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Post by rcq92130 on Nov 3, 2014 20:26:32 GMT -5
THANKS, geh! All back together and running with new jug, piston, head. Will start to break it in tomorrow.
Where ya been ?
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Post by rcq92130 on Nov 3, 2014 19:43:56 GMT -5
OK, about placement of the pump I wired my new (small psi) pump up to see how high it could be and still suck up the gas from the underfloor gas tank. There was no problem with the pump ABOVE the carb level. That said, I ended up deciding to ,locate it down where the tank is - just to make sure it has not effort gobbling gas. Here are a few pix showing the pump clamped to the kickstand cross bar. Note - I took a 1 inch piece of radiator hose (rubber) to make sure neither the pump nor the clamp touched the cross bar. That's just so the clicking of the pump is not transmitted through the frame of the scooter. At first the pump is quite loud, but the instant it gets it's first gulp of gas it gets quite quiet. Maybe the rubber isn't really needed ----    I know you said you didn't want to hear about wiring, but a few more cents. You want the pump "on" when the key is on, and "off" when the key is off. So, you want to go to a wire in the front that gets +12 volts when the key is "on". It MAY be fine to simply splice into this wire, run a new wire back to the pump, and run the pump directly off this ignition wire --- but it's not great practice. All standard electric pumps use a relay --- the wire from your ignition key ONLY causes the relay to close (very, very low current used), and the OTHER pins of the relay go (a) to the battery and (b) to the pump ---- so when the relay closes the pump draws right from the battery, not from the ignition switch. These pumps are pretty modest in the current they draw --- probably about 1 amp --- so maybe it would not overload the ignition switch even if you just ran pump current directly from the switch. But it's not a great idea; relays are cheap; just a good thing to do. I think it was "scooter" (the guy who posted the great stuff about vac. pump psi) who mentioned having a separate switch that automatically closes whenever there is engine vacuum (as soon as you start the engine the switch closes; when the engine stops the switch opens), so you don't accidentally turn leave the key "on", with the pump running, and walk away - draining the battery. My experience is the pump makes just enough sound (with the engine off) you will hear if it's still running - kind of a buzzer to let you know you left your key in the switch and the switch "on". But it's certainty easy to add a switch in the wire running from the ignition key back to the relay. Just FYI: I don't have one.  |
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Post by rcq92130 on Nov 3, 2014 19:36:09 GMT -5
Hi Mr. Martin!
1. About pressure regulation: The VOLUME (gal/hr) of gas the pump can spit out is a non-issue, as long as it is enough. I think for our little mouse fart engines there isn't a pump made that "isn't enough".
You asked about the PRESSURE in psi (completely different than volume in (gal/hr). Again, i don't think you will find a pump that provides too LOW a pressure - but your question about "too HIGH" is legitimate!
"Scooter" did some pressure measurements on his vacuum (OEM) pump and found the psi to be from 1.5psi to 4psi. So, anything in that range is fine since it simply duplicates what the OEM vacuum pump provides. Keep in mind: the vacuum and the electric pumps work the exact same way: a diaphragm is pulled back against a spring, compressing the spring; at some point the "pulling force" is released and the spring forces the diaphragm back down, pushing fuel through a 1-way valve. The only difference is the vacuum pump uses engine vacuum to pull the diaphragm back while the electric pump uses a small motor or electromagnet. The engine can't tell what is inside the pump pulling the diaphragm back. However, the vacuum pump's psi drops off as engine RPM increases, while the electric pump is constant at all engine speeds (a plus).
If you have an electric pump that puts out, say, 8psi you might want to use a regulator to drop what the carb's needle valve actually sees back down to about 4psi.
The carburetor does NOT regulate pressure - only volume. The gas flows through a needle valve into the carb bowl. The "height" (level) of the little pool of gas in the bowl is important to getting the right amount sucked into the engine, so there is a method the carb uses - involving floats (that float on the gas pool) - to keep the level of gas in the bowl at the right height. If the level is too low the floats, of course, drop down to where the gas is. This opens the needle valve, letting more gas into the bowl. When enough gas is in so the level is up to the correct height, the floats - haven risen up with the gas - push the needle valve into it's "seat", shutting of the flow of fuel into the bowl. This all goes on continuously as gas is used and needed. SO~~~~ the PRESSURE going into the carb isn't important (assuming it's "enough" - say, 1psi) AS LONG AS IT IS NOT SO HIGH IT OVERWHELMS THE NEEDLE VALE AND FORCES GAS IN WHETHER MORE GAS IS NEEDED OR NOT. 8psi "might" be a problem; 4psi is not.
