Topic: 650 cam in a 550 - ride report

[redcaesar]

Any idea if the swap will work in 500 as easily as in the 550?

[Maxacceleration]

I think I'll go the Webcam route. Cost a little more but no tach changes, correct?

[ct_racer]

Hymodyne, I also have the 605 kit in my k2 500.  If you get that thing in there can you let me know if you had to modify the head? and how the clearances were on the pistons were?

[Soos]

I think I'll go the Webcam route. Cost a little more but no tach changes, correct?

Yeah... But about 200+ $$ difference in cost.


l8r

[texaninseattle]

nah you can get a re-grind for $150

[rookieridercb550]

Thank you soo much for posting this beautiful article! Where can one get a tach set up from a 650 and any ideas of around how much?

"nah you can get a re-grind for $150"- Where?

[754]

When looking at a cam, how do you tell if they are 500/550 or 650 cams?

[hymodyne]

lobe length; longer lobes on 650

[hymodyne]

Hymodyne, I also have the 605 kit in my k2 500.  If you get that thing in there can you let me know if you had to modify the head? and how the clearances were on the pistons were?

I had to widen the sides of the head where the cam lobes pass, don't know about piston clearance yet as I haven't actually installed and fired her up. the 650 cam I have is going in my 550 project engine this winter. I'm re-using my Reike'd stage 2 head for this project off my 605 overbore engine.

hym

[noose74]

i couldnt read if you mentioned it but is there a certain year of 650 cam that works? like if i have a 76 550, do i need a 76 650 cam? or is there a range of cams that work? thanks

[moham]

i couldnt read if you mentioned it but is there a certain year of 650 cam that works? like if i have a 76 550, do i need a 76 650 cam? or is there a range of cams that work? thanks

It's been said previously that any 79-82 sohc 650 cams should work in any 550 (with the addition of the 650 tach gear). I have a 79 650 camshaft for my 74 550 but do not have it installed yet, but I certainly trust the others that have done it.

[Ecosse]

When looking at a cam, how do you tell if they are 500/550 or 650 cams?

If you're not able to compare side by side does anyone know of part number/ production cast markings or something else to identify the different cams?

[754]

The only thing I have is the numbers anmd major dia of lobes, I posted that info on a thread asking to ID the cams.

As I have an NOS 650 head, I checked to see if they fit and they do, but they may even be 550?

Anyone know haw many teeth on tach drive, these have 5.

[scunny]

650 cam has 5 helical (?) cut thingys and the tach drive into it has 10 teeth

[d3buttz]

sweet post-im sold on it and i won a cam on feebay for 21.50 today- thanks for the confidence on this swap!

[noose74]

what did you search under ??

[d3buttz]

i searched "cb650 camshaft" , try "cb650 cam" for short too,but, watch out for the early 80's night hawk ones(or something like that) those pop up too under that search-they wont work.

[cb650]

A 82 nitehawk is still the same sohc4.  83 changed.

[moham]

A 82 nitehawk is still the same sohc4.  83 changed.

A quick search (not wikipedia) shows that the Nighthawk moniker referred to cb650sc from 81-84 (81-82 in the US, 82-84 in UK)

[cb650]

Dont matter what your search showed.  A 82 nitehawk is sohc4 with the same engine just black and chrome.  Yes it was the first year of the SC moniker but it was a SOHC4.  And the SC went on the UK untill 84 as the "luxury custom" as a single cam as in the same engine as a 79 650 singlecam. And honda did use the SC on the new dual cam.  Check out the 650 site there is a new menber with a nitehawk SOHC4 with pics.
http://www.hondacb650.com/viewtopic.php?f=2&t=658

[754]

So does 5 teeth make a 650 (only) cam , or does 550 have that too.?

 If anyone had a lobe measurement off a known 500/550 cam then I would be sure what I have.

[moham]

Dont matter what your search showed.  A 82 nitehawk is sohc4 with the same engine just black and chrome.  Yes it was the first year of the SC moniker but it was a SOHC4.  And the SC went on the UK untill 84 as the "luxury custom" as a single cam as in the same engine as a 79 650 singlecam. And honda did use the SC on the new dual cam.  Check out the 650 site there is a new menber with a nitehawk SOHC4 with pics.
http://www.hondacb650.com/viewtopic.php?f=2&t=658

As far as I can tell, my previous post says exactly what you just stated...I am in agreement with you. I wasn't distinguishing sohc or dohc, just the name "nighthawk". I was trying to provide confirmation for your earlier post.

[Soos]

So does 5 teeth make a 650 (only) cam , or does 550 have that too.?

 If anyone had a lobe measurement off a known 500/550 cam then I would be sure what I have.

No 550/500 cam measurements, but I can get you some off of a 650 here when I get off of work this morning.


l8r

[Ryan 550k]

I just ordered my 650 cam for my 550, and I'm curious-
Without having it in my hands, and I've never seen the tach gear for the 650 cam, do you think the tach drive gear for the 650 would plug into the 550 cable? Or would the 650 cable and gear plug into the 550 tach gauge itself?
That would be much easier than swapping the entire tach, etc.

no. the gearing is simply different. you need the the 650 drive, gear, cable, and tach.

I recently purchased a cylinder head with cam off an 82 650 nighthawk.  I'll be swapping out my 550 cam for this one pretty soon.  But I just have one more.........that's right, ONE MORE fu*#ing question for this thread.  And sometimes I need to have things explained to me like I'm 8, so here it is.  As I understand it, I can swap the cam's but my 550 tach won't work, understandable.  So I need a new drive....(what is that?), gear......(what gear), tach cable and tach.  Ok so the tach cable and tach I understand.  Does the tach itself have to be off an 82 650 nighthawk?  Or can I find any 650 tach that will work and replace?  Any idea if it'll fit in the stock tach housing on my 78 550?  Also, is there anything else out of this head that I can use in my 550?
I think that's all

[FunJimmy]

It doesn’t have to be this difficult. The issues with tach and tach drive are based on the fact that the two cams have different tach drive ratios (gears). You need to use a 650 tach drive assembly with a 650 cam and the same is true with the 550 cam. You know, 550 tach drive with the 550 cam, just in case I’m typing too fast for you. Both tach drive units simply install in the head and the cable attaches to both the tach drive and the tach itself. The cable is not model specific so the cable is not the issue. Got it?

As for the tachometers, they are both visually the same (except for the face), so they will both install in the same manner and in the same housings etc. I would bet money that the tach internals are also the same and that the difference is in the scale of the face. Considering that most of these old tachs don’t read accurate anyway, what does it really matter what tach you choose to use anyway. If you really want accuracy recalibrate the face using an electronic tach and make the location of each 1000RPM on a new face, or just install an electronic tach and plug the cable drive hole in your head.