Working on a YZ 125.. Can't get it to start.....

[2fastandfurious]

Ok heres the deal. I have a YZ125. Its a 89'. The bike ran GREAT for the most part a few weeks ago. No all of a sudden I cant get it to even pop a bit. I took apart the carb and cleaned it. Its spotless. Getting full spark. I have about a gallon of 60:1 mix for the purpose of jsut getting the bike to pop. But i have had no luck. I was dragged around my house several time with a friends quad. And besides the tone change when i gave it more throttle the engine doesnt sputter or even pop a bit. What electrical things should I be checking??? It seems thats what it has to be. I also sprayed some starting fluid in the air filter which should ALWAYS make a engine sputter. Nothing though. Please let me know if you can help me.
Ben
PS What about engine compression and jet sizes???????

[Redram]

Make sure your battery has a good charge on it. My bike won't start when my battery is low.

[BlazingYamahaYz]

i dont think the yz's came with a battery, i think they use the coil and CDI or whatever....just thought i would point that out:)

[TheX1992]

do you have compression? and since its a 2 stroke (i think) how do the reeds look. if you have spark already i dont think its the battery because pull starting it you wouldnt need battery. maybe your not getting spark at the right time. check your fuel line too because it sounds like your not getting gas TO it. but starting fluid would have made the 'puff' you were saying. make sure you have a clean filter. what color is the spark plug after trying to bump start it? process of elimination :scary:

[2fastandfurious]

I dont think that first reply guy even read what i wrote........:rolleyes:

[BlazingYamahaYz]

Originally posted by TheX1992
do you have compression? and since its a 2 stroke (i think) how do the reeds look. if you have spark already i dont think its the battery because pull starting it you wouldnt need battery. maybe your not getting spark at the right time. check your fuel line too because it sounds like your not getting gas TO it. but starting fluid would have made the 'puff' you were saying. make sure you have a clean filter. what color is the spark plug after trying to bump start it? process of elimination :scary:

less than 10rs on fresh .02 rebuild, reeds replaced last year and only used with the rebuild, timing could be off, there is fuel getting to it, took off the line and cleaned it, filter is clean and lubed.........and help?

[NTPRacing#19]

def check your reeds.

[2fastandfurious]

I ahve a compression guage..... What should the engine put out as a compression????

[300exazzkikr]

the first thing i would do is a compression test on it. You said it had lots of spark so it can't be the coil. Not sure about other electrics too much but as long as it's getting spark you should be good. Next i would go over the fuel components again. Get some choke and carb cleaner. Take the carb off spray it real good, take a look at the reeds make sure they look they're doing good. Then check over the fuel lines. pull the plug and see what's going on inside. It should have "puffed" when you put the starting fluid in thats why i would do a compression check. sorry about the long rant but hope i helped.

[2fastandfurious]

When you say check the reeds what do you mean???? What should they look/not look like???

[BlazingYamahaYz]

i should mention- last year(and i have only ridden it 10hrs or less since all this)......all summer my bike was under construction, POS YAMAHA, anyways....i replaced the head and base gaskets on the engine, cuz it was leaking, then i had to re-hone the cylinder/bored it .02 over with a wiseco piston and ring, then i replaced the ignition coil, then came the reeds, carbureator got cleaned(or so the dealer said..they were supposed to check the exhaust too, and re-pack, but the too damn lazy, charged me for it too:huh :grr ), then i had to get a new kill switch, new carburetor jet after cleaning it again, and that brings me to today.....so new reeds, piston and ring, kill switch, coil, carberuator more than cleaned....thanks so far the replys have been all helpful....:)

[NTPRacing#19]

they should be there and not cracked. if any are missing thats your problem. the reeds should look somewhat like white plastic or carbon fiber depending if they are v force reeds

[sly400ex]

Originally posted by 2fastandfurious
When you say check the reeds what do you mean???? What should they look/not look like???

make sure they are not broken and there also shouldn't be a big visible gap between the reed and the valve. Make sure the compression is at least 120psi. Also, make sure the boot from the airfilter to the carb and boot from the carb to the cylinder are all tight. Hope this helps.

