fhol
Scoot Member
Peugeot Kisbee 4T 2016
Posts: 81
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Post by fhol on Sept 10, 2018 12:56:02 GMT -5
diynuke: Thanks, i'll keep all that in mind. Haven't had time to do anything more on moped for a few days cause my electric bike broke down and i use it to get to work so had to give it priority. Still having problems with it, think hal sensor(s) in hub motor is the culprit, but i'm unsure. Anyways, will give the 84 jet a try later when e-bike is sorted.
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shortman1166
Scoot Member
Posts: 52
Location: Lafayette, Indiana
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Post by shortman1166 on Sept 10, 2018 16:51:59 GMT -5
I finally got mine figured out. I ended up changing quite a few things but the problem seemed to be the accelerator pump timing was off slightly, I bent the tab to make it engage quicker and I also went up to a 31 pilot jet, and finally moved my needle to the middle position from the 2nd richest setting. Took a while but it seems to be running much better off idle now.
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fhol
Scoot Member
Peugeot Kisbee 4T 2016
Posts: 81
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Post by fhol on Sept 11, 2018 10:56:16 GMT -5
shortman1166: Glad you figured it out! Interesting solution too! Too bad i don't have an accelerator pump in my carb. For me, complete FAIL today. Thought i'd use scooter to go buy parts for my broken e-bike... but now scooter won't run after a few days of not using it. Had to crank alot just to get it to idle but as soon as i touch accelerator, engine dies. Noticed fuel filter wasn't filled up properly. Gonna change to 82 main jet, put needle in middle pos, and use the drain screw at bottom of carb after refitting to make sure fuel filter is filled. That will be the evening task.
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fhol
Scoot Member
Peugeot Kisbee 4T 2016
Posts: 81
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Post by fhol on Sept 11, 2018 15:52:50 GMT -5
Its alive again! I put in 82 main jet instead of 86 and moved clip down to middle pos, and gained a little power. It went 2 km/h faster up the same hill, 45 km/h now. Have started to compare engine power that way. Not very scientific, but still. Hesitation on par with previous setup, so i think hesitation problem must be something else... more on that later. About jets again... i'm thinking that the surface area (of course) of the hole is roughly proportional to the amount of fuel it gets on full throttle. So if i do some calculations with A = pi*r^2 i get: 78 jet gives A = pi * (0.78/2)^2 = 0.48 mm^2 80 jet gives A = pi * (0.80/2)^2 = 0.50 mm^2 82 jet gives A = pi * (0.82/2)^2 = 0.53 mm^2 84 jet gives A = pi * (0.84/2)^2 = 0.55 mm^2 86 jet gives A = pi * (0.86/2)^2 = 0.58 mm^2 88 jet gives A = pi * (0.88/2)^2 = 0.61 mm^2 90 jet gives A = pi * (0.90/2)^2 = 0.64 mm^2 ... 98 jet gives A = pi * (0.98/2)^2 = 0.75 mm^2 (a big jump!) And so since i first replaced the original 78 with 86, one would erroneously think i got a 86/78 = 1.1 = 10% fuel increase BUT taking the areas for the same jets we get 0.58/0.48 = 1.21 = 21% fuel bump and that makes sense, because it ran very rich with the 86. I'm a newbie on carbs though, so probably alot more variables to consider. Just for fun, looking at the 98 vs 78 jet, there is a 56% increase in area of hole but 98/78 is only a 26% difference. So as you can see, increased diameter of the hole is not linear to the increased surface area of the hole. Therefore, when i come to think of it, i will from now on go up/down ONE size of jet on each test and try not to cut corners. There is also another variable - manufacturer precision. The new jets i bought were made by Naraku, the old one, who knows? Can i really compare jets accurately between two different manufacturers? Plus that there are lot more variables to this, like fuel flow abrasion of jet and needle over time and so on. Weather conditions and... you get the point. Anyways, i had troubles getting the fuel filter to fill up. Tried the drain screw on carb whilst still connected to fuel tank (open lid), tried sucking hard in the vacuum line going to petcock but filter just won't fill up like it did when i first fitted it. Nothing seems wrong with the fuel line. Its like i can barely see any fuel in the filter, even if i run the scooter for 20 minutes. That petcock... on first removal of carb, it just wouldn't stop flowing out of it despite no vacuum in vacuum line. But now, it's like it is half-stuck closed. Really need to replace it with a manual petcock. Any advice on which one to buy to replace it and get new to fit snug without modifications? Current one: By the way, also put in brand new spark plug with 0.8mm gap, today, like it would help, lol! Measured carb too while at it. Fuel side inner diameter ~ 18.5mm, outer 27-28mm. Air side outer diameter ~ 38mm. Good to know if i need to fit an aftermarket "hi flow" air filter. Nah, new premium brand carb or fiddle with pilot jet is what i'm doing next, after i've fixed my e-bike!
