Aces High Bulletin Board
General Forums => The O' Club => Topic started by: helbent on January 03, 2012, 07:34:59 AM
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Hey fellas, Im bored. Seeking advice so I can think I am doing something constructive.
I bought a 99 ultra 150 jetski that was not running. I tore it down completely, rebuilt the motor and replaced some electronics.
Its been running great, everything perfect and functioning properly. Gaining confidence in the ski I stopped premixing my fuel, started to trust the oil pump. I also started using a non ethanol fuel, then the last couple times Ive had it out I have lost power to a cylinder and have had to limp it back home on 2. Pulling the plugs the front one had had its gap closed up, replaced the plug ran great then dropped the same cylinder again. What is crushing this gap closed? Is the piston hitting it?
Looking for ideas from anyone, since you guys are the smartest people in the world, before I go tearing into the motor when I get home in a couple weeks.
Thx
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(http://img259.imageshack.us/img259/6342/005ei.jpg)
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I would say yes, seen it before.. Some factors to take in to account.. Don't don't take this wrong please.. I usually see it when using low quality rod and wrist pin bearings, they get loose pretty quick, (just normal tho, no worries).. Also when the engine heats, the rods lengthen a bit.. Was the head or Jugs Shaved?? Try Spark plug Standoffs.. Or cheaply, double the washers..
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Sounds like it may be hitting the piston. Why is another story. Are you sure it's the right plug for the engine? Could be too long. When you rebuilt the engine did you change the rods? They may have stretched.
I'd run the piston to TDC and look thru the plug hole for damage on the top of the piston.
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Didnt shave anything, put stock pistons back in. Had the crank re-tooled while it was out, one rod had remnants of piston in the bearings and was moving side to side a bit.
So you dont think i need to pull the heads and take a look. I really dont want to buy another gasket set. Have way too much money in this already. Seems funny that this would happen after 30 hours instead of right away.
Also I have seen oil collecting in the hull.
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i've zero experience with 2 stroke engines.....but the closed spark plug gap.......the only thing that can do that, is the piston hitting it. pull the plug, then shine a flashlight down into the cylinder, and see if there's any marks on the piston top. that'll give ya a clue. it sounds as if something's running a little hot, and stretching a bit..........
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Getting confused now.. New rods pressed?? New mains & seals? Old pistons? New Pistons? sorry, lol!
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1 New rod, the center, new mains and seals, pressed (not exactly sure what the guy did). New pistons, rings and wrist pin bearings (3). The center cyl was the initial cause for the rebuild.
So, if it gets hot, the rods stretch. (could be because it runs fine for a bit then i drop that cyl)
By not mixing my fuel, could be causing excessive stretching?
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If you made solid contact, it would have smashed the plug.. Probably just the bearings loostening up.. They do that.. I have LOTS of 2stroke exp..
By all means, I would pull the head.. But that's me.. Still, if you made solid contact, the plug would be smashed! Use plug indexers to lift the plug a bit higher..
Assuming you know the oil injector is working, oil won't be a factor in that.. By stretching I meant natural expansion of the rods length, due to normal heating.. There is sometimes little spare room for error..
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1 New rod, the center, new mains and seals, pressed (not exactly sure what the guy did). New pistons, rings and wrist pin bearings (3). The center cyl was the initial cause for the rebuild.
So, if it gets hot, the rods stretch. (could be because it runs fine for a bit then i drop that cyl)
By not mixing my fuel, could be causing excessive stretching?
by not mixing the fuel, you could be running a little hotter, thus causing a slight bit more stretch. the oil lubricates, and cools.
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OK, this is my plan,
check the piston for damage, extend the plug, keep trusting the oil pump and keep using the no ethanol gas.
hopefully this works for me
appreciate the help fellas.
If i get time to mess with it when I get home in a couple weeks, ill be sure to let ya know how it worked out.
gonna be cold, but have wetsuits =)
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:aok
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i wish i could've been more help, but like i said.....i've got zero experience on 2 strokes. for whatever reason, i've just never had a reason to have worked on them. looks like pakefront got ya covered though. :aok
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Are you using the recommended plugs for Kawasaki or are you using regular automotive plugs not the (NGK's)? I have a Kawasaki 1100 STX, only seen that happen when not using correct plugs.
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my 2stroke experience is with sleds, and no expert by any means. Seems as thogh if a piston slapped the plug you would hear it, and it may create a hole thus loss of compression. Hard to say not knowing lol.
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Didnt shave anything, put stock pistons back in. Had the crank re-tooled while it was out, one rod had remnants of piston in the bearings and was moving side to side a bit.
Also I have seen oil collecting in the hull.
The oil leak could be in the pump/tank system,minor! I editted most of your post to point out something,Had crank retooled? Undoubtly this is the main cause,could be the throw is out and the piston travels more than it should,could be bering slop causing the same,could be many things combined to cause the piston to hit the plug.
