3.5 Briggs Funny noise?

pasadenaboneshaker

pasadenaboneshaker

New Member
#1
#1
Yesterday my buddy bought a used mini bike with a 3.5 Briggs. Everything was going great, ripping up and down the street, racing me on my 49cc pocket bike and passing me like I was standing still. We took a break then went back out to ride but this time was different. It made a grinding sound when he tried to start it, as if something was rubbing in the motor. It was hard to get it to idle but when it did the sound went away. Were new to mini bikes, is this something common to 3.5 Brigg motor? :confused1:
 
pasadenaboneshaker

pasadenaboneshaker

New Member
#4
#4
The pull cord does return easy. I'll check the pull start set up. If something is rubbing in the pull start section will it stop the motor when it's idling? Because thats what it's doing. Once it's running and at an idle, it will make that buzz noise and then stop the motor.
 
minidragbike

minidragbike

Supporting Speed Nut!
#5
#5
I would really have to be there to actually know what's going on. It might have something to do with the factor governor setup, if it's effecting the idle.
 
G

GTO

#7
#7
And want to know what it was. :wink:

Some engines will start then die if one of the holes in the nut at the bottom of the float is clogged.

Let us know now,, none of this Machanics secret crap. :eek:ut:
 
pasadenaboneshaker

pasadenaboneshaker

New Member
#9
#9
GTO said:
And want to know what it was. :wink:

Some engines will start then die if one of the holes in the nut at the bottom of the float is clogged.

Let us know now,, none of this Machanics secret crap. :eek:ut:
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GTO, were not keeping secrets. He can't tell what the problem is unless he hears and sees it for himself. I'm in Pasadena and he's in L.A. I'm going to bring the bike to him tomorrow, if I catch him. I'll tell you what it was as soon as I find out.:thumbsup:
 
The Restore Kid

The Restore Kid

New Member
#10
#10
I am GUESSING... from what I've seen. the OLDER Briggs engines up till about the mid 60's had a steel wheel that the rope recoils around AND the racheting grabber thing on the crank is not full length. So I am Guessing here, that either #1 I would say it is in the recoil. MOST likely just rust and dirt build up in between the Shroud itself and your recoil pulley. They'll do that and sound like hell but it's about 99% harmless. I know I ALWAYS will tear them down and oil the ratchet system and clean them up in between the shroud and roller like I was saying. BUT being that you're new to the engines and the fact that those recoils CAN be a little testing to take apart and put back together I am gonna say. Just take the shroud itself off with the 3 7/16 bolots then lay it just so where you can dump some oil ib back of your recoil system and the just pull it a couple dozen times and it should pretty well wash all the crap out and lube it up so it will quit makin the scratching noise. OR sometimes but not usualy ( normaly a very beat engine) If your shroud is bent out of wack it can either put a bind on your recoil pulley and or cause the crankshaft to hit the shroud where the crankshaft sticks out past the end of the rachet clicker thing there. You should be able to EASILY see that kind of damage though and it would also cause a constant noise. Sooo I would say just take the shroud off and oil it. I am guessing thats your problem and the easiest fix. PS Briggs engines from anywhere before about 1990 are nearly indisructable. I have several I buy for like 5 or 6 dollars out of the scrap irony aluminum pile at the local junkyard and go through them and will build high performance oversized carb port and polish super compresion briggs 5 horse engines and let em SCREAM as many rpms as you can get out of them and they just sound better the faster they run. The old tecumseh engines will run pretty strong too but I've seen litteraly 100's of them with a huge hole in the backside of the block where the rod exited the block. Good luck with your bike. I love to hear about them saved instead of destroyed forever. I'm restoring a 69 Rupp Goat a buddy got out of the garbage a couple days ago. HEY EVERYONE !!!! Who has an original Rupp Goat chain gaurd? I have the piece that bolts to the engine but there is a second piece that is missing. Sorry. no camera to speak of so pics are a bit difficult but I will see what I can do about posting some pics. I'm new to the site but have ALLOT of cool stuff. The Suicycle is the Badest ass minibike around
pasadenaboneshaker said:
Yesterday my buddy bought a used mini bike with a 3.5 Briggs. Everything was going great, ripping up and down the street, racing me on my 49cc pocket bike and passing me like I was standing still. We took a break then went back out to ride but this time was different. It made a grinding sound when he tried to start it, as if something was rubbing in the motor. It was hard to get it to idle but when it did the sound went away. Were new to mini bikes, is this something common to 3.5 Brigg motor? :confused1:
Click to expand...
 
javimanic

javimanic

New Member
#11
#11
The Restore Kid said:
I am GUESSING... PS Briggs engines from anywhere before about 1990 are nearly indisructable. I have several I buy for like 5 or 6 dollars out of the scrap irony aluminum pile at the local junkyard and go through them and will build high performance oversized carb port and polish super compresion briggs 5 horse engines and let em SCREAM as many rpms as you can get out of them and they just sound better the faster they run. I love to hear about them saved instead of destroyed forever.
Click to expand...
do you run with the plain bearing sidecovers or do you ALWAYS use a bearing style sidecover with these built 5 hp motors?
 
5

5hpbriggs

New Member
#12
#12
some do some dont. It is better to run with the bearing cover it trues the crankshaft up a little. Most people usually run them with alcholhal 12 hp engines and everybody runs them with outlaw and open motors
 
The Restore Kid

The Restore Kid

New Member
#13
#13
It just depends.. The bearing crank is ALWAYS better for durability, but if you are staying in the stock cam old beater motor catagory, a bushing backing plate will hold up as long as theres oil in the motor..
 
Richard Trotter

Richard Trotter

#14
#14
sometimes the starter ratchet gets dirt and grim inside it. When this happens it makes a grinding sound and the starter rope pops out or goes slack. To fix it, pull off the starter ratchet and clean the shaft it fits over. The ratchet is threaded onto the crank. I use a punch and hammer against the ears on the ratchet. Spin it off and clean the crank end and inside the ratchet. A little light grease helps it keep working right.
 
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