XJ550 cam swap/aftermarket options

I'm looking for some serious/expert advice on this.


Is anyone using aftermarket cams on a XJ550? Also, has anyone heard of swaping cams between the 600 FJ/FZ or RADIAN onto the 550?

Why i'm asking?

Well, I was checking out the megacyclecams catalog(http://www.megacyclecams.com/catalog/catalog.pdf) and I was looking at cams for another bike. I noticed something on page 64.... They group the following bikes together:

YAMAHA 550 SECA, 600 FJ/FZ (1981—1992) and RADIAN (1986—1990).

The cams do indeed look the same when looking at pictures online. Here are the stock specs on each:

Stock XJ550 cams: .308" 233° 279" 228°
Stock 600FJ cams: .326" 244° 307" 244°

.354" 254° for both intake and exhaust seems to be the highest they want you to run on stock pistons.

Has anyone tried bolting a set of 600FJ cams into a 550 head to see what it does? Other than bend the valves ofcourse 8O

 

Interesting; whose specs were those?

According to the factory book:

The XJ550R (Seca) intake .307" and exhaust .280" no timing numbers given;
The XJ550 Maxim; intake .268" exhaust .268" again no timing numbers.

That's one of the few differences between the 550s, Maxim and Seca.

Here's the thing about swapping cams on these motors in general: Unless it's a brand new motor, you're either building a race engine or it's a reliability crapshoot. The cams run directly in the heads, no bearings or bushings, right in the head casting. It doesn't take very many 10,000rpm miles before the cams and head become a "matched set." Disturb that match at your own risk.

Which (along with an utterly complete lack of aftermarket hi-po parts) is why most guys that raced them simply dropped in a whole 600 mill. They tend to last longer.

If you have a Maxim motor (5K5) you might want to look for a Seca (4U8) head w/cams. Keep in mind the carbs had different needles and pilot air jets.

If they don't respond, reach out to forum members Thrasher and Dinoracer. Both have club-raced 550s; and Thrasher recently put his back on the street. With an entire FZ600 motor in it, as raced.

 

You bring up some very good points.

The specs were listed in the MegaCycleCams catalog. So atleast they were somewhat close.. almost..

The Seca and Maxim heads are the same, other then the cams, correct? So the plan would be to buy a matched set if I go with Seca parts?


I'm never one for messing up perfectly good motors, but 550 parts seem to go for pretty cheap. I would be willing to track down a head just for trying this out.... but now it looks like you may have opened another can of worms for me..... I wonder if the stock oil cooler off the FZ600 would fit on my 550.. in fact I wonder how close that whole motor is to the 550 since you bring up swaps...

 

Early FZ600 motors should be the same. They had slightly smaller carbs than the FJ600's due to lack of space for an airbox. Also yes, the oil cooler will bolt directly on.

 

The 600 exhaust cams don't have the tach drive gear machined in them. So if you go with a 600 cam you will need to go with an electric tach, too. You can also just run a pair of intake cams, but again you lose the tach gear.
The FJ600 had the hottest cams, but they are also hardest to find.


Ken

 

Here are the specs to my Yoshimura cams.

 

@pjb03:


What is your idle like with the yoshi cams? Also, did you need to mod the pistons to make them clear?

 

It idles nice. Not a whole lot of lope to it. Motor has an aftermrket big bore kit in it. The pistons are different. I seem to remember they have more dome to them than the stock pistons.