I hate to tell you this but before you do unrepairable damage I'd tear it down and check it throughly. If you throw a rod,center cylinder,you can destroy that tripple beyond repair!
YMMV.
:salute
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Remember, this is a two stroke, one piece roller bearing rods on pressed pins.. Rah Jo???
A rod kit, is the rod, the roller bearing, 2 thrust bushings, and the crankpin! Ya don't regrind
em undersize like a car engine, they are pressed and trued.. If it was out of true, it never would
have made thru reassembly.. Would be bound up in the case.. I've twisted a few, lol!
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Sounds like you are lean on one cylinder.
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Sounds like you are lean on one cylinder.
My first guess.
Always look at the simple fix, first :aok
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Sounds like you are lean on one cylinder.
Not sure how being lean would close a plug gap.
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Not sure how being lean would close a plug gap.
cause he's the leet 2 cycle mechanic, and has had one up to 234.543 mph in the floating mile. :devil
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Not sure how being lean would close a plug gap.
The leaner the cylinder, the hotter it runs, and a possible cause of thermal issues...
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The heat causes the electrode to soften up and then it bends closed.
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they will not bend closed without physical interference.
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Over heating will have other tell tale signs. A plug chart like http://www.ngksparkplugs.com/tech_support/spark_plugs/faqs/faqread.asp (http://www.ngksparkplugs.com/tech_support/spark_plugs/faqs/faqread.asp) can help identify conditions such as over heating. This might help eliminate heat as the problem, maybe look to carbon build up or something else that is impacting enough to bend but not destroy the plug.
I have forgotten the washer on an old 2 stroke once, and it was just enough to smash the electrode, that did some scarring, and the second time my electrode bent was nothing more than I let some debris get in there while doing a field tune up, it was bent but not damaged so I reset the gap and rode back to the truck to replace the plug.
Side note, having been a rabid 2 stroke jet ski fanatic quite some years ago, how many times have you fouled or flooded the cylinder in the middle of the lake, pulled the plugs while floating, turned the ski over to drain the water and put it back together again :D Ahh the good old days of diving under water off a massive wake lol
Lot of good advice in this thread, got some solid 2 strokers backing you up.
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they will not bend closed without physical interference.
Yes they will.
I have one from a 280zx turbo that ran lean and bent closed.
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Yes they will.
I have one from a 280zx turbo that ran lean and bent closed.
I had a '75 Kawasaki H1 Triple that did that. Center cylinder. Put the mercury stick on the carbs, evened them out, problem solved.
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so are these plugs then using bimetallic electrodes?
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Try using a slightly shorter and cooler range plug. That is the cheapest alternative.
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so are these plugs then using bimetallic electrodes?
You choose the wrong side of any technical argument because your experience is outside the area in which you intend to argue.
You believe your limited persective to all that there is but you are wrong.
Argue within your depth and you will rarely be wrong.
cap spams thread in 3.....2.....1.....
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i already stated i had no 2 stroke experience.
i asked a simple question. answer it, or don't type.
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When the electrode is near hot enough to melt into liquid, it is every easy for act of combustion to influence the very flexible electrode to move.
(http://farm8.staticflickr.com/7004/6648274605_4ace9d7e28_b.jpg)
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now was that so hard?
you brought up something i was overlooking....and to be honest, i hadn't thought that compression pressure could/would ever be able to do that.
i ain't the arrogant @#% you think i am.
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Helbent
Just out of curiousity, what NGK plug are you using? Just curious is all. If ya wouldn't mind just post both numbers on the box end flap. I am a pretty avid snowmobiler, have had my share of 2 strokes apart and rebuilt myself.
If the piston is hitting the grounding strip on the plug, you will see it plain as day with the plug out. If its getting hot enough to melt it together, the top of the piston will be nice and clean, maybe even a whiteish color. That's a pretty decent indication of lean.
If it is due to lean out, there are a number of possibilities then. Carb sync, carb passages plugged, air leakage, or even exhaust leakage can do it.
Go with your plan, your on the right starting track for sure :aok
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When the electrode is near hot enough to melt into liquid, it is every easy for act of combustion to influence the very flexible electrode to move.
(http://farm8.staticflickr.com/7004/6648274605_4ace9d7e28_b.jpg)
Yes that is possible, I have seen that before too, far worse than that actually, lol.. But by the time that happens, you should already be hearing the KNACK KNACK KNACK sounds of detonation.. I have a 490 2 stroke race bike that a single NOS piston costs $800,(if you can find one) running 50:1 Spectro, race gas and 13.5 comp, and 2.2mm BTDC timing.. That's the ragged edge on an aircooled 2stroke man.. Gets real spendy when ya make a booboo in tuning.. After a lifetime, I don't make many.. I keep a tuning logbook for my different bikes, so I don't forget how they have been altered last! Gettin feeble minded too..
