On my st170 2002 alda, I have discovered that the intake valves are not sealing for some reason. Piston 3 just exhaling everything out of the gsxr750 no3 inlet, yes inlet, not outlet. Nightmare. Anyone know of any problems associated with the 2002 st170 head that would cause this?
Im half way through taking the head off when all will be revealed. Stopped at 11.00 this evening. Engine was from ebay over a year ago. Supposedly in perfect condition.

Alternatively, does anyone have one in good nick around the Southampton/Hants area. I can travel a bit too.

A full engine would be ok.

I have a good head but in West Yorkshire

why not just get the valve seats redone? doesn't usually cost all that much and you start with a clean slate

You really need to see what the issue is. It may be simple, but unlikely to be anything horrendous. If you get it sorted you can be confident that the head is all ok.
BTW when I took my "good" ST engine apart i found the rings were very gunged up and I am not certain they would have freed up. A hone and new set of rings was not expensive. And while in there, new bearings and ARP bolts.....but hopefully refreshed for many thousands of miles.

Thanks. all will be revealed in a couple of hours. It may be a bent valve. Opinions vary on conflict or non conflict engine. It was passing a huge amount of compressed air back out the inlet.

It is from two bent valves. No damage to piston thankfully. I will get a set tomorrow and lap them in. There was about a 1mm gap to one edge on both. One of the risks of an ebay/breaker engine.
Hope to have it done tomorrow. :-)