XJ550 vs XJ600 HP figures

XJ550 : 50.00 HP (36.5 kW)) @ 9000 RPM 528cc

XJ600 : 72.00 HP (52.6 kW) at 10000 RPM 599cc

The 600 has bigger carbs and supposedly bigger valves/cam but I wouldn't have thought the extra 71cc and that would give you a 40%+ increase over the 550

 

What source did those figures come from? They sure look funky.
My 550 Seca is not so far behind my 750 Seca in power, plus it's 80 lb. lighter.
Bill

 

Intersting. A lot of other factor contribute to hp besides displacement. Still, that seems like a big jump. I'd like to know what's different between the 2, comprssion, valves, etc.

 

The road tests here in the States put the 550 Seca at 52-55hp; still that is a big jump.

Improving combustion chamber and piston/valve technology might account for some of the increase as well; compression ratio and bore/stroke numbers would be interesting...

 

The current 600's are at 110 - 120 HP. It would be interesting to see a graph starting in 1970 that averaged HP / CC , you would see quite a bump in the '90's.

The first Harley 1200 CC made 7 HP !!

 

yeah, I remember back in the 80's it was a big deal when a LITERBIKE produced 100hp.

 

My CBR F4 makes an HONEST 100 rwhp... the F4 will vary between 92-95hp stock, up to 105hp in race trim.

The current 600s are making 110 rwhp - 120 in race trim.

My old 600 was 80-90 rwhp (1995 zx600r C model)

I am REALLY surprised the XJ600 made it to the 70s. That is really good.

I had a graph of bikes power to weight ratios... and it was pretty startling...

 

I'm still comparing with the earlier XJ600 2 valve motor


XJ550 Bore x stroke: 57.0 x 51.8 mm (2.2 x 2.0 inches)
Compression: 9.5:1

XJ600 Bore x stroke: 58.5 x 55.7 mm (2.3 x 2.2 inches)
Compression: 10.0:1

The 600 up till 1987 has the same HP spec as the 550, then in 1987 it takes a jump up

Here is where I got them from
http://www.bikez.com/motorcycles/yamaha_xj_600_1987.php

 

I wonder if they suddenly changed how the numbers are arrived at?

 

Hmmm.... Haynes manual gives the valve sizes as 31 and 27mm.

I recently bought one of these - see my siggy - the carbs are 32mm Mikunis, there is no YICS and the xj600 owners guide doesn't actually quote a power output but while I was looking around several ads quoted 73 bhp and not the lower output of the later diversion/secaII model.( The 600 engine is very close to the 550, wheras the diversion engine is quite different)

I did read that the XJ600 was the first of that capacity, closely followed but the other manufacturers so pehaps Yamaha had it in a fairly high state of tune - for 20 years ago.

My old girl is having a bit of a service for her MOT test (Annual statutory inspection) but I have noticed a definate surge in power over 7000 rpm.

 

XJ600 = 70hp?? My Ass.
'86 FZ 600 has a claimed! 58 hp (by Yama.. who traditionally exaggerates ALL HP claims) and the fz is alegedly a quicker bike than the xj variant

 

I found this 1985 test, from

PHP:

http://motorbike-search-engine.co.uk/classic_bikes/KAWASAKI-GPZ600R-VS-YAMAHA-XJ600.php

 

550 are 26mm and 30mm and they run a 28mm carb

So I now I need to find myself a 600 head to go on my 550 bottom end

Anyone got a map of the ignition curves?

 

Then there's worldsfastestxj550 , who doesn't come around here much.

http://www.xjbikes.com/Forums/viewtopic/t=7135.html

I think he has the highest claimed top speed here at 148 MPH

http://www.xjbikes.com/Forums/viewtopic/t=14306.html