Scooterotica

Cant get the full picture of the nature of this seizeure, but a piston even as badly damaged as yours can still be made to run reliably at full power.....but what concerns me is that its seized mostly to one side, and as one side of the piston is scored mainly above the wrist pin where as the opposite side seems to be more scored below the wrist pin....This would make me suspect that the con rod could be bent.....Im not saying it is but i would check it first, if it were mine, as most engines seize where its hottest "OVER THE EXHAUST PORT"..... Failing that the piston could be sub-standard...... machined wrong....or its had a poor re-bore...I Hope you get it all sorted.....

what is 'walkerising' ?
joe

joespeed wrote:what is 'walkerising' ?
joe

Someone elses words....

"Walkerise" your barrel......This will prevent that perenial problem of 175 conversions the good old heat seizure, but it takes balls to do this to your shiny new barrel. Mix Brasso with fine valve grinding paste and apply to your piston. Make a dummy conrod out of wood to use as a handle, and move the piston up and down in the bore until the high spots are removed and the piston and bore are a matt grey in appearance. Remove any sharp edges round the ports with fine wet and dry paper and clean, clean, and better clean the barrel to remove any trace of abrasives etc. When you've finished cleaning it start cleaning again as any abrasive left will shorten the life of your engine to about 10 miles.

Dave Webster used this tune and it certainly worked for him.

If your on a tight budget use a jetex 22m carb and std 200 jetting including the slide, this will run very slightly rich thus providing extra protection against seizure but will run clean as a whistle.

Run it in for 600 miles or so, there will be a bit of bore noise until the rings bed in but this will dissapear as the miles stack up.

a mate of mine used to use VIM!!!

well dan,i've never heard it called that,i have done this with cars including crank shell bearings ,pistons in the bores as well,
an old hand used to say 'if tha dunt larn owt in a day its a day wasted'
regards
joe

Ive done this lapping process many times.... but before I tried to reclaim this piston, I would check to see why it seized....It dosnt quite resemble the normal heat seize usually at an even height on the piston skirt, its all too much to one side and over a transfere....

li 150,s kitted up to 175...........really do benefit from the indian 200 type head cowl.............

I find myself agreeing with Shocky more and more as I read this forum :shocking:

My SX150 had a tight rebore and heat seized continually. I bought a 175 kit to run while I sorted it yep, guess what, that heat seized too (I found out too late that the bore clearance on these kits is a bit random to say the least!).

So I got a Sealey 3 leg hone for about £20, from Machine Mart I think, and gave the SX a good going over. Telescoping gauges are a poor substitute for a bore mic, but worked for me. I gave it 5 or 6 thou clearance as I was totally pi$$ed off with it seizing and it's not given a bit of concern since.

I'm going to hone the 175 kit next, with a bit of porting (couresty of sizes from Adam Winstone ).

Good luck, and let us know how you get on!

drunkmunkey6969 wrote:
Dave Webster used this tune and it certainly worked for him.

I'd suggest he probably did in the middle of a race meet when he'd just had a seize and didn't have a spare piston___________I doubt he'd recommend it as a best practice for sorting out this piston, on a road going scoot

Dave Webster told me to lap in my Yam piston prior to running it on the road, back in 1981....done it too a few since, no need for long the running in process, but I suppose if its done wrong you could do damage....