jets

[Bhawkins854]

Anyone have an idea what int. Jet size I should be running. I have an 2008 117 with a lot of new motor work. Heads, compression, cam, ignition, pipes etc. I'm at an .032 now, I know zipper has all the way to a .040 l, just trying to get a ballpark so I can purchase! The bike idles fine, and good when you roll the throttle but pops at the carb when you crack it.

 

[Tom Chop]

I think that more information is in order before any recomendations can be made. The people where you had the work performed should be able to to set you up.

 

[Bhawkins854]

I put the motor together, had my heads sent out, I've been discussing different options with the mechanic from the place I bought it. I've just read lots of info and seems I'm running lean on the int. Jet. I live in Minnesota so I can't get her out for a test ride exactly. Id be happy to get this issue with the popping in the carb fixed so I can Dyno it in spring without any issues.

 

[Bhawkins854]

The jets from zippers are about ten bucks a pop. Just seeing if anyone has ran into this problem and has a suggestion for a size before I start buying( or guessing on what size to buy)

 

[Bowhunter]

S&S Cycle | Carb Quick Guide

This might help you to decide which way to go with the jets

 

[outdoorsman26]

we have quite a few people that are running the 31-32 int and 78-80main, there are some people who have done such work as you have hopfully they will chime in!!!

 

[moog5050]

33 int and 78 main with only upgraded ac and pipes. I am guessing you will need something slightly bigger. Better to start a little rich and move leaner than vice versa.

 

[francoblay1]

Hummmm..... interesting reading here....

I am at sea level in the Mediterranean Coast of Spain... right now we are below Zero Celsius (Freezing) my dog does not stop sneezing via the air cleaner... I ve been opening the screw to the max... so far that almost fall out! it does not stop sneezing, but the spark plugs are black as coal. brrrrrr.... I have to open the catb up and find out what intermediate is in there, right?

One more thing..... What about removing that "Auxiliary Bowl Vent Plug" as this manual states if the air filter has been changed??? S&S Cycle | Carb Quick Guide

Thanks

 

[outdoorsman26]

One more thing..... What about removing that "Auxiliary Bowl Vent Plug" as this manual states if the air filter has been changed???

I removed mine couple yrs back it it helped!!
working on a thunder jet today

 

[francoblay1]

I removed mine couple yrs back it it helped!!
working on a thunder jet today

Thanks for your input Matt, I will have to try it, I will let you know the results.

 

[moog5050]

Franco

Colder air is more dense with oxygen and can lean a motor out. That coupled with the popping to me would suggest a lean condition. I would check the int jet and maybe try one larger. Its an inexpensive test. I am not an expert on tuning, but that's what I would do. Also, there is a link to a plug table that you can use to compare your plugs somewhere on this site. It may help you identify whether you are running lean. Good luck.

Brian

 

[Bhawkins854]

This problem I have according to that carb guide and lots of other reading is that I'm running too lean. I think I will try the .034 int. And see where that puts me, thanks for all the help

 

[Moespeeds]

When in doubt always drop 2 jet sizes because a lean condition is much easier to diagnose than a rich condition. A rich bike will run fine all day long, and in my experience most guys are running rich without realizing it. If you have an open intake remove the bowl vent. For heavy decel popping try opening the mixture screw 1/2 turn at a time, but I wouldn't go farther than a full turn out. S&S has an excellent how-to on their website. To jet a bike here's how I do it.

Turn off the accel pump
Warm it up and adjust the mixture screw
Take it out for a ride to see if anything is obviously off. If not, drop 2 sizes on the intermediate jet. Always make bold changes, one at a time, until you dial it in. Once I dial it out of lean, I'll usually go up one more jet.

Do the same for the high jet, which is pretty simple. The S&S WOT test is easy and quick. Get it lean, then dial it up

If you are running a very free flowing air cleaner, you may get a stumble where the intermediate and high jets overlap, somewhere around 2k rpms. If this is happeneing, try opening up the air bleed until you dial it out.

Adjust the mixture screw again. With really short pipes opening up the screw a bit should help with popping.

Adjust the accel pump

 

[Moespeeds]

Just an FYI on my 2004 117 ci with short pipes and a stainless creations open intake, I ran a .028/.074 with a .066 airbleed and the bike runs great. I've got this same engine in my chopper now and it seems a hair lean but I've been riding in sub 40 deg weather and I made these pipes so it's tough to tell what's causing the backfiring. Once I get the cam in there I'm gonna tune it again anyway so I'm not sweating it for now.

 

[Bhawkins854]

I will have to follow that procedure when it warms up and I can take it out for a test run. Just running ot in my basement now, and I can actually take and turn my A/F mixture screw all the way out before the bike wants to stumble. If I can dial in my int. Jet now it will make life a lot easier in spring. My intake is the only thing stock pretty much after this build, so I'm assuming i would leave my bowl vent?

 

[francoblay1]

Franco

Colder air is more dense with oxygen and can lean a motor out. That coupled with the popping to me would suggest a lean condition. I would check the int jet and maybe try one larger. Its an inexpensive test. I am not an expert on tuning, but that's what I would do. Also, there is a link to a plug table that you can use to compare your plugs somewhere on this site. It may help you identify whether you are running lean. Good luck.

Brian

I am going to open the carb right now and check what size jets are in there... I do think is running lean, but what gets me is the spark plugs being so black... (rich)

I will let you know what do I find shortly.

Any suggestions on removing the "Auxiliary Bowl Vent Plug" ?

I am running stock pipes but they are open (no baffles) Air Cleaner is a K&N Spike model.

About Moe´s comment on the "Air bleeder, opening it up" can it be regulated? or it needs to be changed to a bigger size?

 

[Moespeeds]

For a spike pull that bowl vent. Your air bleed is a high jet, but I believe stock is .040. If you can find them in .005 increments I'd get a handful, .050, .055, .060, .065 or close to those numbers. You can also make your own by simply drilling them out to the size you want with a good sharp bit and preferably a drill press.

 

[Germanbiker]

Hmmm,

here in Germany I'm running 34 / 78 in summer time. NOT rich!

Have a XXX Carb, K&N, opened BD Air cleaner cover and open exhaust with X-pipe. 34 intermediate was made for me by Bob of Performance S&S Carburetors by Triple X Carbs - American Made Highly recommed his cars!

Going to install 585 cam plus programmable Thunderheart ignition .

Jochen

 

[moog5050]

Its surprising that we should go leaner when in doubt. I assumed richer because lean could damage the engine. But I guess if we are in the ball park to begin with, and a lean bike is easier to diagnose, it makes sense. Thanks for the info Moespeeds. I will take your advice over mine on tuning any day. Good practical how to.

 

[francoblay1]

Right, just popped the carb open... my intermediate jet ia a 029.5.... is it to small????

and a 0.74 the big one.