Author Topic: 650 cam into a 550 (Read 9366 times)

squirley · « **on:** March 09, 2008, 09:12:12 AM »

I have read all the articles I could find regarding this subject, but all threads seem to end at the point where someone says that they will give it a try, but there is no follow up story.
I am currently putting my engine back together after a stock spec rebuild, but have ported the heads and would like to take advantage of this. I would very much like to drop in a 650 cam in an otherwise stock engine, and need to know if this will work? I am aware that the dimensions are the same, with the stock 650 cam being very close to a 550 street cam. Has anyone done this and actually ran it?

kayaker43 · « **Reply #1 on:** March 09, 2008, 09:16:39 AM »

No help from me but I want to know the answer too?

I'm 99% certian it will work if you use the 550 cam sprocket. It would be a very cheap and effective mod, I'm surprised there's not more interest in it??

rachet · « **Reply #2 on:** March 09, 2008, 09:31:32 AM »

I'm interested in this as well. I'm planning on building a 500 and want to get as much power out of it as possible.

Rachet~

number13 · « **Reply #3 on:** March 09, 2008, 09:37:07 AM »

Funny you should mention that.
I was just talking with member Kevin400F
last Thursday. He is attempting that upgrade
right now and has encountered a few problems,
mainly some clearance issues.

squirley · « **Reply #4 on:** March 09, 2008, 09:39:17 AM »

I have heard that there may be some clearance issues, but nothing a dremel couldn't fix I don't think. But I could be wrong here.

Soos · « **Reply #5 on:** March 09, 2008, 10:02:17 AM »

I have heard of clearance issues as wel.

I have dropped a 550 cam into a 650 head to check compatibility.
It dropped in.
All the bearing surfaces are VERY close in diameter to the 650's(within 0.0003 inches)
The cam lobes however are SIGNIFICANTLY different.

With the height differences between the 550 and 650 cam lobes, I could see those as possibly being a clearance issue on a 550 head.

A file and a steady hand and a lot of time should give clearance.
Or in a pinch a dremmel and some beer would suffice.

l8r

Jay B · « **Reply #6 on:** March 09, 2008, 01:20:11 PM »

What about tach drive issues? I've been wondering about this also, it's been mentioned here that the tack will be way off with a 650 cam.

kayaker43 · « **Reply #7 on:** March 09, 2008, 02:43:06 PM »

I might have heard something about the tach too, but that doesn't bother me.

I hope this thread doesn't end the same way with no answers. Its probably buried in the archives somewhere, but I couldn't find it. This is a common question and I'm sure its been done. Someone needs to take a week with a micrometer and two engines then publish an interchange manual. I would pay for $20 for one.

squirley · « **Reply #8 on:** March 09, 2008, 03:21:01 PM »

I as well have heard about tack issues, and this is an example of the questions that lurk in the previous threads that never get answered. I guess I will just find myself a cam and install it, check for clearance issues and do what needs to be done.

paulages · « **Reply #9 on:** March 09, 2008, 05:50:57 PM »

Quote from: kayaker43 on March 09, 2008, 02:43:06 PM

I might have heard something about the tach too, but that doesn't bother me.

I hope this thread doesn't end the same way with no answers. Its probably buried in the archives somewhere, but I couldn't find it. This is a common question and I'm sure its been done. Someone needs to take a week with a micrometer and two engines then publish an interchange manual. I would pay for $20 for one.

i can tell you just about every difference between the 550 and 650 engine if you need to know. don't think i'd have time to publish any kind of compatibility manual, but i've played with just about every combination of parts in mocking up my 718 engine. i believe that 650 cam lobes contact the cam case on the 550, but is easily remedied as suggested above. i'm pretty sure i have a 550 head open, i can try to fit a 650 cam onto. i'll get back at ya.

squirley · « **Reply #10 on:** March 09, 2008, 06:24:24 PM »

That would be awesome Paulages. If you do find points of contact, would you mind givine a heads up as to where and how much? Thanks
By the way, you wouldn't have an extra 650 cam for sale would you?

olds-cool · « **Reply #11 on:** March 09, 2008, 06:51:01 PM »

From what I've read, some have clearance issues and some don't. My cam is on it's way. I'll be putting it into a 500 head. The tach problem can be solved by switching out the tach drive gears. There were rumors that the tach had to be switched too but I'm doubting that one.

FunJimmy · « **Reply #12 on:** March 09, 2008, 10:16:06 PM »

Jens

I have a 550 head and 650 cam out in the garage.
I should be able to post pics of the clearence issues for you tomorrow.
They should be ok with the dremel work.
I'll also check the speedo drive ratios too.

What I'd really like to know is the lift and duration of the 650 cam.

Anyone up to that?

