Please see this thread http://gstwins.com/gsboard/index.php?topic=53160.0 (http://gstwins.com/gsboard/index.php?topic=53160.0) for my Exhaust set up, that I will eventually have to jet for, and know I will need help. Homer has been extremely helpful with suggestions on Jetting in that thread, but I wanted to create a separate jetting thread to keep it focused just on my future jetting woes. For those that don't want to sift through a linked thread, here is a pic of the exhaust I created and need to jet for.
(http://inlinethumb24.webshots.com/45655/2535711990073478356S600x600Q85.jpg)
About 10 Years ago I added a Carbon Hindle Can, and Header Pipe, I also bought a Dynojet Stage 1+3 Jetting Kit for it. My memory is a bit vague on just what I did, but I know I had to drill out a plug in the carb body (Why?), changed the mains and needle and other stuff I'm sure I forgot. Anyways, prior to creating the new exhaust, the bike I believe was still lean after re-jetting, it would pop mildly on decel, off throttle, but it didn't hinder performance to much or rid-ability.
(http://inlinethumb18.webshots.com/44433/2340989980073478356S600x600Q85.jpg)
(http://inlinethumb24.webshots.com/26071/2114000810073478356S600x600Q85.jpg)
(http://inlinethumb44.webshots.com/5035/2714806900073478356S600x600Q85.jpg)
I think the Kit required me to drill out 1 of the 2 plastic plugs in the bottom of the slides seen in this pic below.
(http://inlinethumb50.webshots.com/46513/2369455220073478356S600x600Q85.jpg)
I have bags of jet(Mains?) ranging from 118 to 139, I was using 122's. I think the open clear bags in the top of the pic are the numbers for the needles I'm running currently, the fatter ones in the pic. These needles have a washer between the c-clip and plastic spacer.
(http://inlinethumb32.webshots.com/6751/2760691630073478356S600x600Q85.jpg)
Are these the Pilots? I think that they read R61?/ 1225 (Maybe a decimal point between the 2 and the 5, too small to read correctly without a magnifying glass), I don't have any additional ones of these.
(http://inlinethumb35.webshots.com/2914/2178454460073478356S600x600Q85.jpg)
What Jets are these?
(http://inlinethumb12.webshots.com/20875/2823143750073478356S600x600Q85.jpg)
So, looking at the exhaust in the linked thread, and taking into account Homers real world experience with a similar exhaust, where should I go with the jetting? I will be running the Lunch Box K+N Filter as well. Homer eventually settled on 145's, 2 washers on the needles, and 2.5 out on the A/S(Which are on the bottom flange area near the bar that connects the car bodies, correct?) Homer states he always felt it to be Rich on the Bottom end and Lean on the top.
So, what do others suggest? I'd like to start out with something close, while the carbs are off for cleaning. I know I'll have to fiddle with it, probably a lot once it's all together but at least your suggestions will help me get close, while everything is accessible and already removed.
Main Size/#=?
Pilot Size/#=?
Needle #=?
Washers=?(How thick mm, do they vary or are standard size ones used?)
A/S=?
Thanks Guys....
No, I said I THINK it was 145s, etc. I lost my logbook.
I think I went up to 150 or so before I got lazy and quit.
The ones you call "pilots" are the mains, and vice versa.
Yes, there's a decimal: 122.5 (They go up in steps of 2.5; you'll frequently hear them referred to as "steps" in the vernacular.)
Never screwed with the Dynojet stuff. But start BIG. Bigger than the matrix suggests. Yours aren't restricted, remember. At least 155 (maybe even 160), stock pilots, 2 turns (as a baseline). Don't shim the needles until you get the top and bottom sorted out. Maybe bump up to 45's or so. Just gonna have to find out, once it's running.
I would NOT run that motor with 122.5 mains.
And getcha a trickle charger.
Edit: And change the thread title to Epic Exhaust. Take pride in what you do, says Dr. Seuss.
So, in my pics, what I have labled as Pilots are actually the Mains? and the bags of Jets I have on the table, are actually Pilots? Anyone care to post any pics of the Mains, Pilots and such...I'm not a dolt, but come from the Dirt World, were things look a bit different and are in somewhat varying locations. I suppose I should get a manual.
Why did the Kit have me Plug/Drill the plastic plugs in the Slide (Drilled one out as pictured)? What affect does this have, and should I drill the other plastic plug out?
Should I leave the thicker needles in, or go back to stock? If I leave the thicker, KIT needles in, why shouldn't I keep them shimmed with the 1 washer?
Why did the kit have me remove the metal plug on the carb bodies?
So, it sounds like going right to a 145 Main is a good starting point?
Stock Pilot? (Why stk. pilot?) If the Off Idle to 1/8th throttle settings end up rich, wouldn't going down on the Pilot help this circuit?
Please, be very deliberate with y7our advice.
