AaronLister

These are the piston portions on inmotion. again, mine measures 71.80mm i’ll ring the place that will be doing and see what they think too. Thanks guys!

Thanks, the cost hasn’t been very much at the minute but that’s because the welding, caroming, shot blasting and powder coating has been done through work. The polishing cost me £250 for all parts expect the engine block as it wasn’t fully stripped at the time. But I thought about welding it as to keep costs down and as it’s something I can do myself. I’ll have to pay a company to turn the weld down on a lathe though as I don’t have access to one. The engine rebuild company i’ll be using said they can bore the sleeve out. But they need to know what size the next oversize is. It’s 71.80mm standard so will it be 72.30mm? I’ve seen oversize kits at that size

I was thinking about tig welding it? So it could maybe fuse together and burn in well? Rather than stick welding as that won’t be efficient really. There is no play or wear in the con rod, big end, small end and all the bearings in the engine are so smooth. These will be changed anyway because there’s no point doing half a job. Thanks for the information, I might look for another engine and do as you said about making 1 good engine out of 2. I only started on this forum today, is there anywhere or anyone local to Wakefield, West Yorkshire that I could contact if I get stuck or need parts sourcing if anyone knows? Thanks guys ??

I took the job of restoring my uncles montesa cota 247. The project has been on going for a few years now as I haven’t always had the time or money to get stuff done. But now I’m getting somewhere, all parts are polished, chromed or powder coated. I have the task of the engine now, once this is rebuilt I can begin to build the bike again! But the problem lies with the crankshaft mainly, when I dismantled the engine and started to take parts out/off I noticed the crankshaft is broke on the flywheel side. Each side of the woodruff key has broke off. The broken parts were still there just not fixed on. So my question is what can be done with this? I’m a welder/fabricator so I can weld this up and get it turned back flush on a lathe if that’s possible? I can’t really afford to be buying a new crankshaft, plus the fact the one I’ve seen comes from America. I have attached a picture of the crankshaft, the broken end is visible any suggestions would be great thanks! Also, the piston that was in measures 71.80mm, what is the next oversize to this please?