815cc & 907cc Piston/Cam Kits

[eclipsespeed_1986]

I was looking around the web and stumbled onto this.

http://www.gsxrzone.com/enginekits.html

Its a piston kit for the 750s. I was wondering if anyone had any experience with these and the power increase it yields. I have a 600 that i bought for 300$ and swapped in a 750 motor, but now am looking at adding this to the mix. So any thought or opinions are welcome.

Thanks,
Keith

[eclipsespeed_1986]

Anyone??? Ive searched around but havent really came up with any feed back on the kits. Im just trying to find out if its worth the money and what kinda gains ill get. Plus i would like to know what kind of carb mods im gonna need. Just a jet kit, or a new set of carbs?

Thanks,
Keith

[gobigorange189]

i say if your gonna spend that much money, just buy a gixxer

[arsenic]

is it worth the money? I say not at all, you'll end up with a really nice Katana engine, but it's still a Katana engine

[eclipsespeed_1986]

is it worth the money? I say not at all, you'll end up with a really nice Katana engine, but it's still a Katana engine

Correct me if im wrong but aren’t the katana and older oil cooled Gixxer motors pretty much the same thing. Im guessing carbs, pistons, and cams are the main differences in them. So wouldn’t this kit pretty much take care of the differences. I know its a good amount of money and i know could buy something else thats faster for the amount ive invested so far but i like my bike. Ive spent a lot of time and effort on it already so the extra cost for a rebuild isnt that bad to me.

So i guess like i said does anyone know what type of power increase im looking at and what i need to do with the carbs to make this work. And finally any pro/cons between the two kits? I want my engine to stay reliable so if either of these kits are gonna change that id pass them up. But if not im all for it.

[GregS]

You could buy a GSXR engine for half that money or even a Bandit 1200 or RF900.

Don't forget that if you make that "upgrade" to a Kat engine, you'll need to totally rejet the carbs to get it to run properly. After that you'll have a fast Katana that won't handle as well or accelerate as well as a GSXR.

The Katana is a good sport touring bike. The power band is wide and the motor tuned for torque. If your Kat is in need of a top end overhaul then a piston kit would give you improved power while keeping the characteristics of the engine. A decent piston kit sells for 1/3 to 1/2 of the kit you found.

Just my opinion. You certainly are welcome to yours.

[Dago]

The main difference after that kit would be the carbs. The Katana's carbs are only 36 mm. However, properly jetted with that kit I'd be willing to bet your engine would be making more power than any stock 88-90 GSX-R 750 . . . maybe even any stock Bandit 1200 (but your overall durability would suck compared to the Bandit 1200 I'm sorry to say). Both platforms would also weigh about the same. Everyone complains the Katana is so heavy, in reality it's just the difference in weight of a fat guy and an average guy when comparing it to even brand new GSX-Rs.

Of course. the bike feels a lot heavier than that because of the way it is balanced, but the higher demand performance physics people tend to notice don't change. The weight being proportioned higher on the katana will even require you to act less like a monkey in high-lean angle turns to gain fast cornering speeds . . . but I don't feel like going into that or the fact that you'll have to show more finesse at low speeds. My main concern after all that power would be the transmission and clutch and how they probably won't hold up to any realll application. In the end, I'd say if you're not looking at going all out and forging and boosting the motor, don't bother getting the awesome pistons, cams, and springs for it when you can swap in a Bandit motor that'll make 130 wheel horsepower with stock $350 GSX-R cams and a $140 jet kit. I know it would seem like the complete suck to swap in the new motor after just putting in the 750 motor, but that's what I'd say to do as opposed to that kit.

If you just want to keep the 750 motor, just throw on an Ivan's jet kit, timing advancer, iridium spark plugs, and be happy would be my best recommendation. That estimated 10 or so horsepower wouldn't throw all the other parts so far out of operating spec that they'd be a durability risk in my honest opinion.

[loudnlow7484]

The main difference after that kit would be the carbs. The Katana's carbs are only 36 mm. However, properly jetted with that kit I'd be willing to bet your engine would be making more power than any stock 88-90 GSX-R 750 . . . maybe even any stock Bandit 1200 (but your overall durability would suck compared to the Bandit 1200 I'm sorry to say). Both platforms would also weigh about the same. Everyone complains the Katana is so heavy, in reality it's just the difference in weight of a fat guy and an average guy when comparing it to even brand new GSX-Rs.

