kick starter locked in top position 1984 Fantic 300 pro

[Skinner]

How does the carb bowl come apart from the carb? There seems to be no external screws holding the 2 pieces together? I removed the drain plug but I cant see it holding the 2 pieces together. I don't want to try and pry the 2 sections apart and ruin the gasket.

[grib]

It is only held on by the drain plug/main jet holder, it also fits over the bottom of the choke jet with an o ring - its probably this that is holding it, there is an o ring between the bowl and carb body too, no gasket. It should come off if you wiggle it enough.

[grib]

Is there a hole in that yellow pipe?

[Skinner]

There was, I replaced it? Was I wrong?

Is this top pin meant to be tight or is it made to go up and down?

[grib]

Without a hole in the pipe no fuel will be drawn out of the carb, the two stubs are float bowl vents and need to be open to atmospheric pressure, a lot of people (me included) don't use a pipe at all on the vents.

The 'pin' in your photo is the float needle which allows fuel to flow in to the carb. The needle should be a free fit in the other part (the needle valve), if you turn it upside down it should fall out. It could just be gummed in place with old fuel/oil, but the chances are it needs replacing, if it doesn't shut off properly you will have crankcases full of fuel.

 

Page 4 here; http://dellorto.it/wp-content/uploads/2015/10/dellorto_manual.pdf

Edited November 5, 2017 by grib

[Skinner]

Good Morning everyone,

Good news, I installed the new coil and there is a spark. Now I have another issue. The gas isn’t flowing from the tank to the carb? I have to fill the hose manually and then it doesn’t flow into the carb?

Any Ideas?

I cleaned the carb and it all looks good. The only issue I have is the travel of the fuel valve. I see that there is a rubber tip on the end and it does move freely. My concerns is the little amount of travel. Should there be a noticeable amount of travel when the float is moved? Is this even a concern when the gas isn't flowing .

 

 

I put a few drops into the spark plug and it fired for a second.

 

It was nice to hear it for a 10^th of a second.

 

Cheers

Jerry

Here is the valve before I cleaned it

 

[vintagenut]

Hi Jerry,

Just read your post and am in the midst of a similar problem with a Sherpa T I'm working on.

A couple of thoughts if you haven't already sorted this out...

1. Are you sure fuel is flowing freely from the tank fuel valve?  Drain a bit into an open container and check that your fuel from the tank is unobstructed.

2. Further down the line, check the filter screen located behind the 10mm bolt securing the fuel inlet housing (my term) that your fuel line from the tank connects to.  If the filter screen is blocked by residue or debris, no fuel will flow into the bowl. Clean and replace.

3. Still no flow? With the bowl, floats and rubber tipped fuel valve that you cleaned up removed, re-connect your fuel line from your tank to your carb and, over a fuel-safe container (like I need to even say that), see if you get fuel to flow freely into the container.  If not, you have blockage along the passageway between the the fuel housing beyond the screen (mentioned in #2 above) and the fuel valve housing where your rubber-tipped valve lives.  Remove the adjustable fuel mixture screw on the outside of the carb, remove all jets, remove the fuel housing and screen again and spray all passageways liberally with your favorite aerosol carb cleaner until you get cleaner flowing from the fuel valve housing into your container. Also spray any overflow tubes that may reside in the bowl itself. Reassemble all including the bowl.

4. Still no flow? Did you follow up on Grib's recommendation?  To test, remove that yellow vent tube you replaced and give it a shot. You can run without any tube whatsoever or a pair of tubes open to atmosphere but if you connect both vents with a single tube (a common setup) you HAVE to drill a hole in the tube at the height of its arc (the mid point of the tube) for air to pass through or fuel will not enter the bowl of the carb.

Finally make sure your floats aren't getting hung up in some way when you reassemble your carb. I once had a carb that a previous owner had replaced with the incorrect float. It physically fit but wouldn't move once the bowl was in position. If you're sure the correct float height has been achieved, give the carb a gentle shake to see if you hear float open/closed movement within the bowl.  With such a tiny carb, it won't be much but you should hear something moving.

Hope this helps.  Best of luck!

Christian

 

[Skinner]

Thanks for the info.

 

I will try all this again. I have done everything you suggested except the fuel mix screw. Good weather is coming Mon and Tues. I don't have a garage just a tool shed. ( limited space ) .

The gas comes out of the tank freely and when I add the fuel hose, the gas comes out 1 inch then sucks back into the fuel tank. I have to remove the fuel line partially and the gas will fill the line and carb. It fires up and idles a little high for a few seconds then it revs up higher to redline then it just cuts off. The fuel doesn't suck out of the tank into the hose or into the carb. I have to remove the hose from the tank and then it flows til the bowl if full? 

