Gotta Super Rat that quit firing

sunshinebiker

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Mar 24, 2013
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Surfside Beach, TX
I installed a BGF motor kit that turned out to be a super rat. It went together pretty easily, and I loaded it up with fuel. A few start attempts and it fired up. I rode it slowly around the block, stopped and restarted. All was good. I took it up the street about a mile or so and rode it back.

I started it again and it started to bog down under throttle. It stalled and I restarted it. I locked down the clutch and ran it for a couple of minutes to adjust idle. to restart it. No go. Brought it in the garage. I have:

Checked the fuel filter to make sure it wasn't clogged up with tank crud

Verified that the kill switch functions properly

Opened the magneto cover and no wires were broken or pinched, and continuity checked good on all wires.

I checked resistance across the magneto (red to ground) and it was 568 ohms. Red to spark plug wire was 1478 ohms and black (ground) to spark plug wire was 913 ohms. Do these values indicate a good or bad magneto/coil?

Is there a specific clearance between the flywheel and the magneto pickups that is required? There were scrape marks on the flywheel where the pickup rubbed the aluminum part of the flywheel.

Also, the flywheel has three magnets next to each other. When looking at the flywheel installed, the magnet in the middle has more attraction to a piece of steel than the ones on either side of it. None of the magnets has a great amount of pull compared to the magnets in a lawnmower flywheel, but I don’t know if that is normal for a smaller engine.

Any advice or recommendation you have would be very helpful.
 

Norman

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could you describe your engine better? china 2 stroke or is it a 4 stroke?
BGF has sold different types over the years. My experience with him is sometimes you get a good engine and most of the time you get a turd.
Photos help too.
Norman
 

sunshinebiker

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Mar 24, 2013
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It's a 2-stroke 66cc. Clutch grabs and holds good.

It appeared to have been run tested as the spark plug that was originally attached looked like it had been run for a short time.

Here are the pix.
 

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2door

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Your discription of the magneto, magnets and wire colors are not consistant with a Chinese 2 stroke, no matter the name, brand or vendor. Typically you'll see a blue, a black and a white wire from the engine and a corrosponding blue and black wire from the CDI. Kill switches come with a variety of wire colors but they are not significant.

The magneto magnet (rotor) has only two magnetic surfaces, or lobes.
We'll need to see some clear photos of your magneto and how you have it wired. Remove the left side cover and take a picture of your magneto.

Tom
 

maniac57

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Oct 8, 2011
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It's a new one on me. I've never seen a china girl like that. Looks like it was part of a pull-start conversion maybe?
 

2door

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Okay, anyone ever seen anything like that before?
I'm always ready to learn and I've not seen a magneto like it. Must be something very new or very old.

Tom
 

2door

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It's a new one on me. I've never seen a china girl like that. Looks like it was part of a pull-start conversion maybe?
That's a good bet. Those ears had to have had some function.


The strange thing is the coil. Only two screws?
Tom

EDIT: Looks like a high voltage lead (spark plug wire) coming directly from the coil?
 
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2door

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I think what we're seeing here is a totally new and never seen magneto where the CDI has been combined with the mag coil in one unit much like the 4 strokers have.

My bet is the "red wire" the OP says he has is a kill switch (ground) wire that plugs into the spade clip we see on the side of the coil.

Tom
 

sunshinebiker

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Mar 24, 2013
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Surfside Beach, TX
Here are a few more that show the 3 magnets on the flywheel. The scrapes on the wheel appear to be from the magneto pickup making contact with the wheel at some point; I can't tell if it happened after installation or if it came to me like that. I didn't open the magneto cover until after the engine quit running.

The 3 screw holes on the cover lend me to think that it is a super rat, as well as a view on gasbike.net, that appears to show the back side of the flywheel.

http://www.gasbike.net/magneto-magnet-super-rat-2902-prd1.html

I've read on several forums that the magnets go bad before the magneto coils do, but I don't know what the strength of the magnets should be.
 

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sunshinebiker

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Mar 24, 2013
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It does appear to be a very new or very failed product. I have only found one of the coils for sale on a site in Australia for AU$60. Seems spendy to me, and would take forever to arrive.
 

2door

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Regardless of what it is you need to try to confirm that you have ignition.
Have you tried that and how?
I have to think the red wire is part of a kill switch circuit. It shouldn't be touching anything for the engine to run or get fire to the plug.

Tom
 

sunshinebiker

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Mar 24, 2013
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Surfside Beach, TX
Red wire goes to the spade terminal; black to the engine case. I took switch out of the circuit to simplify testing. Then I spun the rear wheel while holding the plug (attached to its wire) against the engine head. Didn't have the nads to actually hold the business end while it was turning. Been shocked by a few thousand volts too many times in my life.

I do know that magnetos require a pretty strong magnetic field to generate enough energy to create a spark, and a fairly rapid rotation.

But, so far I haven't been able to get any spark to appear.

Any tricks you know about checking for spark is appreciated.
 

BigBlue

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Nov 29, 2011
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Here's more info. on the Super Rat engine from Grubee, about half way down the page:
http://www.grubeeinc.com/USA/Magneto Mystery.html

Looks like there is a ground connection on the CDI MAG. I'd make sure the unit is securely grounded. I don't know how much play you have between the CDI MAG and the rotor. It maybe too wide. You may want to see if you can cut a business card length-wise and place it between the CDI MAG and the rotor. Push the CDI MAG against the rotor and tighten the retaining CDI MAG screws. Remove business card. this may give you the proper gap for spark.

Good Luck,

Chris
AKA: BigBlue
 
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maniac57

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Oct 8, 2011
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Here's more info. on the Super Rat engine from Grubee, about half way down the page:
http://www.grubeeinc.com/USA/Magneto Mystery.html

Looks like there is a ground connection on the CDI MAG. I'd make sure the unit is securely grounded. I don't know how much play you have between the CDI MAG and the rotor. It maybe too wide. You may want to see if you can cut a business card length-wise and place it between the CDI MAG and the rotor. Push the CDI MAG against the rotor and tighten the retaining CDI MAG screws. Remove business card. this may give you the proper gap for spark.

Good Luck,

Chris
AKA: BigBlue
Reminds me of using a matchbook to clean and gap the points in my '62 Dodge...
Used the striker to clean the contacts and set the gap with the cover.
Good memories...
 

Norman

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First time I've seen an engine kit with that magneto set up. I personally think a set up with points and condenser might be the way to go on these engines like the Russian engines had. Anyone can work on the old school stuff.
The new and improved isn't always improved.
Good luck, I hope you can get it running.
 

nightcruiser

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Mar 25, 2011
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That is indeed the Super Rat design, quite a bit different than the standard ignition. Its my understanding that they are rare because nobody put up the money to get the EPA certification for that motor, because it is so costly, so they do sell outside the USA but not so much inside. There are some additional changes in the motor, bearings and intake if I recall....
 

sunshinebiker

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Mar 24, 2013
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Surfside Beach, TX
Well, considering my luck, that isn't a surprise. Do you have anything to support the lack of EPA certs for the engine? That may be my way of getting BGF to replace it, since he sure wouldn't want an EPA rectal probe.