I kinda regret saying anything at all, without having it in front of me.. I am making a few assumptions, that the guy knows what he is doing for one, he sounds OK to me.. And all things being equal and straight up, as said with the motor.. Being as the big end went prematurely, (rod kit), so that usually means a vacuum leak at the intake port.. But again, injector motors usually squirt the oil right at the rod bearing.. I am assuming the builder made the correct moves to prevent an overlean, blah blah blah.. Without having the thing in front of me, I can only go by what the guy says..
Watercraft and whatnot are an odd combo of tech, like an Outboard/Motorcycle/Snowmachine hybrid kinda deal.. Interesting lineage/parentage of the machines too..
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For 15 years i road and raced in expert limited and super stock class in region 5. I would go back to pre mix and do a compression test to see if their is any issues. I cant remember a time were i experienced a problem with the piston hitting the plug. You might get lucky and be able to use the gasket if you need to pop the head. O ring heads were a gift from the gods when they first came out..
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Lots of advice and I appreciate all of it fellas :salute
Dont know when I am going home, but it looks like I have a few things to try.
I was thinking return to premix also, thanks, persuaded me. Will test cpmression also
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OK, got home, put 3 new plugs in and premixed fuel. Ran it in driveway, front cylinder seemed cold. Put it in water and its definately down a cyl. Guess Ill have to crack it open and see whats wrong.
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I have a 1974 lambretta with a high compression nicosil alloy barrell and head 180cc, exspansion chamber clubman. ( I have broke two cranks using this kit :banana:)
From my experience of skimmed barrel head it might be that you require a thicker gasket to the cylinder head.
with the Mugello skimmed/or squished head you are supplied with various head gaskets depending on how far you want to increase the compression.
Compression closing the gap seems a little excessive, if such pressure was excerted on the plug it would strip the alloy head plug thread before cloing the gap. ( i have had this happen where by the plug becomes a bullet and fire's across the workshop)
I have seen melted plugs and squashed plugs but not from compression.
My Lambretta require a new up gear and ugraded clutch to cope with increased compresson.
Is there variants of spark plugs for said barrel?
I would be interested to see pics of you stripping barrel down, many heas together might be able to help you with this problem.
I remember rebuilding my engine and forgetting to put my a new roller bearing in the crank :) it still looks at me that caged bearing when I am looking for something :old:
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Nice Bike Zack, would you post a pic of it for me,I was in my prime when those were new,might breath some life into this old codger!
:salute
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Well, had a piston down. Scarred up the cyl so i had it sleeved, other 2 honed, ordered new parts that my machinist broke and finally got it all back together last night. Came home tonight and went to fire it up. Fired up after a bit priming, ran it for about 15 minutes. I noticed some water come out an exhaust connection so i shut down and tightened those bolts. Went to refire it up and I am getting a whirring sound from what i think is the magneto. the starter is not moving and this part is after the start button and before batt, CDI, starter, and everything else.
thoughts on that? thx <S>
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Well, had a piston down. Scarred up the cyl so i had it sleeved, other 2 honed, ordered new parts that my machinist broke and finally got it all back together last night. Came home tonight and went to fire it up. Fired up after a bit priming, ran it for about 15 minutes. I noticed some water come out an exhaust connection so i shut down and tightened those bolts. Went to refire it up and I am getting a whirring sound from what i think is the magneto. the starter is not moving and this "whirring" part is after the start button and before batt, CDI, starter, and everything else.
thoughts on that? thx <S>
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woops
ok its not that magneto nor ignition coil
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The whirring sound is probably the starter spinning. It sounds like it's not engaging the starter gear for some reason or another.
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not the starter. thinking a celinoid
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solenoid or starter relay, had a starter relay go bad on my harley and it made an odd noise. not sure how jet skis are setup
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yeah relay, will look into that
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maybe if you can locate the relay you can tap on it, that worked for me a couple times, end result is replacement lol
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this doesnt show as much as I thought it might but might help you in some way
http://fiche.worldofpowersports.com/wps/showmodel.asp?Type=13&make=kawasakipwc&A=79&B=12
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Yeah been looking at that. The whirring is coming from the trim module which makes like zero sence to me.
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If not the piston hitting the plug could a few drops of water getting sucked in the intake do this?
Another thing to check is the piston head. See if you can spot a dent on the piston where the spark plug would have hit.
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Just cleaned contacts to ground, starter and starter relay box. Everything is working the way it should. Ill put it in the water tomorrow and see what she'll do. If everything is perfect, I will attempt to sell it.
Thanks for all the advise tho gents :salute
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that will be the 2nd happiest day of your life :D