TM/TS pistons and crank. What's the difference?

[farmer58za]

Hi All

I'm at stage 2 of my TS 250 MX conversion. I have got a TM 250 top end which needs a new piston. The TM piston is no longer available. I can get a PRO-X piston for the TS, which will fit the TM, but did the TM piston have a shorter skirt at the inlet side? I also heve a TM ignition. Does that bolt straight onto the TS crank?

Regards
David Haines
Johannesburg

[cyclegod]

I don't know about the piston issue but the TM and TS share the crank so the taper/magneto mounting is the same.

[Lozza]

TS skirt will more than likely be longer which is a good thing.

[Freakshow]

You can still get the TM piston in wiseco's off the top of my head its a 389 code,  what size do you need ?
 they go up to P8 (2mm) i have some but depends on the size you need.

[GD66]

Pro-X stuff may well be ok in mx applications, but I have sighted several examples that they aren't cutting the mustard in LC Yamahas used in historic roadracing, cracking from the gudgeon hole up the side, through the ring lands and across the crown....

[tony27]

Aren't Pro-x owned by the same people as wiseco, read an article a few years ago that said most piston manufacturers were part of the same group of companies. From memory vertex, arias & possibly wiseco were the same. Can anyone confirm that?

[GD66]

I rather doubt that, for a start some of the above are cast, and some are forged.

[Davey Crocket]

I've been told by a reliable source that Wiseco make the pistons for Pro-X and a couple of others. Pro-X and the others do their own finishing of the piston.

[LWC82PE]

I think you will find that the early TM pistons probably superceed to the last of the air cooled pistons (82 TS250ERZ) Wiseco list the same piston which covers every TS/TM/RL250 from 82 back to early 70's. Different part numbers are probably due to updates in ring thickness much the same as what someone mentioned about the yamahas the other week. Doc should have a definite answer on this, but i reckon you will be fine with the TS Pro X piston. if the Pro X/wiseco piston has a longer skirt you can always trim it to match a TM piston if thats the case.

[DR]

Leith is spot on, the difference in part numbers do indicate different ring type, thickness and even butt ends as opposed to the regular overlap of the locating pin. If you buy a piston kit complete you'll have no worries but sourcing pieces from here and there may provide mismatches due to the above mentioned. I wouldn't be worried about trimming any excess skirt length as Lozza stated as there are more benefits to be had leaving it there. Bottomline is the TS250 piston kit is a straight fit up and run as is the TM internal rotor ignition. The clutch and primary drive is another item that could be swapped with for the TM item as there are a couple of advantages to be had using TM bits in this area also

[Lozza]

Wiseco, Vertex and probably Arias are part of the Dover group. I have never heard of Pro-X cracking up in LC's but I have heard that said about TRJK( ) pistons. One of that brand pistons caused this damage in all of 1 min run time.

[LWC82PE]

I thought the Pro X headquaters are in Netherlands as there is always 'Netherlands' written on the boxes but the actual parts are made in Japan, probably by the same casting companies the jap bike manufacturers use as the Pro X slogan is 'equal to or better than OEM'

[Lozza]

Pro-X is the retail brand name of ART a company who makes most Japanese OEM pistons. Another company called RIK makes the rings.

[farmer58za]

Thanks guys.
I'll get a Pro-X piston. They're off the shelf here about the equivalent of $160AU. Before I buy though, I'll do a check up on the piston fitted to the TS. If it looks worse for wear, I'll wait a couple of weeks for an OEM one from Suzuki which BTW is a bit cheaper than the Pro-X.
Hopefully, the TM ignition still works!
Havid