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fhol
Scoot Member
Peugeot Kisbee 4T 2016
Posts: 81
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Post by fhol on Sept 13, 2018 14:25:41 GMT -5
Update: Fuel filter full the next day! So i went for a ride again but it made no difference.
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fhol
Scoot Member
Peugeot Kisbee 4T 2016
Posts: 81
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Post by fhol on Sept 13, 2018 14:51:44 GMT -5
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ratdog
Scoot Enthusiast
Posts: 342
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Post by ratdog on Sept 14, 2018 1:50:28 GMT -5
IMHO, I would not be going to a smaller carb. The experience I have has showen that the BBK are limited by the 18 mm carb. I have had excellent results with the 22 mm carbs. To me, it seems like you would be reducing the power gain of the BBK with a smaller carb
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Post by diynuke on Sept 14, 2018 2:02:52 GMT -5
You don't want to get that carb xD. looks like an 2stroke carb type. or something else.
just search for an simple gy6 carb. they arent expensive and you can find them everywhere. 18mm should be fine. 24mm on an 72cc isn't really worth it. it just consumes allot more gas with a little gain of power which only kicks in at high rpm. so if you could find it there are some sizes between the 18 and 24 but they are not the standard so they are more expensive.
I would suggest first trying an cheap one and then you could go to an better one. like the naraku you picked
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fhol
Scoot Member
Peugeot Kisbee 4T 2016
Posts: 81
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Post by fhol on Sept 14, 2018 14:31:29 GMT -5
Ok, thats why i asked. Seems like i have an 18.5mm carb now. So if ratdog is correct, then i maybe go for 22mm. A little more power wouldn't hurt, if at all possible without cylinder upgrade. I'm a big guy at 1.88m, ~90kg. That is btw the main reason i bought a Peugeot Kisbee - i can steer without the handlebar hitting my knees immediately. Most other scooters have their handlebar mounted too low for my long legs. Anyways, if i change carb, i need one with automatic choke that connects easily preferably without any extra electronics. Don't want a "racing carb" with a small button on it for choke since i can't reach the carb when seat is mounted. Not too keen on mounting a wire-choke either. Also don't want to buy a new one that is the same model as i have now.
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fhol
Scoot Member
Peugeot Kisbee 4T 2016
Posts: 81
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Post by fhol on Sept 14, 2018 15:32:27 GMT -5
Memory lane (mostly off-topic):
Btw, back in the days some 20-25 years ago, aged 13-16, i had a few mopeds, not all at the same time. A Yamaha DT50 '84 (main one), a Honda MB50, three Suzuki K50 and an old 3-wheeled moped with a Saxonette 1.5hp automatic transmission engine. Can't find any photos of it or remember the make/model. You could like flip open the "cabin" over the two front wheels. It featured a windscreen and a small roof but was open in the back. Great fun drifting it during the winter!
No hesitation problem on any of them. All i did was move clip and fiddle with air/fuel mixture screw and they worked great. Didn't even change jet once. All mopeds were 2-stroke though, some with aftermarket carbs power exhaust, 60-70cc cylinder and high comp top. Did all the service/tuning myself including for example changing connecting rod and bearings on the DT. It had a 24mm Mikuni carb in the end. One K50 had a 20+mm Dellorto and there was a crappy Bing with 'on the fly' adjustable jet on the Saxonette. Can't remember brand of original carb on Yamaha DT, but it also worked flawlessly if i had the 49cc cylinder mounted.
