ok, so i got the nc30 running back onto 4 cylinders, was running on 3 before, now it runs a little rough and unresponsive above 5k revs, but it does run, and it runs grand below 5k. i took the yammy system off and put on the standard nc35 system with quill endcan. its running 120/118 jets. i take it, its running like a bad hangover now because the jets are too big for the system, and i should return to standard jet settings? and would anyone remember what they are, lol?

david

I think the standard jetting is 115/118.

Take a look at the NC30 carby jetting guide that's stickied at the top of this section, it'll tell you what the standard settings are, and what to do when you swap the tail pipe for an aftermarket one. I'm not sure how different the NC30 and NC35 systems are, give or take that the NC30 doesn't have a flange for mounting the can and the NC35 does, so I'm not sure if it will make any difference to what jets you need.

monkeywithaplan wrote:i took the yammy system off and put on the standard nc35 system with quill endcan. its running 120/118 jets. i take it, its running like a bad hangover now because the jets are too big for the system, and i should return to standard jet settings?

The standard rvf exhaust system is very restrictive, this and the standard muffler are responsible for a significant power drop (particularly in the midrange) compared to even the standard nc30 items. It's my belief that these 2 items only are responsible for the rvf's reduced standard power output (53hp). Changing them for aftermarket items is the easiest way to gain power on a standard rvf.

What I'm saying is that you might not be able to fix the power drop. I have a standard rvf system on mine with an aftermarket muffler, 118/120 jets and it runs fine.

Does it rev at all well above 5000 rpm or acts like it has dropped a couple of cylinders?

it was running on 3 cylinders because one was starved of fuel, adjusted float bowl height, problem solved, running on4. now its a bit of a dog above 5k, like its starved of fuel, or has an air leak. vacuum hose all good. i had the diaphrams out and checked them all, all good. carbs cleaned. air/fuel back to standard 2 turns out. checked all inlet manifold rubbers, all good, no leaks, but tightened the crap outta them anyways. she bogs down after 5k, but not all the time, its almost like there is an air leak, but i'm certain there isnt.
and with 115/118 being standard, then a little jump up to 118/120 shouldnt be bogging it down like this. i'll swap over to standard jets anyways, see if it makes a difference.

completely stumped. i know its just a fueling issue, but buggered if i know what exactly it is, lol

thanks for all input :)

You running a std speedo, may be ignition dropping into speed limit mode and dropping rear cylinders once above 5000 rpm.

as it turns out i am a total div. had the rear leads on the wrong way round. got a good second hand set i had thrown on, short and long leads were switched on the coils and hence the confusion.

i am a complete plonker *takes a bow*, lol

monkeywithaplan wrote:as it turns out i am a total div. had the rear leads on the wrong way round. got a good second hand set i had thrown on, short and long leads were switched on the coils and hence the confusion.

i am a complete plonker *takes a bow*, lol

Do you mean just the rear two plugs?

As long as the front plug leads goto the front cylinders and the rear plug leads goto the rear cylinders it doesnt matter which way around they go, its a wasted spark system and both plugs fire at the same time.

If you call the rear cylinders A and B then the plug leads from the coil can goto either A or B..

As Neosophist said, waste spark means rear cylinder plug leads can go on either plug. What did you change, both leads including plug caps? If so maybe you had dud leads/caps that gave you poor running of the rear cylinders and is now fixed.