Sump Compression Issues After Rebuild!

[rhysjones]

Ooosh, ok taken on board. Was pretty happy with honing result but yeah realise i could well have stuffed it up without even realising. But strange though that the first 200-300 miles were trouble free?

Misunderstood earlier sorry - i didnt properly check ring gaps in cylinders. I managed to get one ring in the first cylinder but struggled to push it down n was worried about not getting it out again so no didn't get a true check... Almost no lip at top so was confident the midway points would be alright :/ and when assembled the pistons were very snug and took some firm tapping to get them down to the crank. (This of course may mean nothing!)

I'll whip the head off n have a look over the weekend anyway n see if I can find any little surprises.

Cheers for all the responses lads, got a good list to keep me thinking!

[rhysjones]

So there were some good theorys about what the sump compression problem could be.... unfortunately we were all wrong. Hopefully my pictures show - the downfall was a combination of me and the spring compressor during the rebuild :( piston 4, looks like the end of the top rail of the oil ring popped out as I tapped the piston into the cylinder and bent up. Job was buggered from the start and soon wore that nasty groove in the bore. Gutted.

[james butler]

Sorry to hear this buddy but at least you found the problem.
Couldn't you send the block to be bored out to 1.9?
Might make a tasty improvement on hp and torque, plus keeps the original block.

[rhysjones]

Considered it very briefly but with a healthy DX block sat in the shed the swap (keeping the EX head) seems more financially viable.... £300/400 for a rebore? Plus the big pistons :/