2 Stroke 1998 CR80R

Trfsrfr

Trfsrfr

I dont think it's gonna happen.
I got the carb super clean, float was right at 19mm like it should be, put it all back together and it popped once. Kicked it a bunch after and I dont think it has enough compression. Pulled the plug, it was wet.
When I kick it the engine keeps spinning for a second afterwards.
I got it to run for about 3 seconds.
I think the cylinder is coming off before any riding takes place.
 
Mihylo33

Mihylo33

Trfsrfr:
I dont think it's gonna happen.
I got the carb super clean, float was right at 19mm like it should be, put it all back together and it popped once. Kicked it a bunch after and I dont think it has enough compression. Pulled the plug, it was wet.
When I kick it the engine keeps spinning for a second afterwards.
I got it to run for about 3 seconds.
I think the cylinder is coming off before any riding takes place.
Click to expand...



I would say that 134psi was a false reading then. Especially since I read it was 7kicks in. 1st kick at 134=running bike. Pull that pipe snap a pic
 
Trfsrfr

Trfsrfr

Hey Mike,
Thanks for the response and your earlier plug boot idea, I now see how that screw thing works, and I chopped about 7/16 off the end and screwed it back on.
I dont think I need to post a pic of the piston; it's very clean like it was when I first looked at it with some minor wear marks on the exhaust side, just like you would expect it to look when it has obviously been washed down with fuel.
So I think it's safe to say that it needs a new top end.
So along with that thought, this gets me back to where I was with the KX; is this a NicaSyl cylinder as well?

When I was looking at it before purchase, I was more interested in the entirety of the bike, along with the price, and when dude (16) gave me the VIN, (which I ran at the DMV) It came up clean, but when his soccer Mom came out to meet me I was more assured because it didn't come with a title...
But I was concerned about how the engine kept spinning for a moment after I stopped kicking it. Now I think I know why this happens...low compression.
 
PALMER84ONE

PALMER84ONE

Well, late to the party but... Even low compression and spark the engine should run. Just real crappy. But it sounds like you got all the good advice and are on the right track. :thumb:
 
2strokesteve89

2strokesteve89

Trfsrfr:
@Palmer, you can crash my party anytime, no worries.
As long as were at it, Andy, M33, BigDan, Timoyz, Redordead, 2strokesteve, 2wheels, Snowflake, and whoever else I forgot to mention, all welcome at my place anytime.
You guys all rock, let me know when your in town and first round is on me.
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Now you've done it, you let @PALMER84ONE in your door, he's gonna go straight to the crapper and permanently plug your toilet.
 
O

ossagp

2strokesteve89:
Depending on what year that YZ is it would be hard to compare readings, a 2005 YZ is at 12.3:1 which would put that one at 180 psi at sea level, my post was simply illustrating how to get an idea of what a healthy reading should be. I agree it's not a exact science but it gives a good baseline to go by.
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For a single kick. I know at 15 i was using that arithmetic and bewildered by the difference in that and the gauge.
You can hold the power vavle open on that one, and with starting type kicks drop exactly 3 pounds on my gauge. those things aren't there to seal ANYTHING at a lower rpm, change the way the timing acts etc, 180 is low for that one when fresh though.

The yz 85 mentioned was a little more representative. anyway, you can see why lots of shop manuals don't print compression readings.
 
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O

ossagp

2strokesteve89:
Depending on what year that YZ is it would be hard to compare readings, a 2005 YZ is at 12.3:1 which would put that one at 180 psi at sea level, my post was simply illustrating how to get an idea of what a healthy reading should be. I agree it's not a exact science but it gives a good baseline to go by.
Click to expand...

For a single kick. I know at 15 i was using that arithmetic and bewildered by the difference in that and the gauge.
You can hold the power vavle open on that one, and with starting type kicks drop exactly 3 pounds on my gauge. those things aren't there to seal ANYTHING at a lower rpm, change the way the timing acts etc,
2strokesteve89:
Now you've done it, you let @PALMER84ONE in your door, he's gonna go straight to the crapper and permanently plug your toilet.
Click to expand...

Somoan?
 
Trfsrfr

Trfsrfr

ossagp:
you can see why lots of shop manuals don't print compression readings.
Click to expand...
Yeah I noticed that.
It says 'Test cylinder compression' then tells you what could be wrong if compression is low, or what to do next if it is normal, but doesn't specify anywhere what low or normal is.
I am just assuming it's too low because when I kick it keeps spinning briefly afterwards.

Is this a nicasyl cylinder?
 
Mihylo33

Mihylo33

Trfsrfr:
Yeah I noticed that.
It says 'Test cylinder compression' then tells you what could be wrong if compression is low, or what to do next if it is normal, but doesn't specify anywhere what low or normal is.
I am just assuming it's too low because when I kick it keeps spinning briefly afterwards.

Is this a nicasyl cylinder?
Click to expand...


If it spins excessively chances are that the top has popped. Yes that cylinder should also be nikasil.
 
PALMER84ONE

PALMER84ONE

2strokesteve89:
Now you've done it, you let @PALMER84ONE in your door, he's gonna go straight to the crapper and permanently plug your toilet.
Click to expand...
You are thinking of a guy that was here way before you. Redswr I believe was his handle. Not only could he plug a toilet, and make a toy hauler uninhabitable for the rest of the trip (ask rack), he was one of them perverts that scared girls from a single sentence.
Trfsrfr:
Ah shit...one of those guys huh?
Wouldn't be the first time though.
As long as he fixes a bike on his way through I guess it'll be okay since I have a roto-rooter available, so it shouldn't be permanent...
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Got me all wrong. Steve is just jelly his ass is frozen for the next 6 months so he has to vent.
 
Trfsrfr

Trfsrfr

Mihylo33:
If it spins excessively chances are that the top has popped. Yes that cylinder should also be nikasil.
Click to expand...
Yes, it spins too much.
So we are back at the 'send it off' to wherever stage...
No problem. Zach hasn't seen the bike yet, but once he does and sits on it (Wed), I am sure he will be all about taking it apart and getting it running. This will be a great primer for his intro to basic mechanics.
He's been wanting this, so I will use it for his consumption.
Any advice on the rebuild process is appreciated of course...pretty sure I can get a whole top and bottom kit from Motosport for around $280.00, but need to know more about the Nikasil thing, and what not to do...
 
PALMER84ONE

PALMER84ONE

Nikasil is not something you hone.
Nikasil is a very hard plating that if you can't feel a grove on your fingernail, than its good. Nikasil can be out-of-round. So you should measure the bore in many directions to get a good reading.
You should be able to see "cross hatching" on the cylinder wall.

You "can" ball hone the cylinder (I don't recommend and others might) but you run a risk of chipping the camfer edge on ports.
 
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