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YZ125 won't start

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Hi I'm starting a new thread because I've done a lot of different stuff on my bike since my last thread about this problem.

Basically my bike just dies after a minute or 2 or riding and then I spend at least 30mins trying to get it going again and if it does go it dies again after a minute or 2.

I don't know if it's because of moving and something is bumping around and making it cut out or if it's to do with when it gets warm.

Every test I have done has proven my theory wrong, I intially thought it was that there was no spark when it got warm but I got it going on a stand and got it real warm and it still had plenty of spark, then I put it in gear on the stand and got it moving around with the wheel been spun by the engine and it went fine and didn't cut out, so I jumped on it went down the road and again just bogged out and died. Remembering that every time it dies it won't start again.... so I bump started and away it went. Then I rode it into the garage and turned it off, kicked it over and started first kick. So rode down the road again and boom bogged out and died. I now literally can't get it to go at all, occasionally it sounds like it's about to go but then doesn't.

What I have tried so far...

- Top end rebuild

- New spark plug

- Full carb clean

- New fuel

- New air filter

 

It is definitely getting fuel, the plug comes out wet, and it is getting heaps of blue spark, and well air seems fine. I just did a top end rebuild in case it was compression but still no change.

 

Is it time to take it to the professionals now?? I've spent so many hours on it now and I'm over it. I have no idea what else to try. Fuel, spark, air and compression! What else could it be...I'm stumped

Thanks for any help

 

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Sounds like you're getting too much fuel, crankcase is probably full by now.

 

When you cleaned the carburetor, have you:

checked and adjusted the float/fuel level?

checked the fuel inlet needle and seat for wear?

 

Reeds damaged/not sealing properly around each petal ?

 

Edited by mlatour
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Year? 

Reeds can be a factor if chipped and not sealing.

A carb kit with all new brass and needle (complete Japanese kit) is what I do, screw cleaning and reinstalling when the kits only $30. Set float and your done for a long time. 

Electrical: coil getting hot and not functioning proper. Get out you tools and manual and get to checking resistance ohms etc. 

If it ran before for a long time without issue, and all you did was antop end, what else did you fiddle with? Are the kill switch leads in good order, not pinched, no bare wire? 

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Here's a picture of the reeds they aren't really sealed very well around the corners?? Should they be?

Carburettor needle and seat looked good, I didn't adjust the float level because to me it looked fine, and how would float level just change by itself anyway? If it was fine before why would it change??

Will do a ohms test on the coil today.

Kill switch has been tested, no change when disconnected 

IMG_1376.JPG

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Here's a picture of the reeds they aren't really sealed very well around the corners?? Should they be?
Carburettor needle and seat looked good, I didn't adjust the float level because to me it looked fine, and how would float level just change by itself anyway? If it was fine before why would it change??
Will do a ohms test on the coil today.
Kill switch has been tested, no change when disconnected 
IMG_1376.thumb.JPG.6a637c957c446e5fc56ea6186734e09d.JPG

Reeds are gone replace them , before replacing them just flip them they're bent too much .

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Float level 'looks fine' isn't accurate enough,

higher or lower than specified will alter the metering.

 

Rule of thumb, if you can't remember last time the reeds were replaced, 

they're probably due to be replaced again.

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Just as the mlatour said, looks and being are two different things. Flipping the reeds may yeild anoth 5 hours at best but dealing with brittle peddles. Replace reeds, set float, go again. 

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Okay huge update to this whole situation! we're are almost there.

So I was reading online about the muffler maybe been blocked and to disconnect it to rule that out, when I disconnected the muffler from the expansion chamber a couple tablespoons of black oil dripped out, I put the join back in after that, at the same time I replaced the spark plug cap as well. Then boom away it went! I couldn't believe it, started it 4 times first kick, rode up and down the rode a bit as well, this was late at night so left it for the morning. Then this morning started up first kick again every time, this time I gave it a good run through the gears. So here's the only issue now. It seems to just not hit the powerband in 1st, 2nd or even sometimes 3rd gear. The bottom end feels perfect but in those gears when you hit the point where it should powerband it is like hitting a rev limiter and there's no power and you have to change gears to get anymore speed.

Would the reeds be doing this??

Thanks

Edited by Caleb Riordan

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It's a chain of events,

the silencer's packing was soaked because the engine runs super rich,

worn reeds  & wrong (too high) fuel level are probable causes.

 

Engine 'stutters' or 'feels like it's hitting a rev limiter' is also an indication it's too rich. (lean = bog)

Edited by mlatour

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Okay ill flip the reeds around and if that doesn't help ill take it to the mechanic to get float level set right because I don't trust my method to get it perfect.

I saw a post on another forum with the same problem, they said it ended up being "it was the little plastic piece that holds the needle in position in the main jet, so it was loading up until higher rpms where the gas was needed rich" 

Maybe I put this part back together wrong because I did take the slide and needle thing apart.