OK - since this got so long I'll do another comment with some pix.
Hope this is helpful and not just boring.
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Post by rcq92130 on Nov 3, 2014 16:47:31 GMT -5
That last one might be of use...thanks! I never really thought we could put the taida stuff on our engines. But I guys as long as it's 54mm spacing it all should fit. Edit: The reason I want to avoid boring my case is down time. I don't have a car so it sucks to have to get a ride for a week wile I'm waiting on the boring to be done. Wile if I had an already bored out case as part of a kit, I can just reassemble it almost as fast as I tore it apart. See what "Scooter" just posted. I think Scrappy has something like it also. Pricey, especially given you only use it once ... But use it, slap it on EBay, get most of your money back and move it on to the next guy. A thought, anyway. |
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Post by rcq92130 on Nov 3, 2014 13:49:40 GMT -5
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Post by rcq92130 on Nov 3, 2014 0:54:49 GMT -5
Hi Shannen
If you strip down the case .... the step of enlarging the hole (boring it out) is trivial. ScootDwgs even sells a do-it-yourself tool. Just my opinion - but don't think that should even be a consideration presuming you have the thing stripped (and thus ready to be bored). And - just my opinion ..... but why buy a new case (with an already bored out hole) when you have a perfectly good case the simply needs it's hole a bit larger?
ps: the gaskets for this a really, really cheap --- but I had to get a full gasket kit (just to get a 60mm jug gasket) and have no need for the crankcase gaskets. Just let me know if you want them & I'll send them.
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Post by rcq92130 on Nov 2, 2014 22:05:53 GMT -5
ps: in case you didn;'t see it, our buddy "scooter" did some great work measuring the actual pressure produced by the stock (vacuum) pump ..... which varied from 1.5psi to 4psi, depending on engine rpm. NOTE: the vacuum pump is fed directly into the carb. inlet. itistheride.boards.net/thread/6945/using-gauges-guessingSo, your electric pump is a perfect "electric" copy of what comes from the factory and can be fed directly to the carb w/o a problem. But there is an advantage: no matter WHAT speed you are operating at, your electric pump will produce the exact same pressure and simply adjust the flow rate to accommodate what the engine needs. |
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Post by rcq92130 on Nov 2, 2014 21:47:17 GMT -5
Hi Mr. Martin! I just finished installing the new (lower pressure) electric pump. New one is 2 to 4 psi; old one was 5 to 8 or 9. As far as could tell, that higher pressure was not spitting noticeable fuel past the needle valve, but I wasn't comfortable leaving that high a pressure and trusting these little Chinese needle valves would do the job. So a lower pressure pump - in the same range as yours. What with daylight savings time it got dark early, so no pix. I'll take a couple tomorrow. Regarding regulation of pressure: I considered getting this regulator, which can be dialed from 1 to 4 psi: www.ebay.com/itm/141433732680?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AITbut probably won't unless a problem turns up. At that low an output pressure i think it sane to just run the output of the pump into the carb - the vacuum pump got to the same pressure. Remember - the pump only needs to have enough to open the needle valve when the carb fuel bowl runs low, and not so high the needle valve stops shutting off extra fuel when the bowl is full. This isn't like an injection system, where you need to have a carefully regulated pressure (~50psi) because the pressure "regulates", along with the injectors and the duration they are open, how much fuel is injected. In a carburetter system the quality of fuel consumed is not determined by the pressure of the pump at all. It's POSSIBLE you might get marginally better bowl filling if you had a perfectly even pressure from the pump - and these do NOT give perfectly even pressure since they have pulsing diaphragms that push fuel out, and every pulse sends a wave of fuel (and thus a pressure pulse). My belief this is negligible --- and remember --- the vacuum system operated the same basic way, except the diaphragm is driven by vacuum and springs, not a motor. So the vacuum pump probably gives as much "pulsing" of pressure as does the electric pump - which is an unimportant amount. But a pressure regulator would certainly help to even out the pressure leading to the carb if that's what you want. I think it's chasing a problem that isn't a problem .... but who knows. As for wiring the pump: I used a simple relay (as is normally used in cars and motorcycles) - with a line from the key to the coil side of the relay (the other side to ground). Thus, when the key is "on" the relay is closed, connecting the OTHER two terminals. Then, you just run one of the other terminals to battery (use a small fuse inline), and the fourth terminal to the pump. Of course, the pump needs a ground also. About location: I wanted to have the pump at carb level, so the pump's output pressure would be equal to the pressure at the carb inlet. If you have an under floor gas tank (like mine), it would be "nice" to have the pump down near tank level so it need not suck any heights. But, then, the small output pressure of the pump (say, 2psi) would NOT be the same as what you measure at the carb because of the column of gas in the 1 or 2 foot high fuel hose pushing back against the pump. I didn't calculate how this would affect the pressure drop - probably unimportant for these pumps - but still something I worry about. in MY case i had no choice --- there wasn't any place to conveniently mount the pump except to the front of the kickstand cross bar (just behind the gas tank). Seems to work fine, but I'll let you know. Hope this helps. Pressure regulation is, i believe, a non issue. Hook up is best with a relay so you are not drawing the "large" (~1 amp) current through your ignition switch. Location is probably irrelevant also. These things just work; not all that finicky. |
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Post by rcq92130 on Nov 2, 2014 14:55:29 GMT -5
Suonds dubious, Shannon (about fitting w.o boring the case). The 60mm jug JUST BARELY slid in --- a mm larger and it would not have made it. Can't see how they could go 2 mm larger on the piston / liner and not have a larger bottom diameter on the jug.
