Used Engine Advice Needed

[bp011889]

I spotted an old tiller with a 5hp fun power briggs(?) horizontal shaft engine on it that i'm considering buying. Any advice as to what I should look at/inspect/test before I consider actually buying it for a go kart / mini bike? I honestly don't know much about engines, so please be nice.....and specific if possible

 

[freakboy]

if it runs is #1... how does the oil look? if its black it might not have been changed in a long time.. is there gass in the tank? if so how old is it(figure out by smell) its not hard smelling stale gass and telling it appart from fresh.. there any parts missing? if it dont run does it get alright compression?

 

[Doc Sprocket]

Pull it over by hand (starter rope). If it spins freely, there's no compression. If it won't run when you check it out (ie no gas/ whatever) pull the wire off the spark plug. Put the tip of a screwdriver into the rubber boot on the wire 'till it contacts the terminal inside. Holding the exposed shaft of the screwdriver about 1/16" from a resonably clean, unpainted metal part of the engine, like a cooling fin near the spark plug, pull the engine over rapidly throug a few rotations, and watch for spark. (This might be easier with someone's help.) If you have the tools and ability, remove the sparkplug and put a teaspoon of fresh fuel directly into the cyclinder. snug the plug back in, reattach the wire, and crank the engine. Should fire a few times.

 

[bp011889]

Awesome, thanks for the input!

Also, what's the easiest way to measure the output shaft diameter and keyway?

 

[Doc Sprocket]

Tape measure, ruler, caliper, whatever you have. if it's a 5hp, odds are VERY good it's a 3/4" shaft. Generally, pto shaft sizes are far enough apart that the size should be pretty obvious even with a tape measure. (as long as you can get to it). But my money's on 3/4.

 

[bp011889]

Haha for some reason I was thinking it'd be harder than that. Oh well, thanks a bunch man, I'm gonna go check it out tomorrow morning/afternoon and see how much the guy wants for it.

And since I'm still asking questions.....
Whats the max I should pay for a used 5hp engine? (first glance, it's old and it looks like s***, but only time and inspection will tell)

 

[freakboy]

if i were you take pictures alotta pictures just so if you go home and are thinkin bout it you can look threw the pictuers and some times you see something you didnt see in person cause you were distracted talkin to the guy or what not.

 

[acg23]

i got my engine off one of these tillers. it screams!!

 

[solomon]

I would pay $75 for an old used RUNNING briggs 5HP and no more than $50 for a non runner.

 

[fowler]

check to see if the shaft is tapered

 

[solomon]

Shaft wouldn't be tapered on a tiller. Only a generator or a water pump

 

[fowler]

sorry i was thinkling of mustang08's problem but his 5hp came from a chipper

 

[motor_head]

ask if it uses oil

 

[fowler]

it will be 4 stroke

 

[freakboy]

it will be 4 stroke

hes talkin bout if it burns oil...

 

[WI_Chopper]

i bought my 5 hp briggs, with a clutch, that runs fine, and still does, bought it 2 years ago, for 15. Car shows are the place for used small motors, im tellin ya.

 

[bp011889]

15? Holy cow you got a good deal!
I didn't get to go check it out today, too much stuff came up that I didn't plan on :/
If I get a chance I'm gonna go tomorrow and see if it runs and what kinda shape its in and see how much they want for it. (its at a pawn shop so idk if I'll be able to just get the engine.....may have to buy the whole tiller)

Are there any really obvious "bad signs" I should look for right off the bat? (again, noob here. sorry)

 

[solomon]

Leaky oil, missing bolts, home made fixes. Check the oil color and see if the engine turns over smooth. I would recommend taking a compression test with a compression tester as well.

 

[bp011889]

harbor freight sells a cheap compression tester, here:
http://www.harborfreight.com/flex-drive-compression-tester-92697.html

but it has a 14mm size and an 18mm size? i didn't know spark plugs had different thread diameters like that........would that tester be good to get for testing small engines? and what is the most common thread size for spark plugs, the 14 or 18mm?

 

[solomon]

both. Most small engines use the smaller thread and larger engines like a ford big block 390 use the larger one. It would work fine. You can get a compression tester at any auto store.