Steady Progress, but not there yet. Jets & Pods

[Scudder]

I have a 1978 gs750. I've been going through the normal tweekings and adjustments involved with air pods and jetting. This is what I've done and I am hoping that someone can give me some ideas. Am I heading in the right direction? It seems like it.

1st go around
Uni Pods
air mixture 1/2 turn out
Fuel mixture 1 turn out
main jet: 107.5
Topped out speed 70 mph, with the throttle twisted all the way.

2nd go around
Uni Pods
air mixture 1/2 turn out
Fuel mixture 1 turn out
main jet: 120
Topped out speed 85 mph, with the throttle twisted all the way.

Do the adjustments below seems to be appropriate for the 3rd go around. I hope to make them this weekend after I get some ideas.
Uni Pods
air mixture 1/2 turn out
Fuel mixture 1 turn out
main jet: 125
Topped out speed ______, with the throttle twisted all the way.

Please feel free to give me any suggestions. I feel like I'm close, but I need some expert advice.

Thanks

scudder

[Mike]

Why people continue to get Pods after so many threads about how hard they are to tune and how little gain you get is beyond me.

[tkent02]

Especially people who don't know how carburetors work. Kind of like the ones who don't know Jack about electricity cutting into their electrical systems and then asking for help. Oh well, more parts bikes for the rest of us.
So Scudder, is it too rich or too lean now?
It's hard to tell from here.

[Scudder]

Thought I'd take a stab at you guys for advice. I probably don't know enough to ask the question. This is my last go around before returning to stock. The bike, has be an odyessy in many other ways than just the pod, jetting thing. However, far from a parts bike. Preciate it.

scudder

[tkent02]

Again, is it too rich or too lean? If you don't know this, put the airbox back on.

[BassCliff]

Hi,

As I understand the VM carb operation, you're supposed to have the air screw out at about double the fuel screw, then adjust from there. Start with fuel screw 3/4 or 7/8 out and the air screw about 1 1/2 or 1 3/4 turns out. Plug chops at each throttle opening will tell you what the different carb circuits are doing; pilot jet, needle jet, jet needle, main jet, etc. Read your plugs. You'll find links to carb tuning tips on my little website.


Thank you for your indulgence,

BassCliff

[Scudder]

Too lean, I'm thinkin'. I think I'll just put the box back on like you said, and start over. What concerns me, is the bike had some of the same tendencies before I took off the box, and started down this slippery slope of pod and jets. When I got the bike stock it wouldn't run over 50mph full throttle. Thanks for the advice.

scudder

[Ranger]

Especially people who don't know how carburetors work. Kind of like the ones who don't know Jack about electricity cutting into their electrical systems and then asking for help. Oh well, more parts bikes for the rest of us.
So Scudder, is it too rich or too lean now?
It's hard to tell from here.

I know how carbs work, but I'm going back to stock airbox

Why?

Simple answer: IM BROKE & CHEAP AND DJ KIT IS NOT WORTH THE DECREASE IN MPG TO GET MY BIKE TO RUN RIGHT!

Cost too much damn money for what its worth.

[tkent02]

Too lean, I'm thinkin'.

One or the other. 50/50 chance?

When I got the bike stock it wouldn't run over 50mph full throttle.

That sounds serious, it's probably good to get this one fixed before making any big modifications.

[DrImodium]

I just got done rebuilding and tweaking a GS1000 and had headache after headache with it. Be smart.....Go back to your Mega Welcome and take a look at the most common issue's section. Go through your bike one by one and verify that everything on that list is good on your bike. Once you have it running right, stock, then you can start modifying it. If you dont get it running correctly in stock form, you will just end up chasing your tail around.

Simple checks:

Rust in your tank
Petcock is fully operational
Airbox is sealing correctly
Intake boots and IB O'rings are still good
Getting healthy spark on all four plugs
After rejetting, make sure your plugs arent fouled out. Replace them if they are

Most important thing when messing with jetting........READ YOUR PLUGS. Plugs are an easy way to see how the motor is doing.

This isnt hard and it isnt rocket science. Break down the mechanics of everything and research. If you cant afford to do research and teach yourself this stuff, your better off taking your bike to a mechanic who already knows what he is doing. Theres a trade off to wrenching on your own stuff.

[rustybronco]

I have a 1978 gs750.

What exhaust is on it?

125's might be in the ball park with a 4 to 1 exhaust and pods. WAY too big for pods alone.


50 mph top speed in stock form? fix what's wrong with your bike first! it should do at least 110 in stock form.

[chuck hahn]

All i can add is now i dont feel so isolated.

[Scudder]

Exhaust is 4 to1 with a modified muffler made out of an exhaust tip. The muffler is more free flowing that the old beat up 4 to 1 muffler.

I now realize that I should have gotten everything figured out stock before modifying anything. Too late for that, unless I retrace my steps now.

[rustybronco]

Too late for that, unless I retrace my steps now.

No it's not...


check/adjust valve clearances.
compression test
check point gap(s)
measure voltage at the coils
measure coil secondary resistance; plug cap to plug cap.
measure fuel levels with external tubing.


did you raise the needle height in the carbs?

[Adler]

With that kind of loss of power are you sure you're firing on all 4 cylinders?