[Zooman]

I am having another problem with this damn Tilotson carb on my 69 Olympic 335cc.  I put another new filter on it and cleaned the carb again.  I have already put a rebuild kit into it.
The sled starts no problem and will idle fine.  I drove it around for around 10 minutes before it started bogging down.  This lasted for around 5 minutes, I was able to feather the throttle and it would take off again.
Then it would bog down and I would have to play around with the choke lever just to get it to rev up enough to get it into the garage.
What could this be?  I played around with the high and low needle settings and it didn't make a difference.
Is it running lean and when I give it some choke it runs richer?
Let me know what you guys think.  I hate this damn carb!!
Matt

 

[Zooman]

When I jiggle the choke off and on does it make the sled run richer?  I had it running good this afternoon by flipping the choke off and on while I was giving it throttle.
So what exactly is happening with the carb that when I give it some choke it runs ok?
Matt

 

[mopar4u]

When you give it choke you are starving it from air.  Check your impulse line, sounds like there may be a leak.  Check your in and out fuel lines as well for small air leaks.

 

[Zooman]

This tillotson is on a single 335cc rotax.  There is no impulse line.  I did check both fuel lines and they seem ok.
I am at a lost why the sled only starts to bog when it warms up.  And I also don't get why when I flip the choke on and off while I feather the throttle why it will run decent.
Matt

 

[Allen Avram]

There are a couple things to check...Inside the carb where the diaphram that has the little round metal button in the center of it pushes down on a metal fulcrum... make sure the top of the fulcrum is level with the sides of the carb housing... if the fulcrum sits to low it will not allow enough fuel to enter from the needle and seat.  Also check the needle and seat, if there is a noticable ring around the needle then replace it. Also check to see if there is water in the gas tank, you may have to syphon the tank and treat it with some alcohol...Hope this helps...Al.

 

[Zooman]

I have tried all those things that you just mentioned.  I have enven put a new needle and seat in.
Today when I tried to start it with the choke on I pulled it 30 times and it wouldn't start.  I checked the plug and it was dry.  I dumped a little feul down that carb and it started but it back fired and bogged really bad.  I notice a little oil and the back of the head towards the front of the sled.
Could this be a blown head gasket?  Would I be able to tell if I took the head off?
What do you think?
Matt

 

[Allen Avram]

Matt: Try this, unscrew the fuel line from the carb blow into the fuel line you should hear air bubbles coming from the fuel tank then draw  on the fuel line to make gas come out of the fuel line, if I recall I think there is a return fuel line from the carb to the tank, maybe the two lines are crossed, also there is a number of gaskets inside the carb and they have to be placed in the proper position to get a vacuum signal from the motor when it is pulled over.  Check the decompression valve on the exhaust side of the motor, that may be where you saw the puff of smoke...usually if you have a leaky head gasket it will whistle where the leak is....On the side of the carb flange there will be a stamp like HR or HD, if you have a snowmobile dealer in your area he may have a exploded view of your carb that shows how your diaphrams are to be placed in the carb...it doesn't have to be a ski-doo dealer...just one that has been in business since the seventies... I hope this helps...I will be the in the office Saturday, give me a call.  Avram Funeral Home, Ask for Al Avram, 989-843-5441  (EST)  Low speed jet screw set at 3/4 open, High speed jet screw set at 1 1/4 open.

 

[Zooman]

Hi Al thanks for the help.
I have already put a rebuild kit into the carb(HR).  I found a web site with a diagrahm and put my gaskets in the right way.
Just before I had this big problem I ran the sled for about  hours with no problems.
It was running good when it back fired a couple of times and died on me.  Now I have been having all these problems.
I will blow on the gas lines like you said.
I don't understand why there is no gas getting into the cylinder with the choke on.  It used to start on the second pull with the choke.  What could cause this.
When I am pulling it over I am getting gas back down the return line so I am pretty sure the feul pump is working.
I also took the carb off and gave it a good cleaning again.
Matt

 

[Zooman]

Would a sticking needle from the needle and seat cause some of these problems?
I put a new needle and seat in.  When I took the carb apart again I noticed the needle was sticking pretty bad.  I had to give the carb a couple of good wacks to get it to fall out.
How do you stop this from happening?

Matt

 

[DOO-MAN]

HEY ZOOMAN,
WHAT WAS THE NAME OF THE WEBSITE W/ THE CARB GASKET DIAGRAMS.
THANKS,  DOO-MAN

 

[Zooman]

Ok man here ya go;
http://www.mercurysnowmobiles.com/hrcarb.htm



Would a sticking needle cause some of these problems that I am experiencing?  I cleaned the carb agian today and I had to give the carb a couple of good whacks to get the needle to come out.
Matt

 

[DOO-MAN]

HAVE YOU TAKEN THE WELCH PLUGS OUT AND REPLACED THEM? WE HAD A 69 SKI-DOO 12/3 THIS PAST WEEKEND THAT WOULD ONLY RUN ON A SQUIRT CAN. WE HAD JUST PUT A WHOLE NEW CARB IN IT EXCEPT THE WELCH PLUGS AND THATS WHAT IT WAS. THE WELCH PLUGS WERE LEAKING BY.

 

[Zooman]

Hey Doo man.
Ya I did replace the welch plugs on this tillotson.  When I put my new ones on I even put some clear nail polish around the edges to make sure they sealed.
I talked to a small engine guy who gave me that tip.
I will put the carb back on today and see what happens,
Matt