YZ80 Problems.

[Jmetz]

In the interest of not annoying the hell out of Jim, I thought I'd post this here.

I just bought a 2000 yz80. It was not running when I bought it.
Back story:

The kid I got it from said the kickstart was jammed and the clutch wasn't working. He said his friend installed new clutch plates and it hasn't worked since.

I took the bike apart and cleaned it up. Cleaned out the carb and rejetted it. Cleaned the airbox and all of that. New plug etc. Took the clutch cover off and fixed the kickstart and also took the clutch plates off and re-installed those correctly.

Clutch still doesn't seem to work. If you pull the clutch, the pressure plate moves out and it seems to function but if you put the bike in gear and roll it with the clutch in it acts like no clutch at all.

I put the bike back together so I could see it run. I put fresh gas in and I take it out and to start it. It won't start. As I'm kicking it, if I open the throttle the tone gets deeper and if I hold the throttle open for a few kicks it makes a loud sound like a psssssh. I know great descriptor.

Anyway I have no idea why it won't start or what the hell that sound means. :)

As always, your help/suggestions is appreciated. :D

[Nick_Ninja]

Take it to Jim. :D

[Sortarican]

..., if I open the throttle the tone gets deeper and if I hold the throttle open for a few kicks it makes a loud sound like a psssssh.

It's normal thet the tone gets deeper, not sure what the psssssh is though.

Do you smell gas?
Did you clean the plugs (they foul easily).
Remove the air filter and try starting it.

The clutch?.?.?.? maybe the wrong springs?
Does the gearbox go into neutral?

What part of town are you in?

[Ricky]

One thing about the clutch: On the mini-ninja w/o synthetic oil in the bike, after the biek would sit for a few minutes, it would push all the oil out between the clutch plates. But then you'd pull the clutch, and the clutch wasn't necessarily disengaged. When you'd put it into first gear, it'd jump a bit as it forced the clutch plates to turn freely. This was a typical thing with the 250s, and synthetic oil helped a TON. But, with the bike off and in first, I could pull the clutch and make the clutch loosen up before I started it. It made the shift into first gear much less of a "bang".

Maybe not the issue, but I thought I'd mention it...

[Jmetz]

Take it to Jim. :D

I would but I like working on it.


Do you smell gas?
Did you clean the plugs (they foul easily).
Remove the air filter and try starting it.

The clutch?.?.?.? maybe the wrong springs?
Does the gearbox go into neutral?

What part of town are you in?

No gas smell, no flooding.
Brand new plug.
I'll try the air filter thing.

It does go into neutral.

Aurora/Denver

[Sortarican]

INo gas smell, no flooding...

Try pouring a little gas or spraying started fluid directly into the carbs, if fires then dies it could just be the fuel line fronm the tank is clogged.
(I'm assuming it's gravity fed not a fuel pump unit.)

[Jmetz]

I'll give it a shot.

[Jmetz]

Ok. So, the carb is full of gas so that's not the issue. Checked the line and that's clear. The petcock is transferring gas. Pulled the plug cap and the top of the inside had some carbon/gunk so I scraped that out. Still no start.

I suppose it's possible that it might not be getting spark, but I can't tell with out someone to kick it while trying to arc the spark. Is there another way?

[rider955i]

There is another way pull the plug and hold on to it while you kick it over jk. But really once you have the plug pulled sit the plug on top of the head so you can see the gap on the plug. Then kick it over it should be so easy that you could turn it over with your hand on the kick starter while the plug is pulled. Another thing you should be checking out is the compression use a tester then look up what the specs are for your bike if its to low time to replace some stuff in the motor usually piston and rings. Does it do anything when you try to start it at all besides make those noises that you described? If you are still having trouble some auto part stores have a tool that you can plug into the spark plug cap and put it on the plug then kick it over if it lights up there is juice if not you found a problem.

[BigE]

Sounds like the clutch is assembled wrong or the plates are stuck together.
Have you cleaned the carb yet? Does it have spark?
Two strokes are pretty simple so you ought to be able to get it figured out.

[DavidofColorado]

Check the compression first. If not you are wasting your time with others stuff because its not going to start. If you need a quick test put your thumb over the spark plug hole and turn it over. It should push your thumb off no matter what you do. But that is not exact.
If the plug is fouled you might want to change them. But you can clean it up with a wire wheel and it will work for a while. But it will get fouled again.
When you pull the plug do you smell gas on it or in the hole?

