The Exhaust Thread

Post by **CMSMJ1** » Wed Aug 13, 2014 9:48 pm

Looking at the grpahs the lower scale on both is the air to fuel ratio. It appears to drop off the bottom of the scale at 6k revs and so goes into a richer than 10:1 ratio.

They are not rocket science - but are far more ballache than tweaking electronics and injection maps.

*disclaimer - someone else check I am reading it right and it is set that low on the graph is rich - rather than high, and if so, then ignore me..lol

@ our Danish friend - is the bike standard apart from the can?

Viffer · Post by **Viffer** » Wed Aug 13, 2014 9:58 pm

CMSMJ1 wrote:Looking at the grpahs the lower scale on both is the air to fuel ratio. It appears to drop off the bottom of the scale at 6k revs and so goes into a richer than 10:1 ratio.

They are not rocket science - but are far more ballache than tweaking electronics and injection maps.

*disclaimer - someone else check I am reading it right and it is set that low on the graph is rich - rather than high, and if so, then ignore me..lol

@ our Danish friend - is the bike standard apart from the can?

Thanks again CMSMJ1! I think you are reading it right: between 5k and 6k revs the mix is so rich (too much fuel) that the Dyno guy's meassure equipment could not meassure the air/fuel ratio. That's normal for Dyno tests as far as I know. The strange thing is he gave up fixing the bike without trying. I would have paid him a lot but he told me it was impossible even though I know he does carbs all the time and has worked on NC30's before. I don't get it. I wish I could fix it myself. Btw the bike is standard apart from the can as far as I know. Though I'm nor sure of the air filter and I haven't opened the carbs, so basically I don't know very much about the set up. The HP max (58,4) seems standard though. Also, the bike runs perfect on the road at all revs except from 5-6k.

Viffer · Post by **Viffer** » Wed Aug 13, 2014 10:01 pm

In fact two mechanics have checked the bike now and they blame the aftermarket end can for the low torque around 5-6k. This might just be an easy/universal explanation.

Post by **skinnydog0_0** » Wed Aug 13, 2014 10:20 pm

What is the length and diameter of your end can? I have 4 here to compare against and I know all these cans are good

Post by **CMSMJ1** » Wed Aug 13, 2014 10:25 pm

I've used loads of cans and they rarely make much difference on the cut system.

@ Viffer - you may want to read Cammo's carb thread and go from there.

Post by **DocV400** » Fri Aug 15, 2014 9:36 pm

DocV400 wrote:Quick question on the standard NC30 exhaust.
What's the reason for the rods/bars welded across each of the exhaust sections, just upstream of the two-into-one section?

Anyone?

Post by **CMSMJ1** » Sat Aug 16, 2014 1:19 pm

where? Sounds like a non std to me - don't recall any bracing on my OEM, but I got rid of that years ago..

Post by **Drunkn Munky** » Sat Aug 16, 2014 2:21 pm

Just had a look at a stock system and I canr see any either

Post by **DocV400** » Sat Aug 16, 2014 6:31 pm

Sorry, wasn't very specific about what/where they are.
You can't see them normally, other than the welds on the outside, I had to use a Borescope to see them, I was curious as to what they were.
They're approx 5 - 6mm diameter, and pass across the middle of the exhaust's bores.

Post by **skinnydog0_0** » Sat Aug 16, 2014 6:47 pm

That's a standard system, does it have strengthening bars inside?