80/85cc exhaust on a Derbi Senda

[jordanrbaker]

Hi I have a Derbi Sends that I'm currently just working on as I little project. It has a 80cc cylinder and piston 24mm carb and all that stuff.

But it need a new exhaust so I was looking on eBay and used fmf and stock exhausts for 80/85cc are really cheap what would happen if I put it on the derbi and before anyone losses it I will make it fit with custom mounting

Just curious of what the power would be like with say a stock cr 80 exhaust would it be the same as an aftermarket derbi exhaust?

[P.]

No, the CR is more peaky competition/race bike, the Senda is a dinky commuter for rudeboyz. It'll probably fuck it up, rather than make it better. The engines are different and 2 strokes have exhausts designed specifically for that range of engines more often than not.

[rhys99]

Just get an exhaust designed for the bike. loads to choose from, arrow, giannelli, technigas etc
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[stirlinggaz]

hI,
I'm gonna go against what the others have said.
why?
surely an exhaust or rather, an expansion chamber meant for the derbi is meant for the standard 50cc version?
with yours being 80cc I reckon it would in fact be a restriction (especially if you have a biggwr carb as well)
so fitting an expansion chamber off something closer to 80cc might free up a fair bit of extra power.
although I'm not sure 1 from a cr80 fits, I'm sure it will be better than the stock pipe.
just my opinion, ignore it you want

cheers,
GAZ

[ThatDippyTwat]

[stevo as b4]

They do make good pipes for the various big bore kits and stroked crank big cc Derbi engines though. A good exhaust company like Yasuni or Metrakit, Top performance etc would have something suited to an 80cc kit.

A Honda CR80 exhaust might work, best bet would be make one fit and take it to a dyno to see what you get from it. Your ideally going to want a programmable ignition to dial in a totally different pipe though.

[Rogerborg]

I fully advocate buying the most expensive exhaust that you can find.

Then when it doesn't fit, or fvcks the fuelling, ask again in the Workshop section.
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[jordanrbaker]

this guy put a kx 85 exhaust on his derbi
https://www.youtube.com/watch?v=qpVNKSn4Ck0

[rhys99]

[stirlinggaz]

[stevo as b4]

I wouldn't sweat it, that's the problem with 2strokes, every fucker out there thinks they know what they are doing and how to tune them.

We can all read a few books, surf the forums and speak to tuners, and then we all think we know it all and can build the perfect motor that's got explosive performance in our sheds.

I sometimes think I've got something sussed out and know how it works and what to do with it. Reality is I know fuck all about them and what makes a great motor. The more you read and learn about them the more complicated and involved you realise they are and the less you understand about what's going on.

Unless someone has their own dyno, and machine shop and a decent supply of engines to play with, the chances are we'll always know fuck all about what's going on inside and what effect changes to things will make.

For the keen diy tuner with access to such services, it could take 5years of playing and experimenting to take say a 55bhp 250cc to 65bhp.

Sorry to OP for off topic, but you can get good aftermarket big bore suited pipes for the Derbi engine, I'd buy one and set up the carb and ignition to suit, instead of messing about with old cut and shut MX pipes, unless you've got access to the above services?