Author Topic: Black Bomber valve clearances.  (Read 3405 times)

Online sye

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Re: Black Bomber valve clearances.
« Reply #15 on: June 28, 2019, 11:07:08 AM »
Can Newman not build up the follower and regrind?

Offline royhall

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Re: Black Bomber valve clearances.
« Reply #16 on: June 28, 2019, 11:34:12 AM »
They would normally weld on a pad, but by the time two way postage plus costs of the job are added up I may as well buy a new one. I doubt they would have the correct dimensions to work to either. Plus last time it was a two month wait.
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Offline Bryanj

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Re: Black Bomber valve clearances.
« Reply #17 on: June 28, 2019, 12:09:21 PM »
So the gap is too big?

Offline royhall

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Re: Black Bomber valve clearances.
« Reply #18 on: June 28, 2019, 12:27:31 PM »
So the gap is too big?
Way too big.
Current bikes:
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Honda CB750F2 in Candy Apple Red
Triumph Trident 660 in Black/White
Triumph T100C
Suzuki GS1000HC
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Offline K2-K6

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Re: Black Bomber valve clearances.
« Reply #19 on: June 28, 2019, 06:38:06 PM »
It looks like they're not familiar with that adjustment geometry specific to this engine at Newman. With a conventional screw type it could accommodate that change.

Worth taking into consideration for anyone else in same situation,  unfortunately of little help here.

Offline royhall

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Re: Black Bomber valve clearances.
« Reply #20 on: June 28, 2019, 07:46:20 PM »
It looks like they're not familiar with that adjustment geometry specific to this engine at Newman. With a conventional screw type it could accommodate that change.

Worth taking into consideration for anyone else in same situation,  unfortunately of little help here.
I have at least found the problem so am happy about that. And I can put it right without having to strip the whole lot down again. Newman Cams said they had removed a very thin skim, from what I can see and measure that looks close to 10 thou plus whatever they took off the cam itself. That's a lot for the mechanism to make up, and it simply does not stretch that far. Your correct in saying they probably aren't familiar with the layout. Just unfortunate and another one of those things to watch out for, and partly my fault as I should have taken measurements before and after. O well, it's only money.
« Last Edit: June 28, 2019, 07:49:00 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 Bryanj

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Re: Black Bomber valve clearances.
« Reply #21 on: June 28, 2019, 10:48:19 PM »
You could fit what the yanks call a lash cap on the valve stem, its like a small hardened dustbin that fits over the end of the valve stem.

Offline Laverda Dave

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Re: Black Bomber valve clearances.
« Reply #22 on: June 29, 2019, 10:38:18 AM »
I had a similar issue with the 250RS Roy. Newman advised me to send the cam and the rocker arms. They ground the cam and welded pads to the rockers to take up the bigger clearance. From your experience with Newmans compared to mine (earlier post) I think it depends who you get to speak with at Newmans determines the level of advice you receive. I've always been lucky and have spoken with Mike Newman who obviously knows his onions (and cams!).
Good to hear you have the problem sorted now.
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Offline royhall

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Re: Black Bomber valve clearances.
« Reply #23 on: June 29, 2019, 11:08:42 AM »
You could fit what the yanks call a lash cap on the valve stem, its like a small hardened dustbin that fits over the end of the valve stem.
That's an interesting idea Bryan. On this occasion though I think I will replace the rocker arm as any other way is just treating the symptoms and not really curing the actual problem.
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 Bryanj

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Re: Black Bomber valve clearances.
« Reply #24 on: June 29, 2019, 04:47:51 PM »
I just hope they didn't take so much off the lobe that a new follower wont close down enough. Have you told Newmans about the problem as they ought to fix it for free really.

