Need advice on jets

Working on 81xj550. Just put motor back in and started to run it up and road not far nor fast. Before I set mixture screws and balanced the carbs it was wet on the right 2 and black on the left 2. Its much better now, if fact the plugs are all starting to burn light gray. While the carbs were out I put oversize jets in but not may be big enough.
I put 117.5 mains in and 37.5 pilot fuel jets. I dont think Im running it fast enough to be using the main jets but I dont know. No tach at this time. If at the speed Im running should I just increase the pilot fuel or take the main up to the next size larger. Or do they shim the move the needle clip down one. I had the carbs apart but can not remember if the needle has grooves for that.

Forgot to mention, uni round pods 4, 4 into 1 exhaust with no muffler.

 

TALKIN' TECH: Various thoughts on various issues
The pilot fuel circuit is active from idle up to about 2500-3500 rpms, and at about 3000 rpms the main fuel circuit starts becoming involved, and by 4000+ rpms the main fuel circuit is responsible for about 80%+ of the engine's fuel supply conditions.

read above link it contains the info posted and info on plug chops

 

in fifth gear your speedo is close to what your tach would read

 

this link tells you how to select jets
http://www.factorypro.com/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html

you will find it talks about doing main jet first.
I think the only slide needles with clips points are aftermarket I will look tomorrow at a slide i have out of carbs

 

I got no speed o either. It was a broken bare bones when I got it. I ordered the next larger size of jets today. I dont want to burn a hole. From the little I have rode it up and down the road (no tags) it runs great as is. Ive got one of the gunson color tune I bought for my vulcan tuning I may try tuning the mixture with that. I read some of the links you sent, thank you, and it did say that the mixture does affect higher rpms along with idle. thanks again.

 

tune the mixture screws with the color tune, when done then bring the rpm up with the throttle see whats going on in the motor at higher rpm.

 

If you have stock air filter you should use standard jets. If pods, then who knows.

 

I know, but he's not gonna like the answer.

 

When is the last time valve clearances were checked?

 

Pods are sooo difficult to make work , CV carbs are NOT suited to them ,flat slide carbs are not a problem with pods. Even if you "think" it runs great with them, you will have a flat spot somewhere and the power band changes , popping and backfiring are all signs as well as difficulty synching properly. Pods actually rob horsepower slightly , this is not a like adding an open element air filter to a small block chevy . The folks that designed these bikes knew much more than any of us will ever imagine on how to get most out of these bikes.

 

Cruzin - the point that I think fellow members are making is this -
There is no silver bullet for jetting/ needle positions for running pods.
You are your own test engineer for your bike in your environment (elevation, relative humidity, prevailing winds, etc.). Because there are now a new set of variables when you remove the airbox and run pods.

Other people have had success with pods, but their recipe for success may not be the same as yours because of the variables mentioned.

 

if you have a gas analizer and dyno it becomes easier. .
I have a 750 that came with pods top end up hill 85 mph you can feel the studdering/flat spots in all gears on rapid acceleration , bike is ridable and still enjoy riding it but will soon be looking for an airbox for it. PO did this and am going to see what is inside the carbs soon.

when done with my 83 750 stock it will be interesting to compare the both of them.

 

Ill have a go with the color tune, thanks for all the replies guys. The bike had no intake, tach, or speed o when I got it. It ran but ran terrible. I had to replace quite a few shims my # 4 intake was so tight I could not get a feeler gauge in it. I have cv carbs on my xs650 and they work ok on it. I sent those carbs to a guy and he rebuilt them sent them back and Ive run them for 2 years without problems. The first thing I did was to check the valve shims and timing then went on to carbs. I then took carbs apart changed out the jets set float on the bench and back on bike it ran like crap then I set the mixture screws to 2 1/2 ran better then I balanced the carbs and it seems to run fine just have the plugs getting gray. I let you know what happens after the color tune. thanks again.

 

With stock airbox my Seca easily burries the 85 mph speedo

 

yes thats my point about the pods when you need the power it is not there. a lot better on the flats but I am just playing with it right now and will be getting it an air box this winter. bought it with pods and figured i would give it a try riding and see if I can make it a little better, but an air box is in its future.
I feel it makes my comments about pods credible after trying and failing or suceeding . bike is ok if your just tooling around, but I like to know the throttle is there if I need it. I live in the mountains

 

well I tried the color tune plug in all 4 cyl. Nice and blue at idle but cracking up the throttle it turns white. I even increased the mixture a half turn out and still white at higher rpms. half of my jets came but Im waiting for the other 4 next week.

