OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Tech Talk Victa TVS90 Tecumseh -throttle linkage how?

inherited an old victa 4stroke (tecumseh tvs90), worked ok last summer but alas would nt start yesterday. stripped down cleaned,resealed leaking gasket (inlet manifold to carburettor i think), started today but only idled, unless manually opened & closed carburettor directly (roared nicely).

mucked around all day. linkages to govenor (i think thats what its called) correct (pretty certain), but cant figure out how the throttle actually engages with the carburettor...

unless i lost a part...

would greatly appreciate some pointers

thanks heaps
regards
adrianjt

maybe you did lose a linkage ? another post here . tecumseh? have a look at that one , a guy showed me the linkages in detail . i had one the same and it was missing one too , same thing i could use it manualy but its hard to mow when ya gotta hold the gov'

hi, thanks, i have had a reasonable comb thru this topic plus numerous others searches. downloaded quick reference troubleshooting manual. pretty sure linkages correct. but I dont understand how the speed control bracket (wrongly called throttle in 1st post) moves/joins/pushes/engages the carburettor, when bolted in place. the choke (ithink) looks to function ok (and it did start & idled). carburettor appears to be a model #11 if that helps. my setup is almost identical to this

http://www.hobbytalk.com/bbs1/showthread.php?t=262590



its probably obvious, but...

cheers
adrian

Adrian, the process I use to begin an investigation of governor issues is much the same for any mower. It is carried out with the engine stopped. First, set the speed control to idle and verify that the bell-crank on the throttle butterfly is resting against the idle stop (the idle speed adjustment screw). Second, set the speed control to maximum speed and verify that the throttle butterfly is wide open and against its stop. If one or other of these conditions is not met, trace the mechanism to find out why. The problem is just about always one of two things:
1. Stretched governor spring. Governor springs are normally close-coiled tension springs. If they are not close-coiled for their entire lengths, they can't work.
2. Bent or incorrectly installed spring, linkage or governor base-plate jamming the mechanism or limiting its movement so it will not move all the way from throttle closed to throttle open by moving the speed control lever.

Your governor sounds as if it is suffering from one of these ills. I suggest you follow the process of moving the speed control lever and seeing what happens to the throttle butterfly. If it does not move through the full range, find out why. Is the spring OK? Is the linkage free? If the answer is yes to both, it sounds as if it is probably incorrectly assembled or adjusted.

These governors are very simple. At idle, there is no tension on the governor spring and the mechanism is designed so that it mechanically closes the throttle under these conditions. At maximum speed there is maximum tension on the governor spring, and the spring pulls the throttle open. The throttle opening is limited, when the engine is running, by either a centrifugal mechanism in the crankcase or an air vane near the flywheel fan. Whichever of these the engine has, pushes the throttle toward closed, and is resisted by the governor spring. The governor's mechanical element tries to close the throttle and the spring tries to open it. They find an equilibrium at a speed that depends on how far the governor spring is stretched, which simply depends on the setting of the speed control.

If you go through this process and still can't work out what is wrong, post a series of pictures of the mechanism with the speed control set at both maximum and minimum. Hopefully someone will spot what is wrong - but it is much easier for you to do it, because you have the mechanism in front of you, and you can see what moves when.

Thanks Grumpy for your detailed post. I went back at had another go but still couldnt figure out how the speed control plate assembly engages with the accelerator linkage.

hopefully these pics may shed some light on whats not right. thanks again

ps pics taken with throttle cable and carburettor in fully open/fast position
regards
adrian

We may not have progressed very far, because you only posted pictures of the carburetor and linkage with the speed control in the fast position, not the slow position. However, your engine appears to have the Dellorto carburetor - see this drawing from the Tecumseh workshop manual:


The red circle encloses the throttle butterfly bell crank. The only component connected to the bell crank on that engine is the governor link. and on your engine the link has successfully opened the throttle butterfly wide open in your picture:



The red circle shows the venturi area in the bore of your carburetor. You are looking at the throttle butterfly on its brass pivot shaft. The throttle is edge-on, meaning it is wide open. If you pull the governor arm (at the right of the picture, where the rightmost green arrow points, with the governor spring and the governor link connected to holes at the top of it) gently toward you so that you stretch the governor spring slightly more, you will see the throttle butterfly close to the idle position, obstructing the bore and preventing the engine from drawing in much air. When you release the governor arm, it will snap back to the wide open throttle position, due to the force of the governor spring.

The two green arrows show the two ends of the governor link. It runs from the top of the governor arm, to the bell-crank on the throttle butterfly.

The governor spring runs from near the top of the governor arm, to the speed control lever circled in red in this picture:



The speed control cable from the handlebar connects to this speed control lever and sets its position. The governor spring also connects to it. When you move the lever on the handlebar toward fast, the cable moves the speed control lever and stretches the governor spring.

Now, I suggest that you watch the speed control lever, the governor spring, and the throttle butterfly inside the carburetor, while you move the handlebar lever. You should see the butterfly almost closed at the idle position, and wide open at the fast position. This indicates that the mechanism is working correctly. It may or may not need precise adjustment to get the prescribed speed settings for idle and maximum speed.

Incidentally when you removed the two vertical screws that hold the top plate of the mechanism, you destroyed the alignment of the linkage, so it will now have to be set up again with correct alignment.

Dear Grumpy

I am very grateful for your help. The engine is working like a treat, I've adjusted the carburettor as per your advice. Its great.

fyi where I came unstuck was that I didnt realise the play (lotsa) from the accelerator lever resulted in such a small amount of movement on the bellcrank. I was always getting that movement but thought it was just the choke action. hahahha what a goose. Ive learnt/relearnt alot in the last day and will now move on to the whippersnipper, outboard, the spare victa 2 stroke and maybe even get the methanol out for the model airplanes....

better mow the lawn first or I'll get the cold shoulder

cheers & thanks
adrianjt

All looks correct except the govenor arm resting on the crankcase. Bend it back out a bit.


The govenor arm might need adjusting. It might have been bumped on the shaft and now does not have the correct range of movement.


Was the cable that way previous??? Thats a sharp bend, I'm surprised it even moves.
Usually the cable goes in the other way.
You can flip it up at the throttle control on the bar so it does what it says.

Move the controler to the other side and run the cable in that way and it will not have to bend so sharply. To keep the mount holes you could just flip the handle over if its a plain one.


Sideways motor is a bit strange.

I agree with Bob, particularly about the governor arm rubbing against the engine's crankcase. You should bend it outward just slightly so it clears the engine by between 2 and 5 mm. See green oval on picture below: you can pull the top of the lever (where the spring and link attach to it) away from the engine while holding the bottom of the lever in a pair of pliers, until the lever bends slightly down near its pivot shaft. If it rubs on the engine it may not move smoothly under the small amount of force the governor provides.



I'll close this thread. If anyone needs to post to it, just PM a moderator.