1957 VH - Piston Slap, new piston & rebore?

[john.nash]

FYI
(although it's hepolite and not JP)

In the docment repository:

http://www.arielownersmcc.com/members ... /ariel.pdf

contains the ariel info plus all the hepolite technical specs

[john.whiting]

Carl, the piston looks like it was new,maybe it needed a bit more running in.Anyway, as members advise, hone the bore to remove any adhering alloy or roughened iron, and file the rough area of the piston with a fine file, not abrasive paper which will embed in the piston and cause further damage to the bore. Theres no need to file the piston smooth, just remove the high spots which will pick up again, as will any alloy left in the bore. When this has been done properly it wont seize again as the clearance has been increased . If the rings are ok you could use them again, but they are better replaced. John.

[brenton.roy]

Hi Carl, the drags site suggests .005" - .007" clearance and I have found this table for Hepolites in the knowledgebase. http://www.barkshire.co.uk/AOMCC/Knowle ... spx?id=559
which suggests about .0075". I'm not an expert in clearances, but, given the JP, I think you might be a little close on the bottom skirt at .005".
A light hone of the bore would give an extra .001" or so.
Your plan sounds good to me. It's still summer over there and I expect, good riding weather. There's plenty of winter time to sort it out. If you renew everything, you'll spend it running in the motor!
BTW, As far as I know, Drags only sell JP's for 500's, so John - yes, that's a great idea.

[john.nash]

Carl,

Did you solve this ?

What kind of noise was yours ?

I just posted up with "noise" that occured after fitting a JP piston.
I had my rebore carried out by Drags, so they should know their business....

When stripped my engine, after about the first 10 miles, everything looked good (I changed bearings etc) but the noise is still there and (I think) it's getting worse ..

cheers

John

[john.nash]

pm'd Carl and got this response

Hello John,
Yes. Cleaned up the siezed bit with fine file and then spent a couple of hours polishing with dry cloth. Got the cylinder "glaze-busted". Did not replace rings.
I think I just wanted to get back on the road ASAP. Will eventually get round to it.
Runs fine now. No horrible slap/rattling anymore. It was probably the slightly tight clearance of 4.5 thou at the bottom of the cylinder. The glaze-bust probably sorted.
Took her out on a VMCC run the other weekend and she purred along nicely.
Regards,
Carl