KawasakiTrax Community
General Category => General Discussion => Topic started by: Macs80hp440 on August 04, 2013, 02:01:48 PM
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I need new rings for my invader 440. I know rings are made to fit per piston brand. Which brand of rings will fit original invader pistons?
Also, as I understand it, all I need is 68mm rings as the cylinders are still original. Has anyone ever used 68.25mm or 68.5mm rings on original 68mm pistons...? In other words, am I correct in getting 68mm rings...?
This restoration stuff is fun, but it is challenging my brain. Much to learn, eh.
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Make sure you use standard 68.mm rings. I think Dennis Kirk has them plus a few other places. Still pretty common.
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I'm not sure that any of the aftermarket rings will work on original pistons.
Are you sure your pistons are original?
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I am using two different pistons out of two different motors. One motor was rebuilt, the other seems original. So, one of the pistons appears original and the other is a "parts unlimited" style. They both weight the same, so I thought I was ok to use them.
I never thought the rings would not fit the same.
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They might work.. but don't be shocked if they don't
Are the ring groves the same height on both pistons?
I'm interested to hear for they work.
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Are the ring groves the same height on both pistons?
Here are the two pistons I'm going to use. One is nearly new from a rebuild I purchased that I blew up on the other side. The other piston is from a motor I got with a blown piston. The ring seats are the same, the weight is the same (pins, bearing, piston) - but I did notice a small difference in the shoulder of the skirt on each piston. I'm not sure how much this matters.
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Those do look to be the original pistons made by ART. Like Lloyd said, the aftermarket rings don't work. You would need to find genuine Kawasaki ones.
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I haven't yet done the engine rebuild. But I've finally finished my other house projects and it is time to get back into wrenching. Also, I've decided to use the original and the "after market" piston as they both measure (mm and grams) same all around. The rings fit into both the same. The grooves are the same. They both fit and align the same in the jug. But- I know I've been told original piston cannot use non-original rings... So, I pledge to let you all know how it goes.
I generally yield to those more experienced than I. But, I've got a spare motor on the shelf in case I'm wrong. If you don't hear from me by mid-Jan give me a note.
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spi rings are made to stock specs and ive used them on oem pistons,no problem....check the end gap...i think you're good to go...
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I pledged to follow up about the rings and pistons combination. I blew one cylinder during break in this week. I didn't take notes on which side I put the mismatch ring/piston. But after I take it out I'll know more. More to come this week when I tear it apart.
BY THE WAY: break in process showed no air leaks, proper ring gap, proper break in, proper oil operation, and so on...
FUNNY (frustrating) STORY: I could not get the carb tuned and could not get matching signature on the plugs. One would be rich, the other about right. I tried without the air box for a short stint and that seemed to be the only way to get a match. I put the air box back on and made one click adjustments on the needle. That seemed to also get me close to matching plugs. I got tired of trying to find an air leak and tuning back and forth I just drove it anyway. I figured one plug would foul while the other would be fine. I was wrong. So, I went on a short ride. Pulled into a gas stop. And could not get it started to pull away.
FIELD DIAGNOSIS: quick peak in head showed one tiny hole (or dark spot) and some rough looking on the top of piston. No compression. I will dig in this week for more details.
MAJOR DISCOVERY: Call this a rookie mistake, or possibly a error in judgement. I have never seen a carb set with mismatched needles. As it turns out, the reason I could not get a match plug signature was because one carb had a "8" needle and the other had a "7". So, I looked at my other rebuild Invader (also could not get matched plugs) and found a "7" with a "4" needle. Then I grabbed a pair of carbs in spare and found matching "7". Put that pair on the "still running" invader and WHOOOO ... strong running and matched plugs.
IN THE END: I am certain I do not have an air leak in my rebuild motors. Just mismatched needles in the carbs. But, it cost me a casualty in the meantime. I'll keep in touch on the mismatched rings/pistons. But I'm pretty sure I blew it up during break in because of my oversight and stubborn nature.
THE POINT: The mismatch rings and piston may not be the problem. Instead, I learned to look into the carb better when I inherit a pair.
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That should be a lesson for all of us.
I have never checked the needles to see if they match
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Been thinking about this..
How long did you have the sled running?
I'm sure mismatched pistons were not the problem.
Did you pressure test the engine?
Did you put new carb boots on?
I melted a piston after putting new carb boots on once. That was the last set of aftermarket carb boots I will buy.
Lloyd
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I put about 3/4 tank through it before it blew. I oiled the crank and pistons prior to start up- a few drops here and there. I had primed and confirmed operational oil lines. I did 5-6 heat up and cool down cycles of about 5 minutes running around idle or maybe 1/4 throttle- each cycle with oil lines stuck wide open- smoke fun. I retorqued head, coolant manifold (under exhaust) and exhaust manifold. I looked for obvious leaks all around.
After that process, then I let the oil line operate normal with the throttle and ran throttle 1/4 to 1/2 up to short bursts of 6000rpm with track and tunnel suspended (no load). Did this maybe 3-4 times to warm it up and cool down. All the time checking plugs for too lean- they were always rich.