[FZRguy]

Try disconnecting the kill button and giving it a few kicks.
Check all electrical connections.
Stator could be bad.
Remove and clean the carb and gas tank.
Pull the top end.

[Jmetz]

Word guys. I'll be looking into it here in a bit. Thanks!

[Jmetz]

Finally got around to it yesterday. Checked compression and there was none. Took off the cylinder and checked it out. Looks like some metal got in or possible broke off from the ring. I can't tell. Chewed up the head, piston crown, put a nice gouge in the side of the piston from top to bottom, and cylinder. I found what looks to be one of the culprits sitting on the left side of the crank. Not sure if that was the only piece. Looks like there might have been 2. Nasty stuff.

[FZRguy]

Do you think any pieces fell into the cases?

[Jmetz]

Do you think any pieces fell into the cases?

I'm sure it's possible. But I didn't see any evidence of metal in the oil.

[DavidofColorado]

Can you take some pics for us? Sorry to hear about this happening. It looks like you are going to have bore it over or get a new head and piston.

[FZRguy]

Still pretty cheap for a two-stroke top end. Especially at Flat Out where you can order newYamaha parts at 20% over dealer cost. I’d be screwed without those guys.

http://www.flatoutmotorcycles.com/ (http://www.flatoutmotorcycles.com/)

I’d throw a new top end on it first before going to the trouble of splitting the cases. LA Sleeve can fix your cylinder if you don’t want to buy a new one.

http://www.lasleeve.com/master.html (http://www.lasleeve.com/master.html)

[Jmetz]

Can you take some pics for us? Sorry to hear about this happening. It looks like you are going to have bore it over or get a new head and piston.

New head, cylinder, and piston I'm fairly sure. But for the sake of science... Here ya go.

http://img177.imageshack.us/img177/3452/p1010044rw9.jpg

http://img516.imageshack.us/img516/8972/p1010045ku0.jpg

http://img367.imageshack.us/img367/4070/p1010049cx6.jpg

http://img357.imageshack.us/img357/9095/p1010060co3.jpg

http://img182.imageshack.us/img182/6150/p1010061wx2.jpg

http://img237.imageshack.us/img237/8799/p1010062sp5.jpg

http://img237.imageshack.us/img237/4854/p1010066bf1.jpg

http://img155.imageshack.us/img155/5142/p1010068xq7.jpg

http://img371.imageshack.us/img371/9034/p1010072de5.jpg

[Jmetz]

Still pretty cheap for a two-stroke top end. Especially at Flat Out where you can order newYamaha parts at 20% over dealer cost. I’d be screwed without those guys.

http://www.flatoutmotorcycles.com/ (http://www.flatoutmotorcycles.com/)

I’d throw a new top end on it first before going to the trouble of splitting the cases. LA Sleeve can fix your cylinder if you don’t want to buy a new one.

http://www.lasleeve.com/master.html (http://www.lasleeve.com/master.html)

I've been using Babbitts for some parts. The seem to be a little cheaper then flatout on the more expensive parts, and a little more expensive on the cheaper parts. :lol: It's pretty much a wash.

I was looking at sleeves, but from what I've been reading, re-plating seems to be the way to go. Parts for this thing are a dime a dozen on ebay so that's probably the route I'll take. I could've had a cylinder and head for $85 today, but my sniping software malfunctioned. :banghead::banghead:

[FZRguy]

You won’t find evidence of the top end in the oil b/c the crank is separate from the tranny. The oil in the gas lubricates the crank as well as the top end. With the top end removed, the crank should run smooth on the rod and side play should be within spec (0.20-0.70 MM on my 125). That small pin looks like part of the upper rod bearing, and there’s probably more in the crank cavity. Try getting a small magnet down into the crank cavity and/or turning the motor upside down. If the motor has over 100 hours, the crank may need to be rebuilt anyway. I was gonna say that Wiseco makes a 2 MM overbore piston kit that may be enough to clean up the cylinder bore, but it looks toast from the pics.

[Jmetz]

Yeah, I keep wanting to think that the bottom of the crank sits in the transmission oil. As far as that piece of metal, all of the bearings are there.