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Post by jetjock79 on Nov 7, 2013 12:17:46 GMT -6
Roketa 250cc with 257cc motor. After getting her valves adjusted....she ran ok for about a day, but since I was moving....hadn't run her in about two weeks. Before the move.....I tried starting her up a few times, but it sure took a while to get her going. Then after the enrichner cut off.....anytime I gave it gas,....she would die. Thought this may be an issue with clogged jet, so I took out the carb and gave everything a thorough cleaning!! Put her back in this morning, and the same thing happened.....tough to get her started, and the minute the enrich near cuts off, she can't stay running. Tried the mixture screw,....and even tried to get her to idle high again, but no go. Could this just be a bad carb? Or a CDI issue? Starting from cold, she needs a little throttle and help to get started, then runs until the enrich near cuts off. Giving gas after that,....she just bogs down. Mixture screw is at 2 1/2 turns out. Had it to four, and then to 2...... Same thing. What is going on?
I called the guy who did the valves, he isn't a scam artist, and he said to buy a new carb. If she was running ok when I got her after the valve adjustment, what could have changed? Thanks all!!
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Post by JR on Nov 7, 2013 13:59:43 GMT -6
Actually that's not bad advice, carbs are cheap for this scooter. 2-1/2 turns is correct and it'll only bog as far as a carb issue if one of three things are present:
Bad diaphragm with hole or tear in it.
High speed jet partially clogged
Very dirty air filter cutting off air flow
Now on the carb cleaning did you make sure every little orffice hole in the jet was open and clean? Same on idle speed jet?
My experience with the CDI is this, it either runs or doesn't but they have been known to heat up and go out temporarily but when this happens the scooter will not start again until it does cool off.
JR
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Post by richardthescooter3 on Nov 7, 2013 14:41:26 GMT -6
If you remember JR the trouble I had with my scooter, shutting off and dying  You could crank til dooms day and it just didn't want to go. Turned out to be Two things, 1. a bad fuel pump and the air filter was on the wrong side of the metal screen getting sucked into my carb  fix those two items she runs great (no more problems) |
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Post by alleyoop on Nov 7, 2013 15:22:42 GMT -6
I think the FIRST thing to do is RE-CHECK the valve adjustments. He may not have tighten the lock nut good enough and the adjustment has moved. Also if he adjusted them to tight one of the valves may be staying open a little. When you do get it started can you hear the valves little TICKY TICKY or CLATTER CLATTER or NOTHING? If it is NOT the Valves then it is OBVIOUS that the Pilot Jet passage is clogged and the only one that is feeding fuel is the ENRICHER. If turning the FUEL RATIO mixture screw in EITHER direction DOES NOT EFFECT the way the motor IDLES higher or lower the PILOT JET and OR its PASSAGE are clogged. TO VERIFY turn the fuel ratio mixture in both directions and if it does NOT change the IDLE that is the problem. But I really do not believe you need a new carb they are very simple and not much can go wrong with them if you clean out the JETS and PASSAGES. Many just clean out the JETS BUT DO NOT clean out the PASSAGES. Especially the PILOT JET PASSAGE that gas gets sucked out of right by the BUTTERFLY. The PILOT JET outlets are TINY and can get clogged if you do not have a good FUEL FILTER on that may allow very small particles to get by. Everybody the first they say is get a new carb, when they are so simple in operation and only a few things can go bad on them and the parts that go bad can be replaced to boot. Alleyoop  Here is the carb that is probably on your motor:   |
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Post by jetjock79 on Nov 7, 2013 19:23:30 GMT -6
I totally cleaned this carb. Sprayed carb cleaner like crazy through the pilot jet passage until I saw it spraying through those holes. Had to put my finger over the mixture screw hole (had the screw removed). I have to tell you....I truly believe this thing is cleaned...but how strange that I did have it running enough to make it to the third floor of the parking garage, and now...nothing! Fuel filter is crazy clean, everything is doing ok. Can't believe how this thing is acting up.
I must say that since the valve adjustment, it does seem to have a difficult time cranking over the first compression cycle on the cylinder. Even draws enough juice that the lights dim to almost off before cranking over fine.
A carb seems to be way expensive if it isn't the cause. $180 for a "possible" resolution is a little steep.
Thanks all for the advice....valve adjustment guy is going to call me tomorrow to discuss possible resolution.
