March 15th, 2010, 03:58 PM | #1 |
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Bogging on start
Hi guys, couple of questions I hope you all can help me with.
Problem: When starting the bike, the bike has trouble starting. There are times when I have to hold the starter for 4 to 6 (or so) seconds before she would start. Sometimes, holding it down for that long still won't start the bike. Setting the choke to different distances sometimes helps but sometimes actually kills the bike. When I move the choke all the way to fully open, it's actually acting in reverse of what I expect. That is, the bike drops below idle. Background: I just installed a Dynojet Stage 2 Jet Kit and an Area P standard exhaust. The jet kit called for the idle mixture screws to be set to three turns. When I adjusted the screws, I noticed from the factory that they were set unevenly, that is, one screw was set further in, while the other was out more. After adjusting, they are currenlty both set to three turns. Question: Is this a problem with my idle mixture screws set to too rich? Should I back them up? Or is this a case of carb syncing (I have yet to do that). I will attempt Vex's DIY in regards to adjusting the screws but wanted to check first to see if it's something else. |
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March 15th, 2010, 04:01 PM | #2 |
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The factory sets the idle mixes differentially, just as the stock needles are not identical. Once you've rejetted they should be the same on both sides.
I'd try rolling the idle mix screws in a turn; 3 turns out is pretty severe for a 'base' setting (usually it's suggested to step up to the next size pilot jet if you have to go that far for a happy engine). The info I usually use/see says start with 2 turns out from closed and back 'em out (towards 3 turns) a little at a time (I usually use 1/6 turn increments) from there until you hit the sweet spot.
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March 15th, 2010, 04:03 PM | #3 |
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Can you get the bike to run long enough to fully warm up? If so, what is your idle set to at that point?
To adjust the mixture screws I used this alternate method... http://faq.ninja250.org/wiki/How_do_...dle_mixture%3F |
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March 15th, 2010, 04:24 PM | #4 | |
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P.S. The bike idles fine at around 1300 or so when fully warmed. |
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March 15th, 2010, 04:43 PM | #5 |
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you need to tune both carbs so they pass almost the same mixture. At that point, the carbs work together. Any difference between the 2 results in a less than mixture that the engine needs. use the links provided to "tune" the circuits... I wouldn't worry that they are not exactly the same amount of turns out, only that the settings give you the desired results.
Don't forget to sync the carbs too. |
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March 15th, 2010, 04:49 PM | #6 | |
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Also, with Vex's carb sync tool, do you think any "oil" will work? Rather than throw it, I have a few unopened motor oil that I can use. |
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March 15th, 2010, 04:57 PM | #7 |
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Don't know the "why" behind tuning both independently to work together, only know that it works.
You do one carb, get the results you're looking for, then do the other. Worked for me. Any liquid will work for the sync tool, though the higher the viscosity, the shorter the tubing needs to be. Try the oil you have... the worst that can happen is that you'll suck motor oil into the engine if the carbs are way out of sync. |
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March 15th, 2010, 05:18 PM | #8 | |
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March 15th, 2010, 05:27 PM | #9 |
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March 15th, 2010, 05:33 PM | #10 |
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Oh one more thing... maybe a stupid question. The bike does not have to be level when doing the carb syncing and idle mixture tuning, right?
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March 15th, 2010, 06:06 PM | #11 |
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Heh, fair enough. I usually go with the blipping method, if only because it's more fun imo
I usually tune on a rearstand, but I don't think it matters much. Just so long as you don't use slider pucks as stands and lay it over for tuning. However you do want your carb syncher level.
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March 17th, 2010, 05:27 AM | #12 | ||
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Quote:
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March 17th, 2010, 05:32 PM | #13 |
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I have a bike I bought with this same jet/exhaust setup, and have the same "problem". Is there a risk of hurting something trying the starter for this long? I've never been able to /not/ get the bike started though, sometimes it just takes a few tries. I was under the impression that all of these bikes are a bit touchy starting up cold...?
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