Scooterotica

A mates Ebay Aluminium 185 kit seized solid on the way back from IOW, gave the scoot to me to sort,not had a lot of experience with these kits on small blocks,pulled it apart and sure enough a bad heat seize, can you get oversize pistons for these as the bore will need a rebore, is it worth reboring and a new piston, any suggestions ? can`t really see any cause for it either,

you can get oversizes for these no probs, some run them out to a 66mm Asso ! TBH the pistons sold with the kits aren't best quality but I guess you get what you pay for. I prefer to fit a long rod to the crank and use the suzuki piston, of which you can choose the mitaka / pro x / wossner / wiseco / genuine etc, again these run to 66mm so plenty of oversizes which makes the hassle sorting the kits worthwhile in the long run.
If your mate fancies abit of fun, top and tailing the barrel for use with a standard length 107mm rod and Suzi piston can lead to a proper seaside screamer.

Wot carb,exhaust and ignition timing is it using.is the head the one that comes with the kit. The quality of the ports is quite poor tbh, if your having a new piston and a rebore then it wouldn't be a bad idea to have the ports cleaned up and a cylinder head done.
Soullad is right in saying the pistons that they come with are not good quality and do expand quite rapidly, but have a good look round the motor just to make sure that nothing else contributed to it seizing.

Thanks for the suggestions, I think he wants to stick with the std. length rod, its running a 22mm jetex and a clubman. it is a bit worrying not being able to see any obvious cause for the seize, it was running very well, the ports have ben cleaned up, but it was using the piston that came with the kit.

i run my 185 kit with 30mm dellorto.its been ported and head profiled.check fuel flow when over half throttle maybe larger carb and fastflow tap.

Plenty of pistons about, an excellent kit all around. I would go for the best piston you can buy and consider the longer rod on the crank.

J.

If you can do all the adjustments great but just bolting it on will be better than a standard 125 or even 150 set up.

As mentioned check fuel flow, tank venting, etc. Could be a fuel delivery problem. Especially if jetting looked good on the plug chops, etc.