Topic: Who's done the 650 cam in a 550 swap?

[Scott S]

 I have a CB650 cam and about the only thing that's stopping me from using it is having to swap to a 650 tach. I have a perfect set of matched gauges on my 550 and can't quite bring myself to run a mismatched set.

 Can you show me your dash so I can see how the 650 tach looks on a 550?

 Can you really feel a difference in power?

 Did you make any other mods (other than the cam)?

[chimmychong86]

The duration is longer and you will feel the difference! Add to that a little porting, a rejet and you'll really feel it. As for the gauges, you can also switch to 750 for the tach. I unfortunately can't give you pictures of mine because i switched to mini on both. 

[Scott S]

 What years 750 tach? I know the '80-82 work....any others?

[Gordon]

I've been running a 650 camshaft in my 550 for about two years and I'm very happy with it.  Do a forum search (not google custom search) for "650 cam 550" and "550 cam swap" for lots of info and many opinions and reviews. 

You won't notice much in the lower rpms, but hitting 6K is like flipping a boost switch.  It really allows the engine to breathe up there and the power just keeps coming.  I'm also running a 16 tooth front sprocket which brings on the higher rpms sooner, the stock air box with a UNI foam filter, and as per Hondaman's easy mods recommendations I've trimmed the advancer springs, advanced the timing and opened up the air intake.  Details in "The thoughts of Hondaman" FAQ. 

As for the mismatched clocks, you could always do custom or reproduction faces. 

[dave500]

has the 650 tach drive at the engine end got a thread at the cable entry?,unlike the 500/550 which just drops in and a through bolt holds it?

[Greggo]

has the 650 tach drive at the engine end got a thread at the cable entry?,unlike the 500/550 which just drops in and a through bolt holds it?

Identical pieces aside from the drive ratio.

[Greggo]

Oh, and it makes a BIG difference.  I noticed it especially on the freeway - much improved throttle response.

I've been running without a tach for now.  The 650 tachometer won't mount right onto the 500's bracket, which is made for smaller gauges. 

[Scott S]

I've been running a 650 camshaft in my 550 for about two years and I'm very happy with it.  Do a forum search (not google custom search) for "650 cam 550" and "550 cam swap" for lots of info and many opinions and reviews. 

 

 Gordon, I've done many searches and read many a thread about HOW to do it. I was more interested in real world replies from people who have completed the swap.

 Will all 750 tachs work? I corss referenced the 650 part # and it shows '80-82 CB750's, but what about the others? Maybe I stand a chance of finding a matching gauge that way. Or, I could do custom faces, I guess.....

[Gordon]

has the 650 tach drive at the engine end got a thread at the cable entry?,unlike the 500/550 which just drops in and a through bolt holds it?

If I'm understanding the question correctly, the only part you change is the tach drive gear itself.  You still use the same housing from the 550 valve cover.


 

Gordon, I've done many searches and read many a thread about HOW to do it. I was more interested in real world replies from people who have completed the swap.

The reviews are what I was talking about.  There are several threads here where other 550 owners who've done the swap, and myself, have discussed the merits of it.  Hopefully some of them will chime in again here, but if they don't the info is out there. 

[Kong]

I've got two 650 cams sitting here and 650 one tach drive and one 650 tach.  I gave the bike I was building to my son, and all the parts too of course, on the condition that he finish building it.  So I never put it in the bike.  When got the first cam (E-Bay) it was bare.  So I went looking for a reasonably priced tach drive and tach.  I found them on E-Bay too, and got both for another $25 plus a couple of bucks to ship them.

Like you I went out and asked a lot of questions first and also spent about two months looking for comments about them before I finally bought the stuff.  Virtually every comment I found about the switch said the same things you are seeing here.  That is to say the comments indicated that the cam was indeed a good switch for power production.  They were in agreement about it coming on at about 6,000 RPM as well.  Like Gordon I too picked up a 16-tooth front sprocket so as to take full advantage of the movement of the power band up; I actually considered a 15-tooth but decided it was likely to be just a little too much.

As for the tach, the one I got is very much different than the stock one and mixing the two would look like unmitigated hell.  I gave some thought to trying a 650 speedometer to go along with it but I don't know if the thing will fit in the 550's gauge mount or not.  I have had bikes that only had a tach and I've had bikes that only had a speedometer.  While I prefer both I can do with either alone.  If I was just able to have one I'd take the tach over the speedometer.  That said, if I was just going to have a tach I'd probably go hunting for a good looking electronic one and just have a plug machined for the tach drive hole.

