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Post by dakotafig on Sept 24, 2014 15:33:41 GMT -5
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Post by dakotafig on Aug 22, 2014 14:54:08 GMT -5
Ok, quick update. So, I put in a manual valve, and holy cow what difference that made. The thing went from running really pretty good to being rich as all get out. The high speed stutter still happened every once in a while, but it was drastically different then before. Not quite for sure how the fuel valve could make that much of a difference, but it appears like it was being more of a fuel regulator than a fuel valve. That also could explain why such a big jet was resulting in the scoot running really good, at least I guess.  At any rate, vacuum fuel valve in there, runs great, but at full throttle a stutter appears every now and then. With manual fuel valve, runs like crap, really really rich. Next step smaller jets and evaluate again. Anyone have any other thoughts? |
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Post by dakotafig on Aug 14, 2014 0:30:29 GMT -5
JerryScript, I'm planning on picking up (or rigging) a valve to test ASAP. I was hoping to hear an educated thought on my plug color before I ran down to the motorcycle shop in case I should pick up a different jet.
As for the pictures, I could totally see the flash being an issue now that I look back at them. My iphone took a ride through the wash machine and the camera doesn't work anymore. So, I rely on a guy at work to take the pictures and his phone camera isn't quite the same. I knew what I was looking at so I just saw what I knew I was looking at in the photos.
If the fuel valve is to blame, does anyone make an electronic shutoff valve? I don't know if I would want to rely on my memory.
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Post by dakotafig on Aug 12, 2014 13:06:49 GMT -5
Ok, I had went ahead and ordered a new one. It checked its gap and it is 0.025", a little tighter than the 0.027" the old one was. Below is a side by side picture of those. I hope I'm being taken in the correct context by everyone, I just want to understand everything, make sure I'm not missing anything, that would be the engineer in me.  I'm still trying to understand the spark plug color, and hopefully eventually the root of the occasional stutter at high throttle, and quick throttle deceleration. I'm going to go pick up a manual fuel shut off valve to test the theory of the fuel valve loosing enough vacuum to shut the fuel off. I will probably pick up some more main jets, but I don't know how far leaner to go based off the plug color. Thanks again everyone for your help.   |
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Post by dakotafig on Aug 11, 2014 16:55:38 GMT -5
Are you saying point as in like sharp needle tip or small flat tip? Here is a picture I found of the new which looks to me to be the same as mine. What about the color of the plug, how do you think that looks?  |
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Post by dakotafig on Aug 11, 2014 15:31:48 GMT -5
I guess I should be more specific. I didn't gap this plug, I used plastic feeler gauges to verify the gap, which is exactly 0.027" as I believe it should be. Why do you say the tip is broken off? This is exactly how it looked when I bought it.
What is your opinions on the color? To me it looks like a really good color, maybe one tiny black spot where I could drop my main size a bit, but it doesn't look overly rich. Am I not looking at this right?
Thanks,
Eric.
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Post by dakotafig on Aug 8, 2014 8:56:02 GMT -5
I understand air/fuel ratio and how that relates to engine performance. By no means am I an expert on carbs, that is for sure although I understand what and how they do what they do. I just hate tuning them.  I did pull the carb and I have a 125 main jet in there now. I would agree it is probably a touch large, but if I'm going to error I want to error on the side of rich. I ended up in this range by watching my plug. I just pulled it and this is what it looks like, which I don't think looks all that bad. Maybe I'm wrong. How do you guys thing this looks? Also, alleyoop what is the elevation where you live? Here in Kansas we are at 1800 feet. That makes a difference as well if you are at a much higher elevation. FYI my plug is an NGK CR7HIX. Thanks for everyone's input on this. I would agree it could possibly be tuned a bit better but I don't think that is related to my stuttering as it started doing that before I ever touched the stock 108 jet. As for the diaphragm, I had thought of that which is why I bought a different carb, but the issue persists so I don't believe that is it. I think I will run by the local motorcycle shop and pick up a slightly smaller jet and manual fuel valve and see what happens.  |
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Post by dakotafig on Aug 6, 2014 8:55:05 GMT -5
FYI, my valves are adjusted great and I am running a 125 main jet. That is your problem at WOT to fat, stock 150 about #115. Well, I had thought about that as a possibility, and it still could be hurting although if I go smaller it doesn't run as good. But, I had a 108 in there originally (as delivered from China) and it suddenly started doing the same thing even with the 108 main jet. I will try going smaller main and readjusting the carb to see what happens. One other thing I have noticed as a piece to this puzzle is if you are at mid throttle or so and quickly let it go, it will do the same stutter. It almost never stutter's going up a steep hill, and it just goes crazy stuttering if you do wide open throttle down a hill. After I think about it, I might have dropped down to a 120 main jet........ Man, old man memory has taken over....... I'll take it apart to verify and I'll look at my plug again for good measure..... |
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Post by dakotafig on Aug 5, 2014 8:58:51 GMT -5
I am using an uni filter, and it is brand new. I had a K/N style on there earlier but it did the same thing as it did with the stock muffler.
