Have a TVXL195. Engine runs but I cannot adjust the RPMs with any noticable difference. High setting sounds the same as low. Mower loses power under load. Have tried to adjust the governor lever, and both high and low speed adjustment screws. Sometimes the motor will rev up when I move the throttle control down on the mower. Is it something internal? What am I missing? Series 3 carb.
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Governor/Throttle Mystery
- Thread starter sano888
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This service manual has the procedure on how to adjust the carb. Also make sure that the throttle and choke shafts are moving freely. If not you will have to remove the carb and give it a good cleaning and rebuilding.
Have followed the manual for adjustments. Everything moves easily. Rebuilt and cleaned the carb in the ultrasonic. Can't make heads or tails of it. Carb adjustments should not cause it to not to idle down, correct?This service manual has the procedure on how to adjust the carb. Also make sure that the throttle and choke shafts are moving freely. If not you will have to remove the carb and give it a good cleaning and rebuilding.
Not correct. Not adjusting the carb in the proper order and also making sure the governor is adjusted properly, will contribute to your problem. You must make sure your governor is working properly, then adjust your carb, then go back and adjust your governed top speed. How are you adjusting your carb, according to the manual or a hit and miss method? Are you using a tach or do you have the experience to do it by ear? Make sure you have read and understand how both the carb and governor work before starting to make changes.
I have enough experience to get into trouble. Not enough to get out of it apparently. Set both carb needles to factory. Warmed the engine 3-5 minutes. Adjusted main jet on the bowl while at full throttle. Can get it to shut off when tightened. No difference in sound when opened up. Going by ear, no tach. No discernible difference when adjusting the idle jet unless I turn it in. I can get more power under load if I open the idle jet up more. What I cannot do is get the engine to throttle down other than using the idle screw. My concern is that there is something internal going on in the governor not allowing it to throttle down so that it can be adjusted properly. My understanding is that under load, the governor should allow the RPMs to increase to balance out the load. That is not happening. Reaching out to more experienced people because I am at a loss. Trying to fix this for an elderly friend of my sister.
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I think I just might fit into the picture as an experienced mechanic, have worked on engines and equipment for 50+ years and in the industry for 35+. If I remember correctly I did run into this problem once before. Here is a procedure I taught my students years ago. If you don’t think I’m qualified, don’t use it.
Adjusting a carb
This is the procedure I always taught my students to adjust a carb with two fuel controlling needles.
1. Start the engine and move the throttle control to top speed.
2. Adjust the high speed needle (this is the one under the float bowl) clockwise very slowly until the engine starts to bog down.
3. Back the needle out 1/8 turn, the engine should now run smoothly.
4. Now move the throttle control down to idle. If the engine stalls out turn the idle speed screw in one full turn, restart the engine and bring the throttle control down to idle. If the engine is running to fast, turn the speed screw slowly out until the engine seem to want to die and then in 1/8 turn.
5. Now with the engine running, adjust the idle needle out until the either gains in RPM's or starts to bog down. If the engine gains in RPM's, continue to adjust out until the engine starts to bog down. At this time turn the screw in 1/4 turn. Now the engine may be running to fast, so turn the idle speed screw out until you get an RPM you like.
6. Now you must repeat step 5. If the engine bogs down right away turn idle needle back in to your starting point and go to step 7. If it speeds up, repeat step 5 again.
7. Turn idle needle in until the engine bogs down and then out 1/8 turn.
8. Now the engine should run smoothly at all speeds.
9. To check, set the engine to idle, then quickly push the throttle control tohigh speed. If it dogs and does not come to speed, open the idle needle 1/8 turn and repeat.
10. Set to go.
There are 2 reasons I have it done this way is, first the high speed needle controls the fuel going to the low speed circuit and second is that the idle needle controls how much fuel is used when going from idle to high speed. You should also review the section in the manual I posted before starting this procedure.
Adjusting a carb
This is the procedure I always taught my students to adjust a carb with two fuel controlling needles.
1. Start the engine and move the throttle control to top speed.
2. Adjust the high speed needle (this is the one under the float bowl) clockwise very slowly until the engine starts to bog down.
3. Back the needle out 1/8 turn, the engine should now run smoothly.
4. Now move the throttle control down to idle. If the engine stalls out turn the idle speed screw in one full turn, restart the engine and bring the throttle control down to idle. If the engine is running to fast, turn the speed screw slowly out until the engine seem to want to die and then in 1/8 turn.
5. Now with the engine running, adjust the idle needle out until the either gains in RPM's or starts to bog down. If the engine gains in RPM's, continue to adjust out until the engine starts to bog down. At this time turn the screw in 1/4 turn. Now the engine may be running to fast, so turn the idle speed screw out until you get an RPM you like.
6. Now you must repeat step 5. If the engine bogs down right away turn idle needle back in to your starting point and go to step 7. If it speeds up, repeat step 5 again.
7. Turn idle needle in until the engine bogs down and then out 1/8 turn.
8. Now the engine should run smoothly at all speeds.
9. To check, set the engine to idle, then quickly push the throttle control tohigh speed. If it dogs and does not come to speed, open the idle needle 1/8 turn and repeat.
10. Set to go.
There are 2 reasons I have it done this way is, first the high speed needle controls the fuel going to the low speed circuit and second is that the idle needle controls how much fuel is used when going from idle to high speed. You should also review the section in the manual I posted before starting this procedure.
True. High speed jet is adjusted first because idle is such a tiny percentage of that.
2. On a 4-stroke I adjust idle mixture for maximum engine speed. (Max RPM is indicative of the most efficient burn. At idle no one cares about "mixture", the major concern is to stay running.)
3. Lastly, then idle speed is adjusted.
2. On a 4-stroke I adjust idle mixture for maximum engine speed. (Max RPM is indicative of the most efficient burn. At idle no one cares about "mixture", the major concern is to stay running.)
3. Lastly, then idle speed is adjusted.
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Contacted the local career center to see if they could help. The power equipment instructor lives in my town. He was able to stop by. He could not adjust it either. Seemed to think the carb was bad (80%) vs something internal (20%). Kind of made me feel better that it wasn't me. Cleaned the carb again and changed the welch plugs and have it running/usable. Probably should have a different engine ($100 at the pick and pull place). Since this is someone else's will not go that route at this time. Appreciate all the advice.