[Scott S]

 Kong, I see you have a '77 and '78 550. How much bigger (if any) is the 650 tach than the stock gauges? Is the bucket diffrent or just the tach face? Will it fit in the space on the "dash" of the 550?

[Scott S]

 Also, still interested to know if ALL Cb750 tachs will work or just the years that cross reference with the CB650 tach ('80-82)?

[Greggo]

Also, still interested to know if ALL Cb750 tachs will work or just the years that cross reference with the CB650 tach ('80-82)?

An often-asked question for those wishing to fit aftermarket units:

CB750 Speedo  2240:60  Tach 4:1
CB650 Speedo  2240:60  Tach 4:1
CB550 Speedo  2240:60  Tach 20:3
CB500 Speedo  2240:60  Tach 20:3
CB400 Speedo  2240:60  Tach 20:3
CB350 Speedo  2240:60  Tach 20:3

This includes ALL SOHC 750's

[Scott S]

 Thanks Greggo....very helpful.

[1974cb550k]

I had to remove material from my head to clear the camlobes. Other than that a direct bolt on. I bought a tach plug from joker machine and am runnin a gps on mine. Re jetted and put on uni pods. Really kicks in like a turbo at 6000 rpm. Big gain for small $.

[Scott S]

 How much material, where and how'd you do it? Dremel tool?

[cb650]

I have a 550 tack here I swaped out for one of my 650 tacks and it is virtually identical to the 650.   The color and clocking of the face is a little diff but it is a direct bolt in.   Dont know what year the 550 was but all 650 tacks interchange.  Except the nitehawk.

[1974cb550k]

Pencil grinder basically a dremmel. I had the head demoved when i did the new rings just put it on the bench dropped in the cam and spun it. it was hitting in a few areas so i took off the material. i took more than most would but i wanted to lighten the head and make sure it had room for expansion with the heat. I also ported out the heads and the intake runners while i was there. just put the cam in and spin it 360 if it hits on the head mark it with a marker and remove the material. Might be harder to do on the bike as the metal shavings make a mess. Make sure to cover it as best as you can if you do it on the bike. I have heard some guys dont have to remove anything. Maybe you'll get lucky.

[buffalogt750]

I've had a 650 cam in my 1976 550K for about 10,000 miles and I highly recommend the swap. Lots and lots of info in this forum about the swap. Why don't you just use a 650 speedo and tach so they match? I used 1979 650 speedo and tach on my stock instrument bracket. They bolted on with no issues. You will have to use a 650 tach drive. The 550 tach and speedo cables will work. 650 guys will know that the plastic needles in 650 gauges will sometimes warp and rub the glass. I replaced the needles in mine with metal needles from a set of old Suzuki GT750 gauges. Lots of info on taking gauges apart here too. Here's a picture.

[Greggo]

I have heard some guys dont have to remove anything. Maybe you'll get lucky.

I was lucky.  But, we did check by spinning the cam in the head before bolting it in.  The clearances were close, probably a few hundredths of an inch.

[Scott S]

Why don't you just use a 650 speedo and tach so they match? I used 1979 650 speedo and tach on my stock instrument bracket. They bolted on with no issues. You will have to use a 650 tach drive. The 550 tach and speedo cables will work.

 Already have the drive. What about the plug for the wiring harness, lights, etc. Any modifications needed?

[Greggo]

Why don't you just use a 650 speedo and tach so they match? I used 1979 650 speedo and tach on my stock instrument bracket. They bolted on with no issues. You will have to use a 650 tach drive. The 550 tach and speedo cables will work.

 Already have the drive. What about the plug for the wiring harness, lights, etc. Any modifications needed?

Does your 500 have only one light per gauge like mine?  The 650 tach has two light holes, so that would require modification if you want to have full lighting.  Not sure about the speedometer.

[Scott S]

 This will be going into a '78 550K. I'll have to check the dash lights and see how many there are.

[Gordon]

There were no wiring or tach modifications required when I put the 650 tach on my '76 550K.  It was a direct replacement. 

[buffalogt750]

There were no wiring or tach modifications required when I put the 650 tach on my '76 550K.  It was a direct replacement. 

I have the same bike, a 1976 550K.  No mods needed to my wiring or dash to install the 650 tach and speedometer. Use the wiring and lights already on your bike. 650 gauges are the exact same size and have the same number and location of lights as 550 gauges. The only difference in mine was the location of the tripmeter reset knob which is not a problem. If you do change the speedometer and the tach  be sure to get the speedometer from a 1979 model 650. It's the only year 650 that has a 130 mph speedo.