Yamaha blaster sputtering

[blasDa]

More air needs more fuel. It's a ratio.

 

[speedyslyder]

what is carb airscrew set at?
does it run better or worse with choke on?
did you completely unplug the brain of the tors?

do you in fact have a 4 wire stator or 5 wire stator?
is it adjustable timing plate?

pics of engine both sides/tors wires/ anything?

i want to say that 1 of my blasters did that to me once
when i first bought it i first check the carb/then the top end.
the top end showed signs of overheating, also 1 of the circlips was
about to fall off good thing i took it apart.
i think the fix was new set of floats,but i did both at same time soooo not sure.
if gas cap does not vent properly its like sucking on a soda bottle
and never letting up for air.Thats why i mentioned it.

maybe try the electrical threads

 

[best]

But doesn't it make more sense that if you're running an open carb (no filter) you wouldnt you receive more intake? Correct me if I'm wrong.

< Deep sigh...>
You cannot "figure" jetting. It is what the engine needs. A dozen variables to balance.
Buy the right plug because yours will always look rich. A new plug will show mixture clearly.
Warm it up on the old plug and then put the new in. Give it a full throttle run.
The very base of the insulator will show the mixture. Look up "plug chop" to read it.

You can frig around with all sorts of guessing or get it sorted out in a few passes.

Steve

 

[best]

But doesn't it make more sense that if you're running an open carb (no filter) you wouldnt you receive more intake? Correct me if I'm wrong.

< Deep sigh...>
You cannot "figure" jetting. It is what the engine needs. A dozen variables to balance.
Buy the right plug because yours will always look rich. A new plug will show mixture clearly.
Warm it up on the old plug and then put the new in. Give it a full throttle run.
The very base of the insulator will show the mixture. Look up "plug chop" to read it.

You can frig around with all sorts of guessing or get it sorted out in a few passes.

Steve

 

[mlrblaster]

Well it was doing this exact thing when I got it, and I ended up Checking if the crank seals were bad and I ended up splitting the cases to change the seals and it ended up being the cases were cracked. I doubt there's any oil getting in there but I could check again.. and I don't think it's the woodruff key just because I've taken the motor part 3 times and still does the same thing. and if I leave the gas cap open wouldn't that have the gas flow faster to the carb?
And yes I ended up messing with the tune and the needle adjustment and it revs healthy now, but it still runs like crap. It idles really healthy as well

Did I read this correctly?? There is a crack in the cases?? Where might this be?? Did you repair the crack?? Someone correct me if I'm wrong but can't the transmission oil can be sucked through a crack into the crankcase causing what would seem to be a rich issue? What does your plug look like??
I had a similar problem with a late 90's blaster, it would start up on the first kick but die as soon as it fired off. Turned out that there was a hole in the in the cases around the crank and it would suck in the oil from the transmission. The spark plug would be dripping with oil.
I'd be looking a the crack, depending on where it is. Put the filter back in, top ends are not cheap!!!

 

[2strokeAdict]

UPDATE:
Changed the adjustment needle and carburetor. Turns out the carb is bad.

 

[2strokeAdict]

Thank you all for your help I really appreciate it

 

[2strokeAdict]

I replaced both crank cases. And both seals as well as the bearings. The bike was sitting for a while and I tried to save the carb. I took it all apart and it still didn't want to work.. I have a buddy with a blaster and he lent me his carb and it turned out to be just that. The bike started with transmission oil all inside the 2 stroke chamber. And it did this exact thing. I'm honestly really surprised that it even started with a huge hole going to the transmission.. thank you for your time.

Did I read this correctly?? There is a crack in the cases?? Where might this be?? Did you repair the crack?? Someone correct me if I'm wrong but can't the transmission oil can be sucked through a crack into the crankcase causing what would seem to be a rich issue? What does your plug look like??
I had a similar problem with a late 90's blaster, it would start up on the first kick but die as soon as it fired off. Turned out that there was a hole in the in the cases around the crank and it would suck in the oil from the transmission. The spark plug would be dripping with oil.
I'd be looking a the crack, depending on where it is. Put the filter back in, top ends are not cheap!!!

 

[2strokeAdict]

< Deep sigh...>
You cannot "figure" jetting. It is what the engine needs. A dozen variables to balance.
Buy the right plug because yours will always look rich. A new plug will show mixture clearly.
Warm it up on the old plug and then put the new in. Give it a full throttle run.
The very base of the insulator will show the mixture. Look up "plug chop" to read it.

You can frig around with all sorts of guessing or get it sorted out in a few passes.

Steve

Thanks bud I'll put a filter as soon as possible! And I know what a plug chop is.. there's nothing much to these bikes.. they're sensitive. And I had the right plug all along. Thanks for your help bud