Project small engines

[oldschool90]

So I've been doing some work with a couple small engines and I need a bit of help for one of them. The one I'm working on is on a big walk behind rototiller, and the damn thing just doesn't want to start. I've been having to turn it over with a drill because the pull cord was so old it just snapped. It's got spark, and as far as I can tell, it's getting fuel. I also tried spraying starting fluid on the filter and then when that didn't work, I tried spraying it in the carb. The drill turned a bit faster while I was spraying starting fluid in it, but it never caught or ran at all. I went out and rented a compression gauge and in about 10 turns, the gauge reads 45psi with a maximum of 60psi. I also did a wet reading with a bit of oil and at first, everything was the same, but it started to creep up higher to a maximum of 80psi and after I cleared the gauge the pressure built up quicker (0-60 in 4 turns) but after 65 it slows down until it gets to 80. I also noticed that a bit of air is shot out of the carb every turn, and if I turn it over for any amount of time, gas starts to build up at the front of the carb. The gas tank and carb have been cleaned out a few times and spark has been checked a number of times already, and the only other thing I did was polish the valves a bit.

 

Here's a pic of what the engine is on:

 

 

And here's the engine sticker:

 

 

Any help with this issue would definitely be appreciated, as we (our family and a neighbor) have gardens we need to start preparing for.

 

And just for shits and giggles, here's an edger I've also been rebuilding. I'm in the process of acquiring a cylinder hone, and will have it done and running soon (I hope) with a carb off a lawn mower I found at the dump since the old on was trashed and also had missing pieces.

 

 

 

 

[oldschool90]

I forgot to mention that the compression readings were taken on a stone cold engine because I (obviously) couldn't start it and get it to operating temp. Thanks again in advance!

[josh_t]

sounds like you need a valve adjustment or you might need to lap the valves. check those first. it will make a huge difference if thats it. i've had a couple mowers that did that a lot and i never had them running quite right. they would backfire and run real sloppy all the time.

[yello620]

On the tiller, it requires approximately 90psi of compression for a gasoline engine to fire. So until you get that, it probably isnt going to fire and run right. So it is quite possible that the valves need attention.

 

 

 

On the Edger, do you still have the old carb?? I am having trouble with one of the newer style carbs and want to swap to an older one.

[josh_t]

unless its a flathead. lol. those things dont ever get much more than 60-65psi. they have like 6:1 compression most of the time.

[oldschool90]

Good news, I got it running! I have no idea what it was, maybe just sitting for so long? Anyways, that's the good news. Bad news is that anything under full throttle will make it slowly die. It doesn't run rough or anything, just dies. And of course, the throttle lever is so loose that it just vibrates to a slower speed. I also noticed that some "oil" was leaking from one of the fill up points, but it was grey in color. So I drained the oil and a bit of water and this crap came out:

 

 

 

 

 

So I drained it out and ran it for a bit and I'm going to re-drain and fill it tomorrow, along with getting it hot and redoing the compression test. But otherwise, it's running good and even handles tilling without hiccups.

 

 

 

 

yello- I think for now I'm going to keep the original carb just in case this swap does't work out, but if it does I'll PM you about what I've got. Hopefully it won't take too long to get this done.

[josh_t]

water in the oil. lol. must have sat outside. my friends gokart started right up after a close to a year of sitting even under a covered area and pressure built up in the crankcase and it puked that stuff all into the carb and it literally shot it back out. it was nasty. the full throttle thing sounds like the idle passages are plugged.

[oldschool90]

I have read that there is some kind of valve or something inside the carb that is inaccessible for cleaning and is non replaceable. Basically, if this thing is plugged or restricted, you'd be better off getting a new carb. Some guy even soaked one in some kind of solvent/cleaner for a month and it still didn't work right.

 

 

 

I know what I'm doing tomorrow!

 

 

 

 

[josh_t]

i hate tecumseh's. i dont know about that valve but it probably does exist. i never had a motor that wouldnt run and that end up being the problem. usually you can just clean the main jet and emulsion tube and the idle passages and things work well. might not be the case with yours though. just clean what you can and see what happens.

[oldschool90]

I plan on taking the carb off and cleaning everything and make sure the the float is set right.

[josh_t]

sounds like a great place to start. lol. brass float in that carb?

[I'm BLUE]

New carb ... don't even try if other carb has been sitting in water or water in float bowl ... waste of time

 

Do not use carb cleaner on plastic parts ... will eat them!

[josh_t]

i've managed to get carbs working just fine that have been full of water without much trouble. i guess it depends on the carb and conditions though.

[DanielC]

the brass thing you are holding is a jet. Make sure there is no dirt in it. There is a hole down the center of it, that intersects the two holes across from each other, the hole above your thumb.