Need help with mk2 - strange no spark problem
Posted: 27 Dec 2019, 16:09
Dear All,
I hope some guys still read the forum, whom can help me with this issue.
Unfortuntely I think I know the problem, what I don't know is what might have cause it...
So I bought my bike approx 2 years ago, it was a mess and I had to renew quite a lot of things on it to get it working properly.
Last year my CDI failed, and after reading a bounch of post on this forum, I came to the conclusion that best thing to do is to buy a brand new chinese "Lixianda" CDI, the 604 one which fits my bike.
/Have to mention that I have also changed the rectifier, the spark plug, the power valve (which turned out to be causing the problem), and the HT coil as well. And finally the CDI.../
All went well the CDI was working, but the bike developed a very bad engine noise so I decided to take it to my friend, a pro motorcycle mechanic to rebuild the engine.
I don't want to waste your time reading how much I sucked with the rebuilding process using a Hot Rod EXC conrod, machinng from the top end...etc..etc.
So a few days ago, -actually on friday- before Christmas my bike was ready. On saturday I took it for a run-in test ride on the field nearby. It was 10 degrees celsius here in Hungary, so I didn't freeze to death while riding.
I did a couple of turns on the field, I gently twisted the throttle a few times and stopped the bike after. It was running quite rich but I didn't really wasted my time tuning the engine as I just wanted to make a few turns.
I was going fairly slow when it died for the first time. I though the slow ride chocked the bike, so I quickly fired it up again and went out for a fast run to burn-out the fuel built up in the engine.
But the bike didn't revved up properly and soon it stopped again. As I kicked it it was misfireing, I knew it must be a no-spark issue.
I took out the spark plug, it was wet&black, after some cleaning it was giving sparks. So I started up the bike for one last time, as it died very fast and never run again. We have towed the bike in 3rd gear, but nothing. so I took it home, checked the plug but there was no spark anymore.
At home I also checked the power valve line:
-power valve turning nicely
-power motor works with a 4,5V battery like a charm.
-power motor potetiometer works perfectly going from 0-5(ish) kOhm, and 4Kohm on the "fixed ohm" ends.
-Kill switch okay, no contact error
-don't know the exact name, but the big rotating magnet (flywheel?) is not loose or anything
Haven't checked the following yet:
-sidestand switch, which is already shorted (and worked for 2 years in dirt, mud, underwater and all conditions you can imagine), but u can never know...
-magneto for signal to CDI
-rectifier voltage (which is going to be a tricky one, but I thought I'd be rotating the flywheel with a drill to see the voltages?)
What else should I check that could lead to a no spark situtation?
Also I'm in contact with the lixianda guy, but he didn't really gave me too many ideas. Don't get me wrong, he's helpful, but maybe here someone has some good ideas as well.
Looking forward for some helpful thoughts!
Many thanks in advance!
Pumee
PS: Sry, I forgot to mention that I think my CDI is down, thats why my bike didn't revved up bcouse the power valve didn't open anymore. When my first CDI died the simptoms were the same, first no power valve opening, than didn't run anymore, than the sparks went "weak", and finalyy no spark at all)
I hope some guys still read the forum, whom can help me with this issue.
Unfortuntely I think I know the problem, what I don't know is what might have cause it...
So I bought my bike approx 2 years ago, it was a mess and I had to renew quite a lot of things on it to get it working properly.
Last year my CDI failed, and after reading a bounch of post on this forum, I came to the conclusion that best thing to do is to buy a brand new chinese "Lixianda" CDI, the 604 one which fits my bike.
/Have to mention that I have also changed the rectifier, the spark plug, the power valve (which turned out to be causing the problem), and the HT coil as well. And finally the CDI.../
All went well the CDI was working, but the bike developed a very bad engine noise so I decided to take it to my friend, a pro motorcycle mechanic to rebuild the engine.
I don't want to waste your time reading how much I sucked with the rebuilding process using a Hot Rod EXC conrod, machinng from the top end...etc..etc.
So a few days ago, -actually on friday- before Christmas my bike was ready. On saturday I took it for a run-in test ride on the field nearby. It was 10 degrees celsius here in Hungary, so I didn't freeze to death while riding.
I did a couple of turns on the field, I gently twisted the throttle a few times and stopped the bike after. It was running quite rich but I didn't really wasted my time tuning the engine as I just wanted to make a few turns.
I was going fairly slow when it died for the first time. I though the slow ride chocked the bike, so I quickly fired it up again and went out for a fast run to burn-out the fuel built up in the engine.
But the bike didn't revved up properly and soon it stopped again. As I kicked it it was misfireing, I knew it must be a no-spark issue.
I took out the spark plug, it was wet&black, after some cleaning it was giving sparks. So I started up the bike for one last time, as it died very fast and never run again. We have towed the bike in 3rd gear, but nothing. so I took it home, checked the plug but there was no spark anymore.
At home I also checked the power valve line:
-power valve turning nicely
-power motor works with a 4,5V battery like a charm.
-power motor potetiometer works perfectly going from 0-5(ish) kOhm, and 4Kohm on the "fixed ohm" ends.
-Kill switch okay, no contact error
-don't know the exact name, but the big rotating magnet (flywheel?) is not loose or anything
Haven't checked the following yet:
-sidestand switch, which is already shorted (and worked for 2 years in dirt, mud, underwater and all conditions you can imagine), but u can never know...
-magneto for signal to CDI
-rectifier voltage (which is going to be a tricky one, but I thought I'd be rotating the flywheel with a drill to see the voltages?)
What else should I check that could lead to a no spark situtation?
Also I'm in contact with the lixianda guy, but he didn't really gave me too many ideas. Don't get me wrong, he's helpful, but maybe here someone has some good ideas as well.
Looking forward for some helpful thoughts!
Many thanks in advance!
Pumee
PS: Sry, I forgot to mention that I think my CDI is down, thats why my bike didn't revved up bcouse the power valve didn't open anymore. When my first CDI died the simptoms were the same, first no power valve opening, than didn't run anymore, than the sparks went "weak", and finalyy no spark at all)