1982 gs750s Katana Help!!!

[DaveRC]

Hello, I have owned my gs katana for about 6 years now and it has been an awesome bike but last winter I decieded it was time to improve it in any way I can. The mods I have done are listed below:

1982 GS750S Katana
1999 GSX-R SRAD Rear end monoshock convertion
1992 GSX-R front end Lindman built front forks
Honda CBR footpegs
SuperTrap 4-1 chrome header
Busa chrome rear caliper
Thurst sprocket kit 520 convertion 16/50
Air fliter pods

I was wondering if anyone can help me by telling what parts I can put on to upgrage the performance of the engine. I really don't know what can be done to boost HP. I know carbs and cams would give me boost but I don't know what years and models would be compatilbe and what it best for the amount of cash spent. This is the first bike I have ever modified so I am new to all this, If anyone can help me out that would be much appreciated.

thanks Dave

 

[johnrregan]

more power

more power

ok, several ways , first, big bore kit and lumpier cams on your motor can give it more poke,
though the best, an easiest way to get more from your kat, is to remove the 750 motor and replace it with either, a gsx1100 kat motor, looks the same, but goes better, and then you will realise why its the 1100 that everyone wants. and its an easy swap.
or, bin the 750 lump and fit an efe 1100 motor, very similar swap to the first, as the mountings for the motor are the same on the efe motor as the 1100, but the efe has even more grunt than the last one, though you lose the stock motor look,
or, as you have already modified it, so arent that concerned bout it looking stock, bin the 750 lump and get a gsxr1100 motor in there, this is one of the real fave mods, for no other reason than the gsxr1100 motor is an absolute animal, recon to get about twice the bhp of your 750 lump!!!!!

and finally, hang on tight its going to be an exciting ride!

 

[DaveRC]

Thank-you for the info on doing an engine swap. I don't think I will swap the engine unless I find one for cheap or blow the 750 I have. Do you by any chance know where I can buy cams or a big bore kit for my engine? Are there any web-sites that I can look at? Also do you think that putting mid 80's cv 36mm GSX-R carbs would give me a boost and if so is it a big deal to jet the carbs? People say that putting air filter pods don't work well with the gs carbs, do they mean it just won't run smooth or no power or what? Sorry if these are dumb question but I am new to bike mods.

thanks for the help
Dave

 

[johnrregan]

motor

motor

well thats the problem you see dave, and im quoting uk prices here, but i would think that the comparison with us prices is similar, for a big bore kit to take the bike out to , say, 820cc, plus boring the pots, plus gaskets etc, you would have to spend, about ?500, and probably another ?350 ish for a set of cams, giving a total of around ?850 ish for probably getting in the region of 100bhp, plenty of power you have to admit, however a stock katana 1100 motor can be had for in the region of ?200-?300 and that gives you 111 bhp, on a standard lump, also leaves yous stock 750 motor as a spare in case the 11 goes wrong. its actually cheaper to swap the motor for the 11 , and it gets you more power.

 

[DaveRC]

Thanks for the help John, I see now that is is not cost efective to soup-up a 750 engine. I will look for a gs1100 efe engine very soon. I have a GSX-R 600 engine that I was going to put in but I don't like the look of it, under the plastic it's fine but naked it looks like shit. I love the look of the gs engine, very stylish. If the 1100 efe puts out 111bhp I wonder what bhp the katana 1100 puts out? I wonder if any gs750 engine parts are interchangble with gs1100 parts? I see alot of posts about dialing in your cams with sloted cam gears so I picked up a set on ebay for $35, they say you can get 5-10 bhp by doing this. Is that true?

 

[marcovandevelde]

By dialling in cams you can spoil as much as you win. Basically by dailling in cams you shift the power up and down the revrange. Getting lumpier cams (more lift) wll gain you some power, as will enlarging the valves. You need to see what effects your mods have ideally by putting it on a dyno everytime you change it. With the 750 engine it will only gain little bits of power this way really.

