Hitchcocks Forum

During my troubled oil pump phase I seized the 350 on the motorway on the way up to Orewa about 30 minutes of motorway driving north of Auckland. I had an appointment up there and so I had to carry on limping on at 25 to 30 mph with regular cooling down stops and then equally slowly all the way home again. I was waiting to be arrested for holding up the traffic and was expecting the bike to be a total write off when I finally got it home. Amazingly it appeared when I pulled it all down that despite having stripped the oil pump spindle and having no oil pressure that the big end had come through unscathed and only the piston was completely kaput. I replaced it and honed the bore lightly to clean up the slight marks on it and put it all back together again with a new oil pump spindle and multi grade oil. It went ok but seemed to lack the punch it used to have and was very lack lustre particularly on take off. Finally I decided to pull off the head and check it for a gasket leak. What I discovered on closer inspection was that it was quite warped with an 8 to 10 thou wave around the spark plug side stud. Rather than send it to the man I stuck it on my mates lovely Colchester Student lathe. We had to take off around .012" to get a clean cut but it did all clean up rather well. I checked that there was plenty of valve clearance and the ptty strips I put over the piston top weren't even touched so clearly there is tons of room for further compression raising. THe bike has regained its mojo and crackles along nicely again with a nice new .5mm solid copper head gasket

I wish I had access to a lathe. 12 thou will have increased the compression ratio by next to nothing. (Probably within manufacturing tolerances anyway.)

Did it hold just in the four-jaw or did you have to make something up?

No just the four jaw. I took all the rocker box and cover studs out and the valves and trued it with a DTI. Indeed the difference in 12 thou is probably less than a change in cylinder base or head gasket.

PeteF. It just takes care and adult Snugglers, to do a job like that in a 4 jaw chuck.
Personally after clocking something like that in, wetting some paper and sticking it flat on the surface you wish to machine and VERY carefully winding the tool in until it marks the paper or flick it off, makes sure you don't take a large cut and have catsarsetrophy.

Indeed, fine cuts, slow feed and sharp tool. It was pretty well held though. Truing it was a mish though as it had to be centred as well as flat.

papasmurf - "don't take a large cut and have catsarsetrophy"

My partner's car suffered a CATASTROPHE when a tree fell on it :-



When Triumph enlarged their TR6 to the 750 oil-in-th-frame TR7, same considered this a "CAT(Tiger)WAS TROPHY"

I have a catsarsetrophy ::-



I use it as a door stop
John L

That obviously didn't work - I'm beginning to wish I hadn't bothered. Using this message board (for an IT illiterate) poses far more problems than RE ownership ever did........

In case you were wondering, on THIS forum you have to copy the contents of the box marked HTML Code for Websites. most others use the code. Thank you Exile!



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