Scorpion endcan - effects? - mostly resolved

[Cammo]

Although the carbs are interchangeable between both bikes, they are far from similar.

Very correct. Completely different kettle of fish! Why, oh why didn't I just HRC the NC35 carbs instead of dealing with the black art of NC30 carb tuning! Because it's more rewarding, or maybe I'm slightly daft - not sure :)

More rewarding for sure! Aint that half the fun?

[NC35!]

Hi there,

I have bought and fitted the endcan and took it for a ride this afternoon. Once up to temperature, I gave it full throttle through the gears. From a standing start all was well, and it revved clean through the first three gears, but once I got into fourth it felt like it was beginning to stutter, barely managing to hit 14,000rpm. When I changed to fifth, the revs dropped to 13,000 as expected, but no matter how long I held it it wouldn't rev out. Similarly, changing into sixth I lose another 1,000 revs, and it really struggles to hold them, never mind increase in revs.

I also noticed it was running warmer than normal.

When I got back home, I put the standard endcan back on and went back out. Unsurprisingly, the bike would rev cleanly to the red line in every gear.

I assume the symptoms - higher running temps and lack of power at high engine speeds - both point to the same thing, the bike is running lean with the Scorpion endcan.

Given this, does anyone have any guidance as to where to start with the jetting? Dyno time is not really an option unfortunately.

Thanks!

[superlite]

I've never experienced an endcan impacting on the rev range in the way you say. It's only a minor mod and the most you usually pick up is a bit of fuel starvation from the fuel tap. The easy fix is to go up one size in jets front and rear - assuming that the airbox, filter, etc is standard.

[NC35!]

After discussing this with a motorbike mechanic I know who works at the local college, he suggested 115 front and 118 rear main jets and an extra washer under the needle. With nothing to lose, I tried it and it's now revving fairly cleanly all the way through to the limiter and sitting in top gear waiting for seventh to be invented!

It's not as clean at the top as 108s with the standard endcan, but it's 100 percent better than 108s with the Scorpion endcan on.

I think it's a little bit on the rich side now, but it is more than useable until I can afford to put it on a dyno to get it tweaked properly. If the weather holds, I may even buy a selection of main jets and do some playing around myself!

Thanks to all for your input.

[RVFJE]

NC35 - why have you put different size main jets front and rear?
Standard is 108 on all four carbs! Should you not have just fitted say 112's all round?
In any case such a big jump for an end can is a bit much.
The different sizes is NC30 specific isn't it?
Anybody else care to comment?

[NC35!]

NC35 - why have you put different size main jets front and rear?
Standard is 108 on all four carbs! Should you not have just fitted say 112's all round?
In any case such a big jump for an end can is a bit much.
The different sizes is NC30 specific isn't it?
Anybody else care to comment?

After discussing this with a motorbike mechanic I know who works at the local college, he suggested 115 front and 118 rear main jets and an extra washer under the needle. With nothing to lose, I tried it and it's now revving fairly cleanly all the way through to the limiter and sitting in top gear waiting for seventh to be invented!

It's not as clean at the top as 108s with the standard endcan, but it's 100 percent better than 108s with the Scorpion endcan on.

I think it's a little bit on the rich side now, but it is more than useable until I can afford to put it on a dyno to get it tweaked properly. If the weather holds, I may even buy a selection of main jets and do some playing around myself!

Thanks to all for your input.

Hi,

I went with the best advise offered, and I got some results. When time/money permits, it'll go to the dyno for proper setting up. At this time, I need the bike useable and would prefer it rich and revving out to lean and useless in 4th, 5th, or 6th gear.

Thanks

[RVFJE]

That's fine and I agree but my point was NC35's run the same size main jets in all carbs BUT NC30's have larger in the rear for some reason.
Even on this forum some members get mixed up between 35's and 30's when commenting.