Like I said earlier, the only thing I haven't tried is removing the fuel mix screw and cleaning it.

I will keep you informed.

Jerry

 

[vintagenut]

Hi Jerry,

Sorry to hear you're having such a difficult time with this. And working in a shed doesn't make the experience any more enjoyable either, I'm sure.  When I was between places I used to work on my projects in a storage unit the size of a walk in closet.  It was cold (by California standards, anyway), crowded and agonizing with limited elbow room and lighting. The absence of a proper workbench meant having to work on the floor which made for a really miserable time!  Hopefully your project will be sorted out very soon!

So when reattaching the fuel line, you actually see fuel enter the line when you turn on the gas, then it retreats back up the line to the gas tank?  Weird.  Have you tried removing the cap from your gas tank in case the vent line is blocked?  I'm sure that's likely not the issue if you have good, consistent flow from the valve when draining into a can but it's worth a quick check.

Disconnect everything and remove the carb, empty it entirely of any fuel and dry, then put a spare piece of clean fuel tube onto her and, while holding the carb as it would be oriented on the bike, try blowing a breath of air into the line.  Can you feel and hear your breath moving into the bowl? Do the same with the bowl removed and repeat - this time moving the floats through their travel to determine when the valve needle contacts its seat to close the valve.  If the slightest movement upward closes them too quickly, bend the adjustment tang slightly to increase travel allowing more flow into the bowl.  

I'm sure you've likely tried much of this already but, being in the midst of a similar process over here with an old Bing, I'm just tossing out ideas as I try them myself!

Best of luck - I'm sure you'll conquer this soon!

Cheers!

Christian

 

 

[Skinner]

Hey Christian,

 

I removed the carb yesterday and removed everything. I cleaned all ports and jets reassembled and did the blow test. The air flows nicely with bowl removed and a touch more resistance when it is installed. When I plug the float tube connections, the air seems less restricted? When the hose is attached its returns to restricted but still flows.( I do have a small hole in the tube). When the bowl was removed an I blew thru the gas hose, the pin seated nicely restricting the air flow. I have the floats set at 24mm when upside down.

I did notice that there was air coming out of the 10 mm fuel inlet that covers the screen. I gave it a small rotation and tightened the 10mm. now it seals.

I am hoping to re install carb today and find out that the problem was the seal of the inlet. I will feel very dumb if this was the case. All this time, all I needed to do was blow in to the fuel line.

I will let you know how it turns out.

I have had Grib walk me thru many steps as well. He provided manuals and specs to help me set the Carb (he is awesome) . I have set the fuel pin (side of carb) at one full turn open when closed. I cant seem to find the spec for the air screw beside it?

Thanks again

Jerry

 

[grib]

Jerry there is no air screw on your carb, only a pilot (fuel) screw and a throttle stop. Is it the smaller screw without the external spring that you have 1 turn out?

 

Edited November 26, 2017 by grib

[Skinner]

Yes it is.

The bike ran very well. My son rode it for the first time with no issues except the small screw beside the ( fuel ) screw keeps vibrating loose and when I close the choke on the carb after it warms up, the bike revs very high. I need to leave it open to ride it?

I want to thank everyone for their help and guidance . This is a great site and I wouldn't of been able to get this bike running without you guys. Thanks again.

if anyone can answer why this come loose and why I can't close the choke would be appreciated.

The screw when fully removed has a washer and o ring on it ( in great condition ) . if I leave it out a full turn the bike runs well but comes loose. If I screw it in all the way, it revs high?

 

[Skinner]

After looking into this further I have found this part on one of the links you guys provided me. I don't have the spring on my air mixture pin. It is a 36mm pin. can someone tell me if I can use any spring that fits or does it need to be the manufactures spring?

If I can go to a bike shop here in Canada and ask for the length would be nice. does anyone know the dimensions of this spring?  

 

Thanks

Jerry

[Skinner]

As I'm reading more, this pin is called the idle mixture adjustment screw. This is the piece that I don't have a spring for.

I was turning the throttle valve screw open one full turn. oops!

I need the sizing of this spring if anyone has it?

if not, I will order one from your side of the pond. It takes 3 weeks and cost 10.00 quid to ship. the part only cost .63 cents. that's about 25.00 Canadian dollars.

cheers

[grib]

There must be a suppler of Dellorto parts in Canada? I will measure a spring tonight so you have the dimensions as an alternative though.

If you had the throttle valve screw one turn out from fully in that will be the reason for your high revs - unscrew it until it holds the slide open by just a small amount (0.5mm or so) then use it to adjust the idle speed with the engine running.