Thu Oct 04, 2012 3:31 am
My 1950 Cub starts up fine and runs for about 30 seconds and then dies.
Thu Oct 04, 2012 4:58 am
Pull out the jet on the side of the carb, hold a can under there for a few seconds and see if you have a good fuel flow. Clean out the jet while you have it out with a very small copper wire. Try that then see whats up.
Thu Oct 04, 2012 6:42 am
randallc wrote:Pull out the jet on the side of the carb, hold a can under there for a few seconds and see if you have a good fuel flow. Clean out the jet while you have it out with a very small copper wire. Try that then see whats up.
I cleaned out the primary jet but did not check for flow. I'll try this tonight.
Thu Oct 04, 2012 11:24 am
When you pull the jet make sure you have a piece of telephone wire aka twisted pair. One strand is perfect for cleaning the longitudinal (the very little one) orifice on the end of the jet. It is soft and will not score the inside of the jet. Don't use steel as it will score the jet.
Then, if that doesn't solve the problem - check the needle and cage. Sounds like you have debris/varnish that is causing the fuel starvation issue.
Fri Oct 05, 2012 3:44 am
Checked the flow, looks like the float may be stuck. will have to break down the carb tonight. I guess even a beand new carb may have issues.
Fri Oct 05, 2012 5:50 am
Unfortunately, it sounds like you installed a new needle valve and the valve coated with rubberized material. Unfortunately, those rubber tips dont really like the ethanol in our gasoline... If you still have your old needle valve and seat, maybe inspect it to see if it can be re-used...
Fri Oct 05, 2012 11:29 am
No I didn't install the needle valve, I installed a brand new carb. Problem is the new carb's float seems to be stuck. I will have to pull this one off and check it out.
Fri Oct 05, 2012 11:46 am
If the new carb has a rubber tipped valve, that could still be your problem... But taking it off to check is a good idea...
Fri Oct 05, 2012 11:46 am
If you haven't had a cub carb apart, before,be careful when you split it. The thin idle tube can be easily broken.It goes through a small hole from the top section, into the bottom section. Carefully LIFT the top off, don't, try to slide it sideways. Ed
Fri Oct 05, 2012 12:10 pm
Some of the Viton tips do not react well to ethanol. Not all of them -- but some. In no start situations that are starvation related, I automatically check the jet's orifices and the needle/cage for varnish/dirt etc., after checking the up stream fuel circuit for crud as well.
As Ed said, take it apart carefully. That idle tube is kinda expensive
Mon Oct 08, 2012 3:12 am
Thanks for the info. Checked the carb. And needle valve, cleaned
everything installed and she is running great. Took her out for her first test run. The hills were a little tough but it ran great. Now I might tackle the electronic ignition.
Mon Oct 08, 2012 7:03 am
Bob Crawford wrote:............. she is running great. ..............................Now I might tackle the electronic ignition.
Why fix what isn't broke?
Mon Oct 08, 2012 11:29 am
Well where I will be using this is very hilly and the additional power from the electronic ignition will make things a little easier.
I'm sure there are pros & cons when it comes to changing an original.
Mon Oct 08, 2012 1:22 pm
There are always pros and cons. Some of us prefer 6 volt, some 12 volt and some swear by the electronic ignition conversions. It really is all up to you. but whatever you do save all of the parts you take off. Might come in handy if the electronic ignition gives up the ghost.
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