78 GS750 Jetting adding K&N's??

[Anonymous]

Hello PPL
I need help with this, I would like to know (1) What the stock jets (pilot,Main and needle) are in a 78 GS 750. I got this bike missing the Airbox so I put some K&N's on it and it was backfiring from the carbs and sluggish power under load.
Now I moved the Needle clip down to the fourth slot and the pilots are 2-1/4 turns out and it helped alot but still seems lean so I want to know secondly what jetting sizes you get from the heard of "stage three kits" so that i can order the jets also planning on changing the pipes to a slip on so I would need to re-jet anyways.

Thanks for anyhelp!
Jose

 

[Anonymous]

I too have a '78 GS750. I believe mine had 96.5 main jets. I put some individual pods on it and the bike ran extreemely poor. It even started to bog down one day on the highway. I found out that it was my lean mixture that was the cause (duh?). After NUMEROUS tries with the settings, I ended up with the main jets to 105's and positionned the needle to 1 free notch from the bottom (pointy side down, clip side up). The air screw is at 1 3/4 out and I turned the fuel screw below the carb bowl 1/4 turn out. I also have a freer-flowing exhaust so my settings might make your bike a bit rich. My plug color are fine. Unfortunately, it took some tweaking here and there until I got it run right. You'll have to do the same thing. Cycle-recycle sells the Jets (http://www.crc2onlinecatalog.com/Index_Main_Frame.htm). I would buy a couple of different sizes if saving time is critical. I love the way it pulls now compared to the stock settings. I did drop my mileage from 42-38 MPGs. But that might have something to do with the new FUN I have with the throttle. It's only gas anyway!! Best of luck and God bless!!

Vic

 

[robinjo]

I run 116 main jets, had it done by a shop with a Dyno. (K&Ns and 4-1)

 

[Anonymous]

robinjo,

116's!! Wow sounds cool!! Is your exhaust wide open? what kind of mileage do you get? Did the bike shop give you any horsepower/torque figures? Currently I feel as though the bike has more than sufficient passing power on the highways. Speed after 60MPH builds smoothly and predictably until my silly grin turns into a scared stare!! Wacking the throttle wide open doesn't do well as I would like (but I'm not complaining at all). Rolling the throttle smoothly works very very well. Below 60MPH it pulls very aggresively. I would really like to try the 116's myself. Maybe that will help out the "Wacking" issue. Let me know.

Thanks,
vic

 

[Anonymous]

robinjo,

116's!! Wow sounds cool!! Is your exhaust wide open? what kind of mileage do you get? Did the bike shop give you any horsepower/torque figures? Currently I feel as though the bike has more than sufficient passing power on the highways. Speed after 60MPH builds smoothly and predictably until my silly grin turns into a scared stare!! Wacking the throttle wide open doesn't do well as I would like (but I'm not complaining at all). Rolling the throttle smoothly works very very well. Below 60MPH it pulls very aggresively. I would really like to try the 116's myself. Maybe that will help out the "Wacking" issue. Let me know.

Thanks,
vic

Where have you been VICK

 

[Anonymous]

Hi Scotty!! I've been here every day. I'm just really quiet. I love to read all the posts I can. Sometimes I find someone I can give a little of what I've learned. That's what it's all about. I don't have to tell you about that though. Good to hear from you friend.

vic

 

[Anonymous]

Hi Scotty!! I've been here every day. I'm just really quiet. I love to read all the posts I can. Sometimes I find someone I can give a little of what I've learned. That's what it's all about. I don't have to tell you about that though. Good to hear from you friend.

vic

you really gave my spirits a boost a few months back and i have had opportunuty to do similar things for a few of the guys also--I had lost most of my faith in mankind and you turned my opinion a little more toward being positive..
Thanks again

 

[Anonymous]

Hey Jose,

Check out this page for info on how to establish what jets you need for the mods you have.

http://www.motorcyclecarbs.com/jetting/default.htm

Kim

 

[robinjo]

robinjo,

116's!! Wow sounds cool!! Is your exhaust wide open? what kind of mileage do you get? Did the bike shop give you any horsepower/torque figures? Currently I feel as though the bike has more than sufficient passing power on the highways. Speed after 60MPH builds smoothly and predictably until my silly grin turns into a scared stare!! Wacking the throttle wide open doesn't do well as I would like (but I'm not complaining at all). Rolling the throttle smoothly works very very well. Below 60MPH it pulls very aggresively. I would really like to try the 116's myself. Maybe that will help out the "Wacking" issue. Let me know.

Thanks,
vic

Hi Vic, no my exhaust is not wide open, it has a 1.2 inch hole. The bike puts out 60.8 RWHP on the dyno with a very nice curve. I don't know the conversion but I get about 17 kilometers per liter with an average riding style. By the way does anybody know the conversion for liers per kilometer to miles to the gallon???

 

[Anonymous]

Thanks guys for the info. Robinjo 17km to the liter, Is I think (39.97394) 40miles to the gallon (1km is .62137mi and 3.785411liters to a Gal.)

Ok So I am going to order several Main jets. 105 and (maybe one in between) a 116 to try different settings.
thanks alot for the info, I'll post my results here when i figure it out.
So you guys have the same Pilot jets and needle jets????

thanks again
J.S

 

[Anonymous]

http://www.cadvision.com/smithb/whoswho/gs750spe.htm