 

Colortune is only designed to be used (and accurate) at idle speeds.........

 

mixture screw will not help higher rpm tuning that would be jet changes

this chart from color tune is for higher rpm tests
http://gunson.co.uk/items/pdf/Products/G4074_Chart.pdf

section 6 speaks of higher rpm testing in manual

http://www.etoolcart.com/manual/G4074_Inst_Colortune_English.pdf

 

I'd be afraid to rev the motor with the colortune. It just doesn't look as good as an NGK spark plug It is different no doubt so does it actually perform as well? An NGK with the correct heat range and resistance has to perform better than what frankly looks like something not worthy of firing a Chinese weed wacker.Is it really going to demonstrate the same condition?
Maybe if it's good enough at slow rpm it's good for high rpm I don't know, but I'm sure I'll find out, popcorn is ready

 

gunson instructions
"Part throttle If the throttle is opened very slowly until the engine is running at perhaps half of the maximum rated speed, the blue flame should become slightly lighter. The lighter blue is due to a slightly leaner mixture (less fuel) arranged to give improved economy at part throttle operation.
Full throttle When maximum power is demanded (at full throttle position) it is normal to again have a slightly richer mixture, at most engine speeds there will be a yellow flame. Engines with modern electronic engine management systems which have more precise control would not usually give a yellow flame at full throttle, except at times of rapid acceleration."

ME
while you can not adjust any thing in the main jet with engine running, you can use the tool to get a glimpse of what is going on at higher than idle conditions.

 

Thanks XJ550, I read that last night. I thought it couldn't take the heat of higher operation but if Gunson says it can I guess it can.

 

I would not hold it at half throttle for long , just a quick check then go out and do plug chops.

 

I set the colortune at idle, will blip the throttle in between tweaks but just go off the idle color.

I am also of the school that leaving the colortune in too long and exposing to high temps just doesn't seem prudent.. .

 

if manufacture says it ok that is my school of thought, BUT only as a quick check because the chops will give you a better reading.

op has pods and open pipes better of with chops to solve his lean problem but worth a check between jet swaps and heading out to do plug chops

 

From the Gunson Colortune user's Manual (emphasis mine):

• This product may be used at a wide range of engine speeds but should not be used in an engine under load as overheating and product failure could occur. Take additional care when using the product on an air cooled engine which has no fan assisted cooling. On these engines limit the total test duration to 5 minutes and avoid extended running at high rpm.
  

 

While that is true, there is no real benefit (and lots of risks....overheating and damage to the plug among them.....) to using the plug at anything but idle and slightly off-idle rpm's. The "results" (combustion color) that you get at higher rpm's when an engine is not under load is pretty much less-than-useless as a tuning guide. Combustion color is useful at idle because, by definition, at IDLE there is no load, and, as a tuning tool, you want the idle mixture conditions to be as "rich" as possible (just past or at the blue-to-orange transition point) to assist in the idle-to-load transition in the engine's performance..........this transition point is always key to how "smooth" and "useful" the engine performs, especially in typical around-town operation (lots of starts and stops and thus lots of idle-to-load transitions).

To fully and properly tune for mid- and high-rpm under-load conditions, you have to do either:

a) seat of the pants tuning
b) dyno tuning
c) wing it
d) ignore it
e) follow the factory-pro tuning guide (which is really a rigorous version of "a" above): www.factorypro.com and then click on the "Product Support/Technical Support" link at the top of the page, then on the "Motorcycle Tuning Tech" link, and then the "CV Carb Tuning" link.
f) all of the above
g) none of the above
h) some of the above

Note that ALL of the proper techniques for off-idle tuning involve an engine operating under load conditions (including "b", dyno-tuning); there are physics and maths reason for that!

 

All of which Gunson covers (briefly) in their instuction manual.
While not an ideal tool for tuning, it saves a ton of time by allowing a person to get jeting into the ballpark before doing plug chops or dyno runs.

 

... Matti was right, encyclopedic knowledge. I think Chacal is a robot run by a super computer.

Anyone ever actually see the person we call Len?

 

1011100100101 001010 00000100101 110101 01110 11000010101011110,

 

If he's a computer, he doesn't speak binary. Ones and zeros should be in groups of eight.
Err, I mean, "Beep boop boop!"

 

I'm a supercomputer.......