Need help with mk2 - strange no spark problem

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PumeeBaa
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Need help with mk2 - strange no spark problem

Post by PumeeBaa » 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)

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Re: Need help with mk2 - strange no spark problem

Post by xstian81 » 28 Dec 2019, 09:00

If you have just had the engine out and now having trouble with running, I would be inclined to check all connectors and earth pionts.

Also worth checking coil resistance. Has the pick up been set to the correct gap to the flywheel? You can also measure pick up resistance and resistance through the regulato rectifier.

If the plug has got wet, try a new plug also.

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Re: Need help with mk2 - strange no spark problem

Post by PumeeBaa » 28 Dec 2019, 22:45

xstian81 wrote:
28 Dec 2019, 09:00
If you have just had the engine out and now having trouble with running, I would be inclined to check all connectors and earth pionts.

Also worth checking coil resistance. Has the pick up been set to the correct gap to the flywheel? You can also measure pick up resistance and resistance through the regulato rectifier.

If the plug has got wet, try a new plug also.
Many thanks in advance, I'll certainly check these as well and come back to you with the results!

cheers,
Pumee

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Re: Need help with mk2 - strange no spark problem

Post by PumeeBaa » 14 Jan 2020, 07:27

Dear All,

First of all, Happy New Year!

Now regarding the bike, I have checked literally everything and all is fine, as I suspected.
So I guess the CDI is dead.(again)

I've just talked with my also electrical engineer friend, who's a circuit designer as well.
He said that the power valve controlling is quite easy, so he is going to build me an RC valve controller with all kinds of safety, to eliminate further problems, like frying the transistors.

So I'd like to change my bike to some kind of an MK1, regarding the electronics. This means that I'll separate the CDI form the RC VLV controller. So if anything goes wrong with the RC VLV part I can still ride home.

Now I would need your help to be able to make this project easier, and maybe to manufacture a CDI-RC Valve combo for all of you out there having issues like me, and make it affordable for everyone.(end of advertisment :) )

I would need some help if anyone knows any other HONDA product which shares the same flywheel with the MK2-3?
Or seen anything similar, and can be bought nowdays...

Also can someone measure at what RPM the Power Valve begins to open, and at what RPM its fully open?

Whit this little info we would be able to make this new controller. So Please help me out if you have a few minutes to check the RC valve opening/fully open RPM's for me.

I guess the CDI-flywheel problem is not such a big deal, but if anyone has any experience with it, I'd be happy to have your opinion!

Many thanks in advance!

Cheers!

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Re: Need help with mk2 - strange no spark problem

Post by PumeeBaa » 23 Jan 2020, 10:33

Hi all,

Any suggestions which CDI would work with this bike? As I mentioned before I'd like to separeate the CDI and PV controller.

Is the MK1 flywheel compatible with the MK2?
I was thinking that i could be using an MK1 flywheel and an MK1 CDI, and use my own PV controller...?

Or maybe some kind of CR?

Any help would be highly appreciated.

Thanks!

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Re: Need help with mk2 - strange no spark problem

Post by knackeredMk1 » 23 Jan 2020, 21:33

Nothing will work without severe modifications. The flywheels have different timing. So even if you use the Mk1 flywheel and loom with a Mk1 ECU and PV controller it won't work as the pickup positions on the crankcase are different.

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Re: Need help with mk2 - strange no spark problem

Post by PumeeBaa » 27 Jan 2020, 22:06

knackeredMk1 wrote:
23 Jan 2020, 21:33
Nothing will work without severe modifications. The flywheels have different timing. So even if you use the Mk1 flywheel and loom with a Mk1 ECU and PV controller it won't work as the pickup positions on the crankcase are different.
Oh Lord, thats bad news, but thanks for the reply.
Any idea if the MK1 and 2 flywheel's signal positions are the same?
I mean they are not in the same position, as you mentioned, but are they the same layout?
Mine has 4 little "bumps" on the inside, guess thats for the rev signal, and three little "bumps" a bit outer(?)for the TDC and something else as well...

is the MK1 the same? Or it has one longer for the TDC and others?

Thanks in advance!

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Re: Need help with mk2 - strange no spark problem

Post by knackeredMk1 » 29 Jan 2020, 09:31

The Mk1 and Mk2 have different sensor positions mounted on the crank case. From memory (and I can't guarantee this) you would be better off putting a Mk3 system on.

There are definite differences between the Mk1 & 2 but I cannot guarantee there are none between the Mk2 & 3.


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