Quote from: Fry on July 21, 2010, 07:06:57 PM
Mains
(http://inlinethumb35.webshots.com/2914/2178454460073478356S600x600Q85.jpg)
Pilots
(http://inlinethumb12.webshots.com/20875/2823143750073478356S600x600Q85.jpg)
The Dynojet stuff is funky. The drilling and all that is only necessary with that kit. The only drilling you would have to do, normally, would be to remove the brass cap (the "metal cap") over the AF screw (which isn't always necessary). I think once you modify for Dynojet, you have to stay with it. And I THINK their stuff is limited in size or availability or some such thing.
Not sure if you can use washers on the needles with those (sort of a mid circuit) or what. Best just to leave those as-is for now.
Pick any jets you want, pilots included. The main idea is to create a base point that you can compare everything to.
Start high, so you don't run too rich and ruin things. Work down from there, a step or two at a time. When you start to run lean in the mains, bump up a step and fiddle with everything else. Change only one thing at a time, or it starts to get screw REALLY QUICK. Keep a logbook, so you don't forget everything you've tried(the numbers start to meld together after a while).
Example:
Date -
Mains-
Pilots-
AF turns -
washers-
Fuel Octane -
Problems/ Comments -
You're correct that going down in pilot would correct off-idle mixture. But, the idea is to just start somewhere, to have something to compare things to.
Wish I could give you a good starting point, but that's gonna be nearly impossible.
drilling larger hole in the bottom of the slide makes the throttle response change. Either allowing it to rev faster or slower depending on the size of the hole.
Remember when testing jetting make sure the engine is fully warmed up too.
here is a good basic guide for getting the hang of jetting
http://www.pitsterpro.com/forum/viewtopic.php?f=26&t=24
Thanks for the help...
I have a lot of experience jetting highly modified (IE More Troubles More finicky) 2 Stroke engines and am very familiar with the principals of changing one thing at a time and keeping a detailed log book, including atmospheric conditions, though I would assume a 2 stroke is more susceptible to atmospheric changes than 4 strokes. Anyways I will start out big on the Mains.
The current Dyno Jet Needles are considerably fatter than the stockers, and also have a washer sandwiched between the C-Clip and a White Plastic Donut/Spacer. I assume the general consensus here is to keep the Dyno Jet Needle Assemblies as is for now, and just get the mains dialed in. When I get to the Pilot circuits I would assume, any changes that may be needed, would probably lean towards making changes to lean out that circuit? A/S affects Idle? and what else?
Again guys, thanks and keep it coming.
The carb slides are vacuum operated
you plugged one of the holes and drilled out the other hole which
changes the rate(speed) that the needle will rise
the needle slides out of the main jet always
just like a 2T
get it to idle
get it to run at WFO
then work on the transition
you are working in a grey area where a couple have delved
you will be buying and swapping jets and taking notes til you
get to a point where you will deal with the slight imperfections
and say close enough I ain't screwing with it any more.
Just out of curiosity, I'm guessing my creation will be more restrictive than a stk. set up, so wit that in mind, if I'm moving less air out or at a slower rate presumably not having the Push Pull of effective exhaust gas pulses and venturi effects, would't I want to feed it less gas, therefore going down on the jetting and not up?
shorter pipe
big open can x 2
high scavenge rate
jet fat and go down
rich mix gives you black plugs
lean mix burns the engine up
O.K>, that makes sense to me...I'm still a bit away from Firing the motor, tons of nickle and dime shyte left to do, though I'm suspecting Jetting will be the biggest time waster on getting this thing done.
Black Plugs, Bad, White Plugs, Bad....2 Stroke Jetting has taught me to look for Cinnamon.
Thanks man for the help...
Start rich, tune the top end, and work your way down. The 2 circuit carbs wont give you as much control of the mixture as the newer 3 circuit type but it'll still work. I always recommend using a wideband O2 sensor to monitor the AFR. Yes you can do plug chops but it's more time consuming and not real time.
Quote from: Deros514 on July 23, 2010, 08:53:33 AM
Start rich, tune the top end, and work your way down. The 2 circuit carbs wont give you as much control of the mixture as the newer 3 circuit type but it'll still work. I always recommend using a wideband O2 sensor to monitor the AFR. Yes you can do plug chops but it's more time consuming and not real time.
Any affordable Wide Band 02 Kits/tools out there?
Quote from: Fry on July 24, 2010, 05:10:47 AM
Any affordable Wide Band 02 Kits/tools out there?
Nope.
Talk to Seamax, now that he's back. He's got dual underbellies from a company in Brazil called Aluizio, part of a kit. His look like simple straight-pipe extensions, and I don't recall seeing close-ups. Not sure if they're internally baffled. But, he's still running it. Obviously, he got closer on the jetting than I did.
He did send his carbs away to Buddha. Not sure what happened there, or if they remember the settings.
Funny you mention him, while looking through the Pictures Thread, I saw his Black and Red beast, a lot of visual cues similar to mine, especially the perforated sheet metal near the seat rails. His exhaust does look like really small diameter round tubes, perhaps carbon cans for 125cc 2 stroke racing bikes? I shall get intouch with him...
I hate sending anything out, to anyone, I'm kinda stubborn, plus kinda broke...
Thanks.