The bores are a little more scored than I expected, but fine (i'll try and take a pic, but i dont reckon it'll come out very well). Unfortunately I started cleaning the no2 piston before remembering to take a pic. It had a fair bit more carbon than the no3. Before I stripped the head off I checked the valve shims and they were almost all the same as before and still within spec, any differences we no more than 0.01mm so prob just how i judged the grip on the feeler gauges. So I think it's either just the seals or an issue with the clearance between the valves/guides.
Hi Phil,
ReplyDeletemust be frustrating after all the work,I sympathize with you! as you say just may need a new valve seal which are inexpensive, were they replaced when you worked on the head?..also could it be the piston/ honing not accurate?..looks like a lot of oil/carbon build up for a such as short time. was it smoking on the power or overrun or both?
bill
or dodgy/scuffed oil ring?
ReplyDeleteHi Bill,
ReplyDeleteThe head was totally new (bargain find on ebay) so i did use new seals, but they came from one of those gasket kits you can get, so i suspect they just arnt up to the job. It also switched to smoking a little to quite a bit within one track session (the oil all disappeared in that one session too) which I understand is normally seals? (I’m new to 4 strokes)
The guides had already been reamed and the tolerances to the valves were all within spec.
The hone job was good, I used Tony Hartlen for the re-bore/hone (i've used him for years and he's a real perfectionist.) I even got a ring grinder to get the rings to the right size (and angles) and I was mega careful with the oil rings. Basically I’m pretty sure I got the pistons/rings right.
I’ve got the head apart and checked everything; it seems fine apart from being really coked up. So I’ve ordered some genuine Honda seals (££ ouch).
I’m really hoping it is the seals and not the rings, so will put it back together and keep my fingers crossed. At least this way I know the head is 100%