rkrau
Junior Dawg
Posts: 10
|
Post by rkrau on Feb 15, 2013 14:57:50 GMT -5
So I have a Roketa MC-74-150. It's got 120Km on the odometer and I've got an issue that's making me contemplate selling it and cutting my losses.
The tank is full. I checked that. The battery is brand new.
It's hard to really explain what's happening because it's an intermittent and inconsistent cutting of the engine.
I cleaned the carb by taking it off the motor and sprayed it with carb cleaner. Put everything back together correctly, started up and idled just fine.
Last night I take it out for a ride to make sure everything's working. 45 minutes of starting, stopping, going fast, going slow, turning left and right. Flawless! ;D
I meet up w/ some buddies of mine, 2.5 hours pass, I go to start the scooter, no problems! No hesitation whatsoever. I let it warm up a bit, the RPMs drop to regular idle speed, I take off. Slight hesitation under 50% throttle, but it picks up and sorts itself out. 5 Minutes into the ride back home... it cuts out. Great.
Push it back to by buddy's place, try to crank it over. Electric start wont get it to go, so I try the kick start, nothing. When the electric start is attempting to start the engine, if I twist the throttle, the rpms increase and you can hear some sort of sound coming from the engine that sounds like it's attempting to make it work.
I try this for 10 min (intermittent stopping letting the starter motor have a break) and give up.
While riding it a couple days ago, it started fine, smoothed out the idle when the engine was warm, and I took off. 3 miles into the ride and the engine starts bogging down and eventually cuts out. While I'm going 20mph.
I'm losing hope that this will be a simple fix.
Any ideas?
|
|
|
Post by doomsday on Feb 15, 2013 16:58:53 GMT -5
vacuum lock? Try taking the gas cap off when that happens and see if it starts right back up.
|
|
|
Post by woowilly on Feb 16, 2013 3:36:50 GMT -5
I had several of the same symtoms when my CDI started going bad. Somedays it worked [perfect, others it'd die at stoplights and not want to restart sometimes, or sometimes not want to start when I went to go back home after a short trip. It was intermittantly failing when it warmed up aparently before it finally died totally and had a no spark condition. Not long after that my coil died. Ocasional top end miss eventually became consistant the while out on it. It had really weak spark when I looked into it. It's hard to trouble shoot a intermittant problem since it almost always works like it should when you have time to look into it.... For intermittant problems, sometimes the easiest way to track down what's causing the problem is swap out a part and see if it goes away, if not, change something else.
|
|
rkrau
Junior Dawg
Posts: 10
|
Post by rkrau on Feb 16, 2013 18:28:59 GMT -5
It's not vac. lock. I've run it with and without the cap after browsing the forums for other potential problems. I guess I'll start swapping parts out. CDI? Sure why not, just a few harnesses.
Could it also be what i've seen referred as "auto enricher" or auto choke, whatever, that makes the fuel mixture richer. That'll be next on the list.
Dios mio.
Updates to follow new part purchase.
|
|
rkrau
Junior Dawg
Posts: 10
|
Post by rkrau on Feb 21, 2013 20:41:16 GMT -5
THE PARTS ARE IN! Ordered an OEM "GY6 150cc" CDI. New spark plug, (matches gap in original plug). New Ignition coil (whatever connects directly to the spark plug). Installed and here are the results. It needed to be electric started 3 times before it stayed running. I blame it on the cold (28*F currently). Once it was running it warmed up and ran well. I noticed that all the lights; instrument cluster, headlights, and tail lights were alternating between bright and not so bright. After letting it warm up for about 3 min, light throttle caused it to bog down slightly, as if it were going to die, so I let off and let the throttle, and it returned to idle. So I let it warm up a little longer, light throttle, light engine speed increase. Medium throttle, medium engine speed increase. Impressed with this, I let it idle for a while longer. 10 minutes, no issues! Alright, lets call it a night, it's too cold. I let it sit for about 30 min and thought "I gotta see if this works". So I fired it up. Started right away (probably still warm). Ran @ 3500rpm for about 15 seconds, then dropped to a little under 2000rpm. I let it idle some more, blipping the throttle w/o bogging down and it returning to idle, I thought that it was time for a ride. Here's the elevation map that I ran. Up hill, down hill, high speed, low speed. Short bursts of acceleration, long acceleration. No issues. Is it fixed? I'm not sure. I'll give it a longer ride and a longer rest period at a later date. Here's the elevation map. www.mapmyride.com/routes/view/175299834
|
|
|
Post by tankcommander on Feb 21, 2013 23:09:56 GMT -5
I know your pain!!!! And it always happens at the worst time!! Mine usually in the turn lane on a four lane street and three miles from home....... Myself? I have narrowed it down to a throttle cable issue. Worked on it at lunch, rode it around, but still not wanting to get it in traffic. Sure, a wooos, but just would rather not.
|
|
rkrau
Junior Dawg
Posts: 10
|
Post by rkrau on Feb 21, 2013 23:29:10 GMT -5
ANOTHER THING TO ADD! The first couple accelerations upon first takeoff are slightly hesitant until it's been going (that is to say, moving in a forward direction) for a little bit. This varies, but always seems to exist. How long should I let a 150cc engine warm up in 30 deg. temps?
So far I've pushed this thing just over 10 miles. I've been doing some reading and have come to the conclusion that it can be one of these or all of these 3 things.
