Old TroyBilt Tiller Carb

[bgsengine]

Oh yeah.. if it is one with a mechanical governor and the short spring (behind the tank support bracket) the control is adjustable , and easy to bend the tang too far when manhandling it during removal, which would of course change the governed RPM .. may wanna look at that - if the tang is bent almost straight (as opposed to being more of a U-shape) then you gonna have way too much pull on the spring and soon as you hit the control itself, instant zooms and very little rpm range..

[bluemower]

I looked through all the pictures in the IPL and the service manual trying to find the right picture of where to adjust.

Arkie mentioned the correct first step - perform the static governor adjustment. If you do not know how to do this, please ask. Adjustment is described in section 5, page 11 of the service manual.

BGS mentioned the high speed adjustment. The best picture I could find is located in section 4 of the service manual. See page 13, figure 56. Look for the bellcrank near the bottom fuel tank mounting bolt. There is a spring between the lower bell crank and the governor arm. Over the years, the tab (where the spring is attached) has probably been bent to increase the high speed. Bend the tab "up" - just a little bit -to reduce the high speed. This will reduce spring tension on the governor arm. Needle nose plier are probably the best tool. By adjusting the high speed in this manner, you will be able to maintain full travel of the throttle control and maintain the throttle shut off feature (if equipped).

I did not see the factory high speed adjustment, but the owner manual states the best torque is produced at 3000 rpm.

[bgsengine]

Needle nose plier are probably the best tool.

Actually a better one is made by taking a piece of 1/4 inch rod, about 6 or 8 inches long and cut a 3/32" slot in both ends, then bend about an inch and a half in from one end to form a long L shape .. or cut the slot in both ends of a extra long 1/4 inch allen key .. (Briggs actually has a special tool which is basically the allen key with the slots cut in it) works much better (and accesses tight spaces better) than needle nose.. .. same principle of adjustment to set top no load on many if not most briggs engines (regardless of if it has the right spring or not)

But as I said - top no load seems to be his problem (hitting extra high rpm way too soon with control only part open) which can be caused by that bellcrank being way outta whack - it can move you from "loose" to "super tight" with just a very little movement, if it is bent out of shape too much.. Seen it many many times... but since I knew it wasnt right , it was always fixed before assembling carb/tank (or control box in the case of other similar styles) to engine..

[lefty]

Thank you. I guess it is quite possible that I may have bent it a tad when removing the spring. Didn't get a chance to work on it much today...because it snowed all day.

[Arkie]

bsengine is right on about the handy tang bending tool

That Briggs tang bending tool is #19480.

edited with more info:
I had to make two tang benders for carb adjusters few days ago using 1/4 inch and a 5/16 allen wrenches and had to use a Dremel grinder to cut the slots in each end. I left mine straight and use a 1/4 inch and 5/16 nut driver on the shank for good leverage and a long reach, one is bent at 45 degree angle for better access to some of the in behind the carb tangs tangs.

More metal can be left on each side of the slot and the tool stronger if a 5/16 allen wrench is used. (Some of the tang carb's metal is little thicker than 3/32 inch wide and the wider 5/16 wrench is required to have more metal meat on each side of the slot.

[lefty]

Thanks. I took a look at it and it appears to be in a "u" shape. I broke everything down today, including removing the tank and such. It seems to be behaving as if the governor is gone. I adjusted the governor. I did not retard it yet, as suggested. Just to eliminate any variables, I wanted to reattach the old carburetor to eliminate that as it is the only thing that has changed. When it came here, it wasn't running. But I cleaned it up and wanted to give it another try.

Before I disassembled as described above, I ran it after making the governor adjustment with the new carb. The only time the RPM's stayed under control was when all of the tension was off the spring and the throttle spring was able to suck it back to idle. I was riding the line just before the kill would engage, which took all the tension off of the governor spring. As soon as I give it even a hairs worth of throttle, it started running away on me. I would then manually force the throttle closed on the carb with my finger and could get it to run smooth like that. As soon as I let go though, it would start running away again up over 3000 with the throttle lever at slow.

