ytm won't start

[mcbain]

i've got a second ytm 200 that i can't start anymore. it was running fine. i've triple checked the timing and its fine. i tried another carb, still nothing. if i take the plug out and pull it i've got spark. i took the plug from a working ytm, so i know its good.

so i pulled the carb right off and sprayed ether into the intake, and pull it, and it doesn't even catch for a second.

any thoughts?

thx.

[Yamahauler]

Check to see if you have compression. Is the plug wet when you take it out?
Did you try cleaning the carb?

[mcbain]

yup. there's compression. and yes, the plug is wet too, so the fuel's getting in.

the carb is good, i've tried it on another ytm. but just to narrow things down a bit here, i directly sprayed ether into the intake, and still nothing. not even a little bark from it. it makes no sense.

[Yamahauler]

adjust your valves, and are you sure your timing it right? do you have a manual?
If i were you, I wouldnt spray ether in there. If I want to prime a motor, just take the plug out and put 4 or 5 drops of gas down the plug hole.

Just curious, what did you use to check compression?

[Russell 350X]

I know whats wrong with it, its a Yamaha.....lol jk. Check your valves and compression, clean the carb throughly, mabey it even needs a carb kit. My ATC200 won't start and everything is fine and I know it needs a carb kit.

[mcbain]

i've got the manual for this thing, thats how i checked the timing..and done half a million other things to these things over the last few years. (rings, new head, swapped engines, etc..etc.)
i didn't measure compression, but there's resistance there, and if you put your hand over the intake, you can feel it sucking your hand in. or over the exhaust and its blowing out.
i'm just using the ether for testing right now. i wanted to be absolutely sure it wasn't the carb. if it ran for just a couple seconds, i'd turn to the carb, but i don't even get a single second of running with the ether right now.

[YTM200BOY]

when *Edited* or me find the problems we will have to working ytm's i have the same situation i believe as you its so frustrating when *Edited* see people crusin past oyur house :sad: -Joe

[Mike_Ham_250R]

adjust your valves, and are you sure your timing it right? do you have a manual?
If i were you, I wouldnt spray ether in there. If I want to prime a motor, just take the plug out and put 4 or 5 drops of gas down the plug hole.

Just curious, what did you use to check compression?

I just sprayed LIGHTER FLUID in the plug hole

[MichiganRedneck]

make sure your carb is clean. it sounds like timing to me.

[mcbain]

i was thinking timing too, thats why i triple checked it the other day with the manual. i also opened up all the valve covers, timing chain covers, etc, and compared it to my working ytm by pulling the pullstart slowly. timing is good.
i'm thinking maybe a really weak spark? although it looks good and gives me a good shock if i hold on to it.
i'm going to check valve clearances next..

[mcbain]

the valve clearances checked out fine, so i figured i would take the head off to figure this thing out. i found that the intake valve has huge leakage!!!
i've had to cut the valve seats on the head on my other ytm before so it should be nothing to it on this one.

joe, check your compression. i don't have the tools for a real compression test, but the way i knew i had compression problems last night was, i had the plug out. i sealed my thumb over the spark plug hole and pulled the starter. i knew i had a compression issue, cuz i could keep the spark plug hole sealed. there's no way i should be able to do that.

[YTM200BOY]

yes thanks alot man i have great spark and its a wet spark plug but it doesnt really blow my finger off the hole... so my dad and his buddy are taking the head off in 2 weeks. So what main thing should i loook for? Also my exhaust smells really funky for some reason???? thanks -Joe if *Edited* could reply in my thread i would apprecitate it thanks again man.

[mcbain]

well, keep in mind that the finger over the spark plug hole isn't exactly a scientific test. but if you pull the starter hard and it doesn't pop your finger off, then you've definately got leakage.
once the head is off, lay it flat down and spray some fine liquid into the intake (like carb cleaner, or even wd40) if it leaks right out, you've got probs that require valve removal. if it just kinda sweats out a bit over several minutes, you've got a bit of leak, but not enough to not make it start, i wouldn't think. if you can leave it overnight and nothing leaks out, they're perfect, and i wouldn't even think of messing with a good thing by taking those valves out.

let us know what you find out. removing the head is really easy. you will need to remove the muffler and gas tank first. just keep track of the parts as you're removing them. i've got two manuals on these things, so if you need some specs on putting it back together, let me know.