GP150 cylinder - Mick Abbey Tuned - Back to the old school !

[chris2470]

This is not dis-similar to my Ali 225 kit that was ported by the late Dave Betts. It has 3 finger boost ports fed up through holes the piston so the main difference here being that these are feed directly from the main transfer ports, perhaps this will be better option as it would keep integrity of the piston intact, or perhaps they will also feed through her as well ??
Any ideas with the piston yet or do you feel you'll need to re-peg to find space for the ring ends.

[the-brickie]

Like this...



Chris, was it a revvy bit of kit or did it pull well with a good overall range?

[Mick Abbey]

Thanks for all the good feed back lads, I hope that it works as good as I have prodicted to Dan! If all goes to plan the engine (fingers crossed) with all my calculations should be producing around 27 BHP @ the crank with 20 (ish) at the rear wheel @8500rpm. My aim is to bring an old powerlesS design of porting up to todays style of porting, with more power and similar revs as STD + a couple of 100 rpm more so it will still pull the STD gearbox, but with more all round power and more top end speed.

In the end its not all about the bore size, you can kid yourself that puting a bigger piston in will cure your lack of power.....it will help a bit, but if the ports aren't up to the job you have wasted your time. These engines are strangled by thier ports as STD i know that there is a lot that can be done with them to bring them into todays specs.

Cheers

Mick

[J1MS]

Which piston is it using..?

[snoghound]

mick abbey should build a group 4 engine! see if he can mix it up with the front runners

[mark]

or a 125 barrel and make the learners scoot safe

[chris2470]

Hi Brickie, the kit that Dave built for me does have more bottom end torque than I expected to be fair as it's quite a hot tune with 182° of exhaust and 155° of inlet timing. It pulls much better lower down than my standard stage4 200 barrel, it's most probably due to the 3 boost ports but I do not have any data for this. I do feel it could be a lot better still with a Jl3 or Franspeed as it currently only has a Sterling pipe fitted but it does still rev out to 8K in all gears with the standard 5.2 ratio's.

[the-brickie]

Thanks Chris, just what I wanted to hear.

Back to the subject at hand, I had a look at an old 150 barrel last night and have to say the pictures dont do it justice, getting in to the bore to do the work is an art form its self! Do you (Mick) use a magnifing glass or summat?

[soosh]

Didnt the guys from Raferty Newman do this years ago in the 150cc class in the 70`s? Was it the Wildcat or something?

[J1MS]

Didnt the guys from Raferty Newman do this years ago in the 150cc class in the 70`s? Was it the Wildcat or something?

Liner in the Raferty Newman barrel. I think I saw a Chiselspeed barrel a bit like this with boosts up the barrel. I think he did it to a few.