NC35 carb setup help needed

[Speedy]

Speedy
the chart isn't complicated its just fractions of a full turn.

for the tuning, on a next run just have them remove the filter for a run and see what happens. Your A/F suggest the upper end either could use more air, or less fuel. Either filter change, jet change or both. Seeing what happens with no filter is a good first start to see what changes, then replace with a less restrictive one if you see the change in direction you are hoping. If no change then replacing or reducing main jet is next step. As was suggested, more than age, if someone has 'cleaned' the main filters with a piece of wire they could have enlarged them significantly and not realized it.

The chart helps me understand where the 5/8 fraction of the turn is supposed to be; fractions like this aren't something I had to deal with before, hence my ignorance about it, until now!
" if someone has 'cleaned' the main filters with a piece of wire they could have enlarged them", I'm guessing you mean main jets here?
I'll get a new airfilter to start with and go from there; it's the simplest way for now and that way I'll know what the differences are (if any) with both filters!
Thanks.

[Cammo]

So if 13.5 is the optimum A/F ratio

I disagree with this figure, but there are a lot of different opinions around regarding best a/f ratio for max power (on naturally aspirated engines).

For high rpm extended engine load periods I aim for 12.5 - 13.0 on my racebike.


Speedy: I think you might be over analysing things. What is important is that it runs well (and has safe fuelling) on the road.

I also reckon that dynos don't always tell the true story when it comes to jetting because they don't replicate airflow conditions at high speeds. Modern efi bike ecu's adjust fuelling to compensate for this (lack of) air pressure, carbied NC's don't compensate very well for this.

[Speedy]

So what would the safe fuelling be? This is my main concern; I'm not particularly concerned with BHP figures as long as it's reliable and rideable I'll be happy!
Is a lean mix preferable to a rich one, or is that the other way round? And does lean, mean more air than fuel???
Can you tell I'm clueless at this yet? Do you know of any articles on this, that you can recommend?

[Cammo]

So what would the safe fuelling be? This is my main concern; I'm not particularly concerned with BHP figures as long as it's reliable and rideable I'll be happy!

From what peeps have posted on here over the last 5 or so years it seems that a good (and safe!) place to start with rvf's is 112 main jets all round if you run an aftermarket system, perhaps 112f/115r if you have a full free flowing system. This is based on using a standard honda issue paper filter.

When the filter is changed to something more open jetting is really a process of trial and error. When jetted too lean the NC engines will typically not rev to redline (only found by revving out in higher gears where more air is introduced to engine at higher road speeds - plenty of posts on here of peeps experiencing this!). If this is the case a very crude method of jetting right is to up the jet size until it runs well in all gears, then up one jet size for safety.


I'll see if I can dig out a good article later I have on a/f ratios that will help to explain this.

[Cammo]

Good explanation of air/fuel ratios:

http://i19.photobucket.com/albums/b171/ ... b15feb.jpg


Taken from:

[Speedy]

Thanks for that!
I'll be getting 4 new jets soon + a standard air filter and see how it goes with that; 112's front and rear will hopefully be ok with the 3/4 Yamamoto pipes & can.