that it runs as well as it can and is basically not wasting the power due to bad set up.
get it back to together, ride it and if you think it needs something and you are sure...then do it, one at a time.
IMPERATOR REX ANGLORUM
The V4 is the law..
NC30 - No9 - my old mate
The V4 is the law..
NC30 - No9 - my old mate
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- Settled in member
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- Joined: Thu Jun 19, 2008 12:29 pm
- Bike owned: NC30
- Location: Bristol
Re: Carb Mods??
I have noticed a slight delay in pick up on the throttle as I pull away, almost like a hestition. I just wanna try and get rid of those nc30 flat spots and make it as good as I can with basic tweeks!
Trying not to let enthusiasm cloud my judgement
!!
Trying not to let enthusiasm cloud my judgement

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Re: Carb Mods??
I am in exactly the same boat as you my friend, minus the valve clearances and throttle dealy. lol
I decided i wanted better throttle response out of my perfectly running engine, so I took the carbs apart, stripped and cleaned them, drilled the slides to 2.5mm and refitted them.....
Bike has been off the road now for two months whilst I try and save up £250 to take the bike to a specialist to have it re-built and setup on a dyno because for the love of me, I simply cannot get the bike to run correct anymore. I have even tried a spare set of carbs and had no luck, the bike just run horrific now, unrideable even.
My advice would be.. if it was running fine before, LEAVE IT!!! lol.
Mine is going into the dyno shop on saturday to be fixed and tuned up professionally, cant wait to get it back!!
I decided i wanted better throttle response out of my perfectly running engine, so I took the carbs apart, stripped and cleaned them, drilled the slides to 2.5mm and refitted them.....
Bike has been off the road now for two months whilst I try and save up £250 to take the bike to a specialist to have it re-built and setup on a dyno because for the love of me, I simply cannot get the bike to run correct anymore. I have even tried a spare set of carbs and had no luck, the bike just run horrific now, unrideable even.
My advice would be.. if it was running fine before, LEAVE IT!!! lol.
Mine is going into the dyno shop on saturday to be fixed and tuned up professionally, cant wait to get it back!!
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- Settled in member
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- Bike owned: NC30
- Location: Bristol
Re: Carb Mods??
Ok, I think the overwhelming advice for me would be to leave the bloody thing alone 
Would be nice to get it running a little sweeter tho and get rid of the flat spot!

Would be nice to get it running a little sweeter tho and get rid of the flat spot!
- Cammo
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Re: Carb Mods??
Installing an extra 0.5mm washer under the needles helps.Jonesy01 wrote: Would be nice to get it running a little sweeter tho and get rid of the flat spot!
I say go for it!
"It's just a ride" Bill Hicks
- Cammo
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Re: Carb Mods??
I say go ahead and do all that you've suggested, you'll end up with slight improvements all round. Let us know how you go. make sure to set the pilot screws to 2.25 turns out also.Jonesy01 wrote: I understand that swopping the main jets for 118 front/120 rear, adding an extra 0.5 washer under the needles and drilling the slides out to 2.5mm will all help improve the performance of the bike - the only mod it has at the moment is a slip on can and less one tooth on the front sprocket!
Is any of this worth doing and would you suggest it for a fairly standard road bike??
@ Hamster: To be honest mate you must have screwed something up dramatically for the bike not to run right (if it was something you did at all). If you think you screwed up the carbs, replaced them with another set and it still doesn't run right, then it's not the carbs.
"It's just a ride" Bill Hicks
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Re: Carb Mods??
Ok, think I might go for one thing at a time as suggested - maybe the washer under the needle trick!
I'm guessing this would be the best place to start in terms of swopping bits out of the three carb mods?!
Have done the valve clearances and all looks good
, wasn't too difficult either - great guide on here....
I'm guessing this would be the best place to start in terms of swopping bits out of the three carb mods?!
Have done the valve clearances and all looks good
