# Jacobsen Sno Burst Engineering Question



## R P (Nov 24, 2015)

I acquired a thirty year old Jacobsen Sno-Burst with the intent to return it to running condition. The only piece missing from the entire machine was a governor spring which was replaced along with the carburetor diaphragms and spark plug after a quick trip to the hardware store. It still won't start. But that isn't what kept me up all night. It was the carburetor location.

The carburetor is mounted at the bottom of the engine. I have reached the end of 'google' and 'youtube' trying to find an explanation about why and more importantly how this engine is supposed to run with the carburetor mounted that far away from the combustion chamber. If anyone has any links or can give an explanation about how this design is supposed to work I would be grateful.


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## bad69cat (Nov 30, 2015)

Is it a tecumseh? Got any pics..?


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## R P (Nov 24, 2015)

I uploaded the engine pictures to the gallery page, link below

Snowblower Forum : Snow Blower Forums - R P's Album: Jacobsen Sno Burst

I was told that Jacobsen made their own engines, I snapped a picture of the engine identification plate as well and added it to the gallery.


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## ELaw (Feb 4, 2015)

That engine was indeed made by Jabobsen. And it's a 2-stroke engine which means it has no valves and a lot of other differences from 4-stroke engines - including the carburetor location!

https://en.wikipedia.org/wiki/Two-stroke_engine

That cable that looks like it's connected directly to the carb... is that for the choke? If it's the throttle, it's definitely set up wrong.


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## bwdbrn1 (Nov 24, 2010)

That's the way Jacobsen built them. Not necessarily the best for a snowblower, but their Model 321, 2 stroke engines were very successful and long lived in other applications. It was actually a very efficient set up. Fuel mixture in one end, exhaust out the other.

Here's the same basic engine on a 1962 edger. Different carb, but I think you can picture the engine in your Sno-burst.



...and an even older 1948 Bantam reel mower. Not the best picture, but after a little clean up, it still ran and mowed.


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## R P (Nov 24, 2015)

The governor linkage is out of view underneath the carburetor. That is the choke cable in the picture. The spark tester showed a good spark, feels like good compression on the pull rope .. . I haven't disassembled it beyond the carburetor, but if there is an issue with (I assume) points ignition system inside the flywheel then finding parts might be a problem.


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## ELaw (Feb 4, 2015)

If you're getting spark, the ignition system's probably not the issue. If the point gap is wrong it might affect the timing a bit, but that would not prevent it from starting.

I'd be more likely to suspect the fuel system - and those diaphragm carbs can be a little tricky to diagnose. In a float-type carb if the engine's getting no fuel it's often the fault of the float or needle valve, but your carb doesn't have those components! Of course a clog in the tank or shutoff valve or filter could be the problem.

Also I assume you know that machine requires mixing oil into the gas? Failure to add oil would not keep it from starting, but would quickly ruin the engine when it does start!


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## bwdbrn1 (Nov 24, 2010)

If you have good spark, then I wouldn't bother trying to get to the ignition just yet. The problem must be in the fuel delivery. Have you tried dribbling a bit of two stroke mix into the spark plug hole to see if it would try to run?


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## ELaw (Feb 4, 2015)

^^ What he said!

I would NOT try starting fluid on this engine, or if you do, use it very sparingly. As with the gas, starting fluid does not contain any oil and thus could cause harm to the engine.


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## R P (Nov 24, 2015)

I tried a couple times with a capful of gas in the spark plug hole. I didn't hear anything try to start, and didn't see any smoke from the exhaust. A very short burst of starting fluid across the top of the spark plug hole didn't do anything either.


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## Grunt (Nov 11, 2013)

:welcome: to SBF RP. The engine was made by Jacobsen and is pretty unique. Between the carb and engine block is an assembly called a reed block. It is two pieces of spring steel that open and close (like valves on a 4 cycle engine) with engine vacuum and compression to pull in the fuel mixture and push it to the combustion chamber by transfer ports (tunnels) built into the engine block. If the reeds are stuck or broken, the engine will not run.

The sno burst I had in the 1980's would only start if I laid it flat with the handle bars on the ground holding it with my foot and pull started it.

From your pictures, I can see that there are two springs that are definitely in the wrong places and sadly, I don't remember where they should go.
There is a youtube video of one that briefly shows the carb and sno burst linkage.





I do have a PDF version of the owners manual with all the part numbers but no repair information if you need it. Send me a private message with your e-mail address if you want it.


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## Kiss4aFrog (Nov 3, 2013)

I have to ask if the carb is loose from the intake ?? I think I'm seeing a big gap between the intake and the black spacer attached to the carb.


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## R P (Nov 24, 2015)

The reed plate photos of the Jacobsen have been added to the gallery. I traced out and cut new gaskets all the way from the carburetor to where the reed plate attaches to the crankcase and reassembled. Engine running video below gallery link. 


Snowblower Forum : Snow Blower Forums - R P's Album: Jacobsen Sno Burst


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## Grunt (Nov 11, 2013)

Good job RP. What did you have to do to get the sno burst running and did you figure out how the governor linkage is supposed to go?


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