# 1981 Toro engine running lumpy



## AnimalHungry (Jan 29, 2013)

So my 1981 Toro 724 had been running great all winter until yesterday when it starting running lumpy. It seems to idle fine but anything over half throttle and it starts to misfire or sound like it's being starved of fuel. When it sounds like it's missing it also sometimes gives a little puff of black smoke out of the exhaust. Here's a video I shot of it: 




I was thinking to start with the carb and see if the main jet's blocked. Any other ideas greatly appreciated!

Cheers
Simon


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## nt40lanman (Dec 31, 2012)

Generally with a blocked jet, it will run lean and surge. Your machine sounds rich, and your black puffs go along with that. Make sure the choke is all the way off. The cover on the left covers the carburetor. Under the bottom there is an adjustment screw hanging straight down that you could turn in a half turn to see if it improves things. There are plenty of videos on YouTube about carburetor tuning.


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## GustoGuy (Nov 19, 2012)

The Briggs updraft flo-jet carbs can leak at the emulsion tube base were it goes into the venturi of the carburetor and this can cause unmetered fuel to enter the engine and poor running. Corrosion can cause the leak. Some times you can take a q-tip and polishing compound and clean the base up in the carburetor were the emulsion tube threads in. Some will get a small Teflon washer you can buy from Briggs dealer to seal the base. Also the 3 bolt float bowel carbs can warp too and this can cause leaks.


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## woodtick007 (Apr 9, 2011)

Did you know for $100 you can solve all your Tecumseh problems with a Harbor Freight Predator 212cc engine? Just saying


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## Grunt (Nov 11, 2013)

Simple things first. Have you tried draining the old gas which may have some water in it? Change the spark plug? Next would be a carb adjustment and\or cleaning. Could also be the valves need to be adjusted. Here is the service manual for your engine.
http://www.barrettsmallengine.com/manual/tecumsehlheadmanual.pdf


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## nt40lanman (Dec 31, 2012)

forgot it was a Briggs carb.... oops


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## td5771 (Feb 21, 2011)

All good ideas. Try the high jet adjustment on the bottom of the carb. If that doesn't work I am thinking when the last time the points were changed.

It runs good at low rpm, then as you go up the points cant handle it. It misfires then when the points try to get a shot off the is unburned fuel from the previous misfire still around and you great the puff of black smoke indicating a rich mix.


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## GustoGuy (Nov 19, 2012)

td5771 said:


> All good ideas. Try the high jet adjustment on the bottom of the carb. If that doesn't work I am thinking when the last time the points were changed.
> 
> It runs good at low rpm, then as you go up the points cant handle it. It misfires then when the points try to get a shot off the is unburned fuel from the previous misfire still around and you great the puff of black smoke indicating a rich mix.


I doubt it is the points. I would try cleaning all the small holes in the carburetor and then reasemble the carburetor and adjust the high-speed jet to 1&1/2 turns out from lightly seated and see how it runs after you install a new correctly gapped sparkplug for it stumbles the turn high speed jet leaner by an eighth of a turn until it runs better


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## db130 (Feb 16, 2013)

Clearly, this is a Tecumseh and not a Briggs?


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## Ray 1962 10ML60 (Oct 14, 2011)

Follow the Tecumseh instructions above and you should be in business, plenty of YouTube videos on how to clean the carb out. Not sure how all the briggs talk go mixed in here


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## GustoGuy (Nov 19, 2012)

Toro had Briggs 8hp engines on lots of their old machines in addition to the 7hp Tecumseh engines


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## AnimalHungry (Jan 29, 2013)

Thanks for the suggestions guys. It's a 7hp Tecumseh engine. I changed the points and governor before the Winter and it was running great until the other day so I'm thinking some kind of carb issue. It also has totally fresh (premium) gas. I'll strip the carb and see if I can see anything amiss in there and report back.

Cheers
Simon


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## AnimalHungry (Jan 29, 2013)

woodtick007 said:


> Did you know for $100 you can solve all your Tecumseh problems with a Harbor Freight Predator 212cc engine? Just saying


To be honest, the thought had crossed my mind - although it does feel like cheating 

Cheers
Simon


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## motorhead64 (Dec 15, 2013)

If you changed out your points recently, they could have closed up on you. td5771 is right about the symptoms of points closure mimicking yours. Of course, it is always easier to check your carb first for accessibility reasons and I agree you should start there, but I wouldn't discount points as the cause either. MH


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## td5771 (Feb 21, 2011)

Goes without saying to check the carb first, its the easiest. try the adjustment first. hopefully thats it.


