How To tell if your running rich/lean

Post by **ChowderV4** » Thu Jul 29, 2010 10:26 pm

i havent got the money to keep getting my bike on a dyno and i kinda of want to know if im running too rich or too lean.
i know you can tell by a sooty exhaust and stuff but is there any other way of being accurate.
im running an ethos half system, drilled slided, 0.5 raised needles, dual density air filter, 118 front and 120 rear jets.

Post by **ibby4585** » Thu Jul 29, 2010 10:31 pm

Chowder.

im in the same boat really. Im running a full Ethos with a mercury twin stack. Drilled slides, ignitech cdi, standard filter. Im running RO road needles 120f 122 r and im going to up it to 124s all round as i have a nasty flat spot occuring at 9k in top!! I would go up to 122's all round and see how you get on!!

But are you having any running problems??

Kris

Post by **ChowderV4** » Thu Jul 29, 2010 10:35 pm

ibby4585 wrote:Chowder.

im in the same boat really. Im running a full Ethos with a mercury twin stack. Drilled slides, ignitech cdi, standard filter. Im running RO road needles 120f 122 r and im going to up it to 124s all round as i have a nasty flat spot occuring at 9k in top!! I would go up to 122's all round and see how you get on!!

Kris

yeah i have a nasty flat spot at around 5-7k, carbs really need an overhaul anyway, think im going to buy another bank or carbs and swap them over and fiddle with settings until i get it right.
would be nice to ride my bike and have it running perfect, havent had that yet and ive owned it for 7 months . ha!
the thing is i have a feeling its running quite rich atm, wouldnt upping the jets make it worse.
the only reason i think that is cos ive lost about 20miles on my fuel economy and my exhaust exit gets quite sooty, but that could just be because of it not running right.

Post by **Cammo** » Fri Jul 30, 2010 8:30 am

ChowderV4 wrote:yeah i have a nasty flat spot at around 5-7k, carbs really need an overhaul anyway,

That could be the filter causing it. Put a standard filter back in and see if it makes a difference to the flat spot.

Post by **Cammo** » Fri Jul 30, 2010 8:36 am

ChowderV4 wrote:i have a feeling its running quite rich atm, wouldnt upping the jets make it worse.
the only reason i think that is cos ive lost about 20miles on my fuel economy and my exhaust exit gets quite sooty, but that could just be because of it not running right.

I think it's very difficult to guess whether the bike is running rich or lean.

Te exhaust colour/soot will tell you very little - it might only be running rich at idle (for example) which will still soot up the exhaust. The best way to tell whether it's rich or lean (without going to a dyno) is by established jetting setups that are known to work well on nc30's.

Your jetting sounds about right, but that would be for a standard filter. When you throw in a freer flowing filter it can make it run lean.

As for mileage, you might find that if it has a midrange hole you'll be using more throttle to ride through it - hence use more fuel! Not so easy to tell rich or lean.

My money is on lean though due to your filter... an easy fix if it is.

Post by **Neosophist** » Fri Jul 30, 2010 2:00 pm

It's very difficult to tell.

You can get a dyno run for £15 - £20. That'll give you a good graph of how it's running, you can record all of your settings so you know how it runs with those jets etc.

That'll be your base-marker, then it's just a case of going from that.

Unless you have lots of jets, needles and emulsion tubes it's hard to tune at home anyway.

It's not just about perfect fuel / air mix, a lot of it is how the bike actually rides.

http://www.factorypro.com/tech_tuning_p ... gines.html

Have a read of factory pro's carb tuning guide, that'll give you pointers on what to look out for when tuning. You need a good feel for the engine.

Restricting the air-flow will make your bike richer (putting in a standard filter)
Removing your foam completely will make it leaner.

Try both and see what affect it has on the bike, you should know then if it's rich or lean.

It'll probably be lean due to that filter and those jets.

Post by **ChowderV4** » Fri Jul 30, 2010 8:36 pm

Funny thing is I actually can't remember
if I have the standard or the aftermarket filter in, ha.
I'm gunna have a look now.

Post by **ChowderV4** » Fri Jul 30, 2010 9:02 pm

Ok so I just checked and I'm running a standard filter, I have another airbox with the snorkle removed and a dual desity filter , is it worrth trying that?

Post by **Neosophist** » Sat Jul 31, 2010 9:25 am

It'll make it leaner. Try it, probably run like crap but it's easy to change back :)

Post by **Cammo** » Sat Jul 31, 2010 9:57 am

ChowderV4 wrote:Ok so I just checked and I'm running a standard filter

If you're running a standard filter and have a midrange hole, it's most likely associated with the airbox setup and rubber flap.

Is the airbox all standard (many people cut the lower tray up), and does it have the rubber flap in place?

How To tell if your running rich/lean

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