Later
FJ

paulages · « **Reply #13 on:** March 09, 2008, 11:30:38 PM »

i checked with my '79 cb650 cam (1.040 intake height wear limit), and there were no clearance issues in either the head or the cam cover. the actual lobe measurements aren't dramatically different between the two, but the 650 looks to have more duration.

squirley- no, sorry.

kayaker43 · « **Reply #14 on:** March 10, 2008, 10:10:56 AM »

Squirley,.. Ebay is your friend, I just bought one for $25.00. There's another on now for $77 buy it now, but it will probably sell cheaper if you wait??

I would love to see a sticky comparing cam specs. I think the 650 cam would compare to a mild aftermarket street cam for the 550? should be a great upgrade for the price but don't expect too much, its not a race cam.

FunJimmy · « **Reply #15 on:** March 10, 2008, 10:22:20 AM »

Here is a picture of a 650 cam in a 550 head.

You’ll see that the lobes are just touching the casting and would require a little trip to ensure adequate clearance.

Other than a little clearancing it looks fine.

FYI: My 650 cam has 5 spiral cut teeth and there are 10 teeth on the driven gear. This ratio is different than the 550 cam and tach drive.

squirley · « **Reply #16 on:** March 10, 2008, 10:24:55 AM »

Thanks for the pic there FJ and the heads up. I just read that the tach gear drives are different, but nothing switching tachs wouldn't fix.
I am still trying to find info on lift and duration specs on the 650 cam, so if anyone knows, please post up.

paulages · « **Reply #17 on:** March 10, 2008, 11:51:40 AM »

Quote from: FunJimmy on March 10, 2008, 10:22:20 AM

Here is a picture of a 650 cam in a 550 head.

You’ll see that the lobes are just touching the casting and would require a little trip to ensure adequate clearance.

Other than a little clearancing it looks fine.

FYI: My 650 cam has 5 spiral cut teeth and there are 10 teeth on the driven gear. This ratio is different than the 550 cam and tach drive.

there must be inconsistencies in the 550 castings or something, because mine didn't contact anywhere. weird.

squirley · « **Reply #18 on:** March 10, 2008, 12:45:45 PM »

kayaker, you just bought that cam from ebay recently didn't you. I was watching that one and waiting to see what the general response was from this forum before purchasing. You beat me to it, that's what I get for waiting I guess.

kayaker43 · « **Reply #19 on:** March 10, 2008, 01:44:07 PM »

Sorry, wasn't intentional, I've been collecting bits and pieces. The price doubled with shipping from Canada though. Here's an ebay tip, the "buy it now" price goes away after the first bid. Normally I snipe in the last seconds but you could put in a $10 bid to kill the buy it now and you have a good chance that it will go cheaper.

Unless someone else wants it real bad too?

squirley · « **Reply #20 on:** March 10, 2008, 01:48:36 PM »

No worries there kayaker, and I guess seeing his shipping price only a few dollars less than the buy it price had me hesitating too.

kayaker43 · « **Reply #21 on:** March 10, 2008, 01:53:31 PM »

The 550 cam has 3 teeth and the 650 has 5 for the tach drive. Either replace the plastic gear or. remove it and plug. I imagine they can't possiblly mesh well and you'll chew up the plastic gear.

Change the plastic gear or use a 650 tach.

Why on earth would they make a change like that?? I'll bet the tach is more accurate but the cable wear has to be higher??

Also I hear the firing order is different but no one mentions problems from that. The cam chains are different as well as the length, so it would be surprising if the cam timing came out right. I know people are doing it, but has anyone checked the cam timing for accuracy.

olds-cool · « **Reply #22 on:** March 10, 2008, 08:20:14 PM »

speaking of the cam chain, you will have to use your stock 500/550 cam gear

paulages · « **Reply #23 on:** March 11, 2008, 01:33:47 AM »

Quote from: kayaker43 on March 10, 2008, 01:53:31 PM

The 550 cam has 3 teeth and the 650 has 5 for the tach drive. Either replace the plastic gear or. remove it and plug. I imagine they can't possibly mesh well and you'll chew up the plastic gear.

Change the plastic gear or use a 650 tach.

Why on earth would they make a change like that?? I'll bet the tach is more accurate but the cable wear has to be higher??

Also I hear the firing order is different but no one mentions problems from that. The cam chains are different as well as the length, so it would be surprising if the cam timing came out right. I know people are doing it, but has anyone checked the cam timing for accuracy.

the length of the chain is irrelevant, but properly degreeing the cam is definitely a good idea upon installation, regardless. the blanks for those cams are definitely the same, they just have different grinds.

in regards to the firing order: the cams being the same, this only matters if you are doing more involved of a 550/650 combo. the locating pin for the ignition assembly on the 650 is 180 deg. out from the 550. if using points or a dyna ignition, this must either be redrilled or the wiring reversed somewhere in the ignition circuit.

squirley · « **Reply #24 on:** March 12, 2008, 10:13:06 AM »

I was reading older posts regarding the 650 cam and came across a post that claimed the cb cam was only different from the 550 offering about .03 more lift, and no dration.
Does anyone have any new info on this as I would like to not see this one slowly die like the other threads

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Author Topic: 650 cam into a 550 (Read 9366 times)