Doin the 550/673 swap, and I have some ?s

[TeamNeal]

It is kind of odd.... My 650 sprockets are not as hard as the 550 ones for some reason. They look stock, but were there some aftermarket offered yesteryear that were super hardened that we all may not know about?
Also, would just installing the 550 cams in the 650 head be a bad idea? They are both sub 20000 mile motors..... Lots of moly lube and fresh oil ithe head prior to startup should help bedding of cams to caps right? Lemmie know what y'all think. Thanks for all the great links and info guys. It's really helping.

 

[tkent02]

It is kind of odd.... My 650 sprockets are not as hard as the 550 ones for some reason. They look stock, but were there some aftermarket offered yesteryear that were super hardened that we all may not know about?
Also, would just installing the 550 cams in the 650 head be a bad idea? They are both sub 20000 mile motors..... Lots of moly lube and fresh oil ithe head prior to startup should help bedding of cams to caps right? Lemmie know what y'all think. Thanks for all the great links and info guys. It's really helping.

It should be fine, they say you get more top end power but less down low and midrange with the 550 cam, but I haven't gotten there yet so don't know how much.

 

[TeamNeal]

Ok. I will do that then. From all my measurements, the cams from both bikes are identical in every way, with the exception of the sprockets. Lobe height, base circle etc. The only reason I wanted to do this sprocket swap is to avoid interference issues between valve and piston and keep the same ratio between crank gear and cams...

As to the powerband, I am more interested in high rpm powah anyways. I have Texas hill country twisties in my backyard. Plus my power to weight ratio will make my bike faster down low and.up higher compared to my 16v 750 gs. my bike is a whole 70lbs lighter already, still on a diet.

 

[Stahlgrau333]

The cam profile is completely different between the 650 and 550 cams.

650 Cams:
Intake - 7.2mm Lift / 252* Duration
Exhaust - 7.0mm Lift / 252* Duration
Intake Open -20* TDC
Exhaust Close +23* TDC
Exhaust Open -49* BDC
Intake Close +52* BDC


550 Cams:
Intake - 7.2mm Lift / 260* Duration
Exhaust - 7.0mm Lift / 260* Duration
Intake Open -26* TDC
Exhaust Close +26* TDC
Exhaust Open -54* BDC
Intake Close +54* BDC

 

[TeamNeal]

So by swaping the sprockets, and keeping the 650 cams, I would be getting low to mid range torque with the longer duration of the 550 sprockets.... interesting.

Have any of you heard or seen these drills?
http://www.artu.com/drillbits.htm

 

[Guest]

Yes, the 650 cam has better low and mid torque. However, on a motor of this size, I doubt it's all that noticeable. Others may have their opinions, but I ran the 550 sprockets and there is more than enough of a power boost over the 550 that I am happy, even down low. However, I degreed my cams changing the timing significantly from stock so that may have a huge impact over the stock setup.

And yes, Yoshimura made a performance cam that included sprockets. But the sprockets were slotted. The sotck sprocket is not unusually hard so maybe you have some kind of aftermarket sprocket. You could also buy a set off ebay. Even with the cam, they are plentiful and cheap.

 

[Stahlgrau333]

So by swaping the sprockets, and keeping the 650 cams, I would be getting low to mid range torque with the longer duration of the 550 sprockets.... interesting.

Not quite.

You MUST use either the 650E or 550 sprockets, in order to maintain the timing between the crank and the cams. If you use the larger 650G sprocket, you will never get the engine timed correctly, and will probably destroy your valves (if you can even get the chain to fit).

The cam lift duration has nothing to do with the sprocket you use, it is a result of the profile (shape) of the cam lobe:

If you do slot the cam sprockets, you'll be able to adjust the timing and overlap between the two. To modify the lift or duration, you will have to get the cam welded and reground, or buy a completely new cam.

 

[TeamNeal]

Great information guys. Really helpful.

I started reading up on cam timing and degreeing on this website http://www.iskycams.com/degreeing.php

I am starting to understand more about what you are telling me( you guys must think im stoopid:|)

This question is to Sci85, do you happen to have pictures of the cams you slotted ? I just want to compare yours to mine.

 

[tkent02]

Great information guys. Really helpful.

I started reading up on cam timing and degreeing on this website http://www.iskycams.com/degreeing.php

I am starting to understand more about what you are telling me( you guys must think im stoopid:|)

This question is to Sci85, do you happen to have pictures of the cams you slotted ? I just want to compare yours to mine.

