Author Topic: Smokey rebuilt 350  (Read 7840 times)

Offline Nurse Julie

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Re: Smokey rebuilt 350
« Reply #90 on: August 16, 2018, 04:04:13 PM »
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).

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Offline royhall

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Re: Smokey rebuilt 350
« Reply #91 on: August 16, 2018, 04:12:19 PM »
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?
« Last Edit: August 16, 2018, 04:35:08 PM by royhall »
Current bikes:
TriBsa CCM 350 Twin
Honda CB350F in Candy Bacchus Olive
Honda CB750F2 in Candy Apple Red
Triumph Trident 660 in Black/White
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Honda CB450K0 Black Bomber
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Offline Moorey

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Re: Smokey rebuilt 350
« Reply #92 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.
« Last Edit: August 17, 2018, 09:57:57 AM by moorey »

Offline royhall

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Re: Smokey rebuilt 350
« Reply #93 on: August 17, 2018, 11:27:09 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.
That looks interesting. What's the procedure for using it.
Current bikes:
TriBsa CCM 350 Twin
Honda CB350F in Candy Bacchus Olive
Honda CB750F2 in Candy Apple Red
Triumph Trident 660 in Black/White
Triumph T100C
Suzuki GS1000HC
Honda CB450K0 Black Bomber
Honda CB750K5 in Planet Blue Metallic (Current Project)

Offline Nurse Julie

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Re: Smokey rebuilt 350
« Reply #94 on: August 17, 2018, 12:32:06 PM »
A cheap simple and quick diagnostic test would be to pop the lines out, swap them around and see if the problem moves cylinders.
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
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Offline royhall

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Re: Smokey rebuilt 350
« Reply #95 on: August 17, 2018, 12:39:08 PM »
A cheap simple and quick diagnostic test would be to pop the lines out, swap them around and see if the problem moves cylinders.
When you say lines, do you mean the HT leads?
Current bikes:
TriBsa CCM 350 Twin
Honda CB350F in Candy Bacchus Olive
Honda CB750F2 in Candy Apple Red
Triumph Trident 660 in Black/White
Triumph T100C
Suzuki GS1000HC
Honda CB450K0 Black Bomber
Honda CB750K5 in Planet Blue Metallic (Current Project)

Offline Nurse Julie

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Re: Smokey rebuilt 350
« Reply #96 on: August 17, 2018, 12:41:40 PM »
A cheap simple and quick diagnostic test would be to pop the lines out, swap them around and see if the problem moves cylinders.
When you say lines, do you mean the HT leads?
F'kin spell check, LINERS as in barrels.
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
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Offline royhall

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Re: Smokey rebuilt 350
« Reply #97 on: August 17, 2018, 12:44:56 PM »
Good idea, the problem is two rebuilds. Not cheap. I have another set of barrels I can use but they will require a rebore. This time I need to find the"smoking gun" before I do anything. I thought I had last time as the Cruzinimage head gasket had defo gone, but wasn't to be. If I do find a cracked liner I can always rob a sleeve out of the other set and just have one pot rebored. That's probably the cheapest option. But I do need to find the problem this time.
« Last Edit: August 17, 2018, 12:49:27 PM by royhall »
Current bikes:
TriBsa CCM 350 Twin
Honda CB350F in Candy Bacchus Olive
Honda CB750F2 in Candy Apple Red
Triumph Trident 660 in Black/White
Triumph T100C
Suzuki GS1000HC
Honda CB450K0 Black Bomber
Honda CB750K5 in Planet Blue Metallic (Current Project)

Offline Moorey

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Re: Smokey rebuilt 350
« Reply #98 on: August 17, 2018, 02:36:16 PM »
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.
That looks interesting. What's the procedure for using it.

Very simple but very effective. Give everything a good clean with the spray cleaner and dry, then spray on the penetrant which is usually a red dye that works its way into the fault leave a while then clean again, then spray on the developer which is a white powder. If there are any cracks or faults the powder draws out the red penetrant from the crack showing the problem area.  Quick and simple to use. I don't envy you, frustingto say the least.

