I fitted some used 1000SP barrels (with steel liners) to my T3 some years ago, which fitted once a small amount of metal had been removed from the barrel spigots.
They’ve been trouble gree for the last 12 years, but this week there has been a large amount of engine oil being blown out of the breather pipe. There has been no signs of oil being burnt, but my instinct tells me that cylinder pressure is bypassing the rings and pressurising the crankcase.
I’m awaiting another batch of engine oil before I run the engine to check cylinders pressures as the oil level is low.
Whilst I’m waiting, I’ve been looking at my options. One is to replace the barrels with new barrels and high comp pistons. The other is to find a pair of suitable pistons of 88mm plus in size, and have the existing barrels rebored to an oversize to match the replacement pistons.
My question is; does anyone know of a suitable oversize piston type, or point me in the right direction of a company who could supply them?
The barrels were second hand, and I had them honed before I fitted them. i’m going to do a compression test and see what the cylinder pressures are like, before I do anything else. I can get new pistons (88 type B) but can find no information about whether Type B is a 88mm + size.
The letters are tolerance grades within original bore sizes, which were used to match up barrels and pistons in the factory. If you have a Guzzi workshop manual the dimensions are in there.
I suppose the other option is to get the barrels either resleeved or replated depending what sort they are.
Ian
Hope this helps.
For what its worth I have a SP1000 and at 50K miles it just needed a quick hone, new rings and valve guides. Couldn’t get original rings so had to use what is available, those for plated bores. Done 2k so far so good.
Thanks for that information: it’s really helpful. I have found a Dutch supplier (TLM Nijmegen) who may supply oversized rings either 88.4mm or 88.6mm. I am awaiting a reply to my enquiry with them to see if that is correct. If so I can either get a rebore or a hone.
TMJ Nijmegen have confirmed they have oversized 88+ mm ringsets. I’ve ordered two of first oversize ( + .4mm) ring sets, plus base gaskets from eBay, and everything else from Gutsibits. Hopefully the local engineering firm I’ve used before will be able to rebore the cylinders, otherwise it’s a bit more of a trek down to Poole.
