125 Rich or lean pic included

M

MikeinFresno

plug looks a little dry n light colored so maybe lean. Is the pic of piston showing the only damage? If that's it and cyl is not ruined then I would use a little emory cloth to clean it up and run it again with a slow break in and a little more fuel by re-jetting.
 
O

ossagp

It doesnt say lean to me, but if your rig was running rich at another throttle position that what it was on when it seized you can be fooled by a plug. the piston says cold seized to me too.

Rick Peterson from RPM used to caution people about a cold seizure of a different nature: one where the bike is warmed or heat cycled sitting still, then hopped on and ridden through the gears and the radiator gets a big rush of cold air and the cylinder goes "small". I have several bigbore 125's and have never had that happen and typically i warm them up for about 45 seconds and when they run good off the choke I ride off.

if yours has an airleak it can run lean at the more open throttle settings and still be rich (hence the plug reading) at low settings where the vacuum is greater.

fyi mine all run richer on the stock jetting after the big bore work is done. I have 139's and 144's, yamaha and honda (in the past). i have seen some work done by butcher shops that needed way richer jetting and ran like pigs and seized easily because the proper head work was not done.
 
Mihylo33

Mihylo33

ossagp:
It doesnt say lean to me, but if your rig was running rich at another throttle position that what it was on when it seized you can be fooled by a plug. the piston says cold seized to me too.

Rick Peterson from RPM used to caution people about a cold seizure of a different nature: one where the bike is warmed or heat cycled sitting still, then hopped on and ridden through the gears and the radiator gets a big rush of cold air and the cylinder goes "small". I have several bigbore 125's and have never had that happen and typically i warm them up for about 45 seconds and when they run good off the choke I ride off.

if yours has an airleak it can run lean at the more open throttle settings and still be rich (hence the plug reading) at low settings where the vacuum is greater.

fyi mine all run richer on the stock jetting after the big bore work is done. I have 139's and 144's, yamaha and honda (in the past). i have seen some work done by butcher shops that needed way richer jetting and ran like pigs and seized easily because the proper head work was not done.
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That's a good one. That's why I don't start riding until I can feel the heat in the radiator and not the cylinder.
 
P

PawPaw

Looks like a cold seize to me. The mixture may be ok, but can't see a lean condition on that plug . A chop test would be the best way to get a good plug reading.
I do however see what looks to be an indication at the base of the spark plug center core of an indication of a plug that is too hot for the application. That can lead to a cold seizure as well.

Paw Paw
 
6

615kawi

Thanks for the advice guys. The jetting is stock. The cylinder does have the same marking that the piston has but it's not damaged. I can't catch anything with my finger nail when scraping the cylinder. What would be the best way to proceed? Order a new piston and ring and measure ring gap then slowly break the bike in? I've never really broke in any top end. I usually just break it in how I ride it...wide open after warmed up. Another thing to mention is my previous Pistons would get the same markings on the skirt but never locked up.
 
6

615kawi

Mihylo33:
Let's see that cylinder. You've got some issues there and you will probably need some cylinder repair.
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The bike just got done from Eric gorr. I had a sleeve installed From a machine shop before I sent it out. The cylinder doesn't even have a hr of run time since I got it bored to 134 and ported for mid-top. I'm not home to take a pic but I'll have one up by tonight or tomorrow.
 
Mihylo33

Mihylo33

615kawi:
The bike just got done from Eric gorr. I had a sleeve installed From a machine shop before I sent it out. The cylinder doesn't even have a hr of run time since I got it bored to 134 and ported for mid-top. I'm not home to take a pic but I'll have one up by tonight or tomorrow.
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Call Eric gorr. He stands behind his work 100%. However the sleeve was done elsewhere. Not a fan of steel sleeves in nikasil cylinders. Seen too many issues like dropping and spinning.
 
Mihylo33

Mihylo33

2strokesteve89:
Not s fan of dropping and spinning? That's not what Palmer told me.
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You gotta find an old timer that would appreciate that. They are also the only ones that actually sleeve a cylinder correctly. Those guys are few and far between. I think we have one within a 200 mile radius.
 
2strokesteve89

2strokesteve89

Mihylo33:
You gotta find an old timer that would appreciate that. They are also the only ones that actually sleeve a cylinder correctly. Those guys are few and far between. I think we have one within a 200 mile radius.
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Up here we have ADB (Anchorage Drag Bike) Dave over there is the guy I'd trust for anything like that, and I don't usually trust no one.
 
P

PawPaw

A steel sleeve ( with poor heat transfer) plus a forged piston ( that expands faster than an OEM piston) plus riding before several heat cycles plus unknown ring end gap = a cold seize.
You can have that sleeved cylinder plated to help, but it still will have to be properly assembled and broken in prior to any hard riding or it will do it again.
I would do a leak test and go to a colder plug to help.
What fuel mix are you running?
What octane fuel are you using?
Was the head squish corrected for the bigger bore?

Paw Paw
 
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