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## GustoGuy (Nov 19, 2012)

AnimalHungry said:


> To be honest, the thought had crossed my mind - although it does feel like cheating
> 
> Cheers
> Simon


The HF Predator engines are excellent runners and I have 3 of them and they always start with 1 to 2 pulls of the recoil. Check out a replacement carburetor for your 7hp Tecumseh they are often available for $35 or so dollars on eBay and many people say they really work well. It beats wasting your time on a worn out carburetor


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## UNDERTAKER (Dec 30, 2013)

Put that techumseh out of it's pain. Get a new briggs 4 it.


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## td5771 (Feb 21, 2011)

no way, hang on and get that tec running. Any one can have a new motor that runs good. Not everyone can have one thats 30 years old and purring.

Anyway, check the carb adj. If that is a no go recheck the points. Those are the some symptoms and I just had a toro 3521 with the same. Guy described the same symptoms but then it quit all together.

Points, condenser, plug, carb adj and it runs perfect.


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## AnimalHungry (Jan 29, 2013)

So I stripped the carb and didn't see any blocked jets or holes and put it back together with new gaskets. Points were fine but I replaced the condenser anyway. Also replaced the plug which was fairly coked up and gapped it to 0.030". It wouldn't fire on the first 3 pulls then ran for a few seconds on 4th pull and then couldn't stay alive and was pretty smoky. When I had the head off last the exhaust valve was pretty well worn and there was a fair amount of ring slap so I'm thinking it's probably a combination of low compression and general wear that's pushing it over the edge. I spent pretty much the whole day on it and can't really afford any more time, which sucks because I love that motor lol! It might be time to look into that a Predator motor.

Thanks again for the ideas!

Cheers
Simon


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## AnimalHungry (Jan 29, 2013)

Bit the bullet and bought a HF predator engine yesterday to replace the Tecumseh. The only issue so far is that the pulley shafts are different sizes - Predator is 3/4" while the original Toro one is 1". I'll keep looking but any ideas how to get around this?
Cheers
Simon


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## AnimalHungry (Jan 29, 2013)

I was thinking something like this: 




...but I was wondering whether this is what people do? Or is the standard fix something different like finding a pulley with a 3/4" inside diameter?

Cheers
Simon


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## JerryD (Jan 19, 2014)

That Predator engine will not last a third the time the old Tecumseh did. My brother owns a tool rental company, we decided to replace some of the older engines with Predator engines instead of rebuilding the originals like he used to do. The predator engines run great out of the box but only last a summer before they start using lots of oil and start running hot. Needless to say we are jumping through hoops trying to rebuild 6 (4 - briggs, 1 - Kohler, 1 - Wisconsin) engines before the weather breaks.
There is a reason they sell for $100.00.


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## Shryp (Jan 1, 2011)

Most people get new pulleys of the appropriate bore size since we usually go for a larger pulley to spin the impeller faster anyway. A couple have decided to go with the bushing reducer and reusing the old pulley.


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## gsnod (Sep 2, 2013)

Simon -- I just switched over a blown Tecumseh to a Predator the past few days. I used a sheave that went from 3/4 ID to 1 inch OD so I could use the original pulleys. While the bolts lined up perfectly, the Predator still sat back too far. I ended up moving the Predator forward (today) and remounted it. Put it back together today and all is well. All I need is some more snow to try it out on. 

So, here's what I learned....just because the former engines bolts fit, does not mean that the new engine is far enough forward. Check the length of your shaft and your pulleys to make sure they line up. Second, if you don't use a sheave, you'll need to get new pulleys sized 3/4 ID.

If I had to do it again, I'd definitely price our pulleys. My Tecumseh shaft was about 1/2 inch longer than the predator, and that can impact your belt and pulley alignment. 



AnimalHungry said:


> I was thinking something like this: 3 4" x 1" x 1 1 4"Shaft Adapter Sprocket Pulley Bore Reducer Sleeve Bushing | eBay
> 
> ...but I was wondering whether this is what people do? Or is the standard fix something different like finding a pulley with a 3/4" inside diameter?
> 
> ...


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## AnimalHungry (Jan 29, 2013)

JerryD said:


> That Predator engine will not last a third the time the old Tecumseh did. My brother owns a tool rental company, we decided to replace some of the older engines with Predator engines instead of rebuilding the originals like he used to do. The predator engines run great out of the box but only last a summer before they start using lots of oil and start running hot. Needless to say we are jumping through hoops trying to rebuild 6 (4 - briggs, 1 - Kohler, 1 - Wisconsin) engines before the weather breaks.
> There is a reason they sell for $100.00.