But if you are getting a new crank it's a big non-issue anyway! You will already have taken the crankcase apart - at that point boring it out is a snap! Heck - taking the case apart - though not a "terrible" job - was just enough of a pain to NOT make me want the 62 or 63mm BBK. But if you are also going to a long throw crank, and will have the case apart anyway --- heck --- I'd get the absolute biggest damned piston made!
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Post by rcq92130 on Nov 2, 2014 14:50:21 GMT -5
Scoot - if you decide to add an electric pump you will not need a buzzer (assuming you use an electrical relay to energize it. Thought you can't hear the pump at all when the engine is "on" --- if you accidently left the key "on" after killing the engine the pump would alert you. Not very loud, but I think enough so you would notice and realize the key was 'on".
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Post by rcq92130 on Nov 2, 2014 14:45:25 GMT -5
Nice~!
I prefer a standard electrical solenoid energized by a wire that gets +12v when the switch is turned on. the upside is there is no long starter run just to get gas pumped into the fuel bowl - the scooter is charged and ready to go from the first instant. The downside (as mentioned) is the pump runs at all times when the key is "on". As for me I do not mind that - have a radio on my scoot, but have not had it running w/o the scoot running. Anyway, I'm sure a "kill switch" would be easy to de-energize the relay if you wanted to do so manually ... but have not had any reason yet to want that.
My 2 cents.
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Post by rcq92130 on Nov 2, 2014 14:03:24 GMT -5
" ...just like I will eventually win Alleyoop over on using shims"
THAT is funny!
Sorry - was in a hurry this morning; didn't mean to sound defensive. Just wanted to ask why anyone would think one method would inherently be problematic.
ps: "RE: Massive pressure of the fuel pump"
That too is pretty funny! I know you were teasing, but just in case; i think the filter should always be on the SUCTION side of the pump (i.e., zero pressure).
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Post by rcq92130 on Nov 2, 2014 10:55:33 GMT -5
"EFI models come with electric fuel pump and no kick start.
if you have battery problems the only way to start it would be to use a long socket through the fan cover and low speed drill.not an impact wrench, because that would just remove the magneto nut.
"
Or simply jump start it like you do any more modern vehicle (car or motorcycle).
Conversely - when your vacuum pump fails you are screwed until you tear it apart and replace the pump.
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Post by rcq92130 on Nov 2, 2014 10:52:39 GMT -5
What makes you think the Chinese vacuum fuel pump will be more reliable than an electric fuel pump? This thread started because "scooter's" vacuum pump failed. I now have an electric pump because that also happened to me.
No car has been manufactured in over 20 years with anything OTHER than an electric pump (same with motorcycles). As I see it - modernizing your scooter should significantly IMPROVE reliability, not degrade it.
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Post by rcq92130 on Nov 1, 2014 18:34:37 GMT -5
Completely missed that thread; very interesting.
Ive been using vac test forever - on cars & large cycles; tried on the scooter and was confused by the results. Your tests helped a lot\. You got basically what I was getting - and my thought about the engine valve timing being off, or whatnot, appears to be wrong since, i guess, these things just operate at very small vacuum levels. Surprised the vac reading drops to, basically, zilch at high rpm.
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