KawasakiTrax Community
Tech Information => General Help => Topic started by: gixxer6 on January 10, 2014, 07:17:18 AM
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IT'S ALIVE! I finally got my modded 4/6 running. New crank seals, crank replacement, cylinder issues, broken gas tank filler neck repair, a full day of removing and greasing stuck suspension shafts, new rear shock, rebuilt fuel pump, 4 cans of carb cleaner, rebuilt recoil, and probably a dozen other things, it runs!
This 80' 4/6 LTD came with Aaen pipes, ported cylinders, Wiseco pistons, K&N pod filters, non-power jet carbs with adjustable mains, and an EGT gauge.
I've never ran a sled with the adjustable carbs and EGT gauge. What temp should it run??? Am I only concerned about WOT temps?
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... Probes located 8-10" from the exhaust ports... if the probes are too close it will actually read too low. Correct temps should be in the 1100-1350 range. Ideal... 1200-1300. If you see anything near 1400 or higher "you betta pull ova." Give er h--l.
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what?? no video??? That's cool it is running!!! ;D
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The probes are 6" from the cylinders. That should put them about 8" from the pistons. Does that sound right?
I didn't see anything over 1100, but the engine isn't broke in yet. So I didn't run it very hard, just a 3 or 4 second WOT burst. Its still running premix along with the oil injection. Once its broke in and tuned, I'll try to get a video...
Am I only concerned about the WOT temps? Or any temps that that get close to 1400? Can I use the EGT's to the pilot and needle?
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I would guess that with the extra oil, it will run a bit cooler..
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Tom,
Never trust some number as the correct heat range for your motor. Make note of the temp the motor runs at WOT. Verify the piston wash. When you have the correct wash then that is your number.
Easy with the two plug holes to look at the piston wash. Pull both plugs, put a light down one hole and get a good look with the other hole. Too simple.
Many variable elements. How accurately your gauge represents, how far the probes are from the piston, the probes themselves... See the solution? Check the pistons, they will tell you.
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It's 35 degrees out today, I balanced the carbs and rode the sled for about 15 minutes. It was running around 1100-1200. I pulled all four plugs and inspected them. Ground strap is a dark brownish color. I looked at the piston wash. The old piston was solid black, and the piston that I just replaced still looks new. What does this mean?
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The new piston, piston wash is not measurable yet. The old piston wash says you are clearly not running rich since the carbon would have 'washed' off in larger sheets or chunks relatively quickly. There is not much to to note with a short run time and piston wash other than an overall view of correct A/F mixture.
Plugs are my idea of 'getting close' and I have a little extra money. Here is Marks how to, works. Warm the motor to operating temp. Put in one new plug (brand new shiny), the rest old not fouled is fine. Put the sled on a jack stand. Fire the motor up and run WOT for four full seconds. It is not necessary for any more than four but then necessary for at least four. Kill the motor holding the throttle WOT. Pull the was new plug and "used up plug" never to be used again for this procedure UNLESS your motor was marking RICH. Hence the always start rich with your carburetor settings! Get it? Inspection of the grounding strap. There will be a burn line where the metal on the strap goes from shiny new to a faded dull. Where that line draws or burns the line is what tells you the motor is rich or lean at WOT. The goal for perfect is the burn line being centered in the corner bend of the grounding strap. Visualize the grounding strap straighten out making the plug gap around 5mm instead of thirty thousands of an inch with the 'bend' as a reference marker. As the burn line approaches the bend reference mark the motor is rich. After the burn line passes the corner reference mark your motor is lean. The further the burn line is past the reference mark and starts touching the plug thread, panic and put in richer jets before you melt down. As only a reference, I do not warranty, when you get the burn line down to the plug threads you are four jet sizes too lean. Graduate that measured mark on both sides of the reference mark. Start rich and you will watch the line move down the grounding strap. This procedure apply to middle throttle checks also. Last the burning plug line trick can only get you from four sizes and checks rich toward perfect before the burn line becomes un-readable. Two new plugs and you can have the whole job done with a final burn line on the new plug saved in your tool box. Just because you cannot see the burn line approach perfect carburetion you can still use it to verify your motor is not lean. After you are into the lean side of the burn reference run the plug it is useless for this procedure.
