SOHC.co.uk Forums > CB350/400
Smokey rebuilt 350
Nurse Julie:
Cracked liner ?.
Although re bored, did the liner clean up 100%, ie no scoring, or rust pockets beyond what what bored ?.
(The reason i say this is because Trig has rebored some barrels to .25 they still showed a minute mark on 1 liner, continued to rebore all the way up to 1.0 and the marks were still there, pushed the liner out and the rust had gone all the way through to the outside of the liner).
royhall:
My 450 barrels were like that, so a kind soul donated a replacement set to me. I don't recall seeing any rust in the 350 barrels though. I am beginning to suspect there is a crack in the barrels or the head somewhere as whatever I try the problem stays the same. Everything else is eliminated. Tried another set of carbs, took off the electronic ignition and coils and went back to standard, have re-bored again and changed the pistons and rings, re-done the guides, all genuine gaskets and seals. I fear the tops coming off again. I have a spare set of barrels I can go to, may try and get another head. Will probably just shove it to the back of the garage for a while as I'm a bit tired of it. Costing a pile of money if nothing else.
Just a side issue. I can run the engine with the tappet caps off and I don't get wet. Also there appears to be more oil around the inlet valves than the outlet. Is this correct?
Moorey:
If you pull the engine again try one of these to find a crack. https://www.ebay.co.uk/itm/Weld-Crack-Detector-Aerosols-Penetrant-Developer-Cleaner-or-full-set-of-3/183374704949?hash=item2ab1fbf135:m:m3tzZ_DI3GoC4KBNvH9-WHQ We use them to find cracks in leaking vessels and reactors when we cant see the crack with the naked eye. Then when we start welding as soon as heat is introduced the crack opens right up. Maybe yours does not show until heat is involved. It seems like you hav already thrown a shit load of money at it. Good luck with it.
You will need the full kit.
royhall:
--- Quote from: moorey on August 17, 2018, 09:55:34 AM ---If you pull the engine again try one of these to find a crack. https://www.ebay.co.uk/itm/Weld-Crack-Detector-Aerosols-Penetrant-Developer-Cleaner-or-full-set-of-3/183374704949?hash=item2ab1fbf135:m:m3tzZ_DI3GoC4KBNvH9-WHQ We use them to find cracks in leaking vessels and reactors when we cant see the crack with the naked eye. Then when we start welding as soon as heat is introduced the crack opens right up. Maybe yours does not show until heat is involved. It seems like you hav already thrown a shit load of money at it. Good luck with it.
You will need the full kit.
--- End quote ---
That looks interesting. What's the procedure for using it.
Nurse Julie:
A cheap simple and quick diagnostic test would be to pop the lines out, swap them around and see if the problem moves cylinders.
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