1: Dirty Carb. I've taken it off and sprayed carb cleaner through it. But perhaps it needs a really good inspection. (Might even just get a new one to rule out a couple of things that can go wrong, internally, in a carb.) 2: Bad ground. I'm going to (when it's warmer and less freezing) take body panels off and inspect every "ground to frame" connection to ensure they're clean, free of rust and making good contact. 3: Tight valves? I've been reading up on it and it seems like something that would be easy enough to check out... so why not. 4 bolts and you're in? I can handle that. But there's only 78 miles on it. So I'm saving this for last.
|
|
|
Post by ericrockstar on Feb 22, 2013 8:59:59 GMT -5
Did you take the carburetor apart to clean it, or just spray cleaner through it? You just get a tiny bit of varnish on the jets or the flute and everything act all jacked up. I had to clean a Brand New carb because of that. Also helps to run like a small guitar string or wore through them.
And a valve adjustment too. Maybe it was set tight from the factory. Many people go .004 in & .005 ex. That was too noisy for me so I went .003 on both. Really, I think as long as there is a tiny bit of play, you'll be alright. It's when they're tight that the rocker arm is holding the valve slightly open there is a problem.
|
|
rkrau
Junior Dawg
Posts: 10
|
Post by rkrau on Feb 22, 2013 12:41:09 GMT -5
Thanks for the feed back everyone. I'll give the carb another clean and check the valves for clearance.
Updates to follow.
|
|
|
Post by yardog on Feb 22, 2013 17:39:10 GMT -5
I would check valves first.
|
|
rkrau
Junior Dawg
Posts: 10
|
Post by rkrau on Feb 23, 2013 13:44:18 GMT -5
|
|
|
Post by tvnacman on Feb 23, 2013 18:40:34 GMT -5
I check my valves every 1000 miles , If I knew then what I know now I would have done a valve adjustment out of the crate . www.testedscooterparts.com/John
|
|
|
Post by ericrockstar on Feb 23, 2013 18:59:18 GMT -5
With any luck the next thing you'll need is new tires. From running the heck out of that badboy
|
|
|
Post by gy6girl on Feb 23, 2013 22:01:52 GMT -5
Don't forget getting a new coil and spark plug cord, spark plug, and fuel enricher.
They make all the difference in the world.
|
|
rkrau
Junior Dawg
Posts: 10
|
Post by rkrau on Feb 25, 2013 12:54:15 GMT -5
So I fired up the scooter this morning and went to work. Until about 2.5 miles from home, sitting at a light. Dead.
I'm going to take the fuel system apart and check / replace the gas lines going to the carb. Serenity now.
Gettin tired of this mess.
|
|
|
Post by ericrockstar on Feb 25, 2013 15:22:58 GMT -5
Damn. I am sorry to hear that. I wouldn't worry much about the fuel lines. Check the vacuum lines that go the petcock. And check the petcock that its working good and right. Can you see fuel going through the fuel filter. Kind looks like a little bubble. Maybe your spark plug wire came loose.
|
|
rkrau
Junior Dawg
Posts: 10
|
Post by rkrau on Feb 26, 2013 19:02:12 GMT -5
Since it's dark by the time I get home, I'll have to check this stuff over the weekend.
Adjusting the valves: (might be overdoing it with the "this might fix it" but I'm trying to cover all my bases) I bought a set of feeler gauges to check the clearance on the valves. .005mm for intake and exhaust is what seems to be the overall "this will work fine" gaping for the valves.
Checking the vac lines: I've seen propane used to check for vac. leaks by monitoring the engine rpm. I'll give this a shot.
Checking the Petcock: How does one do this?
Checking the fuel filter: F it. I'm just buying a new one.
I'll also check over the entire electrical system. I've ruled out the possibility of a bad ground after checking all the ground locations for rust / corrosion, but perhaps there's an exposed wire or a loose connector. That's killing it.
I filled the tank with 94 octane yesterday, so it's got fresh, clean gas. When I look in the tank (with a flashlight even), it's nice and clean.
When I took the carb off, I let some of the fuel from the tank flush through the lines, and it came through perfectly fine, clear, and copious.
I'll have updates come saturday.
What else could I be missing here?
|
|
rkrau
Junior Dawg
Posts: 10
|
Post by rkrau on Feb 26, 2013 19:24:34 GMT -5
Another point to note.
2008 Model. Purchased with 40Km on it. Currently at 130Km
|
|
rkrau
Junior Dawg
Posts: 10
|
Post by rkrau on Mar 2, 2013 20:19:41 GMT -5
STATUS UPDATE: This morning I drained the gas tank. The gallon "gallon +" I purchased from Autozone couldn't hold all the gas, so I used some plastic bottles. After they sat for a while I observed a non homogenous mixture!! Something else was in the gas. What was it? I don't know, I only used the first "gallon +" to refill the tank. Also purchased "sea foam fuel / engine treatment" 8oz. per gallon. $4.00, why not, I'll drink the kool-aid. Cleaned out the petcock with carb cleaner. Check out this new fuel filter. Far superior from the old one. Cleaned the jets and carb again. Cleaning out anywhere I could spray the carb cleaner. Reassembled, readjusted the throttle / idle speed. Idled for 45 minutes, revving here and there. Shortened the fuel and vac. lines to make a more streamlined, checked for binding and pinching throughout suspension travel. All good. Put in new 94 octane gas. And it all worked out. I took it for a 35 minute, around the block a bunch of times, different speeds, trying to simulate a commute to work. No issues. Went 6 miles out. Let it set for 2 hours, started up fine, rode home, no issues, everything was perfect actually. Perhaps it was bad gas, maybe the carb got dirty from the bad gas again, I don't know. I really don't. I thought back, and it was actually wet out every time the scooter started acting up and dying. I'm going to seal up all the electrical connections tomorrow, just to be sure. Thanks for all the help!
|
|