Using plug color is in the air a little with fuel additives. Color does not apply to the grounding strap only to the insulator ceramic the protects the center electrode from sparking any where except the tip of the grounding strap. This color is another visual check so that you have three A/F mixture checks. One, burning grounding strap, plug color and piston wash. The color never better be white unless you are 'burning' the plug in the above procedure. After you have the plug burnt literally and metaphorically the color will begin to start marking.
Plug chopping ie: cutting the threaded portion of the plug off with a grinder. New plug gets a 1/4 mile run WOT. It will create a black soot line on the ceramic insulation. The relationship of that soot line, much like the grounding strap burn line, identify the motor as rich or lean.
I draw my egt worry line (not really) at 1300 and panic at 1400. In truth until you watch the egt's and see the piston melt temp that gauge is just another measure that has little value. In the end that egt gauge tells you, if you need to pull a plug checking for color or verify the piston wash with any concern. Think of it as a no work, constant communication, to the A/F mixture gauge. I use the gauge all the time in race motors.
Tom, I am going to have to barter information with the price of 4/6 cylinders next time.
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Wow Mark, that is a lot of good information. Thanks! Your next cylinder purchase will be at a discount.
From what you are telling me, it sounds like it is running lean. The carbs have 370 mains and have the adjustment screw in the bottom of the bowl (dial-a-jet?). I have never ran these type of carbs before, and have no idea where to set them to start. I started with 1.5 turns out from full seat, but it sounds like this is too lean... I will turn them out some more.
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the dail a jet equals 90 jet points added at 1 turn out;ie; 370 main jet closed =370...1/2 turn out 370 + approx 45;1 turn out, 370 +90... no effect added after 1 turn....they used these on the nitro and twister f/a motors stock,easy adjust when it gets warm.....
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I've got 370's and the screw all the way out, which is equivalent to 460's. That seems really high to me. Could this be right???
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does sound rich....add up invader jets,120 and 145 =265...thats with an airbox....and stock pipes.....if it has good power it cant be too rich
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The stock 4/6 jets at 120 and 130 (250 combined) are even smaller than the Invaders (not sure why ???, seems like they should be a little larger...). It seems like it makes a lot of noise, but not the power that I'd expect. It currently turns about 8800-9000 rpm.
Maybe I should try going leaner? It's a lot easier than buying and installing bigger jets. If I'm real careful and keep the EGT's down below 1100 I should be safe?
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Tom,
The plug burn will tell you.
1100 Egt tells you nothing until you run the plug burn.
After the plug burn, EGT noted temps tell you the next piece of data.
Last the piston wash will identify with absolute precision for that day's air temp, altitude and humidity (high or low pressure weather system).
Safe is burning a plug and watching where the line burns WOT. The verifying 1/2 throttle plug burn and last 3/4 plug burn. This way you check all of the vital metering systems of your carburetor.
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Ok I gave it a try. Warm engine, WOT 4 seconds, the entire ground strap is dull.
I am going to try a set of 480's. I can't believe I just said that...480's are HUGE!
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Entire grounding strap is burned with 370's, wow. 410's would be the next jump I would make. But not before tearing down the carburetors again for hardware inspections.
370's that sounds mighty suspicious like there must be some other factor playing a problem. The problem is mighty clear, not enough fuel.
I would slap on a different set of carburetors. Four cans of carburetor cleaner? Check that needle jet is clean and your jet needle is the correct length. I am thinking the needle is not getting raised enough to allow free flow of the main. 370's cannot be correct. The inlet needle and seat could also be slowing the flow. Something is wrong. How big are the carburetors? A person could put 600 jets in a 32mm carburetor and the limiting ticket is likely the needle jet and jet needle.
You mentioned replacing a piston? (new piston on one side other old piston) I could be certain the motor is lean and the previous owner knows there is a problem, hence the monster jet. The 550 of mine uses a 250 ± jet 38mm carburetors.
When you finely get to see the burn line on the corner you'll say, "no darn way".
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The carbs were nasty, but I took my time and got them spotless. Every passage is free and clear. I meant to record all of the jet/needle sizes while they were apart, but I forgot. I did notice that they had 40 pilot jets, not that they have any impact on WOT. I am quite certain that they are 36mm carbs.
