Went through 3 motors within a month (pics)

[Bryan K.]

So I purchased a King Motor Fuelie 30.5cc motor for my DBXL. It came with a Walbro 997 carb and I can't figure out what's wrong. Each time I'm able to go through about a tank of gas before the piston shatters into a million pieces. The head is in good shape, so maybe the pistons are just bad quality. I run 1 1/2 turns out on H and 1 1/4 turns out on low for the carb. The entire time the car runs like a champ, no odd noises or any hint of running lean. Perhaps there isn't much smoke at full throttle top end, but I thought maybe that's normal. I know my Baja smokes quite a bit a top end.

Anyways, after rebuilding the motor with new pistons, head, crank, etc. and running through 2 pistons with the exact same problem, I chalked it up to just bad quality parts from King Motor. So I purchased a mint 29cc CY motor off a friend of mine. It's a 2 bolt head, but loads of compression and it was pretty new. It didn't come with a carb so I reused the Walbro 997. Anyways, threw this on the DBXL and it ran for about 3 tanks this time before the motor died and wouldn't restart. The motor was very tight. I could still pull the pull start but I noticed a lot of resistance when the piston moved up into the head. I currently can't pull the head off but I took everything else apart and I could see on the carb side the piston has some massive gouges. The piston on the other side looks brand new and there isn't much scratches on the walls of the head. Any ideas as to what's going on? I'm getting tired of pulling motors and rebuilding them. Maybe the carb is junk and leaning out my motors? The plugs look fine each time I pull them.

I also attached a pic of yet another motor I'm about to install. This is a 30cc 4 bolt CY. Before I run it again, I'm going to get a Walbro 668 and see if that changes anything.

thanks,

Bry

 

[DougStar]

Mmmmm just putting out there you did mix 2 stroke oil in with the gas??
What you explain sounds like a heat seize ?

 

[RENOV8R]

I'm assuming that "1/5 out on high" is just a typo and you mean 1 1/5?

 

[Bryan K.]

I'm assuming that "1/5 out on high" is just a typo and you mean 1 1/5?

Yes sorry actually meant 1 1/2 turns. Was early in the morning. Lol *** corrected now

Mmmmm just putting out there you did mix 2 stroke oil in with the gas??
What you explain sounds like a heat seize ?

Yes i do a 25:1 92 octane pump gas with redline racing syn 2 stroke oil.

Maybe the carb is defective.

 

[Z.hb71]

im saying its the carb. ive had problems with my clone carb not holding a tune so that could be the case, it leaning out and fekin your motor

 

[AnubisBC]

im saying its the carb.

Certainly appears to be the common element here.

 

[Bryan K.]

Are there clone walbro carbs? I know there are unbranded clone carbs but if the walbro name and model number are engraved into the carb its still fake?

Here's the carb in question

 

[DougStar]

Are there clone walbro carbs? I know there are unbranded clone carbs but if the walbro name and model number are engraved into the carb its still fake?

Here's the carb in question

Yes?

 

[Z.hb71]

Yes?

+1

 

[DougStar]

Take a better picture of this....... looks like dirt going in the port .....a massive leak??

 

[AnubisBC]

Yeah, that model number looks printed on the carb. Both of my walbro carbs have the model number engraved, not printed. Could definitely be a clone.

+1 to Doug's observation. Looks like some dirt might have got in?

 

[cbaker65]

It seems that your engines would be hard to start or run crappy if the carb wasn't tuned right ,also ,what about the
altitude or elevation in your area?....That could have an effect on how the fuel burns or even changes on how the fuel
is able to flow to the engine when it heats up ,like in a Barometric change!

 

[evssv]

jus buy a zen 29...job done ?

 

[Seandonato73]

It's too lean, dirty engines normally don't seize, they lose compression, bearings get loose ect. I think what your seeing is metal transfer in the cylinder. That's is caused by 2 things, lack of lubrication or heat. (Normally caused be lack of lube)

 

[Z.hb71]

lack of lubrication

which means lean right
edit: you literally said its too lean in the beginning my bad ?‍

 

[Bryan K.]

Take a better picture of this....... looks like dirt going in the port .....a massive leak??View attachment 53990

That entire piece is plastic. It's brown colour. The silver is just bits of the gasket that have rubbed into the plastic. It's not dirt

 

[Basher5iveT420]

Make sure your gas to oil ratio is correct

When filling up your gas can make sure you’re filling it up exactly to 1 gallon and mix the correct amount of oil into it.

**A 1 gallon gas can, if you fill it all the way up you’ll end up with more then 1 gallon of fuel. So if you’re not careful you end up with the wrong fuel to oil ratio ....

 

[DougStar]

but your other pic is of the exhaust port .....and its so clean no oil?

 

[Bryan K.]

Make sure your gas to oil ratio is correct

When filling up your gas can make sure you’re filling it up exactly to 1 gallon and mix the correct amount of oil into it.

**A 1 gallon gas can, if you fill it all the way up you’ll end up with more then 1 gallon of fuel. So if you’re not careful you end up with the wrong fuel to oil ratio ....

I use this ALM mixing bottle. Seems pretty accurate. I'm in Canada, so we use the metric system

 

[DougStar]