That is the precise reason why I bought a 2 year replacement warranty on the thing for 30 bucks


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## AnimalHungry (Jan 29, 2013)

gsnod said:


> Simon -- I just switched over a blown Tecumseh to a Predator the past few days. I used a sheave that went from 3/4 ID to 1 inch OD so I could use the original pulleys. While the bolts lined up perfectly, the Predator still sat back too far. I ended up moving the Predator forward (today) and remounted it. Put it back together today and all is well. All I need is some more snow to try it out on.
> 
> So, here's what I learned....just because the former engines bolts fit, does not mean that the new engine is far enough forward. Check the length of your shaft and your pulleys to make sure they line up. Second, if you don't use a sheave, you'll need to get new pulleys sized 3/4 ID.
> 
> If I had to do it again, I'd definitely price our pulleys. My Tecumseh shaft was about 1/2 inch longer than the predator, and that can impact your belt and pulley alignment.



Thanks that's really helpful. I can't find any 3/4" replacement pulleys that have two belt grooves so I'm gonna go with the sleeve and use my old pulley. Haven't looked at the clearances and alignment yet but will pay attention to it.


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## Shryp (Jan 1, 2011)

You don't need a pulley with 2 grooves. You just need 2 pulleys. You are overthinking things. 

And, if you need them to be closer you can always install one of the pulleys backwards.


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## motorhead64 (Dec 15, 2013)

pulley sheave products - Grainger Industrial Supply

This place may have just what you're looking for. MH


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## GustoGuy (Nov 19, 2012)

JerryD said:


> That Predator engine will not last a third the time the old Tecumseh did. My brother owns a tool rental company, we decided to replace some of the older engines with Predator engines instead of rebuilding the originals like he used to do. The predator engines run great out of the box but only last a summer before they start using lots of oil and start running hot. Needless to say we are jumping through hoops trying to rebuild 6 (4 - briggs, 1 - Kohler, 1 - Wisconsin) engines before the weather breaks.
> There is a reason they sell for $100.00.


I haven't heard of such a problem with them and I use my snow blower all the time and cart racing teams beat on them all year round with 30+ races with out them failing. What motor oil are you using?. All 3 of my Predator engines run great and the oldest one is over 1 1/2 years old now and it has been used just about every weekend during the summer for hours at a time


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## JerryD (Jan 19, 2014)

GustoGuy said:


> I haven't heard of such a problem with them and I use my snow blower all the time and cart racing teams beat on them all year round with 30+ races with out them failing. What motor oil are you using?. All 3 of my Predator engines run great and the oldest one is over 1 1/2 years old now and it has been used just about every weekend during the summer for hours at a time


Put the engine on a piece of rental equipment that runs 10- 12 hours a day, 6-7 days a week and you will see the difference.


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## GustoGuy (Nov 19, 2012)

JerryD said:


> Put the engine on a piece of rental equipment that runs 10- 12 hours a day, 6-7 days a week and you will see the difference.


Here is a website that talks about HF Predator engines being used in commercial lawn cutting services. 173cc Vertical shaft OHV engine is what they are talking about. No one has said that the engines are failing after one summer and you can buy a 2 year warranty for the engine as well for $20 that is a no questions asked warranty.
http://www.lawnsite.com/showthread.php?t=403856


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## AnimalHungry (Jan 29, 2013)

Shryp said:


> You don't need a pulley with 2 grooves. You just need 2 pulleys. You are overthinking things.
> 
> And, if you need them to be closer you can always install one of the pulleys backwards.


Good thinking. Although for 20 bucks delivered I can get a sleeve so I can use my old pulley. I'll prolly go that way.

Cheers
Simon


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## JerryD (Jan 19, 2014)

GustoGuy said:


> Here is a website that talks about HF Predator engines being used in commercial lawn cutting services. 173cc Vertical shaft OHV engine is what they are talking about. No one has said that the engines are failing after one summer and you can buy a 2 year warranty for the engine as well for $20 that is a no questions asked warranty.
> http://www.lawnsite.com/showthread.php?t=403856


I looked at that post, you have 10 posts by 4 people and none of them have any amount of time on the engine, as per their post.
I'm not here to argue, I wrote about our experience, take it or leave it.

Jerry...
If it were easy, everybody would do it!


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## GustoGuy (Nov 19, 2012)

JerryD said:


> I looked at that post, you have 10 posts by 4 people and none of them have any amount of time on the engine, as per their post.
> I'm not here to argue, I wrote about our experience, take it or leave it.
> 
> Jerry...
> If it were easy, everybody would do it!