If the needle is too long, raising it a notch or two should make a noticeable difference. But I will start by pulling the carbs and verifying that they are clean, then record all of the jet/needle sizes.
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i have a set of 38 mic's on the bench, bored to 39.5, bells cut...[i got them from billy? from ill. off this site over a year ago]..set up for a stock 550...370 mains,42.5 pilot... set up for no airbox,screens on intakes....410s at 9000 rpm on your ltd doesn't sound that far off now imo.... 8)
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Should 410's get you to proper calibration your spread would look like this:
@ -40°F 455 main @-20°F 439 main @0°F 429 mains @20°F 413 mains @40°F 407 mains
This is assuming at the same altitude. More importantly you must infer from the numbers given they are the calculations. I was aimed for your testing done at 20°F. It is better understand the spread of jets you need in your pocket. I use a piece of lexan with the assortment of jets needed for my sled and they stay with that sled.
Kawhead may have some insight. Are you trying to run the airbox? Then the airbox would make Kawhead's 550 very rich because extra vacuum caused from the box sucks more fuel. I have first hand experience how clean your parts are :)
On a bonus side if you carbs do adjust the main 90pts you can run all summer (watercross) and winter with the turn of the screw when you are dialed on. 90pts should make the spread even when it is 110°.
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The spark plug test was done in my garage at about 40°F. About 600ft above sea level. No air box installed, just the freshly cleaned K&N pod filters.
I should have some time tomorrow night to get the carbs off to record the jet sizes.
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Still some though on your motor.
The snow twister 440 motor put out 75hp. 36mm carburetors with power jet.
You are working on a motor ported, Aaen piped potential to 100hp starting from a very similar 77hp stock 4/6 motor. When you take the twister carbs and put them on your stock 4/6, I say sure it works, but use the twister air box.
When you look at 100hp motors, what typical sized carburetor do they run? Ski doo 521 motor at 95hp out of the box uses 40mm VM Miks.
Sproket runs the 4/6 motor in his clone shark. He had his motor dialed in on a dyno @ about 100hp. I would bet he would share the exact information you need for your sled to include hardware in which Mik.
Sure a person can put a two barrel on a 454, then you cannot expect to put out 500 ponies. There is some relationship with Hp and Cfm but I have no reins of that horse for two stroke snowmachines.
I would waste the money and get a hold of some 440 or better mains. Run the burn procedure with new plug. If it dulls the entire grounding strap again, dump the carburetors and flush up some 38s. 40mm carbs require a longer throwing throttle but you can adjust your cables to manage the 38's. Then I would consult Sproket for his final setup.
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A lot of good information read so far. Without knowing the correct heights that Aaen did for you is pretty tough to Jet. 36mm sound too small of a carb. I can tell you what set up I had but the conditions are different. 42mm 35 pilots 390 mains bbo 2.5 cut away 7dhs 2nd clip everything matched meaning intake boot to cylinder glued down with 1104 yamabond, my Compression was 180 lbs per cylinder I ran 116 (c-16) race fuel with Klotz R50 @ 50:1 open carbs (no air cleaner or pods). My engine made 109hp @ 9800rpms so it is possible to reach over a 100hp but more than likely Aaen doesn't give you the maximum according to HP he told me years ago he is more conservative then full out race engines I am Not knocking him he is very talented but there is other people that will push the envelope a little more remember I'm racing your trail riding big difference I never once hooked up a probe to my engines I always started hi on my jetting and read my spark plugs and jetted it accordingly. I know for a fact on Dyno specs a stock engine is way less than 77 or 76hp stock more like mid 60s with a mild porting mod pipes 40mm compression @220 per cylinder my engine dyno'ed out at 86hp with 48 foot pounds of torque @ 9350rpms it doesn't sound like much these runs were on 2 different dyno's, I also ran stock timing, coils and Ngkbr9es plugs
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Oh say your estimated horsepower is 90hp by the time it gets to the track it's more like 40-45 hp and it can be more or less depending how things are set up. Now take your carb specs write them down and start testing keep your notes. The cut away tells you how much air will be allowed through the carb. Champ engines only can run a 34mm carb and make stupid hp but now these engines are way different then say the stock vintage engine
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Yes, there is ALOT of good info here. I really appreciate the help!