Of course. the bike feels a lot heavier than that because of the way it is balanced, but the higher demand performance physics people tend to notice don't change. The weight being proportioned higher on the katana will even require you to act less like a monkey in high-lean angle turns to gain fast cornering speeds . . . but I don't feel like going into that or the fact that you'll have to show more finesse at low speeds. My main concern after all that power would be the transmission and clutch and how they probably won't hold up to any realll application. In the end, I'd say if you're not looking at going all out and forging and boosting the motor, don't bother getting the awesome pistons, cams, and springs for it when you can swap in a Bandit motor that'll make 130 wheel horsepower with stock $350 GSX-R cams and a $140 jet kit. I know it would seem like the complete suck to swap in the new motor after just putting in the 750 motor, but that's what I'd say to do as opposed to that kit.

If you just want to keep the 750 motor, just throw on an Ivan's jet kit, timing advancer, iridium spark plugs, and be happy would be my best recommendation. That estimated 10 or so horsepower wouldn't throw all the other parts so far out of operating spec that they'd be a durability risk in my honest opinion.

I don't know where you get your information.....

The pre98 (I'm just guessing it's a pre98) 750 carbs are 36mm, yes, but so are the 88-89 GSXR750 (same engine, sans cams). The 38mm carbs didn't come until after they went back to the long stroke engines. If you want you can swap the cams, and you'll have a GSXR engine. As for the bottom end/transmission/clutch holding up..... if you make absurd power, you'll need to upgrade the clutch. I don't know the absolute limits on what the bottom end will hold reliably, but I know it's upwards of 130rwhp. I would actually guess more like 150hp, seeing as the 85-87 GSXR750 bottom end (same as the kat 600 bottom end, fyi) will hold 130hp itself.

Ok, so to the original poster..... If you have a healthy pre98 750, then you're probably sitting on maybe 85rwhp. After swapping in GSXR cams (~$350), and doing, say, a 3mm overbore with 12:1 compression (as per Wiseco's kit, ~$575 parts, $labor depends on you, but boring would run you about $150 if you do all assembly and disassembly), a full 4-1 exhaust (~$400), and well set up carburetors ($ depends on your talent with carbs)....... I don't see any reason why you couldn't see 115 or 120hp. That might be a little generous, but I'm trying to be optimistic here.

The down side is reliability. Compression puts a lot of stress on things, unfortunately. Also, 3mm is the max overbore, so if your bores get f**ked up somehow, then you'll need new cylinders.

If you want to find out more about highly modified motors of this type, you could always check out some gsxr forums.

[GregS]

It looks like you are all missing the difference between high HP numbers and usable HP numbers. Are you drag racing this bike or riding it on the street? All the HP in the world is useless if you can't cruise down the highway on your way to that twisty road, or you can't take off smoothly from a stop light without slipping the clutch so much that you burn up your discs every couple months.

[deanocinq]

buy the bigger 1127 or bandit engine and with the money thats left over tune that engine and it will be better than over stressing a smaller engine

[arsenic]

Correct me if im wrong but aren’t the katana and older oil cooled Gixxer motors pretty much the same thing. .

yes, the tuna is based on the 85 GSXR 750 engine, and guess what, 1985 was 23 years ago A lot has changed in 23 years, like everything

[loudnlow7484]

yes, the tuna is based on the 85 GSXR 750 engine, and guess what, 1985 was 23 years ago A lot has changed in 23 years, like everything

Goddamit arsenic...... he said he has a 750 motor..... so the design is only 20 years old!

[eclipsespeed_1986]

Well i guess that about takes care of it... The issue was never really money but if reliablity goes down the shi##er well then you all are right in saying its not worth it because thats exactly what i have the bike for is to rip down the twisties everyday and long trips with my friends which is also one reason i wouldnt want the Gixxer or RR or whatever else. 5-8 hours on one of thoes would kill...

So i guess ill just stick with the 750 and do the little i can for now then look into the 1127 later.

Also is the carb swap to post 750s worth the change just for an ivans jet kit or is a factory pro fine?

[arsenic]

Factory Pro is great. I'd recommend that for 98+ too

[md86]

Nah , you can make do with the FP just fine .