I thought about the diaphragm, but I have had two different carbs on. I do have REALLY bad rattling muffler syndrome. I have another muffler but haven't tried that yet because I have to get a flange cut to weld on the replacement muffler I have. I guess that brings up a good point I haven't thought of, when I first start it and go, it takes a little bit for this issue to start. Once it starts though it is non stop. Maybe like something gets hot and loose in the muffler?
FYI, my valves are adjusted great and I am running a 125 main jet.
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Post by dakotafig on Aug 4, 2014 17:11:02 GMT -5
I have been following a couple of other threads, but none of them seem to turn out like mine. Probably over a year ago one day my scoot started to stutter ever 10 - 15 seconds at full throttle. It would stutter for a split second and then runs fine, then stutters for a split second and then is fine, and so on.
I have tried running with the gas cap open, I have replaced the carb, replaced the intake manifold, replaced all the vacuum tubing as well as the fuel filter. Fuel wise the only thing I haven't replaced is the fuel valve. It is adjusted where it runs fantastic, just not if you run at full throttle for more than a minute or so, then this starts.
I have never adjusted the float in the carb, but that doesn't seem to be a big issue. If I had to take a seat of the pants shot at it, it seems like it looses vacuum and the diaphragm drops momentarily, and then it recovers and runs fine for another period of time until that happens again.
Is it possible to just "run out of vacuum" at wide open throttle after a while? The strange thing is it used to run great and then suddenly this started.
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Post by dakotafig on Jul 29, 2014 13:07:06 GMT -5
On the stock muffler there is a three bolt flange. Does anyone know the dimensions of that flange?
Mine is my daily driver and it doesn't ever go home (ride in with the wife and ride the scoot between offices) so I was just trying to minimize by downtime of needing to trailer it home to take it apart to get the dimensions. I have a good muffler that I can put on it and I was thinking of having a triangular flange made that I would weld to the new muffler and make it match the stock 3 bolt muffler flange.
Thanks,
Eric.
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Post by dakotafig on Jul 29, 2014 12:46:15 GMT -5
I have had the same sort of thing for a long time on my 150, although my cutout isn't that bad, it is just a momentary stall and then it is back up and going for another 30 - 45 seconds until it until it does the momentary stall again. All of this only happens at full throttle. I have gone through the same items, running without the gas cap, adjusted carb, changed carbs ect.
Never once have I adjusted the float level in the carb though, didn't really think of that. Is there a proper method to do that, does running out of fuel seem like the logical answer to this sort of stall?
Mine is a gravity feed system so I have a fuel valve and not a fuel pump, but otherwise same sort of momentary stall.
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CDI Box
by: dakotafig - Mar 11, 2014 23:44:03 GMT -5
via mobile
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Post by dakotafig on Mar 11, 2014 23:44:03 GMT -5
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Post by dakotafig on Mar 10, 2014 10:50:09 GMT -5
On the other side of this, you never know what you will get in a replacement carb. There is always a possibility of something not being right, some wacky jet etc. You could always just start and ride it once every couple of weeks and then no need for the "deep cleaning". Just break out the VERY heavy jacket.  |
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Post by dakotafig on Mar 10, 2014 10:08:19 GMT -5
Guess I should have read the original post a little better, didn't realize the engine was in pieces. Did you put the engine together? I realize this is a dumb question and I don't mean to insult so don't take it that way, but are you positive the timing was correct to start with?
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