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SOHC.co.uk Forums => The Black Bomber Board => Topic started by: royhall on January 25, 2019, 03:00:57 PM

Title: Bomber exhaust cams
Post by: royhall on January 25, 2019, 03:00:57 PM
Just sorting through and cleaning the Bomber engine parts and on inspection one of the exhaust cam lobes has some pitting. Got the best pictures I could manage. What's the best way forward with this as they are rocking horse, or is it okay to re-use? The problem is quite common on these as the oil flow to the exhaust cam is low. Or a long shot, has anyone got a spare exhaust cam in good condition for an early Black Bomber engine that they would be willing to sell.

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Title: Re: Bomber exhaust cams
Post by: Bryanj on January 25, 2019, 03:11:43 PM
If you want to go racing possibly re profile, if its going to be a fair eeather queen(or king) like i am it will probably be OK. I seem to remember that the cams are NOT hardened as the followers are plated hard
Title: Re: Bomber exhaust cams
Post by: MrDavo on January 25, 2019, 03:16:27 PM
If you can't find anything better (I saw a couple for sale from breakers on US eBay when I needed one) I have one that is perfect other than damage to the flange that holds the damper ring in place, see my CL450 restoration thread for details and photos.

It would be fine if you were prepared to risk the damper rubber escaping, I wasn't but it's your call.
Title: Re: Bomber exhaust cams
Post by: Laverda Dave on January 25, 2019, 08:20:38 PM
Newman Cams in Kent can repair that. Ask for Mike Newman. I think I paid £27/lobe for my CB250RSA cam last year.
Title: Re: Bomber exhaust cams
Post by: royhall on January 26, 2019, 10:48:08 AM
Thanks for the help guys. I have sent an email to Newman Cams to see what can be done. At this point I may as well fix the problem correctly. Will let you know what they say and what the costs are. Cheers.
Title: Re: Bomber exhaust cams
Post by: royhall on February 19, 2019, 06:35:27 PM
Newman Cams in Kent can repair that. Ask for Mike Newman. I think I paid £27/lobe for my CB250RSA cam last year.
How long did it take for Newman Cams to return your stuff. They have had mine for two weeks so probably a bit early yet. Don't want to start bugging them too soon. They quoted me about £50 to repair the one lobe as he said they are a bit awkward to do plus £12 for the follower. If you could find a new cam it would be way more dosh than that so happy all round.
Title: Re: Bomber exhaust cams
Post by: Laverda Dave on February 19, 2019, 08:05:47 PM
It took about 2 weeks Roy for both the cam and the followers. When the engine went 'bang' a few weeks later the cam suffered a scuff, I contacted Newmans again to tell them the sorry tale they asked me to send it back to them. To their credit they returned the repaired cam 2 days later and only charged me £20 for the work. Great service.
Title: Re: Bomber exhaust cams
Post by: royhall on February 19, 2019, 09:08:43 PM
Cheers. Sounds like I may be hearing from them in the next week or so then.
Title: Re: Bomber exhaust cams
Post by: kettle738 on February 21, 2019, 07:37:15 AM

I have used Newman Cams several times; the first occasion was for a pair of 450K1 cams and followers back in the early eighties.....at the time, he told me the 450 cam was the hardest he had ever seen according to his Rockwell tester.

That said, they did a superb job and I have been back several times since then, they are one of those rare niche engineering companies that are so invaluable......I'm always grateful to see they are still open when I occasionally drive past.....your cams are in very good hands.

Mick.   
Title: Re: Bomber exhaust cams
Post by: royhall on March 14, 2019, 10:46:03 AM
Well I'm at nearly 6 weeks waiting for Newman Cams. It is with a guy called Ken Newman that frankly isn't worth phoning any more. Last time he couldn't remember the job, then he found it in a bag on his desk piled high with paperwork. Then he couldn't find the letter I sent with it so I had to email it to him again. The company may be good but that Ken guy is totally useless, he is completely unorganised and swamped with work that should have been done ages ago. Not impressed with this outfit so far. May have to ask for the CEO tomorrow and get his arse kicked.

