Two stroke - no power. Help. - Motorcycle-Journal Forums

JCBrewer · 02-09-2004, 03:19 PM

Hey. I got a '98 JR50 that has absolutely no power. I know, I know, they come from the factory like that. But honestly, it was running great but now won't even pull my kids up tiny hills. It starts up great and idles like a champ. Spark plug is nice and clean. Did a carb overhaul just to be sure. I'm thinking it might not have been getting enough auto-lube since the level wasn't changing. If so, what would be the symptoms if that happened. For sure, it would place a lot of wear on the rings and cylinder. So what are the symptoms of a two stroke that needs a fresh top end. It can't be that they smoke, because two-strokes always smoke and they run a dry sump.

Thanks,
John
Huntsville, AL
'98 JR50
'94 XR250R
'77 Z50

The Chad · 02-09-2004, 10:52 PM

no power and lack of compression. do a compression test on it, see what you've got.

JCBrewer · 02-10-2004, 11:53 AM

Did a compression test. Solid 90 psi. If this was a car - or any four-stroke for that matter - I'd say that was low. I don't know these two-strokes though. A search on the web tells me that this may be low for a two-stroke, too, but I can't find something that says, "anything below x psi, means its time for rings."

blackdog · 02-24-2004, 10:22 AM

sounds like to me that the exhaust is all choked up try taking it off and cleaning it out also check to see that it is not choking its self but my guess is the muffler is all stuffed up

JCBrewer · 02-24-2004, 02:44 PM

I found out the problem. I pulled the cylinder only to find that the piston was deeply scored on the lower side. The friction was enormous and the compression was crap. As bad as it was, I'm surprised it ran at all.

02-09-2004, 03:19 PM	#1 (permalink)
JCBrewer Newbie Joined: Feb 2004 Posts: 10	Two stroke - no power. Help. Hey. I got a '98 JR50 that has absolutely no power. I know, I know, they come from the factory like that. But honestly, it was running great but now won't even pull my kids up tiny hills. It starts up great and idles like a champ. Spark plug is nice and clean. Did a carb overhaul just to be sure. I'm thinking it might not have been getting enough auto-lube since the level wasn't changing. If so, what would be the symptoms if that happened. For sure, it would place a lot of wear on the rings and cylinder. So what are the symptoms of a two stroke that needs a fresh top end. It can't be that they smoke, because two-strokes always smoke and they run a dry sump. Thanks, John Huntsville, AL '98 JR50 '94 XR250R '77 Z50

02-09-2004, 10:52 PM	#2 (permalink)
The Chad Site Wrench Head Joined: Nov 2003 Bike: crashed Location: Duncan B.C. Posts: 635	no power and lack of compression. do a compression test on it, see what you've got. __________________ A truly wise man asks more questions than he answers, I think I must be retarted

02-24-2004, 10:22 AM	#4 (permalink)
blackdog Newbie Joined: Feb 2004 Location: Brisbane Australia Posts: 8	low power sounds like to me that the exhaust is all choked up try taking it off and cleaning it out also check to see that it is not choking its self but my guess is the muffler is all stuffed up

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02-10-2004, 11:53 AM	#3 (permalink)
JCBrewer Newbie Joined: Feb 2004 Posts: 10	Did a compression test. Solid 90 psi. If this was a car - or any four-stroke for that matter - I'd say that was low. I don't know these two-strokes though. A search on the web tells me that this may be low for a two-stroke, too, but I can't find something that says, "anything below x psi, means its time for rings."

02-24-2004, 02:44 PM	#5 (permalink)
JCBrewer Newbie Joined: Feb 2004 Posts: 10	I found out the problem. I pulled the cylinder only to find that the piston was deeply scored on the lower side. The friction was enormous and the compression was crap. As bad as it was, I'm surprised it ran at all.

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