Engine won't start.

Agreen said:
Terminology time:

4 stroking - when the engine is "sputtering" or has that "machine gun" feel. Due to having too much fuel (rich)

Bogging - A notable drop in power, without any other strange noises. Sounds like (and feels like) the engine is just spinning down and not producing power. This is due to a lean condition (too little fuel)

Now, the situation you described above with turning off the fuel sounds like it is just normally running too rich. Once the bowl starts to empty, you start to experience a short moment of correct air/fuel mixture and it runs good for a second, then runs out of fuel and bogs entirely.

That could mean a couple things. One possibility is that you are running your oil mix too thin. More oil per part of gas makes the air/fuel mixture more lean. Less oil means a more rich condition. You're experiencing a "too rich" condition, so try a higher oil/fuel ratio? What is yours currently, and how do you mix it?

Another cause can be the needle. It's connected to the carburetor slide with an "e-clip". Move the clip up to go lean, but this only adjusts air/fuel mixture up to about 3/4 throttle.

If changing your gas/oil mix and moving the needle doesn't help, I'll step you through re-jetting the carb.
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Oil mix was moved from 16:1 to 20:1 as per instructed by the manual though that was running fine for quite some time before this. It's mixed in a 1 gallon a bit at a time with a predetermined amount of oil for 2 stroke engine oil. Definitely feels like 4 stroking from the explanation.
 
Wow that's a heavy mixture. So it's obviously not the gas mixture. It's "recommended" by the manufacturer to go that heavy on the oil, but 24:1 is a reasonable starting point, moving on to 36:1.

Anyway, move the needle clip up a notch or 2 and see what happens.
 
Agreen said:
Wow that's a heavy mixture. So it's obviously not the gas mixture. It's "recommended" by the manufacturer to go that heavy on the oil, but 24:1 is a reasonable starting point, moving on to 36:1.

Anyway, move the needle clip up a notch or 2 and see what happens.
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It was sitting on the second one down from the top so I moved it up to the last one.
 
So there's one more thing to try before rejetting, and that's the ignition system. Replace the spark plug with an NGK B6HS. You can get it from any auto parts store for about $2. Gap it to 0.025".

The last effort has 2 paths. Either buy a set of jets, or buy the stuff to solder and drill your jets. And there's ups and downs for each path.

Buying Jets:
Pros
-easier
Cons
-they aren't all made equally (the jet orifices are randomly sized sometimes )
-I don't know any reputable sellers that you can buy them from (*cough gasbike cough*)

Drilling jets:
Pros
-More accurate
-I have a video that explains how to do it
--you can potentially get everything in local stores if you have an actual hobby store nearby
Cons
-not as easy

I'll dig up that video here shortly.
 
I feel like a complete n00b. Looked around at 4 stroking and whatnot since I last posted and researched quite a bit and tried it a couple of times. I'm thinking about posting a video. I do believe it's still too rich though. It's very short bursts. Like small jerks. Wait for 2-3 seconds jerk again. Sometimes 5-6 seconds before another jerk. Deflooded the engine from trying to start it before cause it was literally reeking with gas and tried it again. There were more consistent jerks when I turned the gas back on after it filled with gas a bit but then it just seems to flood again. Would adjusting the float bowl actually do anything to help lean out the gas? I've got a multimeter ordered to check the electrical and I'll probably get the rest of the tools I don't have by early next month. Do I need a torch to heat the jet to use solder or could I just use a lighter? I don't know the temp solder needs to heat at in order to melt. My current spark plug is a BPR6HSA. Gap is unknown.
 
DarkWolf2k said:
I Looked around at 4 stroking and whatnot since I last posted and researched quite a bit and tried it a couple of times. I'm thinking about posting a video.
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I'm glad you're doing the research! Most people would have thrown their hands in the air and given up by now. Unfortunately, it's real hard to describe problems and diagnose them without actually being in front of the bike. A video would be helpful.

DarkWolf2k said:
I do believe it's still too rich though. It's very short bursts. Like small jerks. Wait for 2-3 seconds jerk again. Sometimes 5-6 seconds before another jerk. Deflooded the engine from trying to start it before cause it was literally reeking with gas and tried it again. There were more consistent jerks when I turned the gas back on after it filled with gas a bit but then it just seems to flood again.
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That does sound too rich.


