New 206 won't start

S

Snomo

New member
I just bought a new 206 for my son's snowmobile. A little different application I know but as far as carb tuning should be similar. The first thing I did was set the float height to .860 and turned the mix screw out 1 1/4 turns. It wouldn't start even with choke on, so I started turning the air screw in and eventually seated it. It would start but run rough, if I give it some throttle it does clear up which made me think the pilot was plugged. I pulled the carb and blew out all jets and passages but didn't ever find anything. I put the carb back on tonight and still the same. I've read through the Briggs tuning guide and it points me in the pilot direction as well but I'm surprised the engine will not start with the jets that came installed. Could this be something to do with needle clip height? I thought this was more for mid range throttle. I also wondered if I could be sucking air between carb and engine but I can see the new gasket between the stack and head and the carb has an o-ring. I did notice there is a port open just under the o-ring that doesn't get sealed. Would this be an issue? Any help would be greatly appreciated
 
Snomo

You might have a stuck needle valve, we have had that a time or two. If its just stuck alittle, you can spray some WD 40 down the fuel inlet and let sit for alittle bit. You can remove the bowl drain screw to see if your even getting fuel to carb. If you have my luck, then you will have to remove the bowl. Pull the float off so you can pull out the needle valve out and clean it and the seating surface. We have found this last step will get things running again. Hope this helps..... Pat Collins
 
I agree with Pat but also check your float drop to make sure the needle isn't pulling out of the seat so far that it gets in a bind and sticks open.
 
Thanks for the advice guys, I'll check both tonight and let you know what I find. I know I am getting fuel into the bowl as both times I pulled it, I drained it first. I haven't had fuel coming from overflow but thinking about it now it does seem like something weird is going on with the needle. Thanks again!
 
If you have not checked or set the float height yet, be sure to do so while you have the bowl off. It's easiest to do with the carb upside down on the workbench in front of you, but if you're real gentle you can do it whilst standing on your head with the carb still on the engine. Just kidding. ;)

If the float drop is too low, it will allow the inlet needle to come partially out of the fuel inlet and get caught/wedged at an angle.

Remove the floats & inlet needle, then clean everything extremely well with brakeclean. Sometimes I will use a Q-tip soaked in brakeclean and spin it between my fingers up in the fuel inlet to help clean that area. Re-assemble and set the float height and drop where you want it, and you should be good to go.

Of course, if you have any questions, feel free to call the Briggs dealer whom you purchased the engine from.
We'd be glad to help as well.

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Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
27 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
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If you have set the float at .860" and then put it back together the float should not be sticking.
Make sure you can see through the pilot (idle) jet. It has a reputation of getting plugged up if you leave fuel in the bowl.
The hole through the pilot jet is about .013"
I would recommend never leave fuel in the bowl. Always drain it if you aren't going to be using the engine for a week or more.
If you don't the pilot jet can get plugged and the float needle can stick.
Another problem that happens when kart racing is that a competitor can hop the right rear wheel and hit the carb. If that has happened it can not only damage the carb but it can either crack the intake manifold or bend it where it is attached to the engine.
If it is sucking air (vacuum leak) it may start hard or not idle properly.
With the engine running spray some carb cleaner around the intake manifold. If the engine speed changes, it's leaking.
Good luck
Jim
 
If you have definitely decided it is the carb my advice won't help. We had one brand new engine that would not start the coil was at it's maximum gap, set properly fired on first pull.
 
The engine is brand new out of the Briggs box so it's only been in the sled for a week. It ran well enough off idle to run a couple heat cycles to break it in but now I need to get it running correctly. So the issue with old fuel doesn't apply, also I've had the jets out twice and blew everything out. I did set the float height but did not set the drop. In fact this may be part of the problem because when I pulled the bowl the first time the float fell straight down and the needle fell off. I thought to myself maybe these carbs don't have a stop because I've never had one fall that far when pulling a bowl. I didn't think anything more of it til several people have mentioned it now. But if it is falling too far and getting stuck open shouldn't I have fuel coming out the overflow?
 
That is a good question, I never thought of that. I never took the float off as I was able to slide the needle back on but maybe it came that way? The float height wasnt that far off though.
 
When Walbro quit making the carb it forced briggs to make them. There were some of them that had the post that the float drop tab didn't hit properly and the needle would fall out if you weren't careful when you took the bowl off. You can still set the float drop on these carbs but it's a little more challenging.
Did you actually look through the idle jet and see daylight? If it's plugged you can blow through them with compressed air and won't clean it out.
Where do you have the clip on the slide needle set?
 
I haven't gotten a chance to look at it again yet but hope to tomorrow. I can see daylight through the pilot. I did set the height but wondering if it's too low and can't pick up fuel from the pilot. Also thinking maybe an air leak both which I'll check tomorrow.
 
Well, I took the carb off again and pulled everything out of it. Blew out all the passages and I know that none of the jets are plugged. I set the float height a little higher thinking maybe I needed more fuel in the bowl. Put it back together and no change. I talked with the owner of the place I bought it from and he said they have seen a couple bad intake manifolds. I sprayed some carb cleaner around the intake while it was running and the rpm came up. I haven't pulled it yet plan to later tonight. My own fault for assuming everything there was new so it couldn't be sucking air.
 
I have seen a 206 in which the manifold was turned upside down. This did not come from briggs that way but the owner had things apart and mistakenly turned the manifold over. If looking at the manifold with out the carb on the adjusting slot to align the carb and manifold should be on the left. Worth a look at least. If the manifold is upside down it doesn't let the carb seat.
 
Yup it was on the left when I pulled it off tonight so it was installed correctly. It's hard to tell but looking at the flange on the engine side it looks like the tube isn't centered in the flange. Also on that side if you set it on a flat surface and shine a light on one side you can see it from the other. So it's definitely not perfectly flat but I would think the gasket could take up this space. The gasket looked fine as well.
 
I was really hoping that was it. Even though it is not the problem make sure you align the manifold with the head and then the carb with manifold. We take the slide out to do that. Maybe some sand paper on a flat surface or even a file if it was bad would help straighten the manifold. Check the rules though if you touch sand it it may not be legal. May require a new one. I think they are around $20.
 
Hopefully I can just get a new one sent to me, again it's a brand new engine. I deal with rec motors in Iowa as they sell tons of parts for these mini sleds and Scott has been very helpful. Thanks again for all the tips, will update when I get a new manifold.
 
If it's a new engine why not talk to them?
If it was an engine that i sold i'd be disappointed if you didn't call me with any problems.
 
I did talk with them last week during this troubleshooting process and he gave some good suggestions along with the others I got from here.
 
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