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

[TeamNeal]

Alright guys, just went through 2 carbide 7mm bits. Destroyed them both and hardly did a thing to the cam sprocket. Low speed and lube didnt help except to cause a smoke screen. Im just about to take this s**t to the machine shop. Oh and I got a "simple rat tail file" which didnt work either. Just spent an hour filing and it is still the same size. These sprockets are super hard. Im about to put it back on the 550 cam and use those in the 650 head. Suggestions?

[GSX1000E]

Just a thought here; have you offered to send your sprockets to those that have told you how easy it is? Or those that say that they have done it before?
Are they available from a supplier as adjustable sprockets like other GS models? ($35-50)

[TeamNeal]

Ape racing offers adjustable cam sprockets for 750cc and up but I havent tried contacting them yet. 650e sprockets are 30tooth just like the 550 ones. I got a 650g motor and those sprockets are way bigger. I just cannot seem to find any at the moment. Plus, I already have the stuff, just need to modify it

[GSX1000E]

If no one that has said how easy it is or has done it before themselves offers to do yours, try calling: http://www.z1enterprises.com/ListIte...kets+for+GS550

[Sci85]

All I can say chief is that I in fact DID use a rat tail file to slot my 550 sprockets. and it didn't take me all that long either. Tomorrow I will see if I have any pics. You could also send a PM to Suzuki_Don and ask him what he did. I know he ran the 650 cam.

[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

[Sci85]

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.

[Sci85]

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.