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yamaha cylinder porters step forward
Posted: Fri Jul 11, 2014 10:07 pm
by gman
G'day race fans. I'm looking for someone from the forum who'S spent allot of time porting 2 stroke cylinder? If not a forum member then the guy who does a good job. I have 2 sets of as1 125 cylinders i'd like ported to yamaha gyt specs. I have the specs and the desire to do the work myself but that would require a grand in new tools plus another grand in a compressor upgrade plus the good chance i may not get the best result. I'm happy to pay the required price for the right result. Would also like heads shaved and cc'd to spec. The as1 engine in stock trim running 17mm mikuni's produced 15 odd hp, the gyt spec with 26mm mikuni's, magneto and chambers had a respectable 24-26 hp, all on the standard spec crank. Please if your able to do the job let yourself be known. I'm sure there is someone on google who could do the job but i'm hoping it's a forum member who wants the job.
Re: yamaha cylinder porters step forward
Posted: Sat Jul 12, 2014 11:23 pm
by 2TInstitute
I can do that for you but I can do much much better than old gyt specs. More top end more mid range.
Re: yamaha cylinder porters step forward
Posted: Wed Jul 30, 2014 11:24 pm
by gman
Hello. thank you for replying to my post 2t institute. I'm interested in getting my as1 cylinders ported. I plan to run the as1 muffler's as i have a new set. The original 17mm mikuni's are spiget mounted. I have removed spigets to braze a mounting plate for vm22 mikuni's, the inlet port will need to be enlarged.
Thinking the following other mods. shave the heads for a .8mm squish with 20 dgr taper reshaped to combustion chamber edge.
Run with top ring only.
Either/ remove 60 tho of top of barrell and place a 60 tho alluminium spacer under barrell to rase all ports + Remove 4-5mm of piston skirt to lenghten inlet timing. / or port cylinder"s for timing and open up inlet port tracts plus piston work i am not sure of .
There would be difference in cost for either barrell work, my pocket book is not endless. I'm learning about 2 strokes and performance mods that have been tried. I have a project for this as1 engine, it will be going into a smaller yamaha frame. I'm hoping for a true 100mph top speed from a 46 tear old 125cc yamaha twin.
Anyway i was in the midgle of pm 2t about porting and i thought i should forum post this as i'm hoping this could open disscussion on piston ported cylinders. graham
Re: yamaha cylinder porters step forward
Posted: Wed Jul 30, 2014 11:52 pm
by 2TInstitute
I wouldn't remove material from the top of the cylinder or put spacers under the cylinder all that stuff went out with flares and fondues. We can do much much better these days.
Re: yamaha cylinder porters step forward
Posted: Wed Aug 06, 2014 9:26 pm
by gman
Re: yamaha cylinder porters step forward
Posted: Wed Aug 06, 2014 9:39 pm
by gman
picture"s showing the removel of carb spiget and brazed on adapter for larger carb from an article in the THREE T"S for the two stroke book by Yamaha

Re: yamaha cylinder porters step forward
Posted: Thu Aug 07, 2014 12:15 am
by 2TInstitute
no contest the reed cylinder , that should finish up alright