After that, I ran it for half dozen 5 minute rides up to maybe 40mph (1/2 throttle) for short bursts. During this process I started to be more critical (intolerant) of the rich plugs and mismatched plugs. In fact, several times I could not get it started for fouled plugs. But I never saw a "lean" plug, just a good plug with a rich plug. With this process I made a couple bursts to 3/4 throttle, still not full throttle.
The best plug signature I got was without the air box. This is probably when I got too bold and impatient. (I know- dangerous territory). This got me a lightly gray plug with a brown plug. And, with a short burst of full throttle, it got me 85mph. But still the worst plug was light gray and the other was brown. At this point I had gone through about 1/2 tank and I did not feel like I did anything wrong. And, I figured maybe I should give it a short ride (15-20 minutes).
I puled into the gas with good power and it shut itself down as I pulled to a stop. @#!$ I had the same mismatch plug problem on the other rebuid. Motivated by a fresh rebuild blown up, and frustrated by thinking I had done nothing wrong, I began to investigate the 2nd rebuild closer.
CARB BOOTS: original boots, insulators, and new gaskets. Torque proper, maybe one click tighter... No sign of leak on any of it.
DID I PRESSURE TEST THE ENGINE: No- not on either motor. Frankly, I never have. In my opinion, and lack of experience, after all the "plugs" and closures you need to make on the motor, if it did show a leak I wouldn't know where to look for the leak. I'm always afraid I would get a false reading. So, instead, I did the poor mans tests on the 2nd Invader (not on the blown one). I did a ether spray test at idle around all intakes and engine case. And I did a warm engine half throttle test of the same spaces. Passed all tests. I know- this is not a great test: that is why I call it a poor man's test. Me and my buddy were nearly beside ourselves with why one cylinder on both engines would be lean.
I joked (ok threatened) that I would simply "correct the rich cylinder problem by running one carb lean"...then we both looked at each other and simultaneously said "...what if someone else tried that?"
BINGO- my 2nd motor had mismatched needles. Then I looked at the blown motor and ...yep- mismatched.
That is when I started to feel better that my rebuild was "tight" and "proper"; albeit imbalanced by an oversight and ASS-umption...
Moments like this push an otherwise capable person to the brink of throwing in the towel. But- I'm fine now. I've got some carb rebuilding to do along with the motor. Then, at some point, I'll give that 85mph a try again.
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I would suspect an air leak.
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Yep- air leak seems the natural assumption. And after I look deeper, I may also agree. Tear down will start this week. But for now, it is hard to ignore the mismatch needles between an "8" and a "4". That is a visible difference, once you take a look at it. To me, that alone would create an obvious plug mismatch, and an inclination to think "air leak". Looking back, I wish I would have noticed that mismatch. I would have avoided the risky break in.
I'll rebuild. And maybe consider a air leak test that is more reliable. I don't mind poor mans tests in the field; but this poor man doesn't have much more time and money to spare on this project.
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Have you checked the other jet sizes? If the needle is mismatched I would suspect the other jets may be mismatched also...
When you mention the 4 and 8 needles, I assume you mean 6dh4 and 6dh8? 79' 440 Invaders came with 6dh4's and 81's came with 6dh7's. I doubt that the mismatched needle would be enough to cause engine failure.
Running without an air box on these power-jet carbs is a big no-no. They need the extra vacuum created by the air box to function correctly.
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A air box. & a windshield
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UPDATE: I took the motor apart to inspect the breakdown (as listed in this discussion). It has nothing to do with original piston and aftermarket rings. It had nothing to do with air leaks or poor break in process. It is as simple as a circlip coming out. In fact, the aftermarket piston with matching aftermarket rings is the bad piston. The Original Kawi Piston with aftermarket rings is fine.
Notice the grooves under the rings and the chipped piston is because the circlip must have hit it. The one side circlip made grooves on its own side, then must have moved across under the piston and made grooves on the side that still had a circlip. The rings seemed intact and the piston seems fine except for a chip missing from where the circlip came up from underneath and broke it out.
There are two types of clips- one that has a small bend across the opening, and the type that just sits in the groove with no bend across the opening. The one that came out is the one without the bend... Notice the other circlip with a bend is still in place.
Evidently I did everything fine except using an inferior circlip. @!#$ smallest and cheapest part in the motor. I was 3/4 into a break in process. I thought it was one brief adjustment that ran slightly lean (grayish tan), but it looks like it had nothing to do with break in or adjustments to mixture. The circlip came out and wrecked the jug and piston.
I plan on doing it all over again. I'm pretty sure the crankcase has bits and pieces to clean out. aarrrggghhhh
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Ouch! Sorry for your bad luck! If you need any parts let me know, I think I've got some good used cylinders and pistons. I might even have a NOS piston.
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oem kaw clips have no tab...i've seen a couple tabs break off from vibration?....i've used a few spi piston kits for myself and others,with good results and reasonably priced.