wide open

running some pod filters, and i tried jetting down to a 120 from the 122.5's i ran all last year, i suspected it was running a tad rich, and it was, but today it was pretty cold, also my pipes are wide open, and the plugs came up white... could this be the cold air screwing with my mixture or should i jet back to 122's? anyone running wide open exhaust on a 650? what do you jet to?

Normally, switching to pods and running open pipes requires going to LARGER jets, not the other way. Pods=increased airflow which requires more fuel to maintain the proper air/fuel ratio. White plugs indicates a lean condition. I'd say switch back to the 122.5s and re-read your plugs.

Did you do a plug chop at WOT before reading the plugs? That's the only way to accurately assess the main jets.

How many turns out are your pilot screws and did you go up at all on your pilot jet?

Later, Doug

Follow the link and download... Contains carb tuning of several carbs and Carb theory including touble shooting...

kzrider.com/index.php?option=com_docman&...d&gid=461&Itemid=108

Unless other issues, seems like Mains jet is still too lean....

OMR

it may be due to the cold air as it gets denser when the temp. drops .

well i know the jets were running rich last fall when i put her away, i have jetted it waaaay up from stock. i didnt change any settings on the pilots, but a local jap bike guy said that on those slide mikunis you almost never have to change the pilot, if it idles, theyre fine. ive been running it as is for all last season, and the running rich thing just kinda got to me but i think its mainly the colr air leaning it out right now, i cleaned the filters extensively and boosted back up to the 122.5's, and got a really light brown, so i think that should richen up pretty well when the weather gets up to the usual saskatchewan summer temps, more like 20*c and up as oppposed to 5-10*c that it is right now.

i havent run it right up to WOT and checked, but i did run it at highway speed for a few miles, bout 70-75mph, and then took the reading from that, its definantly running off the mains at that speed, ive been told that the pilot jets in the carbs on my bike do little more than idle.

okay, so what i get from the manuals i downloaded (thanks for the linky OMR! all kinds of helpful useful info in there.) is that at 120, my main jet size is pretty much bang on, maybe one size too rich and that sits well with me, and itll richen up a bit more once i set the needles. ive generally accepted that i have to up my needle circlip by one setting, because midrange is where im leaning out, but just slightly. what i cant tell from the articles is which way to set the clip to richen up, up or down the needle?

my mains should be okay, i might give each of the adjusting screws one half turn to be safe. i cant see it being too ornery, since its been running fine with just main jets up for a while, and not much adjustment is needed, if any at all, since im riding it in the blistering cold the last few weeks i figure thats gonna have the most to do with why my mixture is lean, so a slight adjustment to the mid and lower range, and i figure shes golden. i love how easy these carbs are to deal with.

Lowering the clip will raise the needle and richen the mixture. Roy

The cold air leans it way out. If u run in cold air with any smaller it won't have as much power. My jets are way rich and almost don't need choke for more than to start it. My plugs turn white as snow when it gets around 40 or colder. But the power is to die for. With some bs34's I bet I could rock all over some of these advance the intake, retard the exhaust (for a shitty idle too) guys. MONSTER JETS MAN! drill it! drill it! drill it! BUT. The cops are comin! Your outa spec boy! And just by followin ya your exhaust ruined my o2 sens! Thats gonna cost ya:woohoo:

well, first of all the cops here wouldnt know an out of spec carb'd bike if it came up and parked on their face, nor would they care if it did, as long as you didnt do a burnout and double the speed limit in the process. i love saskatchewan. its literally the southwest of canada.

anyways, so i gave my pilot jet needle screws one half turn in, and actually managed to get out on a warm-ish day, 15-18*c here this afternoon, and went for a nice hard burn down the highway, to reveal a nice, rich, caramel brown plug in each cylinder. so im happy. dont have to screw with the needles, thank god. synced her up, shes ready to groove. i reckon my assumption was right all along, it was the cold leaning her out on me, and when the average temps slide up to the mid 20's i can probably jet down to a 120 main again.

thanks for all the help and info guys, shes good for the season now, hopefully for good, at least as far as carbs are concerned.

eyeofthestorm wrote:

i havent run it right up to WOT and checked, but i did run it at highway speed for a few miles, bout 70-75mph, and then took the reading from that, its definantly running off the mains at that speed, ive been told that the pilot jets in the carbs on my bike do little more than idle.

Its not running off the mains until you open the throttle beyond 2/3. The speed your travelling at has nothing to do with it. The rpm also has very little to do with it.

The fuel circuit/jet that is used is dependent on the throttle input.

You wont know if you have a correct main jet without doing a WOT plug chop.

Get the bike into top gear really early, then crack it FULL. When you get to just over half of max rpm, KILL SWITCH the engine while still holding the throttle open.
Pull clutch in quickly at same time, then stop and look at the plugs.

GL!