|
|
Post by mattnh on Apr 14, 2019 8:51:41 GMT -5
I got this scooter from one of my friends for free last fall, died on him and wanted to give it away. I’ve been working on it for a couple months but no luck getting it to properly start. Currently I can only get it to start with starting fluid, and it’ll only run for a couple mins, or until it’s warm then it dies. It has low compression (about 70psi) and I haven’t done a leak down test.
Here’s what I’ve replaced:
Battery
Fuel filter
Spark plug
Piston(and rings)
Cylinder
Head(and all gaskets)
Carb
Reeds
Any pointers that’ll lead me to something would be great
|
|
|
|
Post by oldgeek on Apr 14, 2019 11:12:29 GMT -5
I got this scooter from one of my friends for free last fall, died on him and wanted to give it away. I’ve been working on it for a couple months but no luck getting it to properly start. Currently I can only get it to start with starting fluid, and it’ll only run for a couple mins, or until it’s warm then it dies. It has low compression (about 70psi) and I haven’t done a leak down test. Here’s what I’ve replaced: Battery Fuel filter Spark plug Piston(and rings) Cylinder Head(and all gaskets) Carb Reeds Any pointers that’ll lead me to something would be great  Considering what you have done it should not have low compression, unless the piston you installed is different from stock. if it starts and runs "until its warm" could be the E choke shutting off and changing your air-fuel mix. You could try unplugging the E-choke to see if it will run longer. If you are not using the stock air box I HIGHLY recommend you install it before doing anything at all. |
|
|
|
Post by GrumpyUnk on Apr 15, 2019 9:20:14 GMT -5
When you installed the piston & rings, did you check the 'end gap' of the rings? If the clearance is too large, the rings won't seal as well and if the clearance is too small, the rings will mechanically be forced against the cylinder wall due to expansion caused by heating up.
New rings should give good compression. When you installed the cylinder, did you feel the rings slide against the cylinder wall? You should have felt the friction of new rings against the sealing surface, and it would feel different between new rings and the old replaced rings. IF the same, something is likely wrong.(lack of ring tension?)
tom
|
|
|
|
Post by rancevas on Apr 15, 2019 11:08:15 GMT -5
1. Have you tightened the screws on the cylinder head to the correct specifications? Under-tightened bolts might cause a compression leak.
compression for your specific model should be around ~100 PSI. Have you tested it while the engine was hot or cold? That impacts the readings.
When testing the compression, make sure the engine is warm. Be careful not to burn your fingers, so wear gloves.
Turn the throttle open all the way and note the readings.
Then, squirt some oil inside the cylinder. About a teaspoon to cover the piston rings. If compression doesn't change - your problem is the head gasked and improperly fastened bolts. If it jumps significantly - the problem might be with the piston rings.
2. When you installed the piston rings, have they moved? If by accident the grooves are aligned or facing the exhaust ports - that might be an issue. An issue that will cause your engine to seize later on.
3. Exhaust. If everything is in complete order, check it. Is the airflow normal? Maybe the silencer is blocked by some debris or else. Note - do not start an engine without the exhaust manifold - your scooter might catch fire. literally. You'll go deaf as well
4. Inadequate fuel amount delivered to the combustion chamber. Try setting your carburetor's air/fuel mixture to fully rich, pull up the choke and see if that makes it run better. If it runs better than before - report to us
5. Loose wires shortening on the frame. Check all of them. If the do - your spark will disappear completeley and the engine will shut down abruptly.
6. Poorly installed reed valves/ reed valve gasket. If you accidentally bent a reed valve while installing it, that might be an issue. Also, make sure you installed the reed valve gasket correctly. I once installed it in between the reed valve housing and an air duct (is that how it's called?). That f*cked my s*hit up.
Describe how it dies. Does it bog down? What sound does it make? Does it just suddenly stop? Does it run for the same amount of time each time you start it?
Anyways, keep on going and the scooter will be running in no time. Motivation is a hard thing to keep when results aren't showing.
|
|
