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Post by kyalami321 on Oct 21, 2018 12:26:21 GMT -5
Hey y'all, Hoping you can shed some light on this issue. I was driving my '92 CH80 (4k miles) when all of a sudden it shut off and no longer started. Prior to that, I had ascended a steep grade at about 30 miles per hour and then went down it at about 45 mph. The rest of the way was flat, easy cruising at about 35-40 mph. It didn't shut off until 2 miles after, when I turned at an intersection. I slowed down for a STOP sign, accelerated a bit more, stopped again, and DEAD. I checked battery, spark, fuel delivery, cleaned the carb. A mechanic said I had no compression. Pulled apart top end, nothing seems broken or visibly worn. Piston is carbonized rings look fine. Camshaft, valve tappets, rocker arms, etc. all look good. Any ideas? My feeler gauge only goes down to .2 mm and valve clearance is supposed to be .05 so will check that next.   |
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Post by kevinharrell on Oct 21, 2018 19:20:03 GMT -5
Without something like breaking a ring or a valve a sudden loss of compression is unlikely. So, your problem is either fuel or electrical. Put the bike back together and give it a shot. You cleaned the carb so if it does not start the problem would have to be electrical. With it stopping after turning at an intersection I would look for a broken wire in the headset, one that flexes when the handlebars are turned.
Good luck.
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Post by kyalami321 on Oct 21, 2018 20:20:40 GMT -5
I was thinking the same, but I put the bike back together, tested for compression by spinning the fan by hand as well as using the electric start, and the needle did not even move. This was with the intake manifold (and carb) and exhaust bolted on. I feel air coming out of the exhaust, but no movement on the compression needle.
With your comment about something in the headset ... if I get spark, doesn't that mean the bike is indeed properly set to run and the ignition set to on?
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Post by chewbaca on Oct 22, 2018 1:08:35 GMT -5
so it sounds like one of your valves is pitted or chipped
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Post by kyalami321 on Oct 22, 2018 7:50:31 GMT -5
My thoughts indeed point to a valve seating issue. I'll pull them again and take a picture for y'all tonight or tomorrow.
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Post by kyalami321 on Oct 22, 2018 7:51:56 GMT -5
so it sounds like one of your valves is pitted or chipped My thoughts indeed point to a valve seating issue. I'll pull them again and take a picture for y'all tonight or tomorrow. |
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Post by kyalami321 on Oct 22, 2018 22:04:21 GMT -5
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Post by chewbaca on Oct 22, 2018 22:48:52 GMT -5
you need to pull the valve out of the head so you can inspect the contact surface
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Post by eman on Nov 2, 2018 17:50:38 GMT -5
Well you've already disassembled it so remove the valve springs and ck the valve seats.
Before all of this I would have put a little oil in the cyl and see if you got compression. By the way you said it shut off I would have bet on a piece of carbon under the valve holding it open a little. I had it happen on the intake and was able to see it when I pulled the manifold.
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Post by kyalami321 on Jan 1, 2019 11:49:47 GMT -5
Just wanted to update this thread .... I ended up junking the scooter after buying another used top end from a working bike online and having the same issue. Shame to see it go but I tried!
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