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BoCephas

1986 250 FourTrax starting trouble

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1986 250 FourTrax. Will start 2 or 3 times, then nothing. Shindy carb kit installed, except for slow jet, which was noticeably smaller but stamped 38 like the old one. All jets, passages, bowl etc. cleaned enough to eat off of. Pilot screw (with all items) backed out 2-1/2 turns (not quite, tried for 2-3/8 like book says),new spark plug installed (.024” gap).

will start with carb cleaner sprayed and then carb will pick up and keep running.

question: why is this necessary after starting like its supposed to a few times?

 

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Welcome to the forum. 

 

So it won't start without starter fluid, but once you start it with starter fluid it won't anymore? 

 

Have you sprayed starter fluid around the intake boot between carb and head with it running to see if it speeds up (leaky intake boot)?

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low compression ?, not enough fuel to carb ?, timing off ?, weak spark ?.

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Several things have happened since I posted the problem. It would start normally for a few times, then only with starter fluid. After going thru the carb again, 11th time, it would only start and run while choked. Went thru the carb for the 12th time, still found nothing wrong. Sprayed thru all jets again, blew thru all passages. Blew thru vent tubing, still nothing. 
I had already replaced plug and checked for air leaks. Reinstalled carb, making sure fit at intake boot was tight, as all the other times. This time it started immediately and idled a little rough. Tweaked the pilot screw ever so slightly and it smoothed out. Took it for a ride up over the hill in second gear and it ran like a new one. Back at the house I started and ran it a few minutes and shut it down. Did this several times and it appears to be fixed. I’ll see what tomorrow brings.

To answer your question ,shadetree, I haven’t checked compression because it has so much power. Fuel is good, spark is good. If I’ve fixed it, I don’t know exactly what the problem was...

thanks for answering my post.

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3 hours ago, BoCephas said:

Several things have happened since I posted the problem. It would start normally for a few times, then only with starter fluid. After going thru the carb again, 11th time, it would only start and run while choked. Went thru the carb for the 12th time, still found nothing wrong. Sprayed thru all jets again, blew thru all passages. Blew thru vent tubing, still nothing. 
I had already replaced plug and checked for air leaks. Reinstalled carb, making sure fit at intake boot was tight, as all the other times. This time it started immediately and idled a little rough. Tweaked the pilot screw ever so slightly and it smoothed out. Took it for a ride up over the hill in second gear and it ran like a new one. Back at the house I started and ran it a few minutes and shut it down. Did this several times and it appears to be fixed. I’ll see what tomorrow brings.

To answer your question ,shadetree, I haven’t checked compression because it has so much power. Fuel is good, spark is good. If I’ve fixed it, I don’t know exactly what the problem was...

thanks for answering my post.

glad ya got it going, ty 4 the update !.

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5 hours ago, BoCephas said:

Several things have happened since I posted the problem. It would start normally for a few times, then only with starter fluid. After going thru the carb again, 11th time, it would only start and run while choked. Went thru the carb for the 12th time, still found nothing wrong. Sprayed thru all jets again, blew thru all passages. Blew thru vent tubing, still nothing. 
I had already replaced plug and checked for air leaks. Reinstalled carb, making sure fit at intake boot was tight, as all the other times. This time it started immediately and idled a little rough. Tweaked the pilot screw ever so slightly and it smoothed out. Took it for a ride up over the hill in second gear and it ran like a new one. Back at the house I started and ran it a few minutes and shut it down. Did this several times and it appears to be fixed. I’ll see what tomorrow brings.

To answer your question ,shadetree, I haven’t checked compression because it has so much power. Fuel is good, spark is good. If I’ve fixed it, I don’t know exactly what the problem was...

thanks for answering my post.

 

This sounds a lot to me like bad fuel and/or junk in the jets.

 

I had one recently where I went through the carb for the customer and it ran great when I left but after sitting for a day it was super hard to start and would not run correctly when it did get started. After taking the carb down again and re-cleaning the jets I found a bit more junk had made its way in.

 

The fix was to install an in-line fuel filter and a bit of sea-foam for a tank and it has been purring since then.
 

Also maybe just make sure your choke is fully seated if the issue returns.

 

oh400ex

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