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03-10-2017, 01:01 AM
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#1 |
 Join Date: Mar 2017
Posts: 4
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Resurrected Scooter, Problem
So my friend had a 150cc GY6 sitting under a tarp that had not been running in a couple of years. I was able to get it running after a new tank of gas, and installing a brand new 26mm carb. It fired right up, idled fine and ran decent on the road, however, it did accelerate a bit weak, especially at WOT.
SO, the plastics were destroyed and a lot of the parts to reassemble them were missing, so I ended up tossing a lot of the junk and going with a naked bike. With the installation of a slightly bigger carb, and the missing airbox parts, I ended up having a little pod air filter, and stock exhaust, and it ran good up until about 35 or 40 mph, where it would top out. Power was pretty weak the whole time, especially at WOT. I figured a rejet was in order because it was running lean. The jet that was in the carb was not marked, so I threw in a 120 and figured I would adjust later depending on how it ran. Started fine, accelerated the same. Along the line I ended up putting in a new camshaft (a NIBBI 6.2 mm) adjusting valve lash, doing an oil change, gear oil change, replacing fuel lines and doing some new wiring work because some of it had dry rotted. So, where I'm at now. Valve noise is definitely louder with the aftermarket camshaft installed, is this normal? I adjusted valve lash to .004 and .003 and it's still pretty loud. The bike still feels relatively weak at WOT, and now once it gets up to 30 or 35 mph, it surges significantly. It feels like it is bouncing off of a rev limiter. How can I fix this thing. I feel like it runs worse now than when I dug it out of a heap after sitting for 3 years. I'm thinking it's still running lean, hence the surging at higher speeds/WOT and lack of power. Thoughts? Also, any way to quiet those valves down? |
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03-10-2017, 02:18 PM
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#2 |
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Join Date: Mar 2017
Posts: 4
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UPDATE: I messed around with jetting. Tried a 125 and it got worse so I figure the main jet has been too big and flooding the scoot out at high RPM. So I went with a 115 and it got better, and a 110 even better yet. Might go one more smaller but things feel pretty good now. Power is back, and no more bogging out under WOT.
Valves still tick a bit but I think its within reason. I've tried everything from .003-.005 on both the intake and exhaust and there still a bit noisy. Must just be because they're slamming shut a little harder due to the higher lift and duration. A side note, after the new camshaft, the exhaust noise is much louder now. I mean significantly. I like it. |
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03-10-2017, 07:14 PM
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#3 |
 
Join Date: Dec 2013
Location: Western New York
Posts: 454
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I've said it before, and I'll say it again....."ticking valves, are happy valves". If you can't hear them, they are too tight...... Intake .003", Exhaust .005".
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2011 Jonway 150cc..16,109 breakdown free miles, and counting
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03-10-2017, 07:30 PM
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#4 |
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Join Date: Mar 2017
Posts: 4
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Intake are at .004 and the exhaust is at .005
The valves were quiet before, and they were too tight for sure. Couldn't even fit a .001 in on either at TDC... I have come to terms with the new noise level and just sealed it up with fresh RTV. I am surprised how much louder the exhaust tone is on this scoot after the new camshaft install. It sounds like it has a performance exhaust on it now. I can only imagine how much louder it would be if I actually had a less restrictive exhaust on it... |
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