Chassis electrical system

**CrazyCarl** · 09-29-2008, 02:14 PM

Originally Posted by forchetto

Magnetos on that bike and many others run in oil. Sometimes on Honda Cub derived engines they run dry, but it's quite normal to run them in oil. Can't understand why...

I've wondered about that myself. It may be possible that the alternator (electrical generator) assembly also needs cooling to maintain regularity of output and efficiency of operation.

Automobile alternators are usually belt driven and air cooled, located outside the engine. Since this is not possible in a motorcycle engine due to reasons of simple design and streamlined manufacturing, oil cooling may be the best way to go.

CC

**forchetto** · 09-29-2008, 07:22 PM

Of course. Never thought of that. It's probably OK on small cubs and the like as the low output combined with the large mass of the magneto would provide sufficient cooling.
On larger bikes they would have to provide slots for additional air flow and that would bring the problem of water in the electrics in the rain or when washing.

On some knock-off cub engines there are problems with water penetration into the magneto chamber, as the maker didn't bother to fit a gasket to the outer casing...

Sometimes things are difficult to believe and our limited knowledge can't accept them. An example is the fuel pumps on some cars that live inside the fuel tank, submerged, and the fuel actually runs through the rotor, commutator, etc with no ill effect and no explosions...

**sllawo** · 09-29-2008, 10:16 PM

ok ok guys but I need new magneto for my bike.... Some proposition?

From which another bike I can take magneto... I dont have idea. I try find on ebay but is nothing...

**forchetto** · 09-30-2008, 06:09 PM

Originally Posted by sllawo

I need new magneto for my bike.... Some proposition?

Try this place :

http://www.china-parts.co.uk/acatalo..._Flywheel.html

You'll only need the stator assembly unless your rotor has been de-magnetised. It has been known to happen, sometimes just dropping it on the floor does it, or heating it with a blowtorch to help removal, etc. A demagnetised rotor makes starting very difficult and lowers the overall power output of the magneto.

One way to test both the output of the high tension coil winding, (the one responsible for the ignition system), and the effectiveness of the magnetic field of the rotor is to disconnect the usually black-red wire and connect a transparent gas discharge tube of the type often used in spark arrester protection in telephone lines, etc with about a 90 volt rating, between this wire and chassis. Kick over the engine and observe the blue spark through the transparent glass of the tube. This tells us that at the very least 90 volts are being generated by the coil at kickstart speeds.
The use of a digital voltmeter in place of the discharge tube is fraught with difficulties. Those meters don't respond quickly enough to get a reading.
An analogue meter will put a too high a load on the (high impedance) winding, leading to low readings.

Here's a tool set-up to do this:

You might get a lot of help on this site dedicated to Skyjet bikes exclusively, there's also a list of dealers. One of them must have the stator and other bits.:

http://www.freewebs.com/skyjetowners/

**forchetto** · 10-13-2008, 07:27 PM

Has sllawo sorted his problem?, has he found a replacement magneto and if so where and how much?, is the wiring sorted out and the bike on the road?...Who knows...
Did I waste a fair chunk of my time Googling for spare magnetos, Skyjet owners sites, making up that test rig, photographing it, resizing it on photoshop, uploading to my server and putting it that post?. Probably.
This is the worst bit of being in a forum. People sign up, ask a pertinent question (or sometimes an impertinent one), get answers and then disappear for ever, contributing nothing to the rest of the posters or forum. Feeling mighty unappreciated at the moment.

**CrazyCarl** · 10-14-2008, 01:25 AM

Forch,

That's the way it is with people sometimes. Help some, but can't help them all. Some will hang around and others won't.

In China I helped a fellow rider sell his totally destroyed ZongShen 200 after he finished a two month trip around China. He left China and left the new bike with me to hold for a dude who would come and get it after a while.

The dude came and was of course underequiped. I gave him a place to stay and a very nice pair of my rain gloves. He swore up and down to send the gloves back to me but never did, despite tries to contact him.

Is it super-lame-

? Sure is. Do I like being treated like a dupe?

Sure don't, but I did what I did because I wanted to and no matter what he did afterwards shouldn't change that fact.

Although it takes a lot of time and other resources to create truely informative and helpful posts, the creator still gets something out of the creative process regardless of how it's used afterwards.

If you think it's bad here, at least you aren't dealing with the media! When dealing with media you get so many doors slammed in your face it can be extremely discouraging. Besides different personalities, the decision makers have responsibilites we don't understand and have certain expectations. Only VERY rarely do you find a good person who's even willing to sit down to give you a real response and honest feedback.

I figure, do what you can, when you can and only if you really want to. Naturally we like to see our efforts appreciated but sometimes that doesn't happen and still, the show must go on!

YMMV,
CC

**forchetto** · 10-14-2008, 05:13 AM

You're totally right, of course. Just another one of my rants.
I also contribute to another UK-based forum where I tire of advising youngsters with grand-sounding nicks such as "big-V-twin" against purchasing things like chopper-styled 50 cc Chinese bikes with Monkey bike engines and 3 BHP / 120 kg and the aerodynamics of a brick wall, that they will be disappointed with the poor performance in a week and what do we get?, they come back asking what they can do to tune them up.
You then find that they can't tell a spark plug from a con-rod and have a budget of $2...
This happens time after time and it's frustrating.

**sllawo** · 10-14-2008, 04:29 PM

Sorry guys I wait for money and when I repair my motor bike I do picture and finish this topic. Sorry I really like my bike and I want help this forum to be more popular :)

I need the time. By the way I pass my driving test on category B but my really love are motor bikes :) I go now drink

and don't worry about my topic I still check :)

**ishie** · 05-12-2011, 08:53 AM

guys i have a problem with my motor bike. last morning i check the engine of it. i dont know what is the problem so i'll bring it to my mechanic. he told me that he's done with the alternator repair. i pay him $43.89. just wanna know if the price is too high?

well i just confused since i am new in driving.

______________________________
the price of alternator repair is too high? thinking!