@Calum You absolute legend! Why did i not think to look on fowlers . Thankyou so much!!, been pulling my hair out all day trying to find them somewhere to no avail. Cheers

@SpookDog yeah thats what i was planning on doing to be honest running it nice and gentle at least for the first 500 miles or so and just gradually increase it. I cant imagine the change of reeds doing a noticeable difference with the mixtures so i'll just as you say keep an eye on the plug after a couple rides or so and take it from there. Looking forward to finally getting it back on road! . Its been left in the corner of the garage as i got another bike

@markus-w
That sounds real nice. Please keep me up to date

@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!

@Arild said in Best Big Bore Kit DTR:

@RubberSalt youve told me most of this as answers to all my questions, still my mind ends up blown after reading this its alot of good information to take in, or try to atleast
Thanks for putting all that together

Well this is all rather very interesting, very very interesting indeed...
After reading that that I might even scrap my plans of a 200 after reading this and seeing what was once an idea become something of a possibility and with both a 4DL setup and 4FU setup spare it’s not like I haven’t got ammo. I haven’t mentioned this either but I also have a spare 4DL head. More ammo?

Also @RubberSalt I have as much to learn as I believe you have to offer. Very well written, whilst I admit it’s out of my depth (at the moment) it’s still easy enough to follow. I also use my phone so I know it can be a pain sometimes. Me and @Arild met the same way you did and had been chatting for a while now, helping each other out and talking about the unexplored possibilities for the DTR so I just got to say welcome aboard and thanks from me and on behalf of my little Swedish g. I appreciate you helping him out a lot, I could honestly only wish to be able to do what you have
Anyways I do believe this could be quite a most interesting endeavour.

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.

Like with most things, the work is in the preparation.