'80 gs 750e 4 into 1

[81gs750bagger]

thinking about new 4 into 1 exhaust, on stock gs750, will this cause me rejet headaches? or can i probably run stock airbox and jets? can somebody help the newbie?

[80GS750]

if you get this you may need jets, but you might be ok with just the exhaust and the carbs stock....

if you change the airbox or put any other aftermarket filter in then you would most definately have to jet it....

i am running pods and an open exhaust right now... and waiting on my stage 3 kit so i can get it to run right... i will probably buy the 4-1 soon though....

[KEITH KRAUSE]

thinking about new 4 into 1 exhaust, on stock gs750, will this cause me rejet headaches? or can i probably run stock airbox and jets? can somebody help the newbie?

If the pipe flows significantly better than stock, then yes, you'll need to tinker with the jetting.
Take some plug reads for later comparison before installing the pipe.
If you then do accurate plug chop/tests with the pipe on, the plugs will tell you what needs to be done. Test the pilot circuit at minimal throttle, the jet needles at 1/3, and the mains at full throttle. If the bike is in otherwise good tune, then any lean plug colors you may see will be related to the jetting. If you notice any surging or slight hesitation when cruising then that's a lean condition. Excessive decel' pop is a lean condition.
Typically, most quality pipes will lean you out some. You may get away with it depending on how many miles you ride and how hard. To me, any extra leanness beyond the factory mixture isn't acceptable. The engine will run hotter because it partly depends on the correct fuel ratio to help cool the cylinders. I'd re-jet if needed, no matter if the mixture/plug reads is only a little leaner with the pipe.
Typically, this means only simple richer adjustment of the mixture screws for the pilot circuit. The jet needles may need to be raised, generally 1/2 position, by shimming up the stock jet needles with a spacer unless you have adjustable needles already. If so, then you would still need to buy some small approx' .022" (1/2 position change) washers to act as jetting spacers. Changing needle height is the most work, but since you spend the most time riding on the jet needles, it needs to be right.
For the mains, typically, an increase of 5 to 10 may be needed. In other words, 1 to 2 full sizes up, with a 2.5 increase being a "step" up.

[80GS750]

well i just ordered the v&h 4-1.... got it for 269 no shipping. as soon as it gets here i will have it on the bike and be playing with my jet kit....

i will be sure to post up here what i had to do with it...

[RJ]

If there's a Dynojet kit available for your bike I would go ahead and get it. It'll probably run you $75-100 but it will save you a lot of time and repetetive carb disassembly headaches.

[81gs750bagger]

where did you buy your v&h from? i ride daily ..about 50 miles round trip to work..i live in country so unless hauling something all my running around is on bike..runs real good , just thinking about 4 into 1..sounds if i do i really need to go to pods and maybe a stage three kit..i don't ride hard..but often..bike is kinda my daily driver although i have two pickups also..thanks for ya'lls info

[80GS750]

the stage 3 kit can be bought for 104 to your door. i have pods, and the v&h will be installed later this week... the stage 3 is on it right now and man does it scream.... i think it runs really good, but i know it could use a little tweaking to run better..

[petelardo]

You've been given a lot of good advice here; keep in mind that a freer-flowing exhaust almost ALWAYS requires rejetting the pilot (idle) circuits, unless the bottom-end was already too rich. It IS possible to be rich in one area, and lean in another; rich is ALWAYS better than lean. Better to have fouled plugs from too much gas, than daylight showing through the piston crowns from not enough gas...

[81gs750bagger]

thanks for all the great info..you guys are awesome

[80GS750]

hey bagger, i got the vh today and put it on. she sounds amazing. i couldnt ask for better. and she runs amazing too. that jet kit made all the difference. i only have to put new plugs in and see if she needs a little tweaking, then im done!

[81gs750bagger]

awesome looking bike i'm deffinitely hooked..gonna be gettin some of those pipes..thanks for the pic and info..i'll post when i get'm added

[81gs750bagger]

did you make your own sidecovers?

[doug g]

I have a v&h megaphone and stock airbox. I installed a dynojet stage one and a uni foam filter. bike runs great except it is a little rich off idle. I need to turn in mixture screws a little to take care of the problem. From 2.5k and up the bike runs great.

[Carmine]

She looks amazing, bro. This inspires me. I hope I can get my heap looking half this good.

[80GS750]

yes i did make my own sidecovers.... didnt want to mess with the originals and this was easier.... little welding and cutting and bam! there they were