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R1 compression problem
smart51 - 13/11/06 at 06:24 PM

Me again. Having taken off the head of my engine and refitted it I ran it up again today. It sounds OK over the noise of a leaky exhaust gasket (got some on order but couldn't wait). I can't hear the 2500 RPM misfire and the exhaust headers only glow very slightly. so far so good.

I did a compression test 110 - 115 PSI in all cylinders. More equal but lower than before. I put a good gulp of engine oil in the bores, rather than a dribble of 3 in 1, and tried again. 170, 200, 205 & 210 PSI. crap.

So I guess its the bores / pistons / rings after all. On inspection, all the bores had honing marks on them plus a couple of small vertical marks, mabe 6mm long and not any deeper than the honing marks, by the exhaust valves.

The question is, is it worth having the engine rebuilt or should I just get a replacement. Yorkshire engines has one for £600.


jambojeef - 13/11/06 at 06:33 PM

Its a good question - not sure what I would do but since its winter maybe its worth taking the engine out and getting acquainted with its internals - its not as if you have the sun beating down and lovely dry sticky roads enticing you out.

Or if slippery roads covered with leaves are your thing - you could always buy the engine and slowly rebuild the other one - or sell the head and box and stuff for spares?

I dunno - have you got somewhere dry to work in?


DIY Si - 13/11/06 at 06:34 PM

How does the mileage compare on the one from malc? Could you sell yours or your gearbox to someone to recoup some of the cost? Or would malc take it as a p/x?


smart51 - 13/11/06 at 07:10 PM

There seems to be a reasonably trade in outer panels / cylinder heads / gearbox internals on eBay. I've been watching a few bits in case I need them myself. The traders seem to get the sales rather than individuals, despite them being more expensive. I guess I could get a couple of hundred quid back from the sale of parts.


NS Dev - 13/11/06 at 07:12 PM

for £600 buy the engine from Malc, flog the cases etc, keep the box internals for spares and maybe keep the head as one to play with for the future?


Catpuss - 13/11/06 at 07:29 PM

Yeah for 600 quid, if its a decent engine and compatible with your electrics I'd go for it.

As long as the scoring isn't too deep you may even be able to get away with re-honing the bores and new rings.

As others say , keep the gear box internals and sell all the engine casing parts as they can go for a bit for people who have had low speed offs.


DIY Si - 13/11/06 at 08:20 PM

Good suggestion from Dev there about the head. Keep it and have a play at a bit of porting if you feel like it. Or get someone to do it for you if you don't fancy it yourself.


smart51 - 16/11/06 at 02:21 PM

I took the car out for a test drive this morning. It is more or less back to how it was before it was repaired. It pulls cleanly above 4000 RPM and had it been like this last week I'd have probably left it. It sometimes doesn't pull at all at low revs, like pulling away from the lights but it hardly matters as I've ordered a replacement from yorkshire engines.

So what should I do with the now running but low compression lump that's sat on my basement floor. Try to sell it as is or break it for parts?


procomp - 16/11/06 at 02:43 PM

Hi have you tried a leak down compresion test. Only trouble i can see is getting an air line into the spark plug holethread what size thread is on the engine. Dont suppose for a minute it is going to be 14mm if it is you could get it done easily.

cheers matt


smart51 - 16/11/06 at 03:48 PM

It has a 10mm spark plug hole.