I've attached a link to a video here showing the travel on the governor arm. Does this look like the normal amount of travel? It could move further at the top if not for the interference as it contacts the engine. The governor spring was never removed from where you see so I know I didn't screw that up. I would assume also that since it's an extension spring, it would get looser with age rather than tighter.
https://youtu.be/PdVieC9Yaj4
Thank you.

[lefty]

I just got done inspecting all of the linkages and installing the old carburetor back on and I'm having the same problem. It seems that at the lowest throttle setting, it will sometimes hold for a bit and then the rpm will start to rise up. Any sort of tension on the governor spring sends the rpms up to over 3000. Could the governor gear have some missing teeth? It seems the governor is not kicking in at all sometimes.

[Arkie]

That travel appears normal to me.

Did you make the static governor adjust with the manual throttle cable disconnected?( by holding the carb throttle wide open and then very slowly and carefully turning the slotted gov shaft CW and then snug the gov arm nut) Then when the engine is started the governor shaft rotates CCW against the governor spring tension pushing UP on the arm and reducing the carb throttle opening. (I think a little bell crank pivot is mounted at the carb casting and changes the UP movement of the gov arm linkage to pull the throttle towards closed) Make sure this bell crank is installed properly and not binding.
Keep a heads up and do not start the engine with that governor arm spring disconnected, the gov arm will rotate CCW fast and hard and might break something inside.
When you have the tank and linkages installed that governor spring is pulling down on the governor arm so as to give fast gov speed. With the manual throttle cable disconnected the carb will be at full open throttle held by the spring loaded governor.
When the engine starts, the gov's Shaft with the slot should rotate CCW against the spring's tension and reduce the carb throttle. (the gov lever with the spring attached should move up)

You say if you connect that governor arm spring so as it's pulling down the engine runs away at wide open throttle when started. That is not normal if the governor is static adjusted correctly and the engine mechanical governor mechanism is working correctly so as to push up on that arm against the gov spring pressure and reduce the no load carb throttle opening.
You need to confirm that your governor is working.

If you can find a Briggs & Stratton Repair Instruction MS-4750-101 to download it has several of the old model briggs carb and governor linkages adjustment procedures with pictures. (and do and don't so as to not damage the governor itself when working on the engine)


Here is a link to one on flea bay.
https://www.ebay.com/itm/Briggs-Stratto ... 4375933764

[lefty]

I have that exact book. Found it recently in my dad's old book collection. He had notes in it too. He died about 14 years ago. I had no idea he was dabbling in repair at some point. Probably when I was very young.

The book said to do the adjustment with the throttle set to full. I did not disconnect the cable while setting the governor the first time. I'll disconnect it now and give it another try to see if that does the trick. I'll report back. Thank you.

[lefty]

You say if you connect that governor arm spring so as it's pulling down the engine runs away at wide open throttle when started. That is not normal if the governor is static adjusted correctly and the engine mechanical governor mechanism is working correctly so as to push up on that arm against the gov spring pressure and reduce the no load carb throttle opening.
You need to confirm that your governor is working.

Yes? If I'm understanding your question correctly. The governor spring connects the throttle lever on the gas tank bracket to the govern lever. When in full throttle, the governor spring pulls down on the governor lever and fights against the governor's urge to move up and close the throttle via the mechanical link (rod) running from the governor lever to the throttle on the carb. When the throttle is moved to the low position, the tension comes off that spring, allowing the governor arm to move upward, which forces the throttle closed via the mechanical linkage (a metal rod) between the governor lever and the throttle on the carb.

What's happening to me is that when I move the throttle up even a tiny bit, putting very little tension if any on the governor spring, the governor doesn't have the oomph enough to fight against it and push the throttle closed via the linkage rod to the carb. This makes me think that there's something wrong with the internal workings of the governor. Does this sound logical? When you say I need to confirm the governor is working properly, do you mean crack her open and lay eyes on her?
I've looked at a bunch of videos and pictures in repair manuals and all of my linkages appear to be hooked up correctly.

Thanks again.