In my experience it is best to set the cams as close to stock values as you can, by using a degreeing wheel and a piston stop. It's an art in itself, look at the search page for explanations.

I fully agree the EFE 1150 or kat 1100 (to keep it insuspicous) motors are the best upgrade you can do. If you insist on keeping your 750 motor, you can put a DIY turbo on it. This mod however needs you to be focussed and committed to make it succeed. It's not difficult but takes some skill, money and fiddling. But no more money than cams and flowjob would take.

If interested in the turbo, look at my webpage http://home.wanadoo.nl/marcovandevelde/turbo GSX.htm

Greetz, Marco.

 

[mark m]

If the 1100 efe puts out 111bhp I wonder what bhp the katana 1100 puts out? I wonder if any gs750 engine parts are interchangble with gs1100 parts? I see alot of posts about dialing in your cams with sloted cam gears so I picked up a set on ebay for $35, they say you can get 5-10 bhp by doing this. Is that true?

The 1100 puts out somewhat under 100 rwhp in stock form. The Kat about the same. My 82 1100E with 4-1 pipe and modified airbox made 102 rwhp and 69 ft-lb on a local dyno. This was as I bought it. I have since added pods, re-jetted it and degreed the cams (set to the stock 110/109 lobe centers) and it is noticeably stronger than before, but it has not been back to a dyno.

As Marco noted, when you degree the cams you are really just shifting the rpm that the torque peak occurs at. You can tune it up or down the rpm range to suit the riding you do. One thing he didn't mention is that the cam timing can be way off from the factory and by accurately setting the timing, you gain free power. This is what I got. My intake cam was way off (about 5-6 crank degrees) and it is now accurately set to the stock timing. This is where I figure most of the extra power came from, the cam was at such a huge lobe center that the engine never really got to take off. I would expect I picked up a solid 4-5 hp with the pods and cam timing, but that is strictly a seat of the pants guess. Next year I plan to fabricate a new megaphone tailpipe and then dyno it after that is completed and the bike re-jetted to suit. Hopefully, I will break 110 rwhp, but I won't know for sure until then.


Mark

 

[melray]

Kat upgrade

Kat upgrade

This may be obvious to you, but just for info's sake:
here in US 'EFE's are called 1150s. They are still to be found, but in shorter supply than 1100s. I have found (stock) 1100s to generally be smoother engines than 1150s. This is only my limited experience, however I notice that Suzuki put weights in the pegs and bar ends on my 1150s that my 1100s didn't have. I think 1150s are vibrators, and not the girl pleasing vibrators that my 650 Triumph is. More like dentist drill vibrators.

Also, I am not a fan of big cams. To me the greatest beauty of the big GSs is the huge fat torque available from bottom to top. These are the 440 Mopars of motorcycles. If I wanted a GSXR power curve, I'd go get a gixxer.

As you clearly are not afraid to modify, you might want to try an 1100 engine unit and the usual mild mods, and if that doesn't do it for you, look for an 1150 head, which will give more power. 1100s turn up as complete motorcycles all the time for low bucks.

good luck- I envy your starting point!

 

[DaveRC]

Wow Marco your turbo gs engine is bloody crazy, I can only imagine what it would be like to ride your bike. I don't know if I would want to in fear for my life, but i guess its like they say as long as you control the power. I don't think I would go as far as fitting a turbo to my bike as of yet, maybe in the future when I have 1100 or 1150 engine and more knowledge about engine performance. I am a beginner to bike building and the gs750 I have is the first streetbike I have ever owned, i bought it a the age of 17 not knowing a thing about bikes. Over the years I have put a few paint jobs on it but nothing special utill last year when I decided to modify it with newer gsxr parts. I have learned alot about gs katnana's and bike's in general and love the fact that I am riding a custom bike I built myself not like all my friends with there stock gsxr's. They used to mock me because of my gs but not anymore, now all I need it some horsepower to go with it's looks. I live in Canada so I don't know if the gs 1100 or 1150's are as common here as they are in the states but I will allways be looking. Once I get an 1100 engine I would like to get the HP to somewhere around 130 bhp, would this be possible with cams, carbs, and a big-bore kit? But that is all in the future, for now I will concitrate on dialing in my cams to stock specs on my 750. I am kinda scared to take the head off cux i've never done any technical engine work like this before. Oh well everyone must start somewhere, I wonder if I can order a degreeing wheel/piston stop kit online somewhere? thanks guy's for all your input and help. I have never used fourms before, I should have been talking to you guys years ago. One thing i can't figure-out is how to insert a picture into a post, I would like to post pics of my bike.