[James70214]

OK
Have you run the bike since you put on the new kill switch? Make sure it is grounded properly. You are getting Fuel? You are getting air? and you have spark. IT WILL RUn if you have all 3 on the dirtbike. Redds should not be cracked or fraying at the ends and should lay flat on the reed cage.

My main suggestion is to make sure all of the wire grounds are good.

[2fastandfurious]

But if something was not grounded right no spark would be created................right????

[TheX1992]

its gotta be timing. he has air/fuel + compression + spark. he just may get spark at the wrong time which, in turn, wont run. i cant think of anything else why it wouldnt run. the killswitch wont matter or grounds either because it has GOOD spark.

[2fastandfurious]

What should my first step be for checking/fixing the timing???
-Thanks

[YZROOSTINYA]

sitting on the bike, the timing cover is on the left. there is a plate with 3 or so screws on it and a wheel in the middle. make sure the the plate is tight and not wiggling around. then typically there are indeations between the plate and the motor casing, or at least some sort of mark that specifies where the plate should sit in relation to the case.

moving the plate forward or backward will retard or advance your timing. if it is not in the right spot it will fire early or late.

if your muffler is clogged also this will make it very hard to start, when you kick it over is there pressure coming out of the exhaust.

your reeds will be fiberglass most likely. and should lay flat on the reed cage.

[2fastandfurious]

It has a FMF fatty pipe with a FMF silencer. When I work on it this weekend I am going to remove the exhuast system at least untill it starts. Thanks for the help guys! What the approx voltage I should be getting from the spark plug boot?
Thanks

[BlazingYamahaYz]

i kicked it today, and held my hand behind the silencer(Power Core, prlly needs repacking, but ben ****** it up by shoving a long screw into the end and it broke off getting stuck in the hole:grr ) i felt air/exhaust or whatever coming through the end....so that might be ok, it felt like the normal amount.....but i still will take the whole system off..thanks so far for the help guys, timing is def. going to be checked this weekend, along with reeds, electrical, maybe carb again, and fuel/air mix.....BTW Ben- i got all the screws and tools picked up, and i have the manual and some extra plugs...and we have to get those nerfs on soon...

[2fastandfurious]

Hey luke, I posted on Google. Heres his response........ I had two different bikes do the same thing. One bike had a bad coil. I
was riding fine, stopped to take a break and wouldn't start.

Second bike, spark plug cap/wire. Same thing, riding, took break, wouldnt
start. I changed the cap (always carry extra now) and ran fine for rest of
the day. Then, next ride the wire broke, so just replaced the cap and wire.

On both occasions, I had spark at the spark plug, just not enough to fire
the bike. Cheap fix, give the cap and new plug a try first.

John Arnett, end of message

Soooooooo just to let you know luke I found the parts we need on ebay for about 30 bucks. There BRAND new coil and boot. I now know what our problem is. Call me :D

[Bean]

my R did the same thing, the cap got all loose, and lost connection with the spark plug once in a while, or it would ride a little high, and still make a spark, but not enough to run right, i replaced wire and plug and it runs good

[BlazingYamahaYz]

i tried calling, seems ur cell phone is all screwed up.....o well talk to ur parents about tomorrow.......

[phatswinn]

with 2 strokes, you need about 115-130lbs of compression to at least run,(or at least thats how it is on scrambler 400's) under that it wont do anything, also i dont understand how it could be timing, unless you took apart the coil and megneto or something? have the compression checked!!!, also to tell if the reeds are dead, take the reed cage out and look at where the reeds touch the reed cage, u can tell if they are touching cuz there will be a spot were it looks wet around the edge, as long as they come with white reeds and i think they do, also make sure the connection between the carb and the intake boot to the motor has a tight seal, if it doesent it will be gettin a too lean air/fuel mixture and may cause it not to run..thats all i can think of good luck
:D

[BlazingYamahaYz]

o yea, also, when i was trying to kick start it the other day, it was i tried neutral, and then it was in first gear, i had the clutch in, and when i kicked it, it moved forward, as if the clutch wasnt engaged:huh and..ben keeps ditching me for his little g/f, so work isnt getting done to my bike or his quad, which we need to finish for thursday:grr