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Hi a few Ts1 piston questions are the Wossner pistons graded a,b,c,d or are they one size fits all, anyone used the Ron Moss Ts pistons any issues? i,m looking for a new C grade piston which seen thin on the ground just now , so just looking at my options , thanks.

Hi, the grading of the pistons is for the platers to match (I believe)
Also, if you have a worn Nikasil / ceramic grade 'A' barrel then a grade 'B', 'C' or 'D' piston could fit, dependant on tolerances.......
Plus, a Wossner / std TS1 grade 'B' piston might not have the same tolerances as a Ron Moss Avanti / TS1 grade 'B' piston ( Ron Moss explained it too me in laymans terms a couple of years ago), I hope I've explained it too you as good as he did to me.......

I always thought 'C' stamped barrel = 'C' grade piston , it's just the Wossners just seem to be stamped 69.95 with no grading A-D unlike other TS1 pistons, though i stand to be corrected on this thought.

Try Harlow Barlow's for TS1 pistons. Very good quality and a good price.

^^
Doe's he have a website? thanks

pm sent.

http://www.pro-porting.com/contact.htm

I recently bought a Harry Barlow grade A piston for my grade B Barrel on his recommendation.

Hi, not sure about the pistons made specifically for the TS cylinder, but Wossner Pistons usually follow a set code
For example the commonly used 70 mm KX piston, part number is 8203 dA.

KX 250, 1978 - 1986
KDX 250, 1980 - 1984

Wossner Part number 8203 ( model) dA (d is for diameter, A for A grade )

This is the 70 mm piston ( 69.94 mm )

The 8203 dB is 69.95 mm, the 8203 dC is 69.96 mm

The 0.5 oversize is 8203 d050, the 71mm piston is 8203 d100.

Note - when using this piston, this uses the 18 mm small end, and different crown profile to a standard TS piston plus check the ring peg may foul the standard TS boost port layout.

Lammer205 wrote:I always thought 'C' stamped barrel = 'C' grade piston , it's just the Wossners just seem to be stamped 69.95 with no grading A-D unlike other TS1 pistons, though i stand to be corrected on this thought.

If the piston is a high silicon alloy cast unit and measures 69.95mm then it is grade "A". These pistons in this size of bore need 0.05mm clearance. This is the correct piston for a 70.00mm bore.
If the bore measures 70.01mm then you need a grade "B" piston which should measure as 69.96
If the bore measures 70.02mm then you need a grade "C" piston which should measure as 69.97
If the bore measures 70.03mm then you need a grade "D" piston which should measure as 69.98
As you can see from above, the grading jumps in 0.01 increments.
Forged pistons don't necessarily follow this rule though because their thermal expansion rates are different. Consult the piston manufacturer for details on their grades.


Usually, most Nikasil cylinders are stamped with the grade somewhere on the cylinder. This is only of any use with a new cylinder. A used cylinder must be remeasured to ascertain the correct piston grade.
This is because the nickel deposit on a new cylinder gets rubbed away within a few hours of use, leaving just the extremely hard Silicon Carbide surface to separate the aluminium of your piston from the aluminium of your cylinder. There is also some relaxation of the cylinder alloy when it has heated up and cooled down a few times. So, it it very important to measure a used bore even though you cannot visually see any signs of wear. Only an internal micrometer can measure this accurately enough. If you have access to the A-D range of pistons, you can use these and a pair of feeler gauges to measure which grade of piston fits best. If you have too much clearance then expect premature failure of the piston with consequential damages.

I usually find that if it was a grade "B" when new, then the next replacement piston will be a Grade "C" then a "D" (If I'm lucky) then its ready for a re-plate or sleeve.

Hope this helps.

that's what I said.............