Bike simply wont start. I don't know what to do.

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Morrow

New Member
Sep 21, 2012
22
0
0
Houghton lake, MI
I got a 68.5cc china girl who ran great. But one rainey day later and she wont start I still have spark, My clutch is fully adjusted. fuel mix and fuel filters are ok. She just wont start. I did replace the plug and I don't know if the spacing is right, And I cnt find my old plug witch im pretty sure is fine, Just lost.:-||
 

Morrow

New Member
Sep 21, 2012
22
0
0
Houghton lake, MI
I checked my compression it came out at like 124lbs, My magnet is near horizontal when piston it at its highest point(just past the poles on the coil) tried it without a muffler and without a air cleaner witch was soaked in gas but its always been that way.




:-||
 

GearNut

Active Member
Aug 19, 2009
5,104
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San Diego, Kaliforgnia
I checked my compression it came out at like 124lbs, My magnet is near horizontal when piston it at its highest point(just past the poles on the coil) tried it without a muffler and without a air cleaner witch was soaked in gas but its always been that way.




:-||
There is the telltale sign. The air cleaner should never be soaked with fuel. Slightly oily damp- yes, as a small amount of fuel does spit back when the engine is running. This is normal for a non-reed 2 stroke. It appears that your carburetor is flooding.
Is the carb mounted fairly level or is it at an odd angle? They will work at a slight angle but the float level needs to be adjusted to accommodate the slight angle.
You need to take it off and inspect the float for leaks. Does the float have any fuel inside of it? It should not as that will convert it into a don't float.

Does the float arm pivot freely like it should or does it get stiff or hung up?

Is there any debris stuck it the float needle valve that would prevent the float needle valve from sealing when the proper fuel level has been reached?
Is the float adjusted too high (common from the factory) and allowing too high of a fuel level inside the float bowl?

Are you using an in-line fuel filter? If not you really need to as the screen inside the fuel tank, part of the fuel valve, is horrible and should not be relied upon. Most folks remove the screen as they clog up quickly and instead use a quality in-line filter.

After stating all that, it also could be that the fuel jet inside the carb has fallen out of the jet holder and when you have the engine spinning at a high RPM, fast enough to draw fuel up and out of the float bowl, the carb is allowing an unregulated volume of fuel into the engine. This too can cause the air filter to become fuel soaked as the spit back will be more than normal.
 

Morrow

New Member
Sep 21, 2012
22
0
0
Houghton lake, MI
My inline fuel filter broke, But when I built the bike I cleaned out my tank and I run my gas through a clean rag when I fill it. I took apart my carb and all seemed well and the float does float Maybe it is adjusted too high?
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
Morrow,
I know you said you read through Aleman's advice for an engine that won't start but you haven't said how you've confirmed that you have ignition. It sounds as if you've covered the bases as far as fuel delivery goes so maybe it's time to move on to the other two things it needs to run.
Air and ignition.
Is the choke plate open and does it stay in the open (off) position?

Have you removed the spark plug, reconnected the high voltage lead, held the plug against the cylinder head cooling fins and spun the rear whel with the clutch engaged? The plug should show a good solid spark at the electrodes while doing this.

Tom
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
Going back to the first post of this thread, you said the engine failed to start after a "rainy day". Even if you have spark at the plug it is possible that the magneto is damp and not giving you all it's capable of. When you were checking the magneto rotor position, did you discern any sign of moisture inside the magneto cover?

We're gonna get you running, Morrow. Just hang in there.

How new is this engine? How many miles before it quit running? Oh, and your spark plug gap should be .024 to .030. I typically run mine @ .028. Seems to be a good ball park figure to start with.

Tom
 

Morrow

New Member
Sep 21, 2012
22
0
0
Houghton lake, MI
That Rainy day was two weeks ago. Maybe 100mi? Im on a little less than half tank of my second fill still running break in mix of 18/1. I dont know what my gap is but a penny just barely fits in the gap.
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
The magnet should be close to horizontal if the piston is at TDC (top dead center)
This could be your problem. The woodruff key that indexes the magnet (rotor) to the crankshaft might be sheered. This will alter ignition timing. That means the plug is firing either before or after it's supposed to.
I'd take a look at the key and keyway and while you have the rotor off check that shaft seal behind it. It is not uncommon for the seal to be the cause of engine problems. They are sometimes not seated completely in their bore and the rotor rubs them and destroys them so you have a massive vacuum leak into the crankcase.

If you remove the rotor be careful about prying on it too aggresively. The crankshaft can be bent by using brute force. Use a puller if possible. I use a faucet handle puller sold at Ace Hardware to pull the rotor from the shaft safely.

By the way, you have an experienced motor bike builder, GearNut, helping you. His advice is solid. Listen to him and to whatever he advises.

Tom
 

Morrow

New Member
Sep 21, 2012
22
0
0
Houghton lake, MI
I wish I could check the key but the bolt has been stripped since day one and I cant get the nut off :( I know I've seen him post in every thread and I try everything he says.
 

Morrow

New Member
Sep 21, 2012
22
0
0
Houghton lake, MI
Ok fresh gas still no go. And after lot of back and fourth I figured my timings ok, But while doing that I noticed my plug is only showing spark a third of the time I ordered a new "triple electrode" plug and a new CDI So I guess I'll update when those arrive or if I can find my original Plug Ill post what happens with that.



:-||
 

Morrow

New Member
Sep 21, 2012
22
0
0
Houghton lake, MI
Thats the same thread I looked in so I went and tried to get it horizontal took a few try's but I I got it horizontal and TDC, So Im pretty sure thats ok like I said I ordered a new plug and CDI a few days ago and I just ordered a new coil for ****s and giggles a few minutes ago