joshk
Scoot Junior
Posts: 12
|
Post by joshk on Jul 9, 2021 6:12:10 GMT -5
I have a 49cc icebear 4t gy6, recently I had put aftermarket carb (so I can adjust screws) and a pod style filter with aluminum elbow, unrestricted exhaust, and removed the PAIR system. It was running well for a few weeks, then started bogging and spurting/popping (sounds like it's rich) going downhill, and loss of torque uphill. Loss of overall power as well. I normally get up to 28-30 mph, then only 15-20, sometimes as low as 10-15 uphill. After a few days going on short rides to help with troubleshooting (trying to adjust the mixture assuming cheap carb mixture screw maybe moved?) the engine now won't start. Has batt power, starter works. It kicks over too. I'm thinking possibly valves (adjusted recently but maybe I didn't tighten the lock nut well enough) or maybe petcock issue. I still have the stock vacuum type petcock. I'm posting here to hear some feedback, maybe there's something else I'm missing? Oh I also replaced the spark plug, and the new one looks like it may be lean, even though I'm popping and sounding/smelling rich.
|
|
|
|
Post by scooter7878 on Jul 9, 2021 6:53:54 GMT -5
If u didn't change the main jet to a few sizes bigger u have been running lean with the air filter and exhaust u should have up jetted a few sizes stock jet is usually 78 u should be at around 85 with the filter and exhaust. Unfortunately at this point there's a chance u damaged a piston or burned a valve from running lean u can try a valve adjustment but it's likely since it was running ok for a while after upgrades that u caused a issue by being lean. A compression test is needed right now to be sure u haven't damaged engine. Either way adjust the valves first bc miss adjusted valves will give u low compression
|
|
|
|
Post by scooter7878 on Jul 9, 2021 6:58:54 GMT -5
Post a pic of the plug
|
|
joshk
Scoot Junior
Posts: 12
|
Post by joshk on Jul 9, 2021 11:02:15 GMT -5
I'm having difficulty figuring out how to post the pic lol! But I do have a compression tester so I will do that and post my results. For what it's worth, until I figure out the pic posting, the original plug was dry but dark just above the threads by the electrode, electrode itself was mostly white (like the color it is brand new) with a little ring of an orange-ish brown band at the tip, on one side of it (?) and the tip (the curved metal piece that hangs out over the electrode) is burnt white.
|
|
joshk
Scoot Junior
Posts: 12
|
Post by joshk on Jul 9, 2021 11:09:01 GMT -5
Fuuuuuudge, you got it bud. I'm only getting about 40 psi. Guess it's time for a bbk/rebuild top end? To top it off, one cylinder head bolt just broke off lol. I'm having a great Friday!
|
|
|
|
Post by GrumpyUnk on Jul 9, 2021 11:48:36 GMT -5
Plug color description sounded lean to me, FWIW. If you have not taken it apart yet, squirt/pour a Tsp of oil through the spark plug hole and re-check the compression. If improvement occurs, it is likely the oil temporarily sealing the rings a bit better. Time for rings/piston/cylinder as needed.
The torque on the nuts used on the cylinder studs is only about 15ft/lb. More than that and you can break the stud, as you found, or pull them completely from the block. Personal opinion is that the composite head gaskets work better than the steel 'shim' style. You will lose a bit of compression, but I like their sealing capability over the steel gaskets.
tom
|
|
|
|
Post by scooter7878 on Jul 9, 2021 13:29:42 GMT -5
Also should have checked valve clearance before tear down not likely but possible could have been a issue
|
|
|
|
Post by scooter7878 on Jul 9, 2021 16:21:09 GMT -5
Fuuuuuudge, you got it bud. I'm only getting about 40 psi. Guess it's time for a bbk/rebuild top end? To top it off, one cylinder head bolt just broke off lol. I'm having a great Friday! . Make sure u up jet with whatever u decide to do I believe they say for every upgrade go up 2 numbers so air filter and exhaust u would go up around 4 numbers if u bbk it I'd probably start around 95 main u can't blow anything by being too rich and adjust from there. My buddy 50cc with exhaust and pod running a 85 or 87 seal level in Florida to give u a idea if bbk I'd put a 95 main and probably a 35 or 37 idle jet depending on what idle jet it had stock. Just air and exhaust u won't need change idle jet bbk I go up two numbers on the idle |
|
|
|
Post by FrankenMech on Jul 17, 2021 13:19:28 GMT -5
Buy a new 'performance' carb that is sold with a cone filter rather than trying to fart around with upjetting a cheap stock carb.
|
|