I wasn't too sure about them either so I bought one for my old doodle bug minibike that my family outgrew since the stock engine was gutless for adults to ride. I was impressed by how well it ran and how easy it started. I read the reviews and they are rated 4 out of 5 stars with 88 reviews including 2 of my own. Now the old Briggs 8hp that I had on my 1973 Montgomery Ward (gilson) did not have a cast iron cylinder liner at all when I pulled the head to clean the valves. I wonder if the metalurgy is poor when compared to the Honda engines since the specifications are simular to the Honda engines and down right impressive when compared to the original Tecumseh L head engines. NR racing even builds these engines up to be cart racing engines and replaces the stock cast connecting rod and stock flywheel with a billet forged connecting rod and billet flywheel that can handle 8500 pms and these engines put out up to 14hp out of 212cc and have beaten many real Honda engines. NR Racing said the the engine block casting and machining quality is much closer to the quaility of the Honda engines then most other Clone engines. Below is the list of product specifications from Harbor Freight. *How often do you change the oil and are you using synthetic or coventional oil?* I have three 212cc Predator engines and all of them run way better than the Tecumseh L head 5hp that I originally had on my snow blower did. Even when the Tecumseh 5hp was brand new it did not start as easily or run even close to as well as this engine does. I use Amsoil in all my engines and my so-called low quality Hyundai Elantra has over 317,000 miles on it and still runs great and does not burn oil. Now according to many so-called experts here Hyundai cars are not very good cars dispite what JD Powers and other professional reviewers have to say about them. Now if these engines were poor engines or burned oil or overheated? I would say so if I experienced this and so far the oldest one of them still runs great. How does an air cooled engine that does not have a thermostat at all overheat anyway? 


Upgraded engineering and construction for improved lifespan 
Durable cast iron cylinder withstands wear and abuse 
User-friendly controls for easy starting and operation 
Fuel shut off for safe transport 
Ball bearing support shaft for long life 
For use on: pressure washers, cement mixers, compressors, mowers, log splitters, vacuums, tillers, water pumps, chipper/shredders, generators, blowers


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## AnimalHungry (Jan 29, 2013)

I'm waiting on the sleeve for the driveshaft which should come today. I live at 10,000 ft though so I'm trying to find the high altitude kit with a leaner main jet, but HF are out of stock and they don't list it on their website. I was just gonna pull the existing jet out and try and find some smaller ones at my local snowblower/chainsaw repair store. Does anyone know if the predator jets are the same as Honda ones (or any other brand jets are compatible)?

I found this kart guy suggesting some easy mods to get more power out of it: AGK - Performance Basics - Affordable Go Karts

I reckon if it's good enough for kart racing it's gonna be good enough for my 1981 Toro!

Cheers
Simon


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## JerryD (Jan 19, 2014)

If you can't find the jet, you can try soldering the hole closed and redrill it using a jet drill. It's a old trick we used to use when cart racing on a budget. It may get you in the ballpark.




AnimalHungry said:


> I'm waiting on the sleeve for the driveshaft which should come today. I live at 10,000 ft though so I'm trying to find the high altitude kit with a leaner main jet, but HF are out of stock and they don't list it on their website. I was just gonna pull the existing jet out and try and find some smaller ones at my local snowblower/chainsaw repair store. Does anyone know if the predator jets are the same as Honda ones (or any other brand jets are compatible)?
> 
> I found this kart guy suggesting some easy mods to get more power out of it: AGK - Performance Basics - Affordable Go Karts
> 
> ...


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## AnimalHungry (Jan 29, 2013)

Thanks - nice idea. I actually found some Honda jets today which should do the trick.

Cheers
Simon


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## AnimalHungry (Jan 29, 2013)

The sleeve arrived and my old pulley slid on fine. I filled it with 5W30 synthetic oil as it's usually running in below freezing air temp. Then I installed a 60 main jet and it started while I was getting it to TDC before I even gave it a good pull. It ran a little lean so I put in a 62 main and it works great - I'm at 10,000ft. The original jet is a 65. I'm in the process of running it in so I've been warming it up and cooling it down a few times with no load. So far so good tho 

Cheers
Simon


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## AnimalHungry (Jan 29, 2013)

I did a bit of searching on the net for parts for this Predator engine and the good news is that it's a clone of the Honda GX200 so Honda parts, and pattern Honda parts, will fit. Also, a ton of kart guys out there modify these things and even push them up to 20+ HP!?!? Here are just a few of them in case anyone's interested: 

Aftermarket Predator Parts
NR RACING THE LEADER IN HONDA GX & CLONE PERFORMANCE
Honda GX160 / GX200 and clone Parts, Box Stock, Superbox

Cheers
Simon


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## 43128 (Feb 14, 2014)

i had the same thing happen to my toro 824 this winter with an hm80, i said screw the fucking thing ive gone through three aftermarket carburetors, the **** recoil starter never engages, and the exhaust valve is leaking, so i got a 196cc honda gx200 clone and i love the thing, bolted right up and only needed to get a 3/4 inch to 1 inch sleeve and it feels like it has much more power than the hm80


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