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Post by geh3333 on Jun 1, 2022 20:29:46 GMT -5
I was riding my scoot pretty hard yesterday on an 80 mile round trip, and halfway home my scoot started making a weird noise which sounded as if it was in the valve area. It wasn't real loud but noticeable with my helmet on . I was riding close behind a big truck on to avoid wind resistance and I was reading between 69 and 76 mph on my phones speedo app. All of a sudden the scoot died and I pulled over . As I was stopping I heard a clank for a second and then I heard the scoot ignite and blow back through the carb and airfilter followed by some smoke . I called someone to pick the scoot and myself up and take us home. I was able to turn the scoot over but u can tell it had no compression and would not ignite. I took the valve cover off and nothing looked broken but when I check the valve clearance the exhaust valve was tight . When I tried to adjust it , the valve spring just kept against the rocker arm . I took the rocker arm assembly off , the valve spring fell off and the bottom half of the valve was left in the head. The valve shaft was still attached to the spring and retainer . I'll post a pick soon .now I have to remove the head and see if the bottom of the valve did any damage to the piston or cylinder.
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Post by geh3333 on Jun 1, 2022 20:33:56 GMT -5
I'm pretty sure the oil pump stopped working and the scoot overheated . I had oil blowing out of the gear oil breather from getting so hot.
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Post by geh3333 on Jun 1, 2022 22:06:27 GMT -5
Catastrophic failure!!
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Post by geh3333 on Jun 1, 2022 22:07:35 GMT -5
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Post by geh3333 on Jun 2, 2022 21:44:52 GMT -5
The piston skirt is pretty much completely gone and inside the engine case.
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Post by geh3333 on Jun 24, 2022 22:37:58 GMT -5
Finally got to take the engine apart and clean it out. New oil pump but im running the stock bore until i get the chance to order another 60 + kit. Im keeping the same gearing and im going to see how far i can push it with a stock bore. I honestly believe i can hit a true 65 mph and cruise around 60 mph. Its all up to how much HP i can create, so im going to force as much air and fuel possible through this thing and see how she runs . Ill post a few pics 2mro.
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Post by geh3333 on Jul 1, 2022 2:47:47 GMT -5
Dropped another exhaust valve !! Not even a mile down the road . I didnt have the rpm gauge hooked up and i know my rpms were high , so its prob my fault. Its weird . The scoot sounded and felt stronger with the stock bore and the 60 mm head i have . Either the belt was slipping or the engine really did have more power . The same trany setup was in and the same roller weights , but the rpms were really high from start up to 55 mph and then the valve dropped. I should have turned around and put heavier weights in or at least cleaned the belt and tranny parts off again.
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Post by geh3333 on Jul 21, 2022 17:33:47 GMT -5
Actually dropped both valves .
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Post by geh3333 on Jul 21, 2022 17:38:31 GMT -5
Heres the piston
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Post by geh3333 on Jul 21, 2022 17:42:24 GMT -5
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Post by geh3333 on Jul 25, 2022 20:36:57 GMT -5
Just blew a third. Something is obviously wrong somewhere. Im going to have to really inspect everything.
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Post by geh3333 on Jul 28, 2022 16:08:54 GMT -5
Just realized i was running 64mm rocker arm assembly with 69mm valves
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Post by mattr on Apr 15, 2024 20:24:02 GMT -5
Just realized i was running 64mm rocker arm assembly with 69mm valves You needed new rocker arms when swapping out a bigger piston or heads? Do they come with the kit? I assume not since u didn't have them on. Did this fix the problem?
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Post by jjoshua20215 on Apr 18, 2024 14:19:46 GMT -5
I'm reading all this and OMG! LMFAO
I told you in the other post you might have been sent the wrong head or rocker arms. Why did you blow 3 top ends in the same manor back to back??? You do know what the definition of insanity is right?
First things first you need to flush out that engine for debris! There is metal in it, and if you ruin the connecting rob bearing, just go get a new engine or prepare for a total rebuild.
I would do 3 oil changes within 10 miles to make sure it's all out. Sounds excessive? That's the point...
The valves naturally close over time but heat and high rpm's will greatly accelerate this.
When you upgraded the engine, you needed to upgrade the cooling as well. High rpm/full throttle runs are good for short bursts, not 80 mile trips. You need some throttle leeway for longevity especially with a bbk.
Throw in some heavier weights to combat your high rpm.
I personally would trash all top end components and start new. You should've done more research before attempting the project.
Even if some of the old parts still work, I'm sure there is damage you can't see that will cause you issues later.
Also, use a heavier weight oil to help with higher temps. Increased heat will thin out your oil reducing its lubricating properties.
Sounds like you just had to learn the hard way and are going to get it right next time.
Those rocker arms and head need to match. Do not try to finesse to get it to work temporarily. The valves never stay adjusted on these things. I think the adjustment changed while you rode up to the point of the valve slap.
Unless a valve broke completely off in the cylinder, I also suspect a foreign material got into the combustion chamber.
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Post by jjoshua20215 on Apr 18, 2024 14:21:38 GMT -5
When you upgrage a GY6 you need to upgrage EVERYTHING. lol
Otherwise, un-upgraded parts will wear out quickly.
I would defiantly inspect the CVT as well. Engine heat transfers to the cvt as the variator is connected to the crankshaft.
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