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Post by cwazywazy on Sept 5, 2016 15:02:03 GMT -5
Also this CV80 service guide from Yamaha I found says "fuel cock" instead of petcock.  |
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Post by 'O'Verse on Sept 5, 2016 15:04:56 GMT -5
Well... I'd say if you can take the cylinder off without dropping the engine or just with taking off the mounting bolt. It's worth a shot to see what your dealing with. Scoots an older model could be gunked up inside there. Could be spotless. Pick up whatever gasket set you plan on going to with in the future. I couldn't tell you if the 80cc cases can take a 90cc cylinder or if 80cc the max. What kind of choke is on the carburetor? Sometimes the older yammy carbs with electric choke just need to be replaced to get it to start...
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Post by cwazywazy on Sept 5, 2016 15:33:50 GMT -5
Used my crappy $5 boroscope through the spark plug hole, can't see much though. imgur.com/a/cj7j4 |
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Post by 'O'Verse on Sept 5, 2016 15:40:55 GMT -5
Looks good. Nice carbon build up. Slight scratch on the cylinder wall.
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Post by gsx600racer on Sept 5, 2016 15:52:42 GMT -5
When you kick it over, are you able to see if there is anything(fuel) blowing out the carb ?
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Post by cwazywazy on Sept 5, 2016 16:14:20 GMT -5
When you kick it over, are you able to see if there is anything(fuel) blowing out the carb ? I haven't seen anything, but then I haven't really looked for it. I remembered that 2 strokes are a lot easier to take the heads off of, so I did that. Looks pretty good to me.      |
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Post by 'O'Verse on Sept 5, 2016 17:14:04 GMT -5
Rings? Yeah that looks pretty well taken care of considering its age. Still hinting towards carb related. Do you have another 2 stroke carb laying around just in case? Make sure you seal it up nice and taught. Oriellys has a pack of sheets of flat gasket material in different thicknesses for around $10. Cut yourself a base gasket. Material left over for a lifetime. Copper spray on the head if you have to.
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Post by cwazywazy on Sept 5, 2016 17:28:41 GMT -5
Didn't bother trying to take off the exhaust to get the cylinder off and I don't have any extra scooter carbs, apart from the guts of a stock GY6 one somewhere..
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Post by spaz12 on Sept 5, 2016 17:52:07 GMT -5
The exhaust might be plugged up.
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Post by 'O'Verse on Sept 5, 2016 18:01:41 GMT -5
Looking back at the pics. Looks dry unless you tried to clean it up. Coat your cylinder with some oil before slapping it together.
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Post by gsx600racer on Sept 5, 2016 22:30:24 GMT -5
I just sent 90GTVert an email with the service manual for the CV80 attached to add to the site. |
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Post by 90GTVert on Sept 6, 2016 8:06:25 GMT -5
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Deleted Member
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Post by Deleted on Sept 6, 2016 8:52:11 GMT -5
timing off?
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Post by ryan_ott on Sept 6, 2016 11:14:43 GMT -5
If you have good spark, but still won't start with fluid likely bad crank seals. Put a few drops of gas mixture in the plug hole with the piston covering the ports. If it fires but can't pull fuel from carb/crankcase I say seals/ reeds. If you feel air moving from the tailpipe (insert pun here) muffler should be clear enough to run.
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Post by gsx600racer on Sept 6, 2016 18:18:11 GMT -5
You mentioned in previous post that you got 90 psi compression. My question is this measurement taken with a "name brand" tool or a cheapy one. Cheap ones are usually not that accurate. It could be 10-20 psi off. If its the case, your reading could really be off by 20 psi and at a 90 reading you could actually be 70. 100-120 psi should be a decent # for that engine to run. In the pics like others( 'O'Verse ) have mentioned the cyl looks dry. I suggested in previous post get some oil in the cyl to help up the compression. This is not a fix, but might enough to fire it off. I also mention in previous post about fuel blowing back thru the carb. If this is happening you might have an issue with the reeds not sealing like( ryan_ott ) mentioned. I would just pull the engine, pull the cylinder and check the piston and rings. The rings could be stuck or broke as well. Make up an new base gasket. Find a good flat surface and sand the top of the cylinder and head to flush them up. Use some copper sealer with or with out the head gasket and reassemble. Then make yourself up a leak tester and check for leaks around the crank seals, cyl to block, cyl to head, and intake manifold/reed cage. Yeah, it would been cool that you spent 20 bucks and got a running scooter. |
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