Offline Nurse Julie

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Re: Smokey rebuilt 350
« Reply #99 on: August 17, 2018, 03:15:09 PM »
Helping you clutch at straws here Roy. Is the valve stem seal intact, a good fit, not cracked or ripped. Easy one to check and costs nothing 😀😀😀
Is the valve stem the correct size, ie, the same as the other valves?
« Last Edit: August 17, 2018, 03:20:26 PM by Nurse Julie »
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
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Offline Laverda Dave

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Re: Smokey rebuilt 350
« Reply #100 on: August 17, 2018, 04:20:39 PM »
Bad luck Roy. I second Moorey's suggestion. We use a similar method on train wheels prior to turning in a wheel lathe. Quick and easy, just make sure everything is as clean as possible to avoid any false results.
Good luck.
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Offline royhall

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Re: Smokey rebuilt 350
« Reply #101 on: August 17, 2018, 04:41:57 PM »
Thanks guys. The stem seals were replaced and all checked for tolerance at the first and second build. Second time it was genuine Honda seals, no seals on the exhaust side as per 350F. Still smoked both times. I'm sure it's not anything to do with seals or wear this time, will be using the crack detection method looking for actual damage when I get round to it. At about 200 miles it started smoking badly all at once which would suggest something has broken or cracked. It will have to wait a while as it's Isle of Man time again on Thursday so will be away for 10 days. Hopefully when I get back someone will have stolen it (agreed value). ;D
« Last Edit: August 17, 2018, 05:21:16 PM by royhall »
Current bikes:
TriBsa CCM 350 Twin
Honda CB350F in Candy Bacchus Olive
Honda CB750F2 in Candy Apple Red
Triumph Trident 660 in Black/White
Triumph T100C
Suzuki GS1000HC
Honda CB450K0 Black Bomber
Honda CB750K5 in Planet Blue Metallic (Current Project)

Offline royhall

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Re: Smokey rebuilt 350
« Reply #102 on: October 27, 2019, 10:31:02 AM »
Sorry for returning to such an old thread but I thought it best to bring it to an end. You may remember I had a smokey CB350F that was refusing to be repaired.

After pushing the thing to the back of the garage under a sheet for nearly a year I thought I would have another go. This time around I am taking no prisoners so am removing all reproduction engine parts and replacing with genuine.

After stripping the top end I checked the barrels and liners for cracks with Dye-pen. They checked out okay. Unfortunately they were now at maximum bore with Cruzinimage pistons so they are unusable with NOS pistons. They are good though so I will sell them on.

Couldn't Dye-pen the head as the casting inside the ports (where it matters) is just too rough. After sending the head to an NDT specialist who checked it with something to do with Eddy Currents (pass) it came back with the problem marked. It appears that after changing the valve guides the casting had a small crack on No.4 inlet that had slowly propagated along until neat oil was being pulled into the cylinder. Bingo, problem found.

After weeks of looking I finally sourced replacement head, barrels, and pistons. The head was like new and required nothing but a clean up, painting, and valves lapped in. The barrels went off to Trigger (thanks for the great work Trig) who replaced some liners then rebored for the NOS pistons. All went back together with NE gaskets.

Only done a few miles on her, but the engine is smoke free and runs superbly. Guess it will have to wait until spring now to run her in properly. Thanks to all members that helped (or tried to help) with this problem. It can feel like a hopeless case but every problem has a cause, it just has to be found.

I treated her to a Spa day and polished everything to within an inch of its life. She looks a real lady now.


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« Last Edit: October 27, 2019, 10:49:55 AM by royhall »
Current bikes:
TriBsa CCM 350 Twin
Honda CB350F in Candy Bacchus Olive
Honda CB750F2 in Candy Apple Red
Triumph Trident 660 in Black/White
Triumph T100C
Suzuki GS1000HC
Honda CB450K0 Black Bomber
Honda CB750K5 in Planet Blue Metallic (Current Project)

Offline hairygit

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Re: Smokey rebuilt 350
« Reply #103 on: October 27, 2019, 10:49:49 AM »
So pleased to know it's finally sorted! I shudder to think how much time and hard cash this issue has caused you, but there HAD to be problem, it just took a while to find it. I think we should have a thread for saving some of these stories and ultimate solutions, there have been a few long suffering owners recently, and others can learn from the experiences.                        Well done for sticking with it and not giving up (plenty of people would would have done!)

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Offline royhall

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Re: Smokey rebuilt 350
« Reply #104 on: October 27, 2019, 10:54:10 AM »
On the hard cash front. This problem has caused me to break my self imposed limit that the finished bike shouldn't have cost more than it's worth. But what else can you do but sell it off cheap with a smokey pot. I'm not selling it anyway so doesn't really matter. However, this little problem ended up putting £680 onto the rebuild cost. Ouch.
Current bikes:
TriBsa CCM 350 Twin
Honda CB350F in Candy Bacchus Olive
Honda CB750F2 in Candy Apple Red
Triumph Trident 660 in Black/White
Triumph T100C
Suzuki GS1000HC
Honda CB450K0 Black Bomber
Honda CB750K5 in Planet Blue Metallic (Current Project)

 

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