80 kdx ignition problems

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bigerestblazer
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80 kdx ignition problems

Post by bigerestblazer »

hey this is my first post so take it easy on me ok? :grin: So i have a friend of mine that owns a bike shop and i was poking around and found a 80 kdx 175 in his back shed that i bought off of him for next to nothing. from the look of the bike its been well cared for he said the guy who had owned it said it didnt have any power and when it had been brought in he couldent even get it to start when kick starting . the guy didnt want to put any money into it so he just gave it to my friend. SOOO i get it home test the compression and its 140 psi and drag it behind my 4-wheeler and it starts so i assume its the stator so i order a moose coil kit and put it in. still nothing so i replace the cdi and swap in a different coil from a running kdx. still nothing and now it wont spark at all since i replaced the coils on the stator but it ohms out to the correct settings. By the way the kill switch is disconnected during this whole test period so it cant mess with the results.SOO my question is is there something im missing before i go spend 500.00 on a pvl ignition system since thats about the only way i see this thing running anytime soon but i dont want to lose the bottom end grunt by removing my flywheel. i really hope i covered everything but if i didnt feel free to ask. thanks
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Colorado Mike
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Post by Colorado Mike »

Why in the world would you think the coil, CDI, etc. is bad if you got the bike started behind your four wheeler? If it made good spark, the ignition was good. I would think the reason it makes no spark now is because you screwed something up while fixing something that was not broken, or one or more of the parts you put in are bad. If I were you I would put it back to the way it was when you got it, thoroughly clean the carb, especially the pilot jet which is probably the real problem, and make sure the floats are working properly.
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Post by fuzzy »

It started when you pulled it? Would it then run fine? Idle?

You're just thinking you have weak spark when your kicking or something?

contact http://www.frpoffroad.com/ to see if he has a stator, instead of switching to a mag, but not sure if that's the problem. Clean all connections real well.

Edit: LOL, Colorado Mike and I seem to be reading/writing to all these posts in harmony today.
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bigerestblazer
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Post by bigerestblazer »

colorado mike- i cleaned all the connections and carb befor i messed with anything else. the only reason i decided to replace the coils was just to see if it would increase the spark. fuzzy- it wouldent idle at all i had to keep it revved up so it wouldent die but it ran awesome as long as it was revved up so yet another reason for my assuming the stator.thanks for the responses i really want to get this bike going havent had a bike in about ten years really looking forward to riding again.
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Post by scheckaet »

sounds like your pilot could be plugged up, or maybe choke not working right. Use some wire to really clean the gunk out.
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Post by Indawoods »

Yeah... sounds like a fuel delivery issue to me too....
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Post by bigerestblazer »

ok i just pulled the carb back off and ran a tip cleaner through the pilot and main jets and checked that the choke didnt have anything in it and it all looks clean . pulled out the reed cage to make sure the reeds werent cracked and they look good. (had a brand new set of reeds crack once on my 250r so thoght that might be the problem) my friend with the running kdx 175 is going to let me try his stator later this week to see if that will fix the problem. hopefully that will do it since everything else looks good. thanks again for the responses.
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Post by Julien D »

Good luck, hope it works. You can check the spark without switching the stator out, you know? I would still bet on clogged pilot circuit anyway. Running a "tip cleaner" (whatever that is) through the jets doesn't necessarily fix the problem. Any one of several tiny passages in the carb could be blocked and cause this exact symptom. This sort of thing is quite common on bikes that sit for any length of time. Stators however, don't usually go bad from just sitting around.
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Post by Indawoods »

Guitar string works best.... it does not damage the jet.
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Post by bigerestblazer »

ok time for an update. swapped the stator and now i have spark but it still wont fire. then i swapped the carb and still nothing. i talk to my friend and he says it has a new piston and rings that the other guy put in and all new seals that he put in when he was trying to get it running. it has a little bit of leakdown when compression tested but i figured thats normal since it hasent had the rings set yet but now i dont know. ive replaced almost everything there is to replace trying to figure this out but nothing. do you think if i drag it and start it and just run it until the rings set that that will help? just wondering if anyone has any other suggestions befor parking it in my shed :cry: thanks
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Post by Colorado Mike »

The rings have nothing to do with a 2 stroke leak down failure since the ports allow the crankcase to pressurize anyway. I hope you aren't using a 4 stroke leak down test method, since the high pressure will likely blow out your crank seals in testing. 2-stroke leak down pressure is about 6 psi. It should hold that pressure for minutes, not just a few seconds. I would make sure the pipe/silencer is clear, take the air filter off, make sure the fuel hose can deliver good fuel flow into a container for a long time. Then try his carb on your bike again. This is assuming the leak down works as it should. If not, you could be sucking so much air in that you don't draw fuel in through the carb.