At this point it may be helpful to point out my intentions for this sled. I'm not going to racing it at events. I'm not going to be doing 100 mile per day trail rides either. I just want a fairly reliable, fairly fast, fun, vintage sled that will give my sons 10yr old MXZ600 fits from 0 to 70.
That being said, I do have a set of 38's, and a set of 39.5 carbs that I could run. At this point I just want to make it run without fear of melt down. I'm willing to give up a few HP that I'd gain from running larger carbs to have the convenience of dial-a-jets.
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you may be able to put your dail a jets on the 38s, same body from merc fa to invader,[major body casting] fa twister used adjustable jets, not power, air box was a very large square tube like that sucked air from behind the headlite,its baffle had large holes the size of your finger to stop the big chunks :o i'd run some 410s or so just to see what the change is.... and this is a great thread.....
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Carbs are apart. They are still spotless.
Slide: 2.5
Needle: 6DH3 (clip in 2nd from bottom)
Needle Jet: 166 Q-0
Main: 370
Adjustable Main: 1.5 turns out (full rich)
Pilot: 40
Seat: 1.5
I didn't know that there are different sizes needle and seats. It looks like that is my problem. The hole in the 1.5 seat is smaller than the hole in the 370 main jet...
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Yes,
I am glad you found the issue.
Q-0 needle jet may end up too rich in the mid range but you will not be lean. Follows something like this: When the clip is in position 5 (as deep as the needle can go) you can put in P-8 and move the clip back to the 3rd position (middle slot). Should it go the other way needing more fuel in the mid range clip position 1 then you can go to Q-2 moving the clip back to the middle position (#3). See the madness?
After you get that inlet seat changed, I would bet 370 puts you in the very rich range. Maybe 320 jets, and but it will be rich. You will get to see the burn line move down grounding electrode and hit home the idea always start rich.
WOT main jetting first then adjust the mid throttle.
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What size inlet seat should I get?
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as memory recalls vaders started out with a 1.5 and went to a 1.2 to stop high speed rough surface flooding....
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I picked up some 1.8's at my local sled shop. When I told the guy what I wanted and why, he looked at me like I was crazy...
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imo thats not the issue but i've been wrong before......
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Being that the 1.8 needle and seats were $20 each, I decided to try the 470 mains. I installed them, put in yet another new plug, and ran WOT for 4 seconds. This time the dull/shiny line was right in the middle of the bend of the ground strap. (I'll be returning the needle and seats...)
I took it for a short ride. It still doesn't make much power, but it's definitely different. It's only running a little over 8000 rpm, and seems a little rich. For some reason, the right side cylinder runs around 200 degrees hotter than the left while cruising mid throttle. At WOT they even out more, and I was seeing 1200 degrees. When I pulled the plugs, the insulator is a real dark brown on one side, and a light tan on the other. I don't know what that means???
I went with 470's with plans to turn the adjustable main in to lean it out. (It's still adjusted full rich).
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470 plus 90=580.....470 plus 1/2 turn from closed=515 thats were i'd try it again....my merc service manual says 1 turn = 90, no effect out more than that....
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That's exactly what I was thinking! I adjusted them to 1/2 turn out, and WOW does this thing FLY! It pulls the full 9000 rpm. I didn't hold it WOT for long, I get nervous when I see the EGTs go up to 1200 degrees and let off...
The right cylinder is still running a lot hotter than the left. Any ideas why???
Thanks all for the help!
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It sounds like you have a air leak. I heard of different brands running two different jetting but not on any Kawasaki engine that I ran both plugs should be a nice golden brown if it's a little on the dark side both plugs you'll be fine. Make sure the carbs you use are exactly set up to each other including throttle pull back ( slides move at the same ). 470 seems rich 350-380 with one turn out 35 pilot. I have to ask do you have a carb chart from Mikuni it would be a good reference or Aaen carb tuning book. The chart will show you what's been tested already you may have to adjust a little but that ain't bad. Remember your engine is air compressor the more air more fuel more exhaust an old friend said that to me when I raced jet skis back in the late 80s.
