Mileage/Reliability for an iron barrelled 225

[mainstand]

Is it a fair bet that it's not ideal to rally 100's of miles on this set up?

I cannot for the life of me source 67.5mm thin rings anywhere so I'm guessing the only option left if I keep this barrel is to go up to 225.

Anyone recommend this way forward or be set against it?

[jonashford]

Nothing wrong with steel barrel for loads of miles

[mainstand]

Yeah I know that mate, as I have done thousands on this barrell, I'm talking about the 225 scenario

[mainstand]

Ive done many thousands of miles on my cast 240. 71mm bore.

going to 70mm is no problem at all. The GT kit ive been ridding this year is 70.5mm bore.

I saw your scoot at Warsop & was going to find you for a chat about this but I had to slope off as the old bill came on site looking for me.

[CHRIS in MARGATE]

I am at 70.8 and have done nearly 7000 miles. Put a new piston in 2500 miles ago due to circlip escaping. To be honest I do run a tad richer than normal and I am forever blipping it to keep fuel going through to cool BUT that bored out and heavily ported iron barrel doesn't stop me from having the "grin factor".
I have revved it to 8650 and it would go some more but I I also ease up a bit at times and back of the throttle to where its richer and 4 strokes a little. Very reassuring sound.
Just back week before from 250 mile round trip rally and I was first through the gates in our little possee, putting my tent up.
Secret is...don't run weak and overheat.

[mainstand]

Eden, didn't I read you have had seizure issues?

[jonashford]

I have a steel lined rb barrel, 72.25 I think the bore is. Runs fine over long distances, keeps cool & hasnt seized once this bore round

[Dimitrios_231]

Hi Eden,was it a Kawasaki conversion?
I'm always thinking of doing one.

[Dimitrios_231]

Fantastic,thanks.

[MickYork]

Fitting one of the large Avanti heads may help with the cooling. They seem to be getting used on Rapido's and TS1's a fair bit with good reports.

[Adam_Winstone]

70mm (225) is no more or less reliable than 66mm (200) as the walls are still plenty thick enough not to give issue. Much of the unreliable reputation is because many people going out to 225 also start altering porting, compression, carbs, pipes, etc, all of which can make a 200 equally unreliable.

I've done thousands of reliable miles on 70mm bores, running them at constant higher touring speeds and putting enough miles on them to need further rebores beyond 70mm. 70.8 is the biggest that I've run myself but I have rebore oversizes going up to 71+mm.

Obviously, the head needs to go up to the correct diameter too (71mm for a 70mm bore, unless do welled for alignment) and the combustion chamber should be increased in volume so that compression remains suitably low for regular reliable use.

Good luck and enjoy

Adam

[jonashford]

I've used an avanti head on my rb for over a year now very good piece of kit

[Dimitrios_231]

This is a standard bore,untuned Autisa 200cc cylinder that I have and feels like the perfect base for a long stroke (62mm) Kawasaki conversion.

[Dimitrios_231]

47.83mm

[Dimitrios_231]

I have triple checked it,on your awesome port timing calculator
I'm not in a great hurry for this project,
Piston,crank,rebore can be found/done easily (they only cost money )
I can do all the porting work on my own but I don't have/use a lathe to reprofile the head.
I'll only start the project,if I first find a reprofiled head that suits.
I don't trust any of the local guys to reprofile the head.

[Dimitrios_231]

This is the start of my 245cc Kawasaki conversion.



It will go on this Lowline replica.

[Mr G in NYC]

Love a Lowline !!!!! Just blown the oil seals on this Ah well back
to the drawing board........or rather the garage......might swap out the Amal
for a flat slide dellorto 34mm......I've also soft seized it three times trying
to hit 75 with only 250 miles on the engine wonder why it
nipped up Stage 6 Stuart Owen lump in it .....its lovely when it runs
I'm learning to come off the throttle and take baby steps on running in an Iron
Barrell.......... Good luck with your lowline project G.

[Dimitrios_231]

Totally amazing Mr G
You are lucky that you didn't lock the rear wheel trying to hit 75 with only 250 miles

I have also soft seized a cast iron barrel which had clocked only few miles because I got too excited and used WOT for less than one mile
They need a lot of patience while running in.

[Mr G in NYC]

Locked this one up at 70+ on the long island express way a few months back.....
Full lock up and burning rubber !!!!!!!!! stayed upright and pulled it over
Stage four tuned..... not run it for a while .....shit petrol and a tad lean and
I think the drive side oil seal went on this also !! !! Note to self ......must ride
these on a more regular basis I'm building the GT200 kit on this with a
cyclone box , bgm pipe and 30mm dellorto, jap race bearings and Af race clutch
basket......and I have promised myself to BABY it for the first 400 miles

And YES they are two different scooters Supertune twins G.

[Dimitrios_231]

Ouch.
I'll post pics in the future, when I'll lock mine
I hope that this has nothing to do with black and white themed Supertunes,because this is my chosen paintwork scheme .