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Eric2.0

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Sep 22, 2010
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Darn. I popped my cover off but I can't see the keyway under the lockwasher. (Did you have a lockwasher under the nut?) So if someone could corroborate that the magnet keyway is supposed to be at "one o'clock" and not "eleven o'clock" that would be great.

Yes..I have a lockwasher and the keyway can be seen after the nut and washer are removed although the keyway sits deep in the grove(I had to shine a light to see it in the slot.
 

Eric2.0

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Sep 22, 2010
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After we sort out which way the magnet keyway is supposed to go, you'll want to gently tap the magnet on the crank to seat it down, maybe with a large spark plug socket wrapped in a rag with a small hammer or mallet. Then tighten the nut and lockwasher down real good.

I found an awesome tutorial on the Grubbe website



Great Magneto Mystery

It says keyway at 1 oclock with piston at TDC.

Seems that those mags are notorious for no start problems... I think I have isolated my problem.. Wish I had another mag to try.
 

Eric2.0

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Sep 22, 2010
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There you go then! All you have to do is pull the magnet off and flip it over! Do it now!
I also found out that the advance and retard is adjustable by moving the slight play in the magnet rotor. So it moving a bit on the crank is normal.

I may have put to much advance in it when I put it back together.

But yes..it says put piston at TDC, keyway should be at 1oclock and rotor flats paralell with magneto arms.
 

Eric2.0

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Sep 22, 2010
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eric change your spark plug they are really easy to foul esp pouring gas in the plug hole.

I tried three spark plugs(NGK B6NS) including the original plug. nothing.

I confirmed the magneto is correct and I get a nice, blue spark. I take it out for a ride and pedal up to 10mph, get the engine rolling and I'll get a slight intermittent pop, but nothing that will keep it running. I pedaled until I literally had to stop and cough while trying to stand up being so dizzy.

Dad and I are going with another round of pulling it with the lawn mower(because I am TIRED of pedaling) and see if it will eventually kick in. If it doesn't this time...It's all I can do and I will be finished.

Sure wish I could find someone in my area that does these things.

Watertown, Evans Mills, Theresa area?? anyone?? please help lol.
 

2door

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Sep 15, 2008
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I also found out that the advance and retard is adjustable by moving the slight play in the magnet rotor. So it moving a bit on the crank is normal.

I may have put to much advance in it when I put it back together.

But yes..it says put piston at TDC, keyway should be at 1oclock and rotor flats paralell with magneto arms.
Eric,
If you're able to rotate the rotor (magnet) on the crankshaft, there's a problem. The woodruff key and the key ways should keep that rotor stationary. You should not be able to move it back and forth. Are you certain the key is in there? If so, check the keyway in the shaft and the rotor. One or the other might be cut too wide. Advancing and retarding the ignition too far could be your problem.
Tom
 

Eric2.0

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Sep 22, 2010
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Eric,
If you're able to rotate the rotor (magnet) on the crankshaft, there's a problem. The woodruff key and the key ways should keep that rotor stationary. You should not be able to move it back and forth. Are you certain the key is in there? If so, check the keyway in the shaft and the rotor. One or the other might be cut too wide. Advancing and retarding the ignition too far could be your problem.
Tom
According to the grubee website, that is normal...

This.. http://www.grubeeinc.com/USA/images/110329/128.jpg

I do agree with you though, because not once have I seen a 2 stroke with so much slop in the keyway.
 

Eric2.0

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Sep 22, 2010
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Sounds to me like an excuse/coverup for poor and sloppy manufacturing.
Another reason why I would never buy any Grubee product.

Probably eh? lol..Wow I am confused, but I agree with you all about this particular issue. Mine is the SD Stinger, but probably the same as a Grubee...who the heck knows.

My patients has grown very thin now.

I'll put the needle in the carb down a notch and see what happens...perhaps it is to rich...deff not oil, because I put a 32:1 ratio in there just to see if it will start without worrying about to much oil blowing the flame out.
 

Eric2.0

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Sep 22, 2010
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So for yo uguys I assume your rotor magnets are solid on the crank without the nut on? Can you cannot turn your rotor back and forth?

This is with the nut off of course...still it shouldn't turn IMO. I can turn it either way a little over half an inch.
 

mapbike

Well-Known Member
Mar 14, 2010
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Central Area of Texas
Tom is absolutely right Eric,

And I will add something else based on some things you mentioned

(1) if when releasing the clutch the engine has enough compression to almost pitch you over the bars, then I would say the compression is fine.

