Camshaft Regrind

[Murf]

As with just about everything else on the 550 the camshaft was knackered with a lot of wear on the lobes.  Finding a good used one seems impossible with all the ones I saw for sale being either as bad or worse than the one I had.  I decided to see if it could be reground and contacted Newman Cams who were really helpful and good to deal with.

I have just got the cam back from them and they have done a fantastic job, the cam is as new.  The cost including return postage was  £159 which I think is very good.  Especially when you consider what people are trying to sell knackered used camshafts for.   

I had a standard profile reground on the cam.  I haven’t used the cam yet but from my dealing with them, the quality of their work and great packing of the returned cam I feel I can definitely recommend Newman Cams.

Photo of cam in the cylinder head is of cam when I first stripped the engine.  I am sure the wear mostly on one side of the cam lobes was caused by the badly worn rocker shaft mountings which cause the cam follower to contact the cam lobe on an angle,  putting all the pressure and wear on one side.  I had 3 very bad shafts in the rocker box.  For the rebuild I have sourced a later rocker box which has the locked shafts to eliminate the problem.

[McCabe-Thiele (Ted)]

Looks like new, is it reground and case hardened or do they metal spray so the lobe dimensions are as original.

I remember Newman's from my ADO15 Mini days, they made affordable alternatives. I could not always afford the prices of BL Special Tuning parts.

[Murf]

I am not sure what was done to mine,  but in general I think it depends on the depth of the wear, if it is shallow then they can just Regrind the lobe and keep costs down.  In terms of hardening again I think it depends on how deep the damage is. If the damage is deep then they can add metal and Regrind.   It’s good to know the cam can be saved.

[Oddjob]

It's a pity they didn't regrind the journal surfaces as well. I'll be using them for my regrind but not going with standard profile next time, they can also do rocker arms BTW.

[Murf]

In practical terms can’t really Regrind the cam journals because the cam journals run directly in bearings formed in the aluminium of  the cylinder head and there are no shell bearings, so no possibility of using oversized bearings.
Now I am not saying it isn’t possible to line bore the bearings in the head out to a larger diameter, then find or make some shell bearings to fit, because I met someone that had done this on a CBX 1000 sprint bike that he he campaigned many years ago.  But the cost is going to be more than finding a head with good bearings.

[Sesman]

Hi, Murf. I think Ken was suggesting building them up, grinding them back and hardening. Though I think Newman will only work on chilled iron cams and as such might not be prepared to go that route…possibly?

[Oddjob]

Exactly what I was thinking Phil. I remember speaking to Stuart Clarke at Newman’s cams about doing journals and his reply was to the effect that they’d hard chrome them then grind them back to original size, even gave me a price of £40 a journal. That’s £160 for all 4 but it may mean saving a cam if just one is scored.

I can copy and paste his exact answer if it helps Murf.

[Sesman]

Ahh, yes. I didn’t think about hard chroming. Nice dodge.

[Laverda Dave]

I was told in the distance past by Newman Cams that Honda cams are made of cold chilled cast iron and are not case hardened.
Newman Cams reground the cam of my old CB250RSA back in 2017. They also added new pads to the rockers and did a great job.

[Murf]

Yes good idea,
 I had not thought about hard chroming the journals as a way to save a hard to find camshaft.
Fortunately the journals on my cam are ok as are the bearings in the head, at least sometimes was ok.

[Bryanj]

Cant line bore a 500 as the ends are solid, they must have been plunge milled with exact size cutters, only way i can think it being done

[Oddjob]

Well if nothing else Murf you've informed anyone with a duff journal that it's possible to get it repaired. That's worthwhile in itself.

I was told by Stuart Dave that rockers were repaired in the same way as journals, hard chromed and ground back to shape. I have about 55 of them somewhere, most good, I threw out all the ones showing wear