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Post by JerryScript on Mar 26, 2015 13:26:01 GMT -5
It's an often overlooked part of carb tuning. Many issues people call bogging and think are related to their a/f screw adjustment are in fact related to the change in vacuum when the throttle is turned more opening up the butterfly and momentarily decreasing the vacuum. For the beginning of the throttle range, that is a tuned via the accelerator pump. If the condition exists later in the throttle range, it is addressed by the needle, either clip height or taper.
You want quick response to quick twist of the throttle, both up and down in rpms from idle to 3k.
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Post by JerryScript on Mar 26, 2015 1:13:12 GMT -5
I personally would order a new one. A good weld can be as strong or stronger than the original piece, but a single bubble inside can make it weak.
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Post by JerryScript on Mar 26, 2015 0:43:02 GMT -5
Bending it more will give more fuel sooner via the accelerator pump, less bend will give the fuel later, and a lot less bend will make the amount of fuel delivered less. Here is a good explanation of how an accelerator pump works: www.thumpertalk.com/wiki/_/tuning-the-keihin-accelerator-pump-r173What I am referring to as the spring is a thin piece of metal in a curved "C" shape on the throttle linkage side. When you twist the throttle, and the linkage gets turned, this "spring" gets pushed against the accelerator pump actuator, which compresses a diaphragm inside. This squirts a bit of extra fuel needed when the butterfly first opens, since the vacuum instantly drops for a moment when the opening enlarges, meaning less fuel is drawn through the jets for a moment. |
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Post by JerryScript on Mar 25, 2015 21:36:33 GMT -5
The final paragraph is troubling, this man seems to think it is appropriate for your employment to be put in jeopardy due to owning a motorcycle!
'The MSNBC correspondent concluded the interview by asking Cornia, “aside from potential profiling from law enforcement, are there potentially any additional consequences of being on this gang list?” Cornia responded by saying, “the purpose of the list is to collect and utilize data, not to create consequences. Aside from notifying law enforcement that you are a registered motorcycle owner or operator, it can show up to potential employers on select background checks."'
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Post by JerryScript on Mar 25, 2015 17:57:27 GMT -5
Went to pick up my niece after school today, and wouldn't you know it, we missed the turn home! Had to take a long detour around the golf courses and man made lakes, and of course a stop at the ice cream shop. Guess I should get GPS so I don't miss those turns and get home on time, but I just don't think it's in the budget!  |
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Post by JerryScript on Mar 25, 2015 17:53:51 GMT -5
If your idle drops, it means you are rich. Perhaps your setup would be best with a 92 main. I'm not convinced your idle jet is the wrong size.
What happens at cruising speed if you let off the throttle 1/8 turn and hold it there? If it speeds up you are lean, if it settles down you are rich.
The bogging at 1/4-1/2 throttle could be your accelerator pump is either to rich or too lean, I would first try increasing the bend in the spring, then go way the other way decreasing the bend, testing after each change to determine which way you need to fine tune it.
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Post by JerryScript on Mar 25, 2015 2:58:22 GMT -5
Definitely Kindred Spirits when it comes to days like these! Always enjoy reading your stories Leo!
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Post by JerryScript on Mar 25, 2015 2:53:46 GMT -5
I doubt if you can find anything currently off-the-shelf to do this, but there is some interesting development going on with laser ignition replacing spark plugs. The lasers are tuned to the combustion point, without being powerful enough to damage any internals. Since the laser shoots through the chamber, the combustion occurs throughout instead of beginning at the point of spark plug ignition. In theory, this should give a more complete burn, resulting in both more power and more fuel efficiency at the same time (rare).
The key here is finding lasers that can handle the temperatures, that's why off-the-shelf components will not do.
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Post by JerryScript on Mar 25, 2015 2:37:43 GMT -5
I was a 52D in the US Army 30 years ago, power generator mechanic. I had not worked professionally on small engines in the 30 years since I got out of the Army. It took me 3 hours to do what should be a 1 hour job because I was unfamiliar with the engine, and took my time making sure I didn't make any mistakes (I still left a guide dowel off, had to pull the jug and re-seat the piston thanks to that oversight).
There are several good videos on how to install a BBK on a gy6 on YouTube. Watch a few of them, then watch the one that makes the most sense a couple more times. Keep your phone nearby when you start the change out, with the video you choose loaded up for reference, and you'll be fine.
The one piece of advice I'll give you without asking for it is to pull the engine. Depending on the scooter body style, you may or may not have enough room to do the swap while still mounted to the scooter, but pulling it will make things soooooo much easier!
Ask as many questions here as you like, everyone here is happy to help out!
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Post by JerryScript on Mar 23, 2015 21:29:37 GMT -5
You can try writing to Nuvinci stating you are developing a new scooter, and would like to purchase one of their developer's kits, or at least one of the hubs you would like to experiment with. The key is brevity, those developing new things do not give tons of details, only enough to get what they want. Use the KISS rule.
I did similar when I needed a glass actuator with almost zero friction for a stirling engine design I've been working on for years. The manufacturer ended up sending me one for free, hoping my design would be a success and lead to large orders in the future. All I told them was I was working on a design project that required a part similar to the one they carry, if I recall it was one paragraph with no details beyond what I required.
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Post by JerryScript on Mar 23, 2015 21:25:06 GMT -5
No way of knowing now, but I would bet a small sum that if you had an advancing angle cdi, your starter clutch might not have been messed up.
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Post by JerryScript on Mar 23, 2015 20:28:59 GMT -5
Don't change the weights until you have done the BBK. You won't know what you need with the extra displacement, and you could end up ordering sets of weights that you don't need. Also, stay away from the racing CDIs, instead order one of tvnacman's advancing angle CDIs, it will help prevent kickback on that BBK during start up. |
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Post by JerryScript on Mar 23, 2015 20:24:14 GMT -5
The suggestion for penetrating oil and a rubber mallet was when I thought the piston was stuck in the jug. Looks like we all should re-read before posting, would save a lot of confusing posts.
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Post by JerryScript on Mar 23, 2015 20:19:47 GMT -5
Wow , if its really a 75 , I hope I wasn't running too lean too long . you may have a bigger issue . maybe someone drilled the 75 out to a bigger size ? At this point the best thing to do is order a new set of stock jets for the carb . You guys hit it right on the nose. I threw a 105 and a different idle jet in there and it did the trick. Now I just have to dial in the idle. Can somebody link me to "Alley's" A/F mixture guide? I've seen it before but I can't seem to find it now. The exhaust is really dirty on idle and rpms are low. But the good news is that it no longer bogs out after the clutch engages. Thank you guys so much! Here you go: itistheride.boards.net/thread/12/4ts-carb-tuning?page=1 |
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Post by JerryScript on Mar 23, 2015 1:46:13 GMT -5
I've never heard anyone say anything other than to change the oil immediately during your PDI. It only takes 5 minutes, and there's no reason to take a chance IMHO. I personally change engine oil, gear oil, fork oil, and brake fluid during PDI.
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