To be honest I forgot to ask for Mike Newman as advised so ended up with brother Ken.
Title: Re: Bomber exhaust cams
Post by: Laverda Dave on March 14, 2019, 01:49:15 PM
That's bad news Roy. I would give them another call and ask for Mike Newman. They have been excellent in all my dealings with them.
They may be swamped with work as they do a lot of racing cams and the new season is about to start. Still, that's no excuse for your parts to be stuck under a mountain of paperwork for six weeks!
Title: Re: Bomber exhaust cams
Post by: royhall on March 14, 2019, 02:39:20 PM
That's bad news Roy. I would give them another call and ask for Mike Newman. They have been excellent in all my dealings with them.
They may be swamped with work as they do a lot of racing cams and the new season is about to start. Still, that's no excuse for your parts to be stuck under a mountain of paperwork for six weeks!
I shall try them again in the morning.
Title: Re: Bomber exhaust cams
Post by: AshimotoK0 on April 16, 2020, 05:45:34 PM
I have pitting on the exhaust cam of my Bomber too and I guess it would be a job for Newman cams in due course.

I looked at this in the manual though and seems the exhaust cam was originally welded on the lobe surfaces  with a hard material (I guess Stellite or somethink like it) What is the situation when Newman repair these cams? .. do they repair the damage with hard material ? Surely they don't just reprofile the lobe profile?

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Title: Re: Bomber exhaust cams
Post by: royhall on April 16, 2020, 05:50:56 PM
They said the hardened part was easily thick enough to take a slight regrind. But they also said they would weld a pad on the follower and didn't. I think it all depends on which Newman you speak to. I got Ken who was just about useless. They did a regrind on the follower and wrote it off, I had to replace it with NOS. You've got me concerning about that cam lobe now.
Title: Re: Bomber exhaust cams
Post by: Oggie400F on April 16, 2020, 05:57:31 PM
“Indication Heat Treated”?
I guess this should be Induction Heat Treated.🤔

Yes I’m a pedant. 🤣
Title: Re: Bomber exhaust cams
Post by: AshimotoK0 on April 16, 2020, 05:58:31 PM
They said the hardened part was easily thick enough to take a slight regrind.

Cheers Roy ... I doing a direct  exchange for a Bomber rear brake lever for the two sprockets & pins  to fix my cam chain ider assemblies with Franco Cappellini. I will ask him about the thickness of the hard welding.. he's bound to know.

http://www.cappellinimoto.it/catalog/motorbike/CB450K/product
Title: Re: Bomber exhaust cams
Post by: AshimotoK0 on April 17, 2020, 08:54:09 PM
I got this back from Franco Cappenneli regarding the exhaust cam.

I don't know the depth of the hardened part of the cams but I don't think it is remarkable, many cams, especially of exhaust I found ruined. I send the cams to the megacycle to modify them racing but it is a very expensive operation, they weld and re-profile the cams also with the original diagram. The rocker arms must be in perfect condition with whatever cam is used.
Title: Re: Bomber exhaust cams
Post by: royhall on April 17, 2020, 10:54:54 PM
Big difference between a slight clean up grind to stock profile and a full profile change for racing. Also the revs will be higher on a racing engine.
Title: Re: Bomber exhaust cams
Post by: AshimotoK0 on May 04, 2020, 10:31:31 PM
Franco sent me a lovely condition  exhaust cam ... as a freebie couldn't believe it. So don't need Newman to do mine now.
Title: Re: Bomber exhaust cams
Post by: royhall on May 05, 2020, 08:44:19 AM
Nice one Ash, that's a proper result.
Title: Re: Bomber exhaust cams
Post by: royhall on May 05, 2020, 05:48:14 PM
Got beat to a good pair of fork seal holders on eBay. Did you get them Ash.
Title: Re: Bomber exhaust cams
Post by: AshimotoK0 on May 07, 2020, 12:30:41 AM
Got beat to a good pair of fork seal holders on eBay. Did you get them Ash.

No mine are already rechromed Roy..  Jason bought them I think but they really needed rechroming anyway .......they were Mick Taylors (kettle738 on here)
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