I remember many, many years ago talking to an engineer who raced (250 K3 I think), he had a cam made and hardened it with the result it lasted less than 100 miles, apparently cams were meonitic cast iron with followers hardened and you should never run two hardened surfaces together

Offline royhall

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Re: Black Bomber valve clearances.
« Reply #25 on: July 02, 2019, 07:52:59 AM »
Your right BryanI should really let Newmans sort it, but if you ever dealt with Ken Newman you would know why I'm buying a new follower instead. I have managed to measure the cam whilst in place in the engine and its fine. Ken Newman mentioned grinding down and welding on a pad if the followers didn't clean up. Looks to me like they may have ground it down and forgot to fit the pad and just sent them out like that. That story would fit as that Ken guy was truly hopeless.
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 AshimotoK0

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Re: Black Bomber valve clearances.
« Reply #26 on: July 02, 2019, 08:36:55 AM »
Your right BryanI should really let Newmans sort it, but if you ever dealt with Ken Newman you would know why I'm buying a new follower instead. I have managed to measure the cam whilst in place in the engine and its fine. Ken Newman mentioned grinding down and welding on a pad if the followers didn't clean up. Looks to me like they may have ground it down and forgot to fit the pad and just sent them out like that. That story would fit as that Ken guy was truly hopeless.

Wow that's bad Roy .. I have often thought about sending cams and followers away to be repaired and that firm seemed to crop up as being a good service on all counts, so it was always my intention to use them if I couldn't find decent used or NOS parts. I still reckon it's best to try to find original parts in good condition or NOS, as there always seems to be that nagging doubt about whether repaired parts are up to the original Honda standards. I have never risked sending a pressed together Honda crank for repair or inspection for that reason. What's best... a crank with a bit of hardened sludge in the flywheel sludge trap, that may or may not work its way into the lubrication system sometime or a wrongly pressed together crank ..... difficult one that. It's going to be a cracking good Bomber when you get it finished though and your rebuilt thread will be a great record of your attention to detail if you ever come to sell it.
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Offline K2-K6

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Re: Black Bomber valve clearances.
« Reply #27 on: July 02, 2019, 09:27:45 AM »
I feel there's room for mitigation here,  not to make an excuse for a supplier as I have no connection with Newman, but the pure reality of accomplishing something of this type.

For an item that is effectively scrap in its damaged form this gives an approach that may bring back into service a part that may not be readily available in the condition needed. Newman appear to know their trade regarding materials and refinishing of cams etc. The specific details of geometry (this is a very tightly designed and specific engine with highly resolved components)  may not be fully a part of their appreciation of the job given to them. It doesn't mean it can't be completed,  but further discussion prior to event may yeald a very satisfactory outcome. You've really to combine the two elements to succeed.

I've known absolutely impeccable machinists that carry out superb work without need to know further intricacies of the component parts,  but it's not always like that.

The crank assembly Ash,  it would probably serve to blow steam backwards through the oil routes to flush out tarring from oil ways etc as an non invasive method to clear it out.  Followed by engine oil to prevent corrosion in storage.

On that point,  sludge, it's an area where "synthetic" oils seem to easily outperform previous types in tolerating higher temperature location within the engine.  I agree completely with the "Dutch " view on this.

I've worked for a long time on a particular car engine that has much in common, material and temperature wise, with these bike engines. Prior to synthetic type oil they were notorious "sludgers " but are completely absent of those effects now with improved oils.  They were specified and designed in the late 1950s too,  which certainly doesn't tie in with "old engines need old oil " mantra often sung out collectively via the Internet.

Offline royhall

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Re: Black Bomber valve clearances.
« Reply #28 on: July 03, 2019, 07:50:38 AM »
Sorry but I don't feel Ken Newman has any room for mitigation. After speaking to him on the phone I thought I had better back it up in writing. Attached is a photo of the letter I sent. I'm not sure I could have done any more than this, after all he's the cam expert. The issue is that I didn't pick up the advice from Laverda120 to ask for Mike rather than Ken Newman.

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When I rang him 3 weeks later he had even managed to lose the letter, and the cam and followers were lying around on his desk under a pile of paperwork. I had to resend him the letter via email as he had no idea what he was supposed to be doing with the cam. After two months he finally rushed the (two week) job back to me. That's why I suspect he forgot to weld the pad on the follower.

I shall be stripping it out again tonight so will be able to compare it to the new one (as long as it arrives today). Will post what I find.
« Last Edit: July 03, 2019, 07:54:27 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 Trigger

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Re: Black Bomber valve clearances.
« Reply #29 on: July 03, 2019, 08:42:25 AM »
Did you send a full spec sheet with all the measurements and service limits ?

I had a run on Corsa 1300 TD heads in for skimming. And the customer coming back and saying, that I had skimmed them too much as, there are no saver shims available for that head. I skimmed the heads until they were flat, which the customer asked for. How am I to know that saver shims are not available at that time.

 

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