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Post by jetjock79 on Nov 7, 2013 19:25:53 GMT -6
I know she is getting enough fuel.....carb bowl always full. Not a pump issue
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Post by JR on Nov 7, 2013 19:59:31 GMT -6
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Post by alleyoop on Nov 7, 2013 20:24:45 GMT -6
I totally cleaned this carb. Sprayed carb cleaner like crazy through the pilot jet passage until I saw it spraying through those holes. Had to put my finger over the mixture screw hole (had the screw removed). I have to tell you....I truly believe this thing is cleaned...but how strange that I did have it running enough to make it to the third floor of the parking garage, and now...nothing! Fuel filter is crazy clean, everything is doing ok. Can't believe how this thing is acting up. I must say that since the valve adjustment, it does seem to have a difficult time cranking over the first compression cycle on the cylinder. Even draws enough juice that the lights dim to almost off before cranking over fine. A carb seems to be way expensive if it isn't the cause. $180 for a "possible" resolution is a little steep. Thanks all for the advice....valve adjustment guy is going to call me tomorrow to discuss possible resolution. Just because fuel is getting into the carb bowl does not mean it is being sucked out into the intake. To Verify crank it and then take the plug out and see if it is WET OR DRY. Yep, I would FIRST re-check the valves especially the EXHAUST valve. You did not say anything about when it does start do you hear any TICKY TICKY or CLATTER CLATTER or NOTHING from the valves. ASK your valve guy what gap did he use to set the valves. He may not know scooter motors and is a car mechanic. Alleyoop |
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Post by fflintstone on Nov 8, 2013 11:08:54 GMT -6
Yup ,it sounds like the valves may not be right--and another thing,the timing marks must be lined up correctly so you can adjust accurately,some mechanics are not aware of the places to find the timing marks to make an accurate adjustment--found this out myself when I bought a used 2008 Roketa MC 250 B from a mechanic--he adjusted the valves and left the intake so loose it went tikky tikky ,sounded like a woodpecker on a tin can--well,not that loud,but it was a mistake some mechanics might make ,not that they are incompetent but not used to scooter motors---we have a tutorial on that in the info section..alleyoop and JR have plenty of info on valve adjustments on this forum--good luck,fflintstone
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Post by richardthescooter3 on Nov 8, 2013 14:59:10 GMT -6
 Here is one of the marks to line up. |
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Post by richardthescooter3 on Nov 8, 2013 15:04:39 GMT -6
 Here is the other one. |
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Post by jetjock79 on Nov 10, 2013 9:44:12 GMT -6
Thanks for all the help guys. I rearranged the plumbing on this thing with vacuum and all. I saw a picture of someone's carb on here, and it turns out mine was done right. She runs fine now though. She doesn't rev up almost at all when cold, the time the enricher should be working, but runs just fine and starts with remote start. The guy who worked on it has a dealership, but mostly does work on 150cc's.
I'm going to take her on a little run tomorrow to see if everything is ok. I'm really looking for some diagrams to see where where the vacuum lines go. Mostly;
-where does the fuel pump connect to (where it receives the vacuum from)
- all vacuum tubes to the carb
There is also something I haven't seen before on these engines, and feel this may just be some sort of emissions thing.....buts it's bolted on to the case next to the rear wheel. Looks like some sort of valve or something that could be controlled via vacuum, but no idea. Can't seem to find it on any engine diagram either. Thanks all!
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Post by JR on Nov 10, 2013 12:07:36 GMT -6
The canister at the back is the carbon canister for the vapor recovery on the scooter, unless it has a broke vacuum line leave it alone. Just in case because your mechanic works mainly on 150's
.thescooterprofessor.proboards.com/thread/44/250-linhai-valve-adjustment-tutorial" rel="nofollow" target="_blank"> .thescooterprofessor.proboards.com/thread/44/250-linhai-valve-adjustment-tutorial
Step by step with pictures, the exhaust valve is critical.
Now on the vacuum lines the fuel pump gets it's vacuum from a hose in these pictures:
Hose number 5 off the Y connector goes straight down to the fuel pump.
Another view:
As you can see the Y connector is fed from one of the two vacuum ports on the intake manifold. Me I go get a new hose long enough to go from the fuel pump to the brass port that the Y connector is on and run a single by itself line to the fuel pump off of that top port.
Then I take the Y connector and put it on the other port to hook the rest of the things that need vacuum up. I like all the vacuum I can get to the fuel pump.
JR |
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..BAD TO THE BONE..