(2) Based on the video you listed, I can tell you that the amount of rotation you are getting with the flywheel/mag. Rotor is to much I've had the flywheel off 2 of my engines and neither of them were like that, best I remember they had very little to zero movement when seated on the crank, that is a problem with either the key or one of the keyways, Now if the nut is tightened down very good while the flywheel is in the proper position it should be fine as long as it fits tight on the crank but yours doesn't, so IMO that is a definite problem that needs to be addressed.

(3) ?.... After a good pull behind the mower have you imediately pulled the plug to see if it has any signs that the engine is actually getting fuel?

You said you have a strong BLUE spark so if that is the case and the timing isn't a mile off that engine should be busting off and trying to run.

In my honest opinion here, you have a very simple problem with this engine that you are missing, and like I brought up origninally in this series of posts.... CORRECT TIMING is essential IF all else is correct.....

IF you do have fuel, compression, spark then timing is still likely your problem and like I said you for curtain have an issue with the play in the flywheel.....that isn't normal on ANY engine....period, that rotor is the link that controls the spark timing in relation to the position of the piston to a great degree, if that engine is firing way too soon or way too late it will not run, and the occational pop you are hearing is just built up fuel vapor being set off by the spark plug at the wrong time.

Fix that lose flywheel issue and make sure you are actually getting the proper amount of fuel through the carb.

I made a new woodruf key for one of my engines by cutting a piece from a flat steel washer with my dremel tool that already has that radius on the edge, tyhat was 400 miles ago on that engine and it's still going strong.


Dont quit on a perfectly good engine most likely, this is a set up & adjustment problem and that engine will run IMHO.

Peace


Eric,
If you're able to rotate the rotor (magnet) on the crankshaft, there's a problem. The woodruff key and the key ways should keep that rotor stationary. You should not be able to move it back and forth. Are you certain the key is in there? If so, check the keyway in the shaft and the rotor. One or the other might be cut too wide. Advancing and retarding the ignition too far could be your problem.
Tom
 

rohmell

Active Member
Jun 2, 2010
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New York
The rotor magnets on all of my engines are fixed to the position that is determined by the cuts in the crankshaft and the magnet. There is no back and forth movement.

I think the SD Stinger is Nantong factory and Grubee is YuanDong factory.
 

Eric2.0

New Member
Sep 22, 2010
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Yepp, with the nut off the rotor magnet I can literally move the rotor magnet back and forth around half an inch each way while the crank remains still. A really sloppy fit of the key and keyways no doubt.

I find it so hard to believe the guy putting it together in China could not see the problem, but then again he could give s crap probably...cheap labor rates and all.
No wonder things seem cheaper built these days since America has almost everything made in China.

I didn't expect a Honda for that cheap, but damn...this is ridiculous. May as well buy these engines with intensions to take it all apart and build it right.

Yes..I get gas..it drips from the exhaust pipe. deff getting gas..plug wet too.
 

2door

Moderator
Staff member
Sep 15, 2008
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Littleton, Colorado
Eric,
There are ways to repair this situation but,
my advice at this point is to contact your seller and ask for a replacement engine. I hope it came from a reputable vendor, one who will stand behind his product. Let us know what you do.
Tom
 

Eric2.0

New Member
Sep 22, 2010
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NY
Eric,
There are ways to repair this situation but,
my advice at this point is to contact your seller and ask for a replacement engine. I hope it came from a reputable vendor, one who will stand behind his product. Let us know what you do.
Tom
Came from 1-888 kit bikes. This was almost a year ago when we got the engine
so I doubt they will give me a new one. I will ask nicely to what they can do though.

I did notice that the key is thin on one end and thicker on the other.. Seems soft and light too. Very cheap looking and not cut very well.

Perhaps they will send me a new key and rotor..

Thanks, guys..for all the help.

I'l take a break, but I will go back to it soon.
 

Eric2.0

New Member
Sep 22, 2010
242
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NY
I'm going to send the link to my video of me moving the rotor to 1 888 kit bikes. Hopefully they will see the problem and work work with me.
 

rohmell

Active Member
Jun 2, 2010
1,531
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38
New York
I think a nice, tight Woodfuff key might take the slop out of the magnet/crankshaft.

If you have a Harbor Freight Tools close to you, this kit has an assortment of Woodruff keys:
80 Piece Woodruff Key Assortment

You might have to Dremel the key a wee bit to get it to the dimensions needed to fit it.