Sputtering Engine

[Lord_Loaf]

You've seen me ask about tires and small engines, now for my final act...
The SPUTTERING ENGINE!

I have this old Motovox MBX (they're universally the same across the entire MBX series) engine that I wired a kill switch to. The only way I was able to get it working was by spraying some starting fluid into the carb. Even then, it just started up for a second or two before sputtering up and dying. I'm doing ongoing research into it myself, but I'd love to hear input from you guys. If anyone wants pics, I'd be happy to supply.

Many thanks!

P.S.:The engine came with no air filter from the dude whom I bought it from, so please point me out if it's not starting 'cause I'm just being dumb

 

[Rampage]

Have you cleaned out the carb yet?

 

[Lord_Loaf]

Have you cleaned out the carb yet?

Not yet, I'll look into it though.

 

[Nosandwich]

Definitely needs a carb clean, and get an air filter on it ASAP!

 

[Lord_Loaf]

UPDATE: I cleaned the carb, changed the oil, checked the fuel line, yet it still only runs when on starter fluid. I know that the spark plug works and that it gets air, the only thing it isn't getting is fuel. I'm thinking it's either the carb itself, the fuel regulator, or something deeper. I'm gonna check out the ignition chamber of the engine for scratches or broken rings sometime soon, I'll keep y'all posted.

 

[bob58o]

Definitely a carb or fuel delivery issue.
Carbs are SOB’s to clean. Have to take it completely apart and poke out every hole. See video link below.

What kind of fuel regulator?

https://youtu.be/vrV-iIx85FA

Replacement carbs are probably pretty cheap.

 

[Texan]

Do you mean fuel filter? They can be put on backwards, so you can check that. Your carb float needle may be stuck closed. Also you user name makes me chuckle

 

[Lord_Loaf]

Me n my brother checked out the carb and saw it faulty so we're gonna be replacing that. We haven't checked the fuel filter yet (on another note I meant fuel filter instead of regulator, my bad). I plan on taking a look at it along with the inside of the engine sometime this weekend. I'll keep y'all posted and I really appreciate the feedback from all of you guys

 

[landuse]

Me n my brother checked out the carb and saw it faulty so we're gonna be replacing that. We haven't checked the fuel filter yet (on another note I meant fuel filter instead of regulator, my bad). I plan on taking a look at it along with the inside of the engine sometime this weekend. I'll keep y'all posted and I really appreciate the feedback from all of you guys

Unless you really have to, I wouldn't take the engine apart to look inside. Taking an engine apart is the last resort when carb cleanings, etc etc etc have failed. There is just so much else you have to worry about like gaskets, putting it all back together correctly etc. Have a look at the more likely problems first

 

[mckutzy]

So what engine is this exactly... Pics???

 

[pulsar2121]

A lot of times with small engine carbs, I'll just replace them as opposed to cleaning or rebuilding them. Replacement carbs can usually be found on ebay very cheaply and will yield better results than just a cleaning.

If you are getting fuel and spark and it's still not starting up, check your compression before disassembling. For a small engine, you should be around 100 PSI or more. You can use AutoZone's or Oreilly Auto Part's loan-a-tool program if you don't want to spring the cash for a compression test kit. They are fairly cheap at Harbor Freight Tools as well.

If your compression is low, then engine disassembly would be necessary to check for any internal damage or improperly installed cam parts. I had the rocker arms move off the pushrods on a similar engine (Predator 79cc) that stumbled me for a long time. Keep in mind those rocker arms have to be put back in place every time you remove the cam on an OHV engine.

 

[Lord_Loaf]

So what engine is this exactly... Pics???

This is a Motovox MBX engine. The MBX series uses the same engine.
https://drive.google.com/open?id=0B-anblyXLW-BSk5kWFRzQkNzN3JvNGhHYjFwTGFiakdwUDd3
https://drive.google.com/open?id=0B-anblyXLW-BRldOZXdZV0tkdzhDSTVzNmg2Q2VGWUdwNUdn

 

[Lord_Loaf]

UPDATE: New carb came in along with the air filter (at last!) and the engine now works, but it sounds weak. Think I'm going to take a look inside next weekend to see what the issue is.

 

[Lord_Loaf]

FINAL UPDATE:
It's alive! IT'S ALIIIIVE!
I got it to work via carb replacement a while back, but I just wanted to give an update.