Speedfight 21mm carb problem

thebest25 · L Plate Warrior Joined: 20 Oct 2006 Karma :

Hi Anyone help, i have a speedfight 2 100cc and have just fitted a 21mm mallossi carb to it , since fitting i have a problem that underload or full throttle it loses power and some times cuts out , have checked choke adjustment and mixture screw is wound right in which made it better but now i am at a loss. any help would be great cheers.

irving · Traffic Copper Joined: 02 Oct 2006 Karma :

thebest25 · L Plate Warrior Joined: 20 Oct 2006 Karma :

Yeah thanks for that would do but old one broken so will have to bugger about with this until its fixed . so any other info that doesn't recommend selling the scooter or similar would be much appreciated.

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

if you want to use a different carburettor and make it work reliably, then you will need exhaust modifications, inlet and exhaust port modifications, possibly some head work too.

the thing about engines generally is that if you change one thing you usually need to change a host of other things in order to make it all work. Otherwise tuning would be easy.

Often you can get away with bolting on an exhaust. Maybe the manufacturer made the bike run a bit rich to pass noise tests or something. Often you can get away with a free flowing air filter. Usually if you do both then you need to rejet. However you have not simply rejetted, but bolted on an entirely different carburettor. This isn't a trivial modification, so I don't think it will be easy to get it all to work better.

I think this is what irving means when he says you'd be better off with the OE carb. If a bigger carb was genuinely better for that engine, then the manufacturers would have put it on.
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irving · Traffic Copper Joined: 02 Oct 2006 Karma :

J.K.R · World Chat Champion Joined: 06 Feb 2005 Karma :

In this case i'd say go back to std carb...

If it was a piaggio based engine i'd encourage you to tune it...peugeot engines are crap Thumbs Down

And btw it'll be a malossi branded carb, probably made by dellorto.

'irving' which parts are you reffering to as 'soft, badly made cheese'?
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