So i'm not a complete noob on mopeds, but it was a *very* long time ago. This is my first one since then. Never had anything faster on two wheels in between.
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fhol
Scoot Member
Peugeot Kisbee 4T 2016
Posts: 81
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Post by fhol on Sept 14, 2018 16:20:56 GMT -5
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ratdog
Scoot Enthusiast
Posts: 342
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Post by ratdog on Sept 14, 2018 16:56:35 GMT -5
Years ago we did not have these “pollution solutions” engines. Now a days the governments interferes with the engine design. As a result, we get “lean burn” engines that have all sorts of issues. Of course on the other side of the coin, we are starting to see EFI which is always better then carbs.
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Post by GrumpyUnk on Sept 16, 2018 10:18:50 GMT -5
fhol, take a look at Qimore competitor Glixal. They have a claimed 'Keihin' marked JAPAN, etc, for a little less shipped. I do not know where you are in the world, so can't get exact compare. I have two(posted 49ccscoot.proboards.com/thread/11639/real-20mm-carburetors-fakes-pictures) that have worked well. They seem to be a bit better quality than the 'gold metal' topped carbs. They have black plastic with Keihin markings. Two for less than $50US was to me a good deal. tom
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fhol
Scoot Member
Peugeot Kisbee 4T 2016
Posts: 81
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Post by fhol on Sept 16, 2018 14:12:36 GMT -5
@grumpyunk: Thanks for tip. Will check that out later.
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fhol
Scoot Member
Peugeot Kisbee 4T 2016
Posts: 81
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Post by fhol on Sept 16, 2018 15:04:32 GMT -5
New findings today. First let me show what i did. EDIT: I'll have to write about it, pics upload won't work today. 1. Measured the intake gasket hole vs the hole in the cylinder head. They are both 18mm in diameter so it seems like buying a 20mm carb and new 20mm intake manifold would _not_ be wise unless i go for a big bore kit with larger cylinder head hole to match it. Correct me if i'm wrong. 2. Fixed a very slight misalignment in the intake gasket vs cylinder head hole. Gasket covered like ~1% of the hole. So a little better fuel flow after fix, i guess. 3. Derestricted air filter box by grinding away a large chunk of plastics in fresh air inlet hole, so there is at least a 30% larger hole now. Almost looked like they had restricted it from factory by leaving that piece of plastics in it (which could not be separated from air box easily). 4. Removed the sponge-like part of the air filter, the one that you are supposed to put air filter oil on. I figured, cars don't use that, so why would my scooter need it unless i run it in very dirty/dusty areas, which i don't. 5. Removed the shiny perforated thin metal mesh that cover the entire air filter on "clean" side. It should increase airflow at least 25% through the filter alone. 6. Removed some restrictive plastic "flash" in the inlet hole in air box where the hose from cylinder head cover connects. So now airbox + filter is how it looks in most cars. Just that ridged papery-filter left and no restrictions. Provided i can get a good carb with correct jets, it should give a small performance boost at least in theory. New test run with pilot 30 (original size), main jet 82 (78 was original), didn't go so well. Before derestrict, on those sizes i felt a small performance loss compared to 78 jet, so i figured maybe it is just a liiittle rich with 82, therefore tried derestrict air box. Hesitation from standstill is always there more or less. Changing main jet didn't do too much on that, i should also say. It started fine on first crank but after waiting on idle 30-60s until what i presume is auto choke letting go (so rpm go down), it wouldn't run very good. I could barely get it moving, much like with the 78 jet and needle clip in topmost position. As soon as i hit the throttle, engine just dies. Now it is definitely running lean instead of rich on the same 82 jet! And i wont be riding it before i've fixed that. CONCLUSION: 1. Buy a new 18mm carb (not 20mm) 2. Get a set of larger pilot jets, and also put in larger main jet to counteract airbox derestriction 3. Maybe do (2) first, on old carb 4. If none of above works, adjust valves and at the same time delete PAIR system + get new exhaust without a cat The hesitation problem seems to be a much more complicated issue than just the size of the main jet.
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