Restored my Tea 20. Not achieving full throttle....

Sub8

New User
Hi all,

I've spent the last 9 months restoring my cousins 55 tea20.

Full engine rebuild to 85mm bore. New carb. New governor assembly, new disi and coil with electronic pick-up.

The manual and this forum have been very useful.

So it starts and runs great. I've set the timing and run through the governor setup procedure.

The issue I have is that I cannot achieve full throttle with the hand throttle when the engine is running. To get full throttle I have use the choke rod.

With the engine not running I can get to full throttle with the hand lever on the governor arm without using the choke rod.

This has lead to believe that the main governor spring, the verticle one around the plunger, may be too soft(26coils).

With the engine running the force of the governor + the carb spring is more than the force of the plunger spring connected to the hand throttle via the linkage? I can see this spring just stretching as I open the hand throttle but the governor lever is not moving.

I bought a new hand throttle assembly which may not have been the correct one, there are 2.

I also had to set the link arm on the carb between the choke plate and the main throttle.

What are your expert thoughts. I took a video I could post later?

Many thanks.
 
'expert thoughts' I have none. Too many other people are experts. I will give you my 2 cents and you can take it for what it is worth.
Engine should hit full throttle with no load.
Governor takes over under a load.
If unable to hit full throttle with no load, either a lack of throttle, fuel or ignition advance.
 
(quoted from post at 12:50:57 05/02/20) 'expert thoughts' I have none. Too many other people are experts. I will give you my 2 cents and you can take it for what it is worth.
Engine should hit full throttle with no load.
Governor takes over under a load.
If unable to hit full throttle with no load, either a lack of throttle, fuel or ignition advance.

Yes not getting enough throttle....

Heres the video link.

https://youtu.be/MJ9yv9Ry3LA
 
If the throttle plate opens fully with the engine off/dash lever at full speed...

And at full throttle/no load the engine is running at governed speed, 2000 RPM...
(If the RPM is not at 2000 RPM, loosen the U bolt, turn the lever on the shaft until at 2000, tighten the U bolt)

Chances are the governor is doing what it is supposed to do.

To check it, start the engine , bring the RPM down to a slow idle. Watch the carb throttle linkage while suddenly opening the throttle by the dash lever. The governor should fully open the throttle, but only for an instant as it will begin closing it down as the RPM comes up.

Another test is to have an assistant sit on the tractor, hold the brakes, chain the rear to an immovable object, or put the front wheels up against a wall. Put the trans in high gear, engine at full throttle, ease out on the clutch. Watch the throttle as the engine comes under load. You should see the throttle fully open.

If it doesn't fully open the link between the carb and the governor will need to be shortened. Be careful though, get it too short and it won't return to idle.
 
(quoted from post at 15:44:57 05/02/20) If the throttle plate opens fully with the engine off/dash lever at full speed...

And at full throttle/no load the engine is running at governed speed, 2000 RPM...
(If the RPM is not at 2000 RPM, loosen the U bolt, turn the lever on the shaft until at 2000, tighten the U bolt)

Chances are the governor is doing what it is supposed to do.

To check it, start the engine , bring the RPM down to a slow idle. Watch the carb throttle linkage while suddenly opening the throttle by the dash lever. The governor should fully open the throttle, but only for an instant as it will begin closing it down as the RPM comes up.

Another test is to have an assistant sit on the tractor, hold the brakes, chain the rear to an immovable object, or put the front wheels up against a wall. Put the trans in high gear, engine at full throttle, ease out on the clutch. Watch the throttle as the engine comes under load. You should see the throttle fully open.

If it doesn't fully open the link between the carb and the governor will need to be shortened. Be careful though, get it too short and it won't return to idle.

Hi and thanks. Yes it did occur to me that it's working correctly. I don't have a tacho so I'm judging by ear. I reckon it's running at about 1500rpm with hand throttle open. Is there a way of estimating without a tacho?

I tried shortening the plunger link but that didn't help and then the plunger wasn't pushing down on the bottom of the governor lever and so it didn't return to idle when i closed the hand throttle.

If I shorten the link between carb and governor lever I think it would make the problem worse as there is now more force / preload in that link? So opening the hand throttle would get even less throttle.

It runs lovely with the choke lever pulled out! I thought governed max speed was 2600rpm?
 
No expert here... happen to own a TEA-20 and service manual.....

Bob..
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Only change the length of the link between the carb and the gov arm IF the throttle is not fully opening with the engine off and dash lever in full speed position.

I got 2000RPM as the top speed from Tractor Data, so go by Johns manual.

You really need a tach of some kind to set the RPM. I've never tried, but if you trust these numbers (from Tractor Data), and have the factory size rear tires, use the GPS on your phone and see what the speed is in various gears, adjust the RPM accordingly would get you in the ball park.
Gear Speeds
 
So as usual in these kind of problems, it was operator error!

There are two throttle levers with the control quadrant in different orientations. Yep - I got the wrong one. So I wasn't getting enough throttle lever travel. Tjhe quadrant was hitting the 'firewall' under the dash at closed throttle.

So I could have dis-assembled the entire dash / cowl and bought the correct lever. Or cut a window in the bulkhead. Guess which one I did?

So now when I open the handthrottle the engine speed goes up further and the governor rod starts to come back and control speed correctly.

So thanks all, simply fix in the end.
 

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