I have a 1999 Trail Boss 250 (244 CC) 2-cycle. It is in good shape because it doesn't have much use. Problem: It is hard to start. I must depress throttle about half way before it will fire and then the engine finally catches up with the starter and it will run. I must hold throttle in about half way for it to run. It will not idle at all. When you goose the throttle it goes wahhhhhh.

Here's what I have done to try to repair so far.
1. Disassembled the carborator, cleaned and installed.
2. Checked oil pump OK.
3. New spark plug.
4. Removed flywheel and cleaned rotor and stator. It had been filled with water and rust covered everything.
5. Checked timing OK
6. Checked spark from spark plug terminal, arcs about 1/2 inch - looks good.
7. Adjusted pilot screw to spec.
8. Blew back throught the gas tank with compressed air. Gas flows freely.
9. New gas, new oil

The engine seems to have plenty of compression because it turns hard from the crank shaft and it has alot of suction at the breather inlet. I have not done a proper compression check.

I tried to "blow the carbon" out of the engine by riding hard to get the engine hot with no improvement.
What is the problem and what am I mising?

Thanks

 

choke cable may be out of wack

 

Since you cleaned the carburetor I would then say to make sure you have the correct jetting for temp and altitude of your riding.

 

Well, I adjusted the choke and carb cables with no help. I'm convinced it is the carboration but not the carborator. How do you check the crank seals?

 

i have had a 92 trailboss 250 and 99 trailblazer 250 BOTH had bad crank seals ...they are easy to replace and mine were only about 16-20.00 cant rember, but cheap... my bikes ran great cold but they got hot and started pinging, lost power and idled REAL high.. when i say got hot i mean 35 degress out side and hot in abou 10-15 minutes.. i burned wieso # 2 out before i figured it out on the old boss...

 

do a leak down test is the best and safest way.