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HB-112 issues


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#1 637Yeoman OFFLINE  

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Posted August 12, 2017 - 03:02 PM

Recently I acquired an AC Hb-112 and I've been having all kinds of issues. Checked for spark, didn't have any, cleaned and gaped points, very weak sparatic spark. So, figured weak coil. Wired up a car coil, got it to run, but it ran poorly. Cleaned carb, still ran the same. It will idle fine, but it sounds like it's under load when mid throttle, and no it's not rich. The governor is acting very wonky. It works fine sometimes, but if you apply any load, it automatically goes full throttle and chokes the motor out. So, messed with the governor spring, and with it running fine for around a half hour, I thought I fixed it. Wrong. I looked in the briggs book and adjusted the governor, which also seemed to fix it. Wrong again. Something is obviously wrong internally. So my question to you is, can I reac the governor with just taking out the synchro-balance parts behind the front cover?

#2 New.Canadian.DB.Owner ONLINE  

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Posted August 12, 2017 - 04:55 PM

Does your governor setup look like this:

 

DSCN3253.JPG DSCN3255.JPG DSCN3254.JPG DSCN3260.JPG



#3 637Yeoman OFFLINE  

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Posted August 12, 2017 - 05:30 PM

Yep

#4 New.Canadian.DB.Owner ONLINE  

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Posted August 13, 2017 - 02:02 PM

If it was me, I would want to know if the engine is actually being loaded down.  I would separate the engine from the various loads one at a time.  I would take the belt off that runs from the bevel gearbox to the hydro to see if that changes anything.  If not, I would remove the belt that runs the power lift group.  Then it would be decoupling the drive shaft to the bevel gear box.   Something has to be loading the engine.



#5 637Yeoman OFFLINE  

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Posted August 13, 2017 - 08:35 PM

Even if that is the case, why is the governor so touchy? And why does it "over react" and automatically go full throttle? Thanks Luke

#6 New.Canadian.DB.Owner ONLINE  

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Posted August 13, 2017 - 09:35 PM

I'm gonna go with: 'cause that's the way governors work.  When your engine is not running, the governor forces the the throttle open.  Engine speed counter acts that force.  When they are in balance, RPM = governor tension = throttle position. As engine RPM drops the governor pulls the throttle open.  A small drop in engine speed with send the throttle wide open in order to bring the rpms back up.  If the rpms don't come up, the throttle will stay open.  Your governor isn't over-reacting, your engine is under-reacting because it is under a heavy load or lacking fuel.

 

You might get those symptoms with a partially or fully blocked high speed circuit in the carb.  If it is, the engine may run fine at idle and maybe higher without a load, but it won't have the fuel flow to go to higher rpms.  When the throttle is increased, the governor opens the throttle but the engine rpms don't come up because there isn't enough fuel coming through the high speed ports in the carb, the fuel / air mix goes lean & the engine bogs & dies.


Edited by New.Canadian.DB.Owner, August 13, 2017 - 09:39 PM.


#7 637Yeoman OFFLINE  

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Posted August 14, 2017 - 05:34 PM

That's the other part I didn't mention, but you read my mind. All of the carbs we put on it, I believe three or so, were clean, and ran good on previous motors, and the hb, but the gas tank was slightly dirty. On the high speed jet there is a little tiny hole that plugs easy, and I'm assuming is the issue now. Moreover, I forgot to set float height, which might be causing the under "load" issues. Thanks for the help, Luke




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