differance between 82 xj 750 and crotch rockets

hey my buddy with a 550 race bike eats my xj 750 for breakfast and i dont understand why! i understand mine is shaft driven as where he is chain driven but besides that both engines seem to be built the same his weighs 380 and mine has been stripped to weigh 400 pounds his is stock mine has 4 to 1 exhaust also is there anything i could do to keep up with the bugger besides buy a new bike i love this thing and dont want a crotch rocket i mean his hets 280 kmh and has 200 cc less then me what will give me more hp :roll:

 

"race bike" pretty much says it all what exactly is his bike? Also from your sig your on a maxim which is not really geared for racing, not as aerodynamic, and overall just not a race bike.

 

My 750 cleans up on some 600cc and smaller sport bikes. What is his 550? And how in tune do you keep your bike? I now that if I don't keep mine tuned it will lose power and not really notice until I tune it and it begins to scare me again.

 

That right there makes a big difference, stoplight to stoplight. It simply takes a bit more to get all that mechanism spinning.

I dunno quite how you got a Yamaha shaftie down to 400lbs, but if you say so... if true, you would think you should pretty much stomp him. What mods have you done to your bike besides the 4-1?

Exactly what 550 is he chewing you up with?

 

Biggest difference is the sport bikes are more aerodynamic and of coarse 600cc crotch rockets have roughly 30-50 more hp. Your working with a bike that was designed over 30 years ago. Engines have came a long ways. There is not much you can do to it. You can spend a lot of money on parts if you can find them. They really do not make any performance parts for these bikes. Best of just to leave it alone if you want more speed your gonna need a newer bike. I must say if you got your bike down to 400 lbs there must not be much left of it thats a lot of weight to get rid of.

 

The 550 has less recip and should wind up faster to get into its HP band. Once he's in the band and shifts and keeps it close you will be toast. His chain drive does not burn up as much HP either.
Is your bike running right?
He should get the jump on you but if your tuned and use the torque you should be able to keep up and maybe catch on the top end.
We were just watching a video that someone here put out with a 750 & 1100 and the 750 was pulling away from the 1100 untill the 1100 got going

 

no there is not much left as you say i skinned it for the race as far as i can tell my bike is running great his is a katana 550 from roughly the same year ihave done nothing but 4 to 1 exhaust and lightened it up is there really nothing i can do cams or easy engine swap n-ething? this thing is comfortable and fun to ride just a little lacky in the power section i would say it feels like driving a fast car so i guess i got power issues cause it doesnt scare me my yz100 has more acceleration then this

 

yes i saw that video it seems just a tad faster then mine

 

The Katana (AKA can-o-tuna) is not known as a race bike by any means. Now the GSXR... The Katana is lighter; your buddy may be lighter than you too. Combined weight might be the difference; yes, the chain-drive will be quicker off the line but the 750s were very potent 1/4 milers in their day and unless you are talking about top speed the Katana's fairing will not make much difference. How is he "eating your 750 for breakfast"? Have you checked your cylinders' compression?

 

Get rid of the stock carbs and buy some keihin CRs, get a performance ignition like the Dyna 2000. Look into better cams too. I swapped stock 750 cams for stock 900 cams on my CB and had a notable increase in HP. I'm not sure what cams will swap in the xj line.

 

is the maxim x terribly different than his bike? I believe I've read that mine puts down around 93hp with a 1/4 mile around the low 11's.

http://www.bikez.com/motorcycles/yamaha ... x_1985.php

I've raced two bikes both from about a 10mph roll to around 80.

One was a newer suzuki 500cc sport bike. The other was a 2002 600cc I dont remember the make just that it was a little beat up. I pulled both of them ESPECIALLY the 500cc. Both guys were amazed and wanted to know what I was riding. Maybe the two guys I raced just suck?? both told me they were embarrassed being beat so bad by an "old bike". That was with only chacal's k&n oil filter mod.

 

How/when you shift makes a hell of a difference too, especially if you are used to other type of bikes. I myself are used to cruisers and want to shift at about 4-5k instead of letting each gear ride out. My xj550 doesn't really "grab" until 7k and above.
Oh well, maybe that's just for absolute XJ beginners like me.

 

i ride out the gears untill close to redline and yea i ride it like i stole it when racing one of my other buddies said his katana is off the hook fast so i guess hes just lcky i will try what keven leven said thanks thats what i was looking for ill try the new carbs and ignition and look into swapping cams maybe another forum entry is in order

 

well it looks and sounds like a race bike n-eways sorry for the confusion

 

his katana is 1986 0r 7 by the way

 

So if the year is right it should have 68 horsepower which is pushing up on your 750. I would guess it is geared for acceleration not top end. My old room mate had a 600 Ninja early 90's era that my 750 cleaned up on even if we switched bikes (me 180 pounds, him 270 pounds). I would guess his bike runs good but you should try the 1/4 mile run with him. You only need three gears over rev a bit in third. These bikes make power well past redline it is just that some parts don't sustain it with out issue.

 

Yeah, I've cooked a few 500's on my 750 max and a few 600's as well.

But there are deff some that have beaten me as well no doubt

 

How do you know his hits 280 kph...? Did he tell you that? I don't believe it! As for beating him, I think you may have to accept that the tpe of bike you have was neve designed for that....don't ge rid of it as it will reward you in othe ways. Just get a sports bike as well!

 

Yes, it is. The "X" is a completely different animal, next-generation and in a completely different league.

The "conventional" aircooled XJs, be they 550, 650, 750, 900 or even 1100 have 2 valves per cylinder.

The "X" series motor has FIVE valves per cylinder. Not four, like a lot of hi-performance engines these days, but five. And liquid cooling, of course. The motor in the Maxim X is the same motor that was used in the FZ series of sportbikes. It's very similar to Formula One race car motors of the same era, but with fewer cylinders. Yamaha was "conspiring" with one of the F1 engine constructors at the time; Cosworth IIRC.

 

Made me laugh. thanks.

 

http://www.motorcycledb.com/Suzuki_GSX_ ... 1986/28136

If these specs are correct, you should be able to smoke him on your 750 max. You have him beat in torque and ponies. weight and the condition your bike is in are obviously other factors, aside from the driver. swap bikes with him and see how it goes.

 

Thanks big fitz!