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Post by jashcb7 on Apr 10, 2019 15:19:36 GMT -5
I recently picked up a 150cc fashion sport sunl. No battery,flat tire.It kicks normal once and then has too much compression and won't kick. Valves are set 0.127 book says 0.12. exhaust pipe removed makes no difference. Pull the valves and look at the piston? Not sure what I would gain there. Oil is at the correct level. Any ideas ? compression release?
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jackrides
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36 minutes ago
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Valve clearance is ok. Tirn the key off, pull the spark plug and kickit over. Does liquid come out of the plug hole? If so, carb float leak.
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jackrides said:Valve clearance is ok. Tirn the key off, pull the spark plug and kickit over. Does liquid come out of the plug hole? If so, carb float leak.
Carb and intake are off. There's no fuel to the carb yet or battery. There is spark. With the plug out it kicks easy enough to check spark.But can't kick it over more than 1 time with the plug in. Kickstarter is working I think since I can stand on it until the compression leaks out. I tried asking in my other thread if a battery would cause an issue but no answer.i just thought if i can get it sputtering on starting fluid then get a battery and fix fuel supply.
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Sorry also just realized there is a 100cc plus trouble shoot if i belong there. But yea it kicks fine with the plug out so it can be the piston or rings?idk
Sorry for the weird copy and paste but I thought I should move the thread where it belongs
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Post by 2stroked on Apr 10, 2019 21:18:10 GMT -5
The Jonway 150 I just worked on was very similar. The kick start would maybe give you one engine revolution then it would fight back. I thought I had messed something up, so didn't put a lot of strength to it, removed the CVT cover and looked, all was fine there. Valves were set right, exhaust was clear... I was stumped.
Put the cover back on and actually gave it a good kick, damn near broke my leg, but it started. So, I wouosnt day that's normal, but it happens....
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Post by jashcb7 on Apr 11, 2019 15:59:46 GMT -5
The Jonway 150 I just worked on was very similar. The kick start would maybe give you one engine revolution then it would fight back. I thought I had messed something up, so didn't put a lot of strength to it, removed the CVT cover and looked, all was fine there. Valves were set right, exhaust was clear... I was stumped. Put the cover back on and actually gave it a good kick, damn near broke my leg, but it started. So, I wouosnt day that's normal, but it happens.... I ended up pulling it apart and found the piston had a lot of build up around the top lip.I sanded that down figuring it was causing to much pressure.My new theory ....It looks like the exhaust valve was set incorrectly when it was running and got hot around the exhaust pipe,the plastic is a little melted.After putting it back together it seems a little easier to kick but will still almost bind up.I got it to that bind up point and Im used to kicking dirt bikes ect,I put boots on,Gave it everything and just as it almost locks up theres a pop and slight smoke....The exhaust pipes off and intakes off at this point.So I got that to happen once or twice but its only if it almost binds up the tries to fire.Im getting good blue spark with a new plug.I would think i could get something off starting fluid. A little back story i found a honda lawn mower on the side of the road a few weeks ago.The plug was trash.The coil was trash.The carb is trash and choke rusted but after the normal steps I got that running with no $ spent.Not sure what the deal is here.Im capable of this type of thing but never had too much compression. Only thing I can think is the rings are to tight?Or bad valve?I was going to rip into it again and try looking at those or just try removing the top ring all together.I know its not right and I would fix all of this and replace the gaskets if I could get some sing of life.Or ill just keep dicking with it for the learning,slap it back together and dump it on someone else  hfhf by Jash Z, on Flickr |
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Post by jashcb7 on Apr 15, 2019 13:40:04 GMT -5
Cleaning the carbon build up did not help. I took the valves completely apart from the springs and they look ok. I tried adding some end gap to the piston rings because they seemed tight. Again I assumed this was a running then parked scooter so not sure why I would be this far into it. So much for carb cleaner and new gas.
I also pulled the Kickstarter cover and checked everything in there.
Putting it back together with better ring gap didn't help.... Putting it back together without the top ring, didn't help... So I tried with just the oil rings and it still kicks very hard. So my last who cares shot in the dark of trying it with no piston rings and it kicks free. So the exhaust is on(need to replace it if I keep her) intake off,It won't give me any sputter on starting fluid.
They way I see it is if I replaced either the piston assembly or the valves I will do both just because of the price. Pretty much cheaper to get the whole kit.$40
Im still confused but think I might order the rebuild kit. In the mean time I might try putting the rings back in idk.
I did air up the tire and that went flat again. The front tire looks new so the rear is probably original 2008 and also needs replacing
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Post by humanshield on May 18, 2019 21:55:16 GMT -5
Compression is a function of the cylinder and head squish area (displacement) vs piston travel. Not how well the rings seal or their adjustment. While those things will affect compression, they do not determine the compression ratio for a motor.
Carbon buildup can raise compression in severe cases. But it still doesn't determine the calculated compression ratio for the motor.
It sounds like your motor simply does not have enough volume at TDC on the compression stroke. In other words, there is not enough space left when the piston is at Top Dead Center. In other words, for every day use, something is set up wrong.
when I installed my 100cc BBK, my compression did the same exact thing. It sometimes hurt my foot trying to start it and the electric starter could not handle the compression. The cure was adding a performance A9 cam. That did two things...lowered the compression AND increased airflow. The net result was it ran better, was faster but also ran cooler and the electric starter worked again.
Use a compression tester to test it. I will almost guarantee you it is above 180 and as high as 210psi. when it gets that high it can be VERY hard to kick over and puts a lot of strain on the electric starter (if it can even turn it over).
For daily use, your compression should be between 160 and 180psi
You may need to lower the compression. The easiest way to do that is install an A9 cam if it doesn't already have one. Or extra head gaskets or thicker / extra base gaskets.
The point is to move the cylinder head farther out....creating more combustion space.
If you Do NOT lower the compression.....
The engine will run considerably hotter and there will be more stress on the bearings and gaskets. Things could fail.
If you DO lower the compression.....
It will lose some power (unless you added the cam) and you will feel it especially at take off.
Good luck....and increase your luck by wearing a lid whenever you ride.
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