Loss of high RPM spark?

[misteright1_99]

I spent a whole day trying to get a mower started recently. Tore the carb all apart, cleaned breather, put it back together and would not start, all day, then took a step back to see what I was missing. Did not oil the foam in beather. Oiled it up like your suppossed to with 30 wt. oil. Bingo started right up. Too much air to fuel...

 

[deacon]

I don't think the one on the bike gets oiled but i don't remember I know I had mine apart.

 

[paul]

mine is oiled. i think it is pretty standard for a foam filter to be oiled

 

[deacon]

If you have oil and it runs then probably it wouldn't act right if it were off. Maybe that is part of his problem.

 

[misteright1_99]

Well I am just speaking in general. I have not even RECIEVED my engine kit yet, and only joined today. Might be worth trying with it on wether they are oiled or not. The restriction of the breather could be accomplished with the choke, but it would not run unchoked because of too much air vs fuel.

 

[deacon]

I think most small engines have a lot in common so speak up anytime

 

[Pablo]

It does effect it to have the breather off, but it should run.

 

[misteright1_99]

Never mind....I got home from work and I reversed the meter leads and got 7.6 meg on blue to plug...so there is some type of diode in there...I think the CDI unit is OK

It started happy as a lark. Sounded good......warmed up slowly jiggling the choke, could rev it OK with choke.....engine warm.....choke almost all the open........give it gas.........gagging low buuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu bowaaaaaaaaaaaaaaa dies. Start and repeat. I think it's the carb.....I tried to get it hot, but it takes awhile......

This is what made me think it might be the breather being off...

 

[Pablo]

Tomorrow I'll put the breather back on.....Old timers - have you guys tried yours with no air cleaner/breather?

 

[deacon]

mine gets warm in seconds. I don't get it has to be the air fuel thing....I haven't was always afraid sand would go through the carb and pit the cylinder walls.

 

[Pablo]

For $22 I might just order a new carb.....Ghost0 will be over next weekend....maybe I'll pinch his carb.....

 

[Bikeguy Joe]

I know it's a bit of a hassle, but have you checked the base gasket yet?

There is also a very slim chance that your crank case seals are leaking, but that would be a loooong shot on a fairly new engine.

I've never run one without the filter, but I have run both oiled and un oiled filters. If you oil it, use light oil and squeeze out ALL the extra you can. I use two stroke mix- put it on, squeeze it out and the gasoline evaporates and leaves just the right amount of oil.

 

[Bikeguy Joe]

Also, please refresh my memory....you said the bike was running fine, then????

How many hours/tanks are on it?

What fuel mix are you using?

 

[Pablo]

Well it never has run that great. I've never been able to give it full throttle under load.....at the time I thought it was just breaking it. It's always taken forever to warm up. It seems to just get worse.

I put the AF back on, decently oiled. Makes no difference.

I reset the idle to 4.5 turns as a starting point, but really it takes so long to warm up it's tough to get a warm idle going.

I'm running 30:1 oil mix, before that about 20:1 to 25:1

It has about 1 tank of fuel give or take on it.

The base gasket looks OK, how should I check it?

Would crank seals cause such a problem?

It seems to be running lean because I have to choke the heck out of it to get it to run, but sometimes when it dies it backfires nasty fuel spray. And the plus are always wet, and rather nasty with fuel.

 

[Norman]

Pablo
Take off the cover on the ignition coil side and take off the mag/rotor check the wood ruff key see if there is a key there. Maybe put the rotor on backwards and try it see if runs worse or if it will run at all. Check the solder joints on the coil while in the cover. You will also be able to look at the main seal behind the rotor if its clean and not oily and nasty its probably not leaking. I'm wondering if its out of time or the key is sheared. Just another bunch of things to try.
Norman

 

[deacon]

I knew there was something about the rotor and the key from the last fellow how couldnt get his to start but I couldn't remember what it was all about. Norman to the rescue again/

 

[Pablo]

Pablo
Take off the cover on the ignition coil side and take off the mag/rotor check the wood ruff key see if there is a key there. Maybe put the rotor on backwards and try it see if runs worse or if it will run at all. Check the solder joints on the coil while in the cover. You will also be able to look at the main seal behind the rotor if its clean and not oily and nasty its probably not leaking. I'm wondering if its out of time or the key is sheared. Just another bunch of things to try.
Norman

I took the cover off yesterday. All appeared OK as I was getting decent signal (-110 to -160VAC) on both the black and blue wires (at the solder joints). BUTT I didn't pull the rotor or look for the key...I will do this tomorrow- it just doesn't seem like an electrical problem...........

So for today's update: I took the carb apart AGAIN - First I tweaked the float lever arm down - problem got worse.....very interesting. Then took the carb apart AGAIN and tweaked the float lever arm up...put it back together and turned the fuel on and had fuel everywhere - oops float is too high.......so I took the carb apart AGAIN and tweaked it down, no fuel blowing out and it ran better....but not quite good.....so I just need a very slight tweak up.

This carb is a freak show....there is something fundamentally goofy about the float and the valve pin....like something is not to specification but I can't spot it.

 

[Norman]

Check my post on the carb, the main jet size and see how yours compairs to mine you may need to solder shut the main jet and redrill the hole. You might try to bend the fulcrum arm on the float instead of the 2 fingers( I don't know which way you did adjust your float) to adjust the float and try to get it to shut off with the float just under level when upside down. While you have the float upside down take a piece of fuel line hook it up to the carb and blow into it and youwill be able to see where the needle on the float shuts off the fuel. You do have the needle on the float in the proper place, it will be sort of in a caged part of the float fulcrum assembly. I hope I'm making since as I'm tired from being at work too much for the last few days. Another question do you have a buddy who has a bike, if so beg borrow or steal his carb and see if it clears up your problem. Then try his cdi coil etc.
Good luck I hope we can get you going.
Norman

 

[Pablo]

Check my post on the carb, the main jet size and see how yours compairs to mine you may need to solder shut the main jet and redrill the hole. You might try to bend the fulcrum arm on the float instead of the 2 fingers( I don't know which way you did adjust your float) to adjust the float and try to get it to shut off with the float just under level when upside down. While you have the float upside down take a piece of fuel line hook it up to the carb and blow into it and youwill be able to see where the needle on the float shuts off the fuel. You do have the needle on the float in the proper place, it will be sort of in a caged part of the float fulcrum assembly. I hope I'm making since as I'm tired from being at work too much for the last few days.
Good luck I hope we can get you going.
Norman

You are making sense. I used your thread on the carb, very handy. When I spread the arms apart, so to speak, it means the same as bending the two fingers down....which means float low. I think the problem started as the float too low. But I bent them up too much and had fuel blowing everywhere....man it's touchy....I need one final tiny tweak up.....argggggggg

 

[Pablo]

Has anyone put a meter on the magneto coil with the engine running?