Dave

 

[mark m]

I live in Canada so I don't know if the gs 1100 or 1150's are as common here as they are in the states but I will allways be looking.

Dave,

The situation is about the same here as the US. 1100's are around pretty regularly, 1150's less so.

Once I get an 1100 engine I would like to get the HP to somewhere around 130 bhp, would this be possible with cams, carbs, and a big-bore kit?

Rosco15 (search on his posts here and you will find the info and his website) is running a drag bike and has dyno'd it in several states of tune. With flatslide carbs and pipe he got 113rwhp. With 1166 kit, stock 1100 head, flatslides and stock cams he got 128rwhp. I know he is trying hotter cams now and is somewhat faster again. So, yes 130rwhp is very reasonable with an 1166 kit, 36mm flatslides and G2 or G3 cams. If that's not enough, an 1150 head is a straight bolt on and has better ports and bigger valves for more power yet, while still keeping the monster torque that the big GS's are known for.

Just for interest, the big bore kit is the most bang for the buck, then carbs, then cams.

I am kinda scared to take the head off cux i've never done any technical engine work like this before.

You don't need to pull the head to degree your cams. Just the valve cover comes off and the cams come out for new sprockets to be installed. Then you set the timing using a dial indicator, etc. Do some searching on this site, there are several threads on degreeing cams. There is a printable degree wheel on this site somewhere that I used for mine if you don't want to spend a bunch of money on a one time use tool. Also look at:

http://medlem.spray.se/biker661/index.html

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

For more info.


Mark

 

[budmerrill]

more power

more power

there is no replacement for displacement...

 

[Guest]

Dave,

where in Canada do you live. Maybe you can use my 1398 formally gs1100 engine. Or one of my other two 1100's

I agree.....forget putting good money into the 750. the katana 1100's are the same hp as 1100e motors just slight changes in generator, piston rods and left crank end. hp is identical. port polish, cams, carbs, pods, header, big bore kit and you are in the 130 rwph. neighbourhood.

I had a 7/11 kat and am getting another rolling 750 kat chassis to put another 1100 in it.
all you have to do is modify the lower mounts by 1" or so and you are good to go.

good luck with the mods..sounds like you have a nice ride already.

 

[marcovandevelde]

Hi Dave,
Thnx for the kind words on the turbo. In fact one of the reasons I built it was to shut up those Gixxer thou and R1 guys. And it does (well in a straight line, anyway). And now one of my new buddies has a 315hp GSXR1100turbo. Bugger. But there will always be someone faster than you I guess.

I understand why you don't want to go turbo (yet), if you're at the bottom of the ''engine knowledge'' ladder then you shouldn't attempt anything like it. I suggest you get a good workshop book on the 750 and/ or 1100. This will take you into the (relatively simple) mechanics of your engine.

Getting one of the engines of katman would be a good idea. They're almost ready to rock-and-roll. The 1398 will have lots of torque and power, but be carefull not to overheat it (bigblocks have less fins). Fit a big oilcooler to it.

Good luck, Marco.

 

[Guest]

DAVID,

Thanks for returning my fender. I am sure it was not broken when I sent it. That would have been hard to miss but I am not infallable, I may have missed it.
I think from now on I will take pics of all items before shipping. If it was busted I was taken, thats why I check everything I get too. I don't know what happened buy I am sorry if it was broken.

 

[Guest]

If you are still interested in the engine I only have one left. You may want to make a deposit on it.
let me know