Dirt bike is a really hard start?

[509rt100]

I just got a 1985 Yamaha IT series bike (friend said it was a 175, but I remember seeing a 200 or 250 on the crank case), and it's a really hard start.

I had to kick it over for about an hour (with periodic breaks for unflood the engine) before it even popped and when it popped, it only ran for about 3 seconds. Haven't gotten it started since.

Have a tried a new spark plug, that did absolutely nothing. Checked the spark and it is getting a nice, fat spark that you can hear crackle from even 3 feet away and has a boat load of compression (don't know the exact value but should run easily off it). My friends had cleaned the carb before giving it to me, so I don't know what else it could be.

[Wild Alaskan]

What is your starting technique as far as choke ect.?

Edited November 17, 2014 by Wild Alaskan

[509rt100]

I pull the choke out, and kick a good maybe 10 times, it doesn't even putt then I push the choke and try it a few times there. If that don't work let it sit for a few minutes.

The time i got it to run for a few seconds, I had the bike at full throttle and don't remember whether I had the choke on or off, but it burped a good 5 or 6 kicks before finally starting.

[509rt100]

I probably should mention that it is only 20 degrees outside (but clear/sunny)? Maybe the fuel is not atomizing/vaporizing very well because it is cold?

[SnowMule]

Clear/sunny doesn't matter.  Bike doesn't care about that.

Temp does affect jetting - some bikes (and snowmobiles) are a little more tolerant than others. 

I fatten my bike up in the winter, since there's more oxygen per unit volume in cold air.

 

I'd bet your problem's in the carb.  Get that straightened out and tune from there.

 

[Wild Alaskan]

I pull the choke out, and kick a good maybe 10 times, it doesn't even putt then I push the choke and try it a few times there. If that don't work let it sit for a few minutes.

The time i got it to run for a few seconds, I had the bike at full throttle and don't remember whether I had the choke on or off, but it burped a good 5 or 6 kicks before finally starting.

Its flooding from a leaky needle valve, lots of yamahas in that era used non-rubber needle valves that leaked easily, make sure you turn the gas off when you are not riding, your going to need to use full throttle to start it (leans it out) for probably about 10-20 kicks when it is badly flooded. when it starts hold it wide open for a couple seconds to let it clear out

[509rt100]

I checked my compression, a freakin' sweet 120 psi (from which I understand is phenomenal for a 2 stroke, especially a cold one?).

And I always turned the fuel off when not riding. My friends had always told me (so I was under the impression) that leaving the fuel on meant that you would not have any fuel by morning.

Is it OK to use starting fluid to help? It ran pretty decently for the short period I had it running.

Edited November 17, 2014 by 509rt100

[bobbyward]

Those came way rich stock.