Suzuki Pistons

roy.craddock
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Suzuki Pistons

Postby roy.craddock » Tue Jan 09, 2018 3:03 pm

Hi as anyone had experience using Suzuki pistons on their Arrow, I had my barrels rebored to +.40 and going through checks , according to WSM page 43 , gap in ring split when placed in the barrel should be .070//073. I can only manage about .012thou on the Suzuki rings. Is the WSM measurement only applicable to the original Arrow pistons does anyone know.?.Any comments gratefully received, Thanks Roy

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Roger James
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Re: Suzuki Pistons

Postby Roger James » Tue Jan 09, 2018 3:21 pm

Roy,
If you had the rebore done for Suzuki pistons you will find the ring gap is smaller because you can run Suzuki pistons with less bore clearance in comparison to Ariel/Hepolite pistons because of their better resistance to expansion as they warm up and get hot. This is due to the better quality material Suzuki pistons are made from. (well original and good quality manufactured pistons, there is a bit of a question mark hanging over some of the new re production pistons on the market these days.)
Having said that I cannot give you any specific figures of what the ring gap should be on a rebore with new piston rings, hopefully someone will come up with figures (and the bore clearance to ask for when taking barrels to be rebored just incase they dont know what it should be).

Jess

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Re: Suzuki Pistons

Postby AndyEames » Tue Jan 09, 2018 4:25 pm

Quick question. Do the original rings have flat ends ? I know the Suzuki ones have stepped ends. I think I can answer that myself. PHC pistons have flat ends, i.e. do not cover the end of the ring peg so will need a bigger gap to allow for the peg.

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Roger James
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Re: Suzuki Pistons

Postby Roger James » Tue Jan 09, 2018 4:50 pm

Hi Andy,
Ariel/Hepolite rings have flat ends that butt up to either side of the ring peg whereas you are correct regarding Suzuki rings where the ends are stepped so cover the peg, I had forgotten about that. Hopefully Flat Land Roger will come to the rescue of this thread.

As a matter of interest, I've just checked a pair of PHC pistons and rings that I have here and those rings are stepped the same as Suzuki rings.

Jess

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Re: Suzuki Pistons

Postby AndyEames » Tue Jan 09, 2018 5:04 pm

The ones I (yours) have , have got flat ends, Roger. How odd.

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Re: Suzuki Pistons

Postby roy.craddock » Wed Jan 10, 2018 9:52 am

Thank you Roger and Andy, I feel a lot more confident now with the rebore, I realise now that the original Pistons and rings are very different than the modern Suzuki types, and as Roger explained 60 years on much better quality metals etc , all explained simply and understandable, it’s great having a forum with so many knowledgeable people on board willing to share their experiences and wisdom to help others Thanks; again Roy

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keith.mettam
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Re: Suzuki Pistons

Postby keith.mettam » Wed Jan 10, 2018 10:29 am

Roy, From a Suzuki service bulletin I have I can quote that the ring end gap clearances for the following 54mm bore models are :-
T20 (X6)...........0.004 - 0.010"
GT250K...........0.006 - 0.014"
GT380K...........0.006 - 0.014"

It goes on to state that the ring end gap should be checked with the ring at it's lowest point in the bore, just above the inlet port having used a piston to push the ring squarely into the bore. Rings should be replaced when the end gap is 0.040" or more.
I appreciate that Arrows and Leaders use GT250 X7 pistons and also that the Suzuki cylinders are aluminium with cast iron liners so the above is a very basic guide. I imagine the X7 clearances will be similar to the models I have quoted. If I was you I would run the gaps at the 0.012" you have measured and run the engine in very carefully. It is important to use either genuine Suzuki pistons or good quality aftermarket ones such as Mitaka.
Regards, Keith.

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Re: Suzuki Pistons

Postby roy.craddock » Wed Jan 10, 2018 1:15 pm

Many Thanks Keith, I thought someone would know the gap measurements,so glad mine is within the parameters Yes these are the real deal,Regards Roy

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Re: Suzuki Pistons

Postby ian williams » Mon Jan 15, 2018 6:58 am

hi roy ;
hopefully ive attached some info for suzuki bikes .

the motocross bikes use a wider gap .

maybe measure the pin diameter in the ring groove on an ariel piston and then deduct from the 0.073" figure if they are not stepped rings , will give you an idea of the ring gap for a stepped ring perhaps .

looks like there is a fair margin if you take into account the motocross specs for the RM125 and for the GT250 which are both 125cc per cylinder .

you can allways widen the ring gap if you fear it being too tight for the ariel and cast iron barrel , the suzuki rings are cheap enough to replace if you want to tighten things up later .

a lot of the time the problems of seizure come with the rebore not giving enough clearance when honing , it depends on pistons used but the italian Gandini pistons need around .005" running clearance if you dont want them seizing .

regards
ian
Attachments
SerBulletin Specifications 1-5.pdf
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RM125K3_SD.pdf
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iansoady
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Re: Suzuki Pistons

Postby iansoady » Mon Jan 15, 2018 10:35 am

I had my Arrow bored to a clearance of .0045" as I didn't want to spend the rest of my life running it in. Excellent compression, no piston slap and no signs of nipping up.

These were pistons supplied by Keith Harding from the Yahoo group.
Ian
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