Spent days cleaning and prepping the head ready for new valves and stem seals, cleaned part of the block today and noticed this, scoring in the bores and in one cylinder if use my fingernail, i can feel the scores.

 

Is this still useable or is it block out to be honed, then i guess over size pistons etc.. camera not great, this is about as close as i could get

 

Advice please.

You say you can feel it with your nail?

Yes just about, but not all the way down the bore, only at the top

Ohh... might me time to buy my car and use the engine... :) (I got to try.. lol)

On my 2 stroke lawn mowers i see piston damage all the time, is it too far removed from a much larger piston ?

 

I can repair them and you may think this crude but often it involves just rubbing down the barrel with emery cloth and making sure the rings are free and they run again, sure power is down from out of the factory but there's more than enough compression for them to run and get through the grass. The cylinder once 'repaired' is much more badly scored than you're seeing.

 

Isn't the next piston in the pic the same though Graham ?

 

I expect rather than a totally healthy 160 psi per cylinder it'll just be down a bit.

 

Is what you're seeing just wear and tear ?

As far as i can tell its normal wear and tear as this is the first time the head has been off and the head hasnt been skimmed before, where as the replacement heads i got have been skimmed before. The rest of the bore looks fine, just seems to be at the top end of the bore.

 

I may for now give it a rub with emery and put it all back together to get it running, then when i get time will get my spare block re honed and go for new pistons etc, service the spare heads ive got and eventually end up with a nearly new engine to put back in at a later date.

Can't think of the name and I can't manage to search it successfully , but while in Halfords the other week I noticed a tripod thing with little blocks attached to it, I assumed that you put this onto a drill and it was for sanding/polishing bores out. (my brain hurts)

Those will hone out no probs Graham but not with the motor assembled ime affraid to say.

Can't think of the name and I can't manage to search it successfully , but while in Halfords the other week I noticed a tripod thing with little blocks attached to it, I assumed that you put this onto a drill and it was for sanding/polishing bores out. (my brain hurts)

 

Honing kit lol, engine out and block apart for that though

Those will hone out no probs Graham but not with the motor assembled ime affraid to say.

 

Thats what i was afraid of, i wish i had just pulled the engine out now instead of stripping it in place. Ive spent so much time getting the heads right, it seems pointless putting them on a duff block :thumbdown:

I guess honing with a diy kit will not remove enough metal to have to go over sized with pistons and rings, although new rings for def if im going that far with it.

Out of interest, How hard was it to get the heads off with the engine in place? And was this on your TT or NA?

I guess honing with a diy kit will not remove enough metal to have to go over sized with pistons and rings, although new rings for def if im going that far with it.

 

I'd agree with that Graham, i did have a honing tool for my 49cc little cylinders that i no longer use, as i fubared it as i got it caught in the finned vents that my cylinders have but the bit it did near the spark plug it did very well :cool3:.

Just for referance graham could you photograph the na piston crown?

Machine mart do an Heavy duty honing tool about £17 .. you will need med compound pads ...

 

rotation speed when using it needs to be slow and oscillating it up and down .. remember to use a light oil too ..

This is the finnish you want Graham and completly wash the bores with dish detergant and water after and once completly dry and straight after rub the bores with clean engine oil or they will start going red in 1 hour.

Out of interest, How hard was it to get the heads off with the engine in place? And was this on your TT or NA?

 

On the NA Steve, fairly easy, just time consuming, would have been easier for me now to have taken the engine out lol

 

Thanks guys, when honed, will i have taken enough material off to worry about bigger pistons?

On the NA Steve, fairly easy, just time consuming, would have been easier for me now to have taken the engine out lol

 

Thanks guys, when honed, will i have taken enough material off to worry about bigger pistons?

 

no but new rings is a must Graham

Cool thats what i had hoped, replacing rings are cheaper than getting pistons too, although if im going that far into the strip down i might look into it and have myself virtually a new engine when done :thumbup1:

Cool thats what i had hoped, replacing rings are cheaper than getting pistons too, although if im going that far into the strip down i might look into it and have myself virtually a new engine when done :thumbup1:

 

you might as well throw a set of rod and main bearings at it too mate...Noz has a set for sale i think

Agreed, it would be illogical to go that far and not change the bearings.