Please help with my new exhaust

[haGGard]

hey,

Ive just had my new performance techingas exhaust fitted to my speedfight 100.

It feels al lot different to ride. Its definatly slower off the line from traffic lights etc but the top end acceleration and speed had increased.

Im assuming this means i need to buy some lighter rollers, right?

Also, does anyone know where i can find an easy to follow guide of how to rejet my carbs (i've heard its an easy job to do, would i find it in the haynes manual?)

Thanks

[mchaggis]

https://www.dansmc.com/carbs2.htm is a reasonably good guide. Also see the spark plug page, as as far as I am aware, there is not any need to rejet unless you are running too rich or too lean. As for lighter rollers, I've not a clue. I don't even know what these mythical rollers are other than fancy bearings?

If they're the equivalent of a flywheel, then call them that and people would understand why making a flywheel with lower inertia would help the acceleration. Hence lower inertia "rollers" would probably help the acceleration whilst sacrificing smoothness.
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[stevo as b4]

rarely does just changing the pipe require much re-jetting, but maybe more so on scooters where you are going from a normal exhaust to an expansion chamber design. Its best to have them set up on a dyno, though as its hard to get it right everywhere, without flatspots, and on a scoot its dangerous to have a hesitant response in traffic, or when you pulling out of a junction, as there is nothing you can do. As for roller's the exhaust manufactuer should be able to advise/supply the correct ones that suit the pipe. If they cant, then i would say try going down 1-2gram on the rollers and try that. You might also need a stronger set of clutch springs if its a high revving pipe, as the motor wont have any bottom end power for pulling away if thats the case.

[Kickstart]

Hi

I would say that you probably do need to rejet. Run too rich and you will foul plugs up and loose power. Run too lean and you stand a good chance of seizing the engine or burning a hole in the piston.

[mchaggis]

[haGGard]

Yeah the the manufacturer specified some rollers i should go with. I'll buy some and see what the difference is, there only about £10 right? I think i will be able to fit them myself as well

I wasnt sure about the re-jetting. Its just when i posted a few weeks ago, some people said it would be a good idea. I leave it for now...

Now, about these clutch springs. Ill look into these as ive just been out on it again and the low end acceleration was pretty poor. Are they as easy to fit as the new rollers?


Thanks for all the tips

[mchaggis]

[Kye]

Rollers basically control the rate the automatic transmission works on a CVT engine (a ped engine), depending on their weight, it determines the rpm the engine runs at during acceleration.

The idea is that you get the roller weights to have the engine sit at peak power all the way the range, like you use gears to keep the engine at peak power.

When fitting a sports exhuast to a scooter it is usually nessecary to:

Fit stronger clutch springs, so it engages nearer peak power rpm since most the bottom - end power is taken away by a sports pipe and added to the top end

Fit lighter rollers - may require some trial and error playing about with, but most exhuasts already come with them now. Since the exhuast shifts peak power higher in the rev-range, lighter ones are needed to make the transmission keep the engine at its new peak power.

[haGGard]

Im a little confused on the whole rejetting subject. I'm just wondering why it would need to be done. I'll try and make myself as clear as possible

Basically my point is this...

Obviously my carbs were jetted fine when i had my stock exhaust on the scooter. Everything on the scooter was factory settings if ya like , so how come when i change the exhaust they need to be rejetted? Does the new exhaust actually affect the amount of petrol etc entering the engine?

Thanks

Neil

[mchaggis]

[haGGard]

Ah gotcha, now i understand

I guess then by rejetting the carbs, my speedfight would guzzle more petrol than it already does?

[haGGard]

Oh yeah sorry, forgot to ask....

Are there any websites i can buy rollers/clutch springs from? I have scoured eBay but found nothing. Tried google too and no luck

[Kickstart]