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try switching carbs from side to side to see if the hot cyl is in the carb
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I switched the carbs (slides and chokes included). The right side still runs hotter, so it's not the carbs. I switched the EGT probes from one side to the other to see if there might be a problem with the EGT's. But I didn't get a chance to run it.
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how much hotter and is that the new piston?
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At idle and just over, the right side is only slightly hotter. In the mid range, just cruising, the right side is around 200 degrees hotter. At WOT its 250ish. The right side is the one with the new piston. The left side didn't look very old, the piston and cylinder both were in excellent shape.
Another thing I noticed is the right side seems to react a lot faster. At WOT the right side shoots right up to 1200ish, and the left will slowly climb.
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hhmm....about down to exaust pipe...when new 4/6s had some pipe issues...one was not flaired/fitted correctly just insde the head pipe...
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Aaen pipes on this one...
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It looks like the temperature difference is a problem with the EGT's. I swapped the probes from one pipe to the other and sometimes they would read the same, and sometimes the left cylinder would read hotter... The probe wires were in rough shape when I got them.
I ran it fairly hard, and the temps only went to around 1100.
I guess my next step will be to get some fresh un mixed gas in it and try to dial in the mains. It must be really close, because it runs really good, and pulls REALLY hard! You should see the smile on my face after riding it. ;D
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Glad your smiling. Here is something to think about 2 different grades of pistons can cause different readings on heat. What I mean about grade is the material making of each piston is different even though they are stock pistons, the Materials made from each other are different this is where the heat comes into effect that can cause different readings
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i agree on the piston material sprocket,expansion rates,etc.sounds like you're close on the mains,you want to be set up so on a hot day you can lean down 40 pts or so, 40 richer when its cold.
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It was in the single digits when I was running it last night. I'll most likely be putting in smaller mains so when the temp increases, I'll have room on my adjustable mains to lean it out.
I still don't know what to think about the inconsistency of the plug color. Anyone seen this before?
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now that its dialed in i'd try a new set of plugs.....it helps if you get a little time on the motor.
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Tom,
Sounds like you have reins managing A/F. The two plug colors can come from combinations of things. Since you have two potentially different pistons that may affect the actual compression ratio opposed to matched pistons this is one of the mentioned combination. No air box has an affect from where each carburetor draws in its air, one air source can be cooler than the other. Imagine air pulled closer from the exhaust pipe is hotter, hotter=less dense and therefore your jetting is rich for that carburetor. Oh the list goes on but you can chase that demon.
Jet your carburetors correctly in accord to this choice, one piston wash, two plug color and three plug burn. When you have no idea where to start with jetting adjustment, then you get to reverse the order just given.
While dial a jet is a fairly good solution, it is another wrench in the dyer. Another system to keep track of is the cause of the problem. An example is maintaining five sleds, where one has Holtzman tempa flow, then an ataac another dial-a-jet. Race day sleds are treated different, in each of my sleds I have a lexan card with the spread of jetting needed for that sled. Using mikuni templated charting I just put in the correct jetting. ONCE you get the correct A/F ratio and you write down the temperature and the altitude you are at then all the other situations are known. Eazy Peazy. No more power to generate with the correct A/F ratio, no pistons to burn down or rings to seize. Gas and go wear out some parts.
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Both pistons are .040 over Wiseco's, one is just a touch newer than the other...
I've got it jetted so it'll run a solid 1200 on both cylinders. I plan to run it until I can check the piston wash, then adjust if necessary.
When I was referring to different plug coloring, I meant the same plug. Normally when I check plug color, the entire insulating portion is the same color, ideally a dark tan color. On this sled, its not. One side of the insulator is a real light tan, the other is a dark brown. And there is a color gradient between. All four plugs look the same.
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Last share,
Check your half throttle with a plug burn and you can put A/F to bed. C-clip guess is not a good solution and is equally important as WOT. Well not quite equally important considering you can cool the piston with a WOT burst before aluminum flows out the pipe.
Piston wash from that end point.
Sounds like your plugs are finishing up coloring.
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How many turns do you have your air screw out ? If it's more than 1 turn out you need to jet up or drop your pin if your clip is on the top setting you Definitely need a bigger jet. Now on one side running hotter than the other is not really common in the Kawasaki now if you ran a rotax then it is common to have different jetting sizes from side to side.