1997 DIO no power

[patallen]

i have this dio that i bring back to life slowly. it now starts very fine, idles perfect but has 0 power. I cant make it rev up. it just goes mweeeuuu (like a cow )and eventualy dies.
rear wheel is free wheeling.
i just cleaned the carb and made sure there was no vacuum leaks. still does it.
any ideas ?

thanks.

[Bear45-70]

Compression check.

[toad772]

I have had this issue twice and both times taking the carb off and cleaning it fixed it.

[odinxxix]

what bear said and what of the air box? is it there? what does the air filter look like?

[patallen]

what bear said and what of the air box? is it there? what does the air filter look like?

there is no airbox for now, i just dont have it. carb throat is fully open. i have a small k&n filter that can go there, no change.

I can make it rev a litle, and it eventualy goes some more but it refuses to stay. It still smoke a lot, like if it where running too rich.

sometime while it bogs or refuses to rev up, it seems to wake up for few seconds, revs up and seems very happy then goes down and die, like if it where miss firing. plug is new, i changed gas too. It starts up right away all the time.

as soon as i find my compression tester i will check it, but having owned 20 different chainsaws in my life, i know that a very low compression 2 stroke motor will still rev up easy unloaded. having now power is something but not beign able to rev up at all without any load is something else.

To me it feels like if runs too rich, or has a firing problem. spark seem healty altough i cant tell while it bogs. The needle on the carb seems to be at its highest position (rich), if its ever adjustable ?.

I tripple checked carb and potential leaks.

fwiw, i am certified automotive mechanic with 25+ years of experience, i know how to diagnose engine problems and work all the time on sidedraft carbs on heavily modified cars (which some of them i own), i just never worked on such scooter. I just assume this would be a common problem.

thanks for all the other replies.

[Bear45-70]

25 years experience with 4 strokes has done nothing to prepare you for dealing with finicky 2 strokes. Install the airbox with new filter and see what happens. I suspect an extremely lean condition (no airbox) is preventing the engine from reaching higher RPM.

[patallen]

25 years experience with 4 strokes has done nothing to prepare you for dealing with finicky 2 strokes. Install the airbox with new filter and see what happens. I suspect an extremely lean condition (no airbox) is preventing the engine from reaching higher RPM.

Do you know for a fact that SA50 motors absolutely need the airbox to work at all ? or its just an assumption ? if thats the case then how come the scooter came to me with a small k&n and i know it was working this way very nice before ?
And how come it is realy irregular ? sorry i dont buy the airbox idea for now.
and i know 2 stroke motor very well. its not because i ask something about the sa50 that you have to talk to me like if i where stupid.

[evilone]

its not because i ask something about the sa50 that you have to talk to me like if i where stupid.

Sounds like you're overreacting to good advice . I suggest the same thing, no air box/filter = LEAN.

[dun rite]

Hello: If it was ran for a long time with the k&n air filter with no other mods ( carb jetting) chances are it was running lean. Running that way for extended periods would not be good for the cyl. A compression check would be a good idea. These little two stroke's are way different than chainsaws. Once they get below a certain compression they just won't run very well at all. The first thing to do would be compression check, hold throttle wide open while cranking engine over until gauge stops moving. should be 800-1200kpa (8.0-12.0 kg/cn2 114-171 psi

[eliteguy50]

Check your jet size. if it is stock- hold your hand over the carb intake to provide restriction.