About VIBRATION

Bugar

New Member
#1
OK, on my mini, ARCO, with 3 hp briggs/ no governor, and re-worked carb, on accelleration, geared 13-72, vibration was OUTRAGEOUS, so in my experimenting, made a brace, of 3/4x1/8 strap steel, from headbolt to the welded frame seat tab- sure did slow vibrations, i figure cut the intensity maybe in half, much nicer to ride now.
And that's what Bugar did today:thumbsup:
 
#2
While I commend you on your ingenuity on cutting down your vibration, I think your setup could possibly damage the engine. With that upper bracket to the head, you now have that engine "locked" to the frame, both top and bottom. If that top frame flexes during hard riding or going over bumps, you could bust that head casting. :doah:Can't say for sure, just a hunch...:shrug:
Michael
 
#4
Harley Davidson has done this for years. I have thought about the same fix as Bugar's mention. My 8hp briggs will rattle your arms numb and make your hands itch. Thanks for the info:thumbsup:
 
#5
Harley Davidson has done this for years. I have thought about the same fix as Bugar's mention. My 8hp briggs will rattle your arms numb and make your hands itch. Thanks for the info:thumbsup:
Harley Davidson Motorcycle/ Arco Minibike= Apples/Oranges
 

Bugar

New Member
#6
Had'n thought bout

The engine being locked in solid like that, I will watch the paint lines to see if am getting much movement , don't want to damage the expensive powerplant, it's been around since 1963 according to the 8# on the shroud, sure runs good tho,. even if it does vibrate bout half as much as a harley:laugh::laugh::laugh:
 
#7
What concerns me is that strap being connected to a SINGLE head bolt. If that frame flexes that is transmitting all of that force from the frame into a very small (and concentrated) point load. That head is brittle and could crack.
Michael
 
#8
What concerns me is that strap being connected to a SINGLE head bolt. If that frame flexes that is transmitting all of that force from the frame into a very small (and concentrated) point load. That head is brittle and could crack.
Michael
michael has a point, the pressure fom a good flex of the frame could pop that single headbolt clean out of the block, maybe ruining your engine.
 
#9
What concerns me is that strap being connected to a SINGLE head bolt. If that frame flexes that is transmitting all of that force from the frame into a very small (and concentrated) point load. That head is brittle and could crack.
Michael
:thumbsup: Three head bolts hold the tank, usually with an additional mount on the bottom. IIRC, HD runs a center mount from both heads, then a transverse mount to the frame- and isn't there a rubber isolator in that center piece?

I do understand the need to get rid of vibration. I'd be looking at flywheel as said above, or shoring up the engine mounting plate.

Why not mount a rubber gasket/isolator at the seat tab area?
 
#10
If that engine is really and truly vibrating as much as you claim it is you have "other" issues. m(e.g., engine balance, engine moiunting plate,etc.) There is NO WAY that you should be having that much vibration out of a little 3 HP engine.
Michael
 
#11
FYI a number of mini's with HS50's cam with head steady's. Looked lie a l shaped bracket from the head up towards the frame and a tab on the frame that bolted to it. My atlas tt5000 has one.
 
#12
FYI a number of mini's with HS50's cam with head steady's. Looked lie a l shaped bracket from the head up towards the frame and a tab on the frame that bolted to it. My atlas tt5000 has one.
What did it bolt to on the head, and more specifically, how many bolts secured it to the engine?
Michael
 

george3

Active Member
#16
Your prob. is the fly wheel. remove it and clean the back side, it has Dirt, oil, and crud built up on it. Other reasons for this damaged flywheel, broken welds on engine plate or weak engine plate, Loose bolts or missing washers on engine mount bottom.
 
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#17
The later Super Broncs had a piece of angle iron welded across the top tubes and was bolted to the cylinder head, I think in two spots. I had one and I thought someone added that piece but I found out later it was from the factory, to reduce vibration and help with the frame flexing/cracking.
 
#19
Your prob. is the fly wheel. remove it and clean the back side, it has Dirt, oil, and crud built up on it. Other reasons for this damaged flywheel, broken welds on engine plate or weak engine plate, Loose bolts or missing washers on engine mount bottom.
Agreed, and what I was referencing in an earlier reply. There is NO WAY a little 3 HP Briggs would/should be typically causing all of that vibration. Something ELSE is wrong...:shrug:
MIchael
 
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