There's nothing wrong with reusing rings. To be fair you've done great job just to get this engine it to this stage when it actually starts and runs.

I agree there's nothing wrong with re-using the old rings,If they are serviceable,
But the symptoms sounds like worn rings or bore's.I have many times seen top end rebuilds create bottom end problems,

Hi, did you put on new valve stem seals? I wouldnt worry too much about the smoke, tho i'd take the cam cover off and make sure everything is still ok, give it a hundered miles or so and see how it goes.
Cheers
Ian

Yep

New guide seals and gaskets.

I haven't had the opportunity to look at which cylinder is causing the problem as yet but will get the chance on Thursday.

I am worried that i cocked up the rings some how but my second guess is that the exhaust guides on cylinder 4 are buggered as they appeared to have a lot of play. i am going to take it apart again anyway as i cant stand things not being right!

Just out of interest do these things smoke a lot anyway, my mates did, in fact it appeared to use all the oil then the bottom end went. !!!!!He is still searching for a new engine!

No they don't smoke and they don't use any more oil than any other bike I've had.

Message understood Evil.

Mang wrote:Message understood Evil.

I did have one that smoked badly and used huge amounts of oil ... but the piston ring had broken so you probably don't want to hear that

Its time for the weekly update on the bike from hell.

As you all know i have been suffering from a smoking problem and I am at my wits end with this bike. I was reluctant to dismantle the bike again as it was actually starting and when I rode it it picked up well and went pretty well but smoked like a factory chimney (not that I have seen a factory in the UK recently)

I was dubious that the earlier compression readings I got were accurate and was lucky enough to be able to borrow a decent gauge to check. The two I have had are shit. The new one I bought has gone the same way as the first, in the bin. The proper gauge I borrowed gave me readings of around 135 average so this combined with the smoking pushed me over the edge to dismantle the thing again.

I can now take the head an barrels off a complete bike from start to finish in 2.5 hours. This is not because i am a good mechanic its because I am a bad one and cant get things right first time.

So during the dismantling I found heavy traces of oil in the exhaust port 2 and a bit on the plug of Cylinder two.

When I took the valves out of cylinder 2 I found that one of the 16 brand new Yamaha valve seals was DEFECTIVE it had no sealing lip on it. under 6x mag you can see that it has not had enough (vitox or whatever they make them out of) put in the mold. That would account for a large part of the smoking.

Now to the compression issue which i should have addressed on the last rebuild when i was ignoring the principle "that if you think something is wrong it probably is" the ring gaps are all on top limit and the bores all have vertical scratches too deep to hone with this tight tolerance on these well engineered engines. I have taken the barrels to my mate that machines performance engines and he has confirmed "too deep to hone". so i am faced with

1. New rings, rebuild and just ride the F@@@ing thing
2. Rebore, new pistons and new rings - that's a lot of dough, edging toward £500
3. Find a Second Hand barrel that is still within limit, hone and buy some new rings
4. Roll the bike down the hill and push it into the newly completed section of the Stroud Water Canal. (Evil for your benefit that's just by the the bottom playground in Chalford)

Well at least being stuck means I can do some jobs round the house this weekend - deep joy!

Anyone interested in shedding any light on this dark period of my bike restoring life is most welcome to have their tuppenny worth but i guess most of you will be out riding as the sun is shining.

Lets look on the bright side - at least pushing into the cannal is down hill

You're being a bit hard on yourself, look at what you did achieve, you rebuilt the top end. When I tried the 660 conversion I'd almost built it before finding the oil "thingy" that goes between the crank case halves, laugh ? ... No.

Similar thing for me, I found a locating dowel on the bench after I finished my engine rebuild...
It sat on the bench for a year before I took it apart again to see where it came from. I checked everything and found nothing wrong., so I rebuilt it again and that was 5 years ago, still working well.
Keep at it you learn something every time you take an engine apart.