Another cam question 4s (2013)

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Jerry Doe

Jerry Doe

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Hey all,

I am getting ready to rebuild my MK3 motor. I am going to use a new standard cam. The old cam is a 4S cam. I am not happy with its condition, but don't know a huge amount about cams. I know my MK2 ran much better with a standard cam versus a norris cam that was in it and best thing I did was to change it to standard, so am going standard in my MK3 too. Anyway questions:

1) Wondering why my bike had a 4s cam? Did the factory use these? Something tells me they did not.

2) See photos below. I consider this 4s cam is shagged out. Would you agree?
 

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Cannot really tell the condition of the cam from the photos other than it has some use. Just because the lobes exhibit polish does not mean they are shagged. I cannot explaing why a 4S cam is in your bike.


But to the point, since you have it apart, go for a good quality cam. I hate to see you put in one of the notorious OEM "soft cams". Do you have a new cam in hand? Suggest looking at Megacycle selection for this application primarily for the reputable quality of the cams they provide.
 
Jerry, you OBVIOUSLY have never seen an ACTUAL "shagged out" cast butter cam from some of the late 850s...

(I'll try to find a photo)
 
I was going to get a standard cam from Ella (oldbritts). What is wrong with that concept? The one they sent me for my MK2 has 8K miles on it and is great. I thought they fixed the OEM hardening issues?
Maybe I need a 560-n-r?
 
Oldbritts has an excellent reputation. Go for it. I suggested Megacycle as I am a creature of habit.

As for fixing the OEM butter soft cams, maybe they did. The question I would have in my mind is which one did the fellow just send me? Not sure of how you could check.
 
Jerry Doe said:
I was going to get a standard cam from Ella (oldbritts). What is wrong with that concept? The one they sent me for my MK2 has 8K miles on it and is great. I thought they fixed the OEM hardening issues? Maybe I need a 560-n-r?
Click to expand...

They did fix the issue, and you SHOULD get a properly hardened OEM cam if you buy a new one. The 560-NR is a great cam at a great price.

Beware "NOS" (New Old Stock) you could POSSIBLY end up with a hardened butter cam.
 
Thanks all-- I will think about it. I know the cam story can go on forever. We have so many cam threads. I probably should have appended one of those threads. Have a great weekend :)
I would like to see a photo of a "Butter" cam though
 
When I rebuilt my 850 motor a couple years ago I solicited advice from numerous Commando engine "experts'

The general consensus was to go with a Megacycle 5600 for slightly increased valve opening along with excellent mid range performance.

I sent my lifters to Megacycle so they could machine them to perfectly match the new cam.
 
I have had excellent results with the PW-3 (Peter Williams) cam fitted. It has improved the acceleration and the motor is more responsive all the way through the rev range.
 
'Shagged out cams' usually have flats on them. It used to be funny in the old days when the guys with Triumphs found their cams badly worn, and the followers used to become hollow. I know of about two guys who had the followers hard faced and reground to the standard shape, and their bikes went slower.
 
Jerry,
I think your cam looks to be in great shape ,practically new, and other than being a 4s, (are you sure it's a 4s) I would keep it and the matching lifters just the way they are. Do a little research on how the 4s will work with the 850.

Other than that, that cam,4s, with the matching lifters has good value and will do well to fund what ever you choose to get. Let me stress the fact that cams and lifters should be considered as a working set when in a used condition. Yours, being like new, should sell well as a set.

Has your head been milled? This would be advantageous to work with the 4s and may have been done. Worth checking into. If reverting back to a stock situation, a thicker head gasket may be needed, as JS holds in stock.

Peter
 
pvisseriii said:
Jerry,
I think your cam looks to be in great shape ,practically new, and other than being a 4s, (are you sure it's a 4s) I would keep it and the matching lifters just the way they are. Do a little research on how the 4s will work with the 850.

Other than that, that cam,4s, with the matching lifters has good value and will do well to fund what ever you choose to get. Let me stress the fact that cams and lifters should be considered as a working set when in a used condition. Yours, being like new, should sell well as a set.

Has your head been milled? This would be advantageous to work with the 4s and may have been done. Worth checking into. If reverting back to a stock situation, a thicker head gasket may be needed, as JS holds in stock.

Peter
Click to expand...

Forget what I said above. Yes that cam look trashed and the fifters are sure to be as messed up. I will take that, what would appear to be worth its weight in scrap, cam and lifters off your hands. And please be assured that i will gladly offer up shipping charges. :twisted:
 
FWIW, I sent my cam and followers to Comnoz along with my head. He was able to check the hardness of the cam for me to verify whether or not I should worry about it being too soft. It came in at mid-range and after getting a follower resurfaced to square it to the cam they all went back into the build. You will have to address the followers with a new cam, right? Might as well drop them all in the mail and have the hardness verified.

Russ
 
Yes is a 4s. I have a few RH4 heads. I am not sure if the one that came with bike was milled and not sure how to tell. I need to have a look at both heads and compare. Now I really don't know what to do. I suppose I need to dig up all the cam posts and start reading.
 
I know what I do not want floating into my mind pressing my spirited throttle luck on the long run. Might consider it a good core for regrind to match what ya really want and end up with hardened refined cam in the process for about same or less than a new one. The whole face of the cam should be burnished by lifter contact so this cam with narrowed contact areas is a bit pensive making to me.
 
Jerry Doe said:
1) Wondering why my bike had a 4s cam? Did the factory use these? Something tells me they did not.
Click to expand...

Not unless someone really screwed up on the production line. Only production Commando engine with 4S was the short stroke 750. On the other hand, there are plenty of examples of Commandos with "wrong" parts coming out of the factory.

Ken
 
hobot said:
The whole face of the cam should be burnished by lifter contact so this cam with narrowed contact areas is a bit pensive making to me.
Click to expand...
I think this is a fairly new cam and the witnesses are that of normal breakin.
 
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