@Arild You can make crazy numbers like that on road going engines....on Avgas.

But then run the KTM engine on that stuff and you'll see high 40's and 50s.

Fueling makes a big difference in power as you can ignite the fuel a lot closer to TDC without risk of detonation.

On Turbo Cars it's a different thing altogether. Means you can increase the boost marginally without risk of detonation. More oxygen + fuel = bigger bang.

So, I'm sure someone somewhere ran a Rotax 122 engine with mid-high 30 BHP. They are competition engines after all. But likely it'll be on higher octane fuels and a serious setup!

Hi all thanks for all the advice it’s really helpful! Yeah he had to skim a lot off because it looks like someone Had prized off the head before with a screwdriver or something and made a big gouge in it! I’ve ordered the copper gasket (budget reasons 🤣) so I’ll try that and see how she goes but if not I’ll give a new head a go. I’ll post an update soon

@rubberfingers

Some have a diamond shape on the pulley end but they all take the same pulley - worth noting so that when setting up you get it the right way round. Best thing thing to do would be to feel up the port with the exhaust off.

I have both a 3SH TDR125 and a 3XP 200WR if you need any info - both engines are in one piece though so cant comment on the internals right now 😉

@Calum thanks for the reply callum. I have a good source of parts so can get the head no problem👍

Yes I'd like to go down the Mick Abby (sp?) route as well but also get him to build a pipe to match the tune along with a new matching ignition set up.

For me the main aim is always to have s bike that runs right with nice healthy mid range power rather than completely all up in the very top end of the rev range.

@Calum the beauty of 2 strokes is you can take the cylinder off really quickly. I'd definitely pop the exhaust off and look up the port. You can buy and endoscope for £5 that plugs into your phone 🙂

And i know that reeds give throttle response and exhaust changes the powerband and maybe gives little extra hp

Team BARacing. https://www.facebook.com/groups/1491149367841270/

any info/help?

AHH!! Stop.

You have to measure the piston ring end gap! And modify so that's within spec.

It's common to see at least one, if not both, rings out of tolerance as it's expected that the user till measure and setup accordingly.

The ring end gap tolerance is in the haynes.

Irongamer on here used to run the Athena kit so might be worth dropping him a message, for a good starting point.

@Glynn123 Just picked up my re-bored and ported barrel off Mick yesterday, looking for £225 including royal mail 1st-class signed for delivery and a free Mick Abbey sticker. 🙂 The Namura Piston Kit cost me £65 from p.j.m.e and Micks labour on top so £225 for all the parts is the best I can do.
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Like with most things, the work is in the preparation.

@2stroketerry thanks for the kind offer but my head and barrel are on their way after a call to Mick. Seems for the kind of time I'm looking for a bigger carb isn't required

Yes mine goes off the clock as well as only 80mph on the clock and thats with a 16t,
pulls well really considering I'm 6ft and 21 stone.lol

Yeah 4FU barrels are plated. So are the Athena barrels IIRC.

It's about £130 to have it replated. PJME will probably drop a liner in there if you wanted them to.

Cheers, I'll call around and see if its cheaper than a big bore kit

@dt125matt No, I mean I used Mick Abbey to get my cylinder done. Can't really comment on how it fairs to stock, since I did loads of mods and didn't really notice much...