edit: After re-reading your posts, all I said above still holds true, but some other points.. It sounds like someone swapped the piston on this thing, and who knows if they knew what they were doing. I once had a "professional" put the wrong piston in my MX bike and it would only want to run at high RPM. It was hard to start and once it ran it took maybe a full minute to get up to high enough RPM to where it would run cleanly. Another possibility is that he put the piston in backwards, but I would be surprised that it would run at high RPM since I believe the intake port would be blocked. On that old bike it's super easy to check though. Take the pipe off and I think there's 5 head bolts on those and you're in. Usually there's an arrow or a dot on the piston crown that points to the exhaust port.
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Post by bigerestblazer »

colorado mike- i took the head and jug off yesterday and the piston is brand new and facing the right way. ill have to check and see if its the right one but the cylinder is scored and the local machinist says he should be able to polish it out without going through the plating. that would probably be a big chunk of its leakdown problem. we'll see what happens tommorow when i go pick it up and put it back together. i dont know why it gave me a pressure test of 140 right off the bat and now barely has compression. freakin screwy if you ask me considering i only ran it for a couple of minutes and the piston looks fine. might of had something sitting on top of the piston that got down there or something i dont know just thinkin out loud. thanks for the help

edit- it is the correct wiseco piston that is no longer available from wiseco so at least i have a brand new one right :grin: if i ever figure this thing out that is :?
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Post by Colorado Mike »

I think you're missing the point on the leak down test. On a two stroke, a leak down test is checking that the cylinder, head, AND CRANKCASE is air tight. That is to say air-tight to the outside world. It's different on a four stroke, which normally has it's crankcase deliberately vented to the atmosphere.

On a two stroke, you could have a half inch gouge running down the bore causing the compression to be zero, and it very possibly could still pass a leak down test. Obviously a two stroke needs compression too, but that's a separate issue from leak down.

In your case, it sounds like you have at least 2 problems. You say the compression once measured 140 PSI and now the motor barely has any. That's pretty odd, without a loud bang between when it had some to now, it's hard to explain. I would wonder if you had put a little oil in the cylinder when you were testing if it would have measured 140 again. If so, that would indicate a ring seal problem. Maybe all will be well when you hone it and replace the rings, but I would recommend a proper two stroke leak down test, and verification that you have a fat pretty spark before investing too much energy in trying to start it.

Good luck and keep us posted.
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bigerestblazer
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Post by bigerestblazer »

well i put the top end back together and honing helped a little not too much. put oil in the hole that helped quite a bit it will blow your finger off the hole so im going to order a new set of rings a see if that helps. im kindof getting tired of fighting with this one so im looking at a 91 kdx250.i just want something to ride that i dont have to put money into all the time so this might be it for the 175 if i get the 250. anyway thanks for the help and if the rings work ill get back to you.
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Post by Indawoods »

I think you need to look for something that is sustainable. If something is toast on the 250 your going to be in the same boat. Look for a 95 and up 200 or 220....
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Post by bigerestblazer »

OK IM OVER IT!!! ive sunk almost $650.00 into this bike and it still doesnt run without pull starting it. it passes a leakdown test,with newly coated cylinder and piston rings ive got 150 psi compression,new reeds, a spark that will jump over a 1/4 inch and a new mikuni carb that i had for my atc250r and it still wont run!!!!! the carb was re-jetted to OEM SPEC and has no problem running the trike but wont even start the bike. it wont even cough. :mad: the timing is dead on since once you pull it it runs like a top.
im regretting ever starting this project just wish i would have put the money into a running bike but hey im stubborn and stupid and hate to admit defeat but im done. anyone needs some parts for a 80 through 82 kdx175 pm me and ill sell you what you want. thanks to everyone who tried to help i really appreciate it and if i pick up the 98 kdx 220r im looking at ill be talkin to ya.
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Post by fuzzy »

Sorry to hear that.

It idles fine and everything once it's pull started? Is the mikuni from the ATC the same carb? OEM spec for the ATC or KDX? Slides same?
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Post by bigerestblazer »

fuzzy- it will idle when pull started. slides ,needles and jets are all the same as kawasaki oem. someone suggested i try a different flywheel as sometimes they get weak but if im getting a nice spark i dont know what that will help. just at my wits end on this one . if i had someone to go riding with all the time i would just pull it but 85% of my riding is solo so that doesnt quite work. guess its back to the quad or trike as the 220r i was looking at sold. hopefully anotherone will came up as i really like my buddys bike. thanks
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Post by bigerestblazer »

Well i lied i couldent just let it go and gave it another leakdown test with pressure and vacuum. pressure it holds just fine and vacuum wont hold at all. i just did pressure before. so i got new crank seals and put them in and wadda ya know it runs. crank seals must have dried over time i dunno? wish i would have thought of trying a vacuum test before all the other stuff i tried but hey at least it runs and i can go play. thanks for all the help guys!
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Post by SS109 »

Glad to hear you got it going. Now, where are the pics? :mrgreen:
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