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Post by styxfan on Apr 5, 2012 11:51:26 GMT -5
Need some (more) help here.
Long story short, there appears to be NO air/gas adjustment screw on my carb so it can not be adjusted.
My scoot, will start, but unless I keep giving it throttle, until it warms up (about 5-10 mins) it will stall. Once it's warmed up, it runs great.
Valves are good, so no adjustment needed there. It has 1300 miles on it.
Can anyone recommend a good replacement carburator?
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Post by styxfan on Apr 5, 2012 14:28:12 GMT -5
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Post by richardthescooter1 on Apr 5, 2012 14:50:30 GMT -5
I know some carbs are like that  but some carbs have a brass plate or cap over the a/f mix screw, sometimes hard to find, post some pictures, if your scoot is a 2008 mc-54-250b, I have the same scoot and my carb has a m/f mix screw. You could have a bad enricher. When was the last valve adjustment? |
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Post by skuttadawg on Apr 5, 2012 16:45:40 GMT -5
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Post by beachbum on Apr 5, 2012 16:58:41 GMT -5
Sounds like your enricher is not the working or the gas port in there is clogged.
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Post by wile on Apr 5, 2012 17:21:00 GMT -5
Here is your Fuel Ratio mixture screw, it is hard to get to. A lot of folks will just loosen the clamps and rotate it just enough to get a screwdriver on the screw make a 1/4 or so adjustment Richen or Lean then rotate it back and tighten up the Clamps and give it a shot. Wile  |
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Post by styxfan on Apr 10, 2012 8:30:00 GMT -5
Was finally able to locate the F/A mixture screw, however, no mater how much it was turned, there was NO CHANGE. I'm starting to guess it would be a good idea to replace the carb.
Has anyone ever used Keihin Carbs? Are the any good/reliable?
Looks like the Keihin N090-015 is the replacement for my scoot. Is anyone familiar with that carb and can offer some feedback?
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Post by richardthescooter1 on Apr 10, 2012 9:53:04 GMT -5
That is a good carb, but let me ask you, when adjusting a/f mix screw, which way was you turning, how many turns out or how many turns in? Are you lean or rich?
On home page: scroll down to: ScootDawg's How to and Information Database (click on this) then it will take you to another page (click on A/f mix adjustment) Worth looking at.
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Post by nulldevice on Apr 10, 2012 10:25:55 GMT -5
As far as I know they don't get any better for unmodified engines and have been used by many manufacturers on a bunch of models in various sizes, for several decades that I am aware of.
I would suggest you do a carb inspection and cleaning to see if there is either some dirt in the carb or if the idle mixture screw tip is broken off.
If you don't want to do the cleaning yourself, don't pay a shop to do it. They can be had for $50 new.
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Post by styxfan on Apr 10, 2012 10:48:51 GMT -5
At present, it is a tad lean as it will stall until warmed up. It will no longer stall after I've driven it for about 5 mins. or so.
Average daily temp here has been mid 40's to high 50s so it's possible it prefers warmer weather.
When trying to adjust the mixture, tried turning as much as 3 turns and tried both directions.
no change no matter what.
My understanding is the Chinese POS carb that came on the scoot isn't very reliable, so replacing it, it's a terrible idea as long as it's with a good replacement.
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Post by wile on Apr 10, 2012 11:06:01 GMT -5
From what you say is happening stalls or bogs until it is warmed up about 5 minutes. That is when your ENRICHER cuts off the EXTRA FUEL, so that tells me it is running RICH NOT LEAN. Right now your getting fuel fed from the ENRICHER and the PILOT JET and since the temp is warmer it is to much fuel.
You need to turn the A/F screw Clockwise to Lean it out, It may take a Full Turn don't know how much it is currently open.
That will happen with any CARB, you can buy a 500.00 carb and have the same problem.
Unless the mixture is computerized it is a MANUAL adjustment.
Wile
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Post by styxfan on Apr 10, 2012 11:22:26 GMT -5
It does NOT get enough fuel (on it's own) for about the first 5 mins. It will stall, unless I give it some throttle when stopped.
After about 5 mins, she purrs like a kitten and runs great. No loss in power at higher speeds (that I've noticed) or anything.
Doesn't running "lean" mean there's too much air and not enough fuel? It would seem it doesn't get enough fuel until it is warmed up.
No matter how much the mixture screw is turned on the current carb, there is no change.
