Small engine shaking too much when running, Why?

GoceKU

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I've bought couple of small generator couple of months back and started a thread on this forum, link: https://www.hobby-machinist.com/threads/old-gasoline-generator-repairs.66014/ The smaller one is finished works as it should, but the Tecumseh HS40 powered Bosch is definitely something wrong, now the carb works as it should and the ignition seems to work right, but the entire engine and generator is shaking so much it walks at walking speed on the garage floor. Any advice what would cause so much imbalance in the engine, i've split the generator of the engine is still shaking, the flywheel key and the flywheel are both good, i've change the oil today and run the generator but it started dying after 15 min of running, it will star on the first pull again and run almost seams the fuel is shaking so much in the carb it starves. It is mounted on rubber mounts to the frame which allow it to move a lot, very strange, any advice is much appreciated
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I would start with ignition timing... sounds like it may be just a little too advanced... firing just before TDC... causing pressure on the piston before it crosses TDC... thus the shaking.

OTOH... firing waaaay too late could cause shaking also.

Check ignition timing first... then go looking for anything loose that shakes or rattles...

Might be a magnetic thing in the genset, however given it shakes with the generator removed... probably the engine.
 
Might also be the mixture on the carb.
 
Is the engine haunting rev up slow down? Try holding the throttle on the carb to see if it's the governor or the springs to control the speed. It should be set at 3600rpm max. Are the isolation mounts on the frame or between the frame and generator ? Most of those will inherently waddle if not locked down. If it's dying at fifteen minutes , inline spark test it running , if no spark when it dies its the ignition , if still sparking Ck the lid on the tank for breather holes. It will hold the fuel if not vented ,. Small jet holes in carb can be blocked or water present also.
 
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I've only worked on those for fifty years , I.do know what I'm talking about.
 
Is the engine haunting rev up slow down? Try holding the throttle on the carb to see if it's the governor or the springs to control the speed. It should be set at 3600rpm max. Are the isolation mounts on the frame or between the frame and generator ? Most of those will inherently waddle if not locked down. If it's dying at fifteen minutes , inline spark test it running , if no spark when it dies its the ignition , if still sparking Ck the lid on the tank for breather holes. It will hold the fuel if not vented ,. Small jet holes in carb can be blocked or water present also.

At slower speed seems to be more stable, at high, on which needs to run to achieve 50Hz speeds up and down, i can see the governor opening and closing the throttle, i can open the throttle by hand but as soon the engine speeds up the governor closes the throttle, the engine and generator mounts are soft rubber and when running it shakes about 50 mm in both directions which causes it to walk, the fuel tank has a breather a aslo run it with the fuel cap backed off, i've been in that carb so many times now i know it is clean and all the jets are clean, could the timing be causing this?
 
Ok we're getting somewhere, on the rod or next to it the throttle link should have an extra tiny spring in a separate hole or in with the linkage. Is it missing ? Is it a bowl carburetor ? The bowl nut does it have an adjustment screw n it? Is there a separate low speed jet in the side ? If there's a adjustable jet take the bowl nut out , unscrew the adjustment screw , in the bowl nut there's a tiny hole on an angle just above the lower part of the thread push a wire thru it to clean it. The low speed adjustment screw may be blocked , if you have 2+2 carb cleaner spray it in the holes , you can use air compressor to blow out to help. With it haunting it's usually blockage or the spring to hold tension on the throttle linkage is missing or installed wrong. As for timing the only timing on those is the flywheel key ... If it's half sheared or on backwards it will make for kickbacks when starting or back fire thru intake valve. Tecumseh are fickle but we're great engines really . They all have oil pumps not just slingers for lube distribution.
 
The small throttle return spring is present and attached right, the carb is a bowl type, The bowl nut has no adjustment screw in it, is solid there is no hole at an angle, i've read all the repair manuals i could find and know exactly what are you talking about, there is an adjustment screw near the throttle lever, the carb is spotlessly clean, infect the entire engine i don't believe it has more than few hours total run time, you can see the points cam is like new, the flywheel key is straight it has some marks but is not damaged, the ignition plate has adjustment and i can hear it misfiring and backfiring when is running not sure is it thru carb or exhaust. The biggest problem now is the violent shaking (vibration),which i think is is making the fuel bowl shake so much is starving for fuel, is there something like contre weight or balance weight that could cause this, when i had the generator motor separated, i clamped the Tecumseh engine to my workbench, all steel very heavy, when i fired it up the vibrations in less then 30 seconds all my wrenches and sockets fell on the ground.
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Check point gap as it is somewhat critical.

The timing can be different depending on gap.

Also check key to make sure not split.

The magneto gap needs correct setting and a matchbook works well.

Check flywheel for chunks of crud or missing fins.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk
 
The magneto gap needs correct setting and a matchbook works well.
Now all you need, is to find a matchbook. .016-.018 If memory serves. Process of elimination. You'll get it. Mike
 
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