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Do you think that maybe like the rest of us,  a manual would be a good thing for you?   It works out to be cheaper than a mechanic who may not be any better than you are.   Unlike the mechanic,  it keeps on giving.   My guess is that since you were in the dark about how a float level could change,  you probably need a procedure to set the float and test it.   I would also replace the needle,  those little spring loaded tips sag after a few years of use.   Replace and reset.   Of course you should see that all the pieces are present and in place as well,   which again,  the manual or at the very least a parts schematic could help you with. 

As far as taking off the silencer,   you aren't the first one to discover that taking that off will make a motor run leaner.   

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1 hour ago, ossagp said:

Do you think that maybe like the rest of us,  a manual would be a good thing for you?   It works out to be cheaper than a mechanic who may not be any better than you are.   Unlike the mechanic,  it keeps on giving.   My guess is that since you were in the dark about how a float level could change,  you probably need a procedure to set the float and test it.   I would also replace the needle,  those little spring loaded tips sag after a few years of use.   Replace and reset.   Of course you should see that all the pieces are present and in place as well,   which again,  the manual or at the very least a parts schematic could help you with. 

As far as taking off the silencer,   you aren't the first one to discover that taking that off will make a motor run leaner.   

I have a good understanding of how to set float level but I would need to get one of those measuring tools to set it right.

I flipped the reeds around but still no change, there was a tiny bit of light coming through the end.

Is there anything I can do before replacing reeds because they are going to be $100 :/

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34 minutes ago, Caleb Riordan said:

I have a good understanding of how to set float level but I would need to get one of those measuring tools to set it right.

I flipped the reeds around but still no change, there was a tiny bit of light coming through the end.

Is there anything I can do before replacing reeds because they are going to be $100 :/

Wtf reeds you getting that cost$100? Lol should be 25-60

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OP is located in New Zealand...

parts worldwide aren't dirt cheap as in the USA, just north of our border in Canada is a good example.

An oil filter for a TTR230 which is listed at 6.75$ USD by online vendors becomes a 16.95$ Canadian (plus taxes) item at our dealerships.

Edited by mlatour
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9 hours ago, Caleb Riordan said:

I have a good understanding of how to set float level but I would need to get one of those measuring tools to set it right.

I flipped the reeds around but still no change, there was a tiny bit of light coming through the end.

Is there anything I can do before replacing reeds because they are going to be $100 :/

yeah, you can SET THE FLOAT.   honest, those reeds are not going to flood your engine.   you can build the same tool for about 50 cents if you already have some epoxy,  if not you can do it for 5 dollars.  you need a small fuel line barb like you can rob off of any other carburetor overflow and the fuel line that comes with it.  if not see your hardware store or a hobby shop that does fuel powered planes etc for the hose barb and the fuel line for it.  drill your carburetor drain and glue the barb in, put on the hose.  After that you can route the house to the air box or just up above the carburetor, hose up, then turned down on the end and LEAVE IT,  and you will be just like about a half dozen guys that won national enduro titles.  (handy fuel drain and you can see your float level,  which unknown to you rises as time goes on.)   That doesn't fix a tired needle,  but it will help a lot.

The reeds need changing,  and if you are paying 100 dollars you are buying the wrong product for a simple reed changout.  I like boyesen dual stages and stock replacements,  but they have long lasting single stage reeds too.  

Edited by ossagp
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3 hours ago, mlatour said:

OP is located in New Zealand...

parts worldwide aren't dirt cheap as in the USA, just north of our border in Canada is a good example.

An oil filter for a TTR230 which is listed at 6.75$ USD by online vendors becomes a 16.95$ Canadian (plus taxes) item at our dealerships.

We pay 10 times for our drugs!!  I liked travelling in Canada a few years ago.   I could hand a waiter a C note for a nice dinner for two and get nearly 80 back in Canadian dollars. 

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3 hours ago, ossagp said:

yeah, you can SET THE FLOAT.   honest, those reeds are not going to flood your engine.   you can build the same tool for about 50 cents if you already have some epoxy,  if not you can do it for 5 dollars.  you need a small fuel line barb like you can rob off of any other carburetor overflow and the fuel line that comes with it.  if not see your hardware store or a hobby shop that does fuel powered planes etc for the hose barb and the fuel line for it.  drill your carburetor drain and glue the barb in, put on the hose.  After that you can route the house to the air box or just up above the carburetor, hose up, then turned down on the end and LEAVE IT,  and you will be just like about a half dozen guys that won national enduro titles.  (handy fuel drain and you can see your float level,  which unknown to you rises as time goes on.)   That doesn't fix a tired needle,  but it will help a lot.

The reeds need changing,  and if you are paying 100 dollars you are buying the wrong product for a simple reed changout.  I like boyesen dual stages and stock replacements,  but they have long lasting single stage reeds too.  

Okay I'll get the float set and a carb rebuild so I can rule out the carb.

Unfortunately here we pay a lot for parts. I would pay atleast $100NZD for boysen replacement reeds. equal to about $70USD. It really sucks...

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