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Post by wile on Apr 10, 2012 11:53:28 GMT -5
Ok, misunderstood how it acts up when cold. It could just be the ENRICHER is not working and is NOT feeding fuel when cold if you have to keep on gooseing it until it gets warm. You can pull the enricher off and look at it. If the Enricher is EXTENDED when cold that is the problem. Wile Here are two pictures of the enricher: 1. If you pull it out and it is RETRACTED it should be feeding it fuel when cold and its good.  2. If you pull it off and it is EXTENDED that is your problem it is NOT working:  |
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Post by styxfan on Apr 10, 2012 13:06:42 GMT -5
Thanks Wile, I'll check that out. I didn't ride it today (too friggin cold and windy here) so I can check that when I get home. If it's extended then I guess I'll need to replace the enricher.
Where is the enricher located?
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Post by styxfan on Apr 10, 2012 13:19:02 GMT -5
Oh Duh. Enricher = Electric Choke, right. Located right on top of the carb.
Sorry, I have a bad cold today.
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Post by styxfan on Apr 10, 2012 16:21:06 GMT -5
How do you remove the enricher, just pull off or is it threaded and you have to twist it off?
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Post by richardthescooter1 on Apr 10, 2012 16:33:59 GMT -5
There is two little screws holding it in place at the base, u shape clip. be careful you don't loose any srews  if the clip is in front you may only have to take one screw out, lose both, but take one out, then you can swing clip to on side, the you can pull it out. |
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Post by styxfan on Apr 11, 2012 13:36:45 GMT -5
I pulled the enricher and it doesn't appear to be extended, so I would guess that it is OK. Attachments:
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Post by styxfan on Apr 11, 2012 14:11:52 GMT -5
Looks to be about 15/16" long. Attachments:
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Post by styxfan on Apr 12, 2012 11:13:53 GMT -5
OK, Valves do not need an adjustment and it's NOT the enricher, it takes me back to the carb.
Does anyone have experience with the Keihin N090-015 replacement carb?
Are they reliable?
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Post by oldsjet on Apr 12, 2012 22:26:59 GMT -5
Dude, why are you so against taking the carb apart and giving it a clean? Cost will be less than $2. Heck of alot cheaper than a new one, plus you would have to pull the old one anyway to put the new carb on.(if labor is the issue)
My money is on that a good clean would fix it.
You said that you have turned the air screw in and out and that neither made a difference. Did you turn in untill it seated? If not, do so and see what happens. I think the general setting for this is 2.5 turns out from Lightly seated. With this screw seated the engine should not idle at all, warm or cold.
Also, I think I remem you were trying to get the idle set. Am I remembering right? Its possible to get the idle high enough that you are above the rpms at which the air screw does anything. Just saying. If your idle is around 2k then youre ok on that front.
One more thing you might try is pulling the screw completely out, stick the straw from a can of carb cleaner in the hole and give it a few blasts, then if you have it, follow that up with a few short blasts of compressed air. Dont get carried away with either, just a couple short blasts.
If this 'quicky clean' makes a diff or clears up the prob even a little, then youve found the issue.
OR, just skip all that crap and clean it properly to begin with.
The worst that can happen is that youll gain some carb cleaning experience!
Brian
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Post by pizzot on Apr 12, 2012 23:10:21 GMT -5
Have you tried tightening the Idle Adjustment screw? Super easy to increase idle speed so that you don't have to stay on throttle until it warms up. My brand new carb had same symptoms, just tightened Idle Adjustment screw, purrs like a sweet sweet kitten now.
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Post by wile on Apr 12, 2012 23:48:39 GMT -5
250 like to idlea little higher than your 150s, the 250s like to idle 1800-2000 rpms. Now it when you start it is idleing lower than that you need to TURN THE IDLE SPEED screw Clockwise to RAISE the idle. Remember when you twist the throttle a little so it does not die the IDLE SPEED SCREW is doing the same thing. What The throttle and IDLE SPEED screw is doing is OPENING THE BUTTERFLY sameo sameo. So try raiseing your IDLE a little.
Wile
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Post by styxfan on May 31, 2012 14:04:07 GMT -5
Wow, I can't believe I've been dealing with the carb issue for three months now.
Anyway, The choice was made to just replace the carb instead of cleaning it or messing with it any more (sorry oldsjet, but dude, that's just how I roll, lol)
I do have a mechanic that will do it for me, but it seems straight forward enough so I think I'll give it a shot (and I'll learn more about the iner workings of my scoot) myself. Besides, if I screw it up I can always to my mechanic to fix my errors.
Does anyone have pics or a vid available of a carb replacement?
I'll also replace all the rubber tubing since I'm in there, is there a type that is recommened?
I look forward to everyone's helpful advice, hopefully I can get to it this weekend.
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but some carbs have a brass plate or cap over the a/f mix screw, sometimes hard to find, post some pictures, if your scoot is a 2008 mc-54-250b, I have the same scoot and my carb has a m/f mix screw. You could have a bad enricher. When was the last valve adjustment?
if the clip is in front you may only have to take one screw out, lose both, but take one out, then you can swing clip to on side, the you can pull it out.