Nothing stupid about it, it is all very confusing for someone who hasn't worked with it a bit.

 

[Guest]

As tkent02 mentioned, it can be confusing at first. I asked a lot of questions and did a lot of reading too before I understood it so ask away!

Here's one before I slotted the cams and a few after. These are gonna be the best I have.

 

[Guest]

And here's an ebay link for a set of 550 cams with the sprockets for 20 bucks.

http://www.ebay.com/itm/1980-Suzuki-GS550-GS-550-E-Camshafts-Cams-/251116018073?pt=Motorcycles_Parts_Accessories&hash=item3a77ae5999&vxp=mtr

 

[tkent02]

Are all the 550 cams the same for all models and years?

 

[TeamNeal]

Nice pictures, but do you have any showing how much you filed them to make them adjustable? Plus, I already have 550 cams and gears. I wont need to purchase more. I just need to get them to fit my 650 cams.

 

[tkent02]

All you need is the width of one sprocket tooth, if you need more adjustment than that just line up the next tooth.

 

[Stahlgrau333]

Great information guys. Really helpful.

I started reading up on cam timing and degreeing on this website http://www.iskycams.com/degreeing.php

I am starting to understand more about what you are telling me( you guys must think im stoopid:|)

Nothing stupid about it, it is all very confusing for someone who hasn't worked with it a bit.

That site is an excellent reference. Thanks for posting it.

As tkent said, there's nothing stupid about asking questions when you don't know. Hell, I learn a TON just from answering questions. The best way to really learn a subject is to teach it.

All you need is the width of one sprocket tooth, if you need more adjustment than that just line up the next tooth.

Most of the slotted cam sprockets I've seen are slotted across 3 tooth positions. This gives the ability to advance or retard the cam up to a full tooth from 'stock' without having to pull everything apart to re-time.

Here's a good pic of what I mean:

Are all the 550 cams the same for all models and years?

I am almost certain that all 550 models from 77-82 are the same. I'll do a little digging to confirm, though.

 

[TeamNeal]

well well... after quite a bit of fiddling around with these cam sprockets, i was finally able to attach them to the 650 cams. i found a carbide burr deep in my tool box that measured 7.65mm ,just a c*nt hair bigger than the holes in the 650 sprocket bolt holes. Chucked it in my drill press and opened them up. long story short, 550 30t sprockets on the 650 cams. now that that is finally done, i can start to reassemble the motor.
p.s. my phone got stolen which had all my progress pictures on it so as soon as my new one gets in the mail ill get some pictures up on this thread so y`all can see whats what.

 

[tkent02]

well well... after quite a bit of fiddling around with these cam sprockets, i was finally able to attach them to the 650 cams. i found a carbide burr deep in my tool box that measured 7.65mm ,just a c*nt hair bigger than the holes in the 650 sprocket bolt holes. Chucked it in my drill press and opened them up. long story short, 550 30t sprockets on the 650 cams. now that that is finally done, i can start to reassemble the motor.
p.s. my phone got stolen which had all my progress pictures on it so as soon as my new one gets in the mail ill get some pictures up on this thread so y`all can see whats what.

How is this project coming?

 

[TeamNeal]

Well, it kinda stalled when my 750 quit running. I then found some damage that needed attention on the 550 frame. A 93 katana 600 with a bent up frame fell in my lap so I swapped the engine and rear end in the 550 and Im saving the 673 for a stock-ish build. I also need cam chain guides as the ones I have have cracked and pieces are missing.

Plus I recently relocated to NYC and everything is in a storage unit until I find a place to set up shop.
So I guess, on pause for the time being. My computer took a major dump so updating my build thread seemed pointless without all my pictures(no pictures, no proof). Any time I post on here it is with a slow "smart" phone... pita!

Id love to finish it as I hear that engine could potentially be a screamer and would love to experience it first hand. 8v 673 vs. 16v 750! Both of these heads have had port work so each intake runner is the same diameter in the same location as the next. Just a simple clean up of the casting and short side radius of the bowls. All sharp edges softened and cc smoothed and polished. Poston tops have been polished, rings gaped, exhaust portmatched. I do like the blind vs sight differences in the before/after work that has been done(refering to the 750 as I have been able to ride the sucker). Very simple old school hot rod engine stuff that makes an already wonderfully designed engine even better.

Im still needing to open the top cases more to accept the 650 cylinders as I think they have about a couple thousandths to go....

 

[boontonmike]

Neal,

I have a full 550 parts back and a bunch of 650 parts so let me know what you need and I can look around. PM me.