Topic: Siezed - then not so much

[Terry in Australia]

Yeah mate, I have to agree with John, a 3 stone hone is good for breaking the glaze on a cylinder, but it'd take you around 100 years to hone each cylinder out to give you the clearances you want. On top of that, if you did succeed to remove sufficient metal, you could possibly taper the bores. Take it to the shop and get them to run their machine hone through each cylinder to open them a tad.

When you had your cases blasted did you remove the oilway caps from the cases? There's one above the points cover and two in the lower case, and you should remove them to flush all the glass beads out of your oilways, if you haven't done so already. I usually use the cheapest super market engine oil to "break in" a newly built engine and change it (and the filter) after 100 miles, just to bed everything in.

I've never used assembly lube, but I guess it's worthwhile. (I don't really, but I'm sure someone will tell me I'm wrong, I've only built a dozen or so CB750 engines over the years, so I'm no expert) Cheers, Terry.

[AbbyRider]

Thanks John and Terry. I'm going to double check my piston to bore clearance tonight with feeler gauges, and if I'm closer than .02mm then I'll take to machine shop. From reading other topics it seems that's the desired number.
I looked at the rings last night and I honestly can't remember which way I had them in the piston. The piston set I bought didn't have markings on the rings, just one side silver and one side black. Another post talked about silver side always up. If I had the rings upside down, would that have significantly contributed to the issue?
Terry - that's a good point about the oil galley caps. I did remove the one above the points cover and cleaned that area out before I put my pressure gauge on. But I didn't remove the bottom ones. Will do all that again to be sure. Once cases are together is there a good method for flushing? Can I remove them and force oil through the topmost one and flush out the bottom?

[iron_worker]

If the rings have no markings then they are probably square cut rings and doesn't matter which way up or down. Sounds like my set from Cycle X ... I talked to Ken and he said didn't matter which way as long as the chrome ring was on the top groove.

I think .02mm is the minimum clearance you'd want and probably max around .03mm for fresh bores (.0008" to .0012"). Service limit is closer to .003" (.075mm) I think? I believe they start drinking a good bit of oil around that point though.

IW

[Terry in Australia]

Terry - that's a good point about the oil galley caps. I did remove the one above the points cover and cleaned that area out before I put my pressure gauge on. But I didn't remove the bottom ones. Will do all that again to be sure. Once cases are together is there a good method for flushing? Can I remove them and force oil through the topmost one and flush out the bottom?

To be honest I've never tried to clean them out with the engine assembled mate, but whatever method you use just make sure you flush 'em good, you'll probably be horrified when you see how much of that super-hard abrasive metal destroying material you have hiding in there. I'd pull the oil pump and disassemble it, as it might have grit in there now as well. Cheers, Terry.

[AbbyRider]

Update: My piston to bore clearances were fine. I sat and stared at the engine many times during reassembly, second guessing whether I had missed something or not. Got everything buttoned up.
While static timing the points plate ended up having to rotate quite a bit from where it had been previous. Not sure if that would have had impact on my issues, but interesting nonetheless.
Used regular 10w40 with a bit of seafoam in it. Primed it and tried starting. Nothing. Used a bit of ether and it started up. Coughed a bit but was able to get it idling. Synced carbs and it's running like a champ. Sounds amazing. Still need to time it properly but will wait for my new brake piston so that I can get it out on the road first.
Many thanks to all who helped out with suggestions, answers etc. It's nice to always have this kind of knowledge and experience so readily available.

[BPellerine]

so it does not try to seize when warm now?glad you got it solved.bill

[Terry in Australia]

All the best mate, I hope you have no further issues with it. Cheers, Terry.

[AbbyRider]

Bill - not so far. Crossing my fingers, but it's running way different than before. Sounds way better, I'm able to idle, throttle response is immediate etc. And maybe most telling is that the pipes are WAY cooler than before.

Terry - thanks mate.

[iron_worker]

So, as a recap ... what do you think the main issue(s) was/were?

IW

[BPellerine]

maybe you will get a ride on the beast!bill

[AbbyRider]

So, as a recap ... what do you think the main issue(s) was/were?

IW

IW - I've been asking myself this same question many times over the last few weeks. Taking a scientific approach would be to change one thing at a time and see the result. But once you've got those cases apart you need to fix every possible contributing factor before you button them back up.
My guess would be the major issue was the remaining glass beads in the system making their way to the crank bearings. And I theorize that the over indulgence of assembly lube didn't let them flush through with the oil. It's amazing how just a little bit of grit in those bearings makes it extremely difficult to rotate the crankshaft.
I'm waiting for a new front brake piston to arrive, but once I've got a way of stopping, I'll be taking it out for a spin. Then I'll do proper timing, and after that I'll do a complete oil change.

[AbbyRider]

maybe you will get a ride on the beast!bill

Bill - let's hope so! Should have it insured and on the road by next weekend. And it sure does sound like a beast when it's running.