DarkWolf2k said:
Would adjusting the float bowl actually do anything to help lean out the gas?
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Maybe. Remember the question earlier about if gas was leaking out the air filter? I kind of got to wondering if the engine (and carburetor) are level or not. If the carburetor's air filter points up, it may be that the float isn't able to do its job (because of the angle) and gas may be pouring in the engine. Maybe.


DarkWolf2k said:
I've got a multimeter ordered to check the electrical and I'll probably get the rest of the tools I don't have by early next month. Do I need a torch to heat the jet to use solder or could I just use a lighter? I don't know the temp solder needs to heat at in order to melt. My current spark plug is a BPR6HSA. Gap is unknown.
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If not a torch, use a cheap soldering iron. They usually come with solder. Try to get the NON lead-free solder. Lead free stuff is harder to melt. Also, thinner solder is easier to melt.

That's a good spark plug, but expensive and unfortunately not worth it. Those will last 100,000 miles in cars. The B6HS (copper core, but otherwise the same) has a lower resistance (better for spark) and is designed to last 30,000 miles in cars. Either way, if they foul up (Google image search for "fouled spark plug") you should replace it. You could clean it, but it's hard to do right without a media blaster. And check the gap (spark plug gap tools are usually under $1 and found at the register at auto parts stores).
 
The spark plug was the only one they could link the chinese stock one to in O'Reilly's system that was also able to have it's crown taken off as per instructed by the manual. It's roughly about 2.99-3.19 each time so it's not too bad. I like the idea of a better spark so I'll try to keep that in mind. The carb is mostly level. Though it's off by 15-20 degrees. I'll check the float with it slightly off like it is when it's on the carb to see if it'll still float like that. Gonna be messing with it for a while more today to see if I can work some magic.
 
Warning: Do not use BPR6HSA as a replacement spark plug!!!!! It has apparently hit the top of the piston and slightly scratched it. I will be getting a B6 or B5HS.
 
DarkWolf2k said:
Warning: Do not use BPR6HSA as a replacement spark plug!!!!! It has apparently hit the top of the piston and slightly scratched it. I will be getting a B6HS or B5HS.
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By slightly I mean there is luckily a small area about 3/4 the size of the end of a pen with a very small indent instead of a larger bigger gouge. THE BPR6HSA WAS SUGGESTED BY O'Reilly's STAFF so watch the size of your spark plugs and always compare them. The Z4C stock chinese plug linked the O'Reilly's staff to that certain plug. This is the first bike I've worked on and I was lucky to not destroy something instantly if I haven't already.
 
Dude any auto parts store will recommend "better" spark plugs. Usually they are platinum or iridium and cost more.

So did the gap get closed off?
 
Agreen said:
Dude any auto parts store will recommend "better" spark plugs. Usually they are platinum or iridium and cost more.

So did the gap get closed off?
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They didn't recommend them because they were "better" but because those were the only ones their systems could connect to the stock spark plug numbers from China or w/e. The gap got closed off. I dropped a B5HS in it. It works but I'm afraid at what cost if there's metal fragments running around in the chamber. I'm glad it's not mine cause the owner wants to keep running it without taking it apart and actually checking. Which I told him is a bad idea if he wants to keep it for awhile but w/e. All this experience I'm sure I'll probably end up buying one myself. The B5HS has a more flat tip like the stock plug. The other one my friend ended up buying wasn't even that far off of stock but it's a slant head so I guess that small clearance in the chamber makes all the difference. Anyway. I got the fuel mixture as close as I can for now. I think the throttle cable needs to be adjusted where it connects to the carb. Seems like it's causing it to be pulled slightly as the idle always seems a little too high. Since I learned better how to tell if it's flooding or if it's lean I've pretty much been able to keep it going nonstop now that the spark plug deals been taken care of.
 
I like enough slack in throttle cable to be able to lift it about 1/8in before it pulls the slide up.
 
crassius said:
I like enough slack in throttle cable to be able to lift it about 1/8in before it pulls the slide up.
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I like it to be a bit tight with just a hair or two of slack. Any info on running in cold / humid climate? Every time it gets cold around here it's literally a wall of mist everywhere that isn't directly in town and sometimes part of town too. It'll go for another 10-15 minutes before starting to act up in the mist. I read that fuel is denser and oil is harder to move so I was thinking a hotter plug on it when the cold sets in at night. Like 6 or 7 during day and a 4 or 5 at night.
 
In other news another friend of mine bought an 80cc out of a shop and one of his engine mount bolts broke off in less than 2 weeks. Lol.
 
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