rd400 rod with suzuki ts 250 piston

[tavspeed]

hi all, anyone know what issues are there, using a rd400 rod with a suzuki ts 250 piston,i.e deck height,piston ring peg positions,does the skirt need altering or the barrell need top and tailing,you can get the parts cheap as chips on ebay,so i am thinking of doing a budget touring engine,not a screamer, might also use a knackered 60 mm crank i have lying about, could this affect anything apart from a thicker packing plate ,cheers all.

[fishi]

RD 400 rod will NOT fit TS250 piston !!!!!

you can not put a 18mm piston pin through a 16mm rod eye !!



fishi

[Rich_T]

You can use a TS250 piston with an RD400 rod if you sleeve the wrist pin hole to 16mm. I made a few nice "top hat" bushes (David Blythe has them now) to convert Wiseco RM250 pistons and they work perfectly. The old issue with bushes was typically they were prone to moving in the piston. The "top hat" principle stops this by making it impossible for the bushes to wander. They are a press fit and also carry the pin cir clips too. Once pressed in (from the inside out, with the top hat brim inner most), they were then honed square(previous versions were not honed). May be I do some more and put them on the website.

The TS250 piston has a crown height of 26mm from above the pin (35mm from CL of pin to edge of crown) and a length of 74.5mm. Depending on what you are doing you will most certainly need packers and or machining barrel.

If you have time and facilities to do this then great, enjoy yourself. If you don't then you'll find that a kit is probable 4 times quicker to get built, probably a lot less money (once you've added everything up) and deliver more performance as usually the ports are better shaped.

[tavspeed]

hi all,was thinkng the ts 250 had 18mm pins,what would be the cost of the top hat bushes,i presume the top hat part is next to the little end bearing,could they be easily pressed out,to use in another ts piston,is there another piston i could use around 70mm with a 16mm pin,as i want to get 225 to 230cc,i have access to a lathe ,milling machine,10 ton press and tig welders,so i am going to do most of the work myself,apart from rebore conversion,and profiling head,what material would you make the bushes out of i.e mild steel,silver steel etc,would have a go at making them but not so sure about groove for circlip,cheers all.

[Rich_T]

Yes the top hat brim sits next to the SE bearing. No, once fitted they should not be removed for two reasons, 1. it is a light press fit 2. the final bore is honed concentric once the bushes are fitted (once they are removed this alignment can not be repeated to the same degree).

I made them from bronze. you should stay away from steel and alloy in this application.

If you send me a mail from my profile, I'll send you an engineering drawing. If you are good on a lathe you might be able to do a rough version. I used a CNC lathe which is frighteningly accurate and it also did the lead in tapers, rads and clip gooves, they worked like a charm. They cost me £15 per pair for 10 pairs. I'm not likely to make any more but try David Blythe as he had the last 3 pairs of me I'm sure.

[J1MS]

The TS 250 piston is one I am thinking of putting in my Rapido 225... Its 4mm shorter than standard Asso piston and if a Vespa Ape rod is 3mm longer & the stroke is taken to 60 mm this leaves the barrel the right length... On a 58mm stroke crank This 1mm will be used to adjust the port timings on the transfers in the barrel either shortening from the bottom top or both.... The Ape rod has a small end size that will accept the Suzuki piston... and the big end of the Ape rod is an easy fit to a Lambretta crank... Not from memory..!! all written down.. I think this is the piston I confused with the TS185..!! as I am in the middle of getting bits together for this one... Re read and corrected

[tavspeed]

hi all,so is the big end pin the same dia. as the lambretta,sounds ideal for the suzuki piston with a 60mm crank,any idea where you can get the ape rod and how much,cheers all.

[J1MS]

Chiselspeed used to stock them for conversions...

[Andy Pickering]

Where is the best place to source the piston (TS250) and jap con rod for this as Im about to start buying for this kit for winter..Is it me or is there a lot doing this..?

[J1MS]

I dont really know where is best price wise, but I used to get all mine from Grampian motors. Rods, Pistons and rebores, but might be a distance from you... Maybe a Wiseco piston off Tinternet could be an option... Grampian did do the Ape rods at about £30 a few years back but Im not sure if they still stock them... also pistons Mitaka or Prox from about £40... but It might be more now... I kept a few old stock genuine pistons and some Matikas I bought a while ago but I still need a new 70mm TS 250 genuine or Wiseco... prefer these to Mitaka... they do turn up on Ebay, but I always forget to bid..