NC30 carby jetting - DIY guide

[ibby4585]

Alright Cam...i followed your guide but would appreciate a little advice.....i have two bikes...one pulls and revs through 14000 with a standard exhaust, 116 118 jets and hits 130mph, the other bike looks like it is standing still after 60-70 mph.... it had a massive flat spot around 6-7000, ticked over like a dog and topped out at around 100-105 mph. i inherited a full scorpion exhaust (basically straight through) when i bought it. I contacted Rick oliver and he said to put 120/122 jets in cause of this exhaust...i followed your instructions but the bike still tops out at 105 although it pulls much sweeter and ticks over like a dream, if i blip the throttle it tries to die..tooooo rich?? Should i try to lean it down a little? should i use the pilot screw or remove the needle washers to lean it up?? I checked the float heights and they seemed perfect. The other issue i have is if im sat at 105mph and slowly release the throttle it seems to accelerate more, you can feel the bike pull...strange feeling when you're thinking about slowing and cornering lol. Ive got good compression, (same as the other bike) why does it top out early? whats a normal top end?? I definately got the bug...vfr 400's are great...i even removed all the annodised bolts and nuts etc if anyone wants them for their shed collection.

Five things I would check! What exhaust actually is on your bike! I'm sure scorpion only make end cans! If it is
your jets are to big! Try 118's all round! My guess is it's a standard cut system with a scorpion end can!

Secondly set the mixture screws as per cammos guide for standard bike/ different end can. third check your gearing! If your bike is topping out at 105 but gets there quicker you may have a bigger sprocket on the back or
smaller on the front or both!
Four! Your bike may be restricted still and hits the limiter in the clock, solution de-restrict with a cheaper resistor or dismantle the clicks and cut the tab out! And finally check your bike has a front snorkel and rubber flap
underneath the carbs !! It makes a massive difference to the top end running!!

Kris

[pauliealdridge69]

the exhaust is defo non standard from the front to the back....stainless steel...with a rear scorpion box which you can see through like a telescope!! None of it is the standard pipe as the other bike is completely standard. Restrictor??? Didn't know about that!! It would explain why it will do 103 in 4th 5th and 6th. Maybe that would explain why it accelerates as i ease off too....still revving enough to go faster as my speed reduces the limiter cuts off and allows more again maybe?!? Ive just got in....battery and rectifier made no difference......dont think its cog size but i'll defo check...my other bike tends to pull away in all gears slighty but you'd think that if it pulled away then eventually with different cog sizes on a long bit of dual carriage way i'd have higher top end...maybe the restrictor stops me getting that far though?

[pauliealdridge69]

just had a little read....mine is a jap import but i have a speedo convertor on it to change kmph to mph so it says i shouldn't really hit the limiter but i can't think of any other reason for it...the other bike just feels like it will go on pulling forever, this one aint too far off the pace really but feels alot i guess when your mate cruises past lol
I have a spare speedo...if i take it apart...what am i looking for? sorry...cheers for your help...(Kris)

[force-v4]

Cammo, this guide - fooking quality!

Thank you.

[ibby4585]

just had a little read....mine is a jap import but i have a speedo convertor on it to change kmph to mph so it says i shouldn't really hit the limiter but i can't think of any other reason for it...the other bike just feels like it will go on pulling forever, this one aint too far off the pace really but feels alot i guess when your mate cruises past lol
I have a spare speedo...if i take it apart...what am i looking for? sorry...cheers for your help...(Kris)

If you have a blue motrax speedo converter it automatically derestricts the bike as you will never reach the restrictor tab in the clocks. Get some pics of the exhaust up on the exhaust thread so that can be identified! Then check the rubber flap, gearing then your carb set up!

Kris

[Cammo]

just had a little read....mine is a jap import but i have a speedo convertor on it to change kmph to mph so it says i shouldn't really hit the limiter but i can't think of any other reason for it...the other bike just feels like it will go on pulling forever, this one aint too far off the pace really but feels alot i guess when your mate cruises past lol
I have a spare speedo...if i take it apart...what am i looking for? sorry...cheers for your help...(Kris)

If you have a blue motrax speedo converter it automatically derestricts the bike as you will never reach the restrictor tab in the clocks. Get some pics of the exhaust up on the exhaust thread so that can be identified! Then check the rubber flap, gearing then your carb set up!

I think in another post it was established that the bike has a 33hp restriction....

[spongy.bob]

Hi all,

I recently managed to get myself a Morwaki Zero twin stack system for my nc30 road bike. It still uses the rear manifold.

I've got a couple of questions:

I've got a set of nc30 carbs (obviously) and a set of nc35 carbs too. What results should I expect to get from each?

The airbox etc is standard. What size needles would you recommend for nc30/nc35 carbs respectively?

Thanks in advance!!!!

ps. Kris, when you say rubber flap, I don't have one on the nc30, but is it the same as the flap that come on the nc35?

[ibby4585]

Hello bob.

Yeah I think it's the same!! You will notice a big difference top end once it's fitted!!

I can't really comment on 35 carbs!

But on the 30 carbs I would start with 122,s all round! .5 shim or buy some RO needles which will be raised already! Got that set up on both my bikes which use twin exhausts and it's spot on!!

Kris

[spongy.bob]

Thanks for that Kris.

So you wouldn't run larger on the rear then?

[ibby4585]

I'm not saying don't but try 122's first then then if it's still not right 124's on the back! I tried 124's all round and it was too much!

Kris