suzuki gs 650 camshafts upgrades...?

[boris.h]

Hello!
building a 550 / 650 motor... I'm going to put on it 550 camshafts with sprockets... Maybe there is a "plug and play" upgrade available, as 750 cam shafts, kawazaki, etc....? Any advice here?

 

[GregT]

Hello!
building a 550 / 650 motor... I'm going to put on it 550 camshafts with sprockets... Maybe there is a "plug and play" upgrade available, as 750 cam shafts, kawazaki, etc....? Any advice here?

It's been discussed before. check the search function. Looks like the late chain drive 650 cams or the rare 650 katana have the best stock cams. Also looks like the cams fitted varied according to the matket the bike went to...

 

[Nessism]

There isn't a whole lot of difference between the 550 and 650 cams. I doubt anyone would notice a difference when running the bike.

There are aftermarket cams on the other hand that would add some poop. Regrinds, where you send them your cams and they weld and regrind a new profile. Not cheap, particularly if you go aggressive and need new springs.

 

[Chuck78]

550 vs 650 cams are sorta like gs750 vs gs1000 8v cams - 4 degrees more duration on 750 cams, a slight bit more lift on the 850/1000 cams. The 550 is longer duration for more high end hp and gnarly exhaust sound, 650 is higher lift but lower duration, traps more of the compression in and gives more mid range street power. The 550 cams are like the 750 cams, perform better in a race and will make more high end overall peak hp, but you really have to wind out the engines to feel the advantage of the 550 or 750 cams.

The 650 pistons are higher compression and the head is more efficient closed chamber and raised runner design, so that engine with either cam is going to be superior to the tried and true hemi head 8v 550.

Reason I read this far was to say that megacycle grinds aftermarket cam profiles for the 550/650. My local shop can get a set of gs750/850/1000 cams and the required valve springs for about $500. Their more mild hot street cam has a good bit more lift than stock and can run the stock valve springs, so you wouldn't have to tear down the head. A valve grind job or at least a lapping job would be a great idea though, will really seal things up better. A professional valve job on a serdi machine with their radiused cut transitions to the seat, and back cutting the valves will really help out with performance .

Actually, the 650 head only uses a 2 angle valve job, which I thought was odd, but Suzuki must have been onto something with the engineering... raised intake ports for more direct airflow

 

[Chuck78]

http://www.megacyclecams.com
Page 52 or 53 of their catalog

Call and talk to their tech support girl, she is a performance camshaft wizard, and will have excellent suggestions for you based on your setup and riding or racing preferences.

Degree in your cam with adjustable slotted cam sprockets or similar cam grinds with different lobe center specs can really change how a cam behaves. I accidentally had mine drastically advanced last summer & I was pulling serious acceleration wheelies and semi-accidentally induced an unexpected 200' uphill redlined burnout at AMA vintage motorcycle days this past summer. It was also substantially harder to kuckstart, much more compression trapoed in the cylinders.
Pulled the cams for some engine work and put back stock and the bike had more top end far beyond recommended redline, but the wheelies weren't much to speak of anymore. Bigger lift cams and higher compression pistons, or slightly milled heads (slight compression bump and I believe slight side effect of advancing cams by shortening the taught front side of the cam chain that pulls the cams) will both have this affect. Higher duration will bleed off more compression but allow the engine to breathe better at high rpm's.

More duration takes away from the crisp torque low end mids and idle.
More lift makes the cams and springs wear faster, and makes the valve opening speed much higher, so the guides will wear faster and maybe even the seats and valves. Duration gives you a faster bike with reliability but less torque down low in the street range without attracting the attention of every police officer within 1 mile from revving to redline to get insane hp.

More lift and less duration, much more fun street engine, wears faster. Consider that when cam shopping. Don't go too crazy on lift. Somewhere between .340 and .395 lift is what I'm trying to decide, while staying around 280 degrees total duration for the same exhaust sound. Slotted cam sprockets so I can play with where the power comes and goes, and how the bike sounds.

The 280 duration gs750 cams sound AWESOME so I am trying to keep that figure while deciding how much lift I want to experiment with. Over .395" is too much for street. Much bigger and you have to run the very pain in the *** shim under bucket setup that is a real chore to make valve adjustments.

 

[Chuck78]

*MUST USE YOUR 550 CAM SPROCKETS WITH A 550 CRANKSHAFT ENGINE... toss the 650 sprockets to not get confused.

 

[Chuck78]

From an old post:

On your bike, the cams are not degreed to a specific setting, they are degreed within a range. On the early GS's the range can be about 100-115+ degrees. This is the main reason two identical bikes will perform differently right out the door. If you have the cams degreed around 110, this will result in more top end/horsepower, but the low/midrange torque will suffer. If you degree the cams around 100-102 you will have more low end torque. I had both my intake and exhaust cams timed at 106 degrees for what I consider the perfect compromise between top end/horsepower and lower/midrange torque.
Higher degreed cams (112-115+) will result in slower warm ups, a hotter running engine, the carburetion is difficult to set correctly and a narrower powerband.
With your cams timed at 104-106 degrees, you'll have a broader powerband, better throttle response and the best compromise between peak and low rpm power, gas mileage will be at it's best too.

Read:
http://www.webcamshafts.com/pages/degreeing.html

 

[boris.h]

thanks everyone for answers.
My first question was if there was a "tip" like using particular "standard" camshafts (kawa bikes, suz bikes, any 4 cylinder /2V). I can look for any better camshaft, but it takes a long time and maybe someone has already done it on a 650 end / 550 bottom..
Ok, for the moment I 'll use my 550 camshafts with sprockets, and work on the "best timing", maybe machining the sprockets to enlarge mounting holes (to permit adjusting sprocket / camshaft) and doing the timing with dial indicators....
About the confirugation, I'll use the standard valves (sufficient diameter for a 650), machining the valves seats to get a minimal surface of valve / head at intake, but just displacing the valve seat on exhaust... the surface has to be large to help temperature of the valve decreasing...
The head is now totally machined (in intake and exhaust ports), lot of aluminium removed, exhaust ports gone to 33mm of diameter, and intake ports --> 32mm diameter to put bs32 carbs with boots....