Hi guys,
I haven't been on here for quite a long time so my query may have been addressed previously - sorry if so!
I have one of the original 1984 TY250 Monos - red frame/steel tank model (#53Y) which is currently getting a
tidy up so I can have a play again next season.
My question relates to the piston fitted to these bikes - I have been told by a UK supplier that the piston from
a Pinky will fit with no mods & will make a huge difference to the way the bike runs. (ports in rear of piston
are different apparently?)
Does anyone here have experience with doing this - I don't really want to buy a new piston assy to find that it
doesn't work & haven't got a Pinky piston I can look at to compare either.
I'm also tidying up the ports in the barrel as per Stan Stephens (UK tuner) in an effort to sort out the rattling &
clanging that these motors suffer from.
Thanks in advance for any info, Andy
TY250 Mono pistons
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Re: TY250 Mono pistons
Hi,
I have done the piston mod 3 or 4 times. From memory it is only the piston crown that is different. It makes a huge difference. Carb had to be re-jetted to suit along with the airbox lid to allow it to breath better.
I have done the piston mod 3 or 4 times. From memory it is only the piston crown that is different. It makes a huge difference. Carb had to be re-jetted to suit along with the airbox lid to allow it to breath better.
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Re: TY250 Mono pistons
Thanks for that Gomey, Did you do any work on the ports or head or did you just fit the Pinky piston assy?
Cheers, Andy
Cheers, Andy
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Re: TY250 Mono pistons
I just cleaned up the ports by smoothing them out. Nothing too drastic.
- from memory the top/crown of the piston is shaped allowing better gas flow to ports.
- from memory the top/crown of the piston is shaped allowing better gas flow to ports.
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- Junior participant
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- Bike: Yamaha TY250
- Club: VMX Club of WA, AJS WA
Re: TY250 Mono pistons
Thanks Gomey,
Did you still have the original TK carb or had you replaced it with a Mikuni?
If it was the original one, where did you get bigger jets from? Yamaha only list a couple of different sizes & of
course they're silly prices too!
Cheers, Andy
Did you still have the original TK carb or had you replaced it with a Mikuni?
If it was the original one, where did you get bigger jets from? Yamaha only list a couple of different sizes & of
course they're silly prices too!
Cheers, Andy
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- C grade participant
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- Joined: Fri Aug 08, 2014 11:55 am
- Bike: Honda RTL
- Club: SQTA/LRMTC
Re: TY250 Mono pistons
I kept the original carb and used a jet reamer to enlarge the jet. Didn't take much. Jet reamers are available on eBay.
Mark.
Mark.
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