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Post by chrisj9880 on Apr 7, 2011 17:49:01 GMT -5
LB1P39QMB So after last season ,in which I put on my first 2500 miles, I decided to do some performance upgrades on my scoot. NGK Spark Plug New Fuel Filter UNI filter. Racing No Rev Limit CDI High Performance Ignition Coil Glass Pack Stainless Exhaust New Kevlar Belt Performance Rollers (7g) - The stock ones were 5g and worn Upgraded to #105 main carb jet (stock was a #79) For the most part, I am pleased with the outcome. I have a top speed on a flat level surface of about 45mph, however it takes a while to get to that speed, maybe 1/2 a mile. I am looking for input on where to go from here. I am fairly certain that I need to go down to a #90 main jet, as I cannot tune the carb correctly...it bogs down when given full throttle, and a quick release off the throttle it has a muffled backfire or spit. Any thoughts? Also I understand that I may want to go with lighter rollers, maybe 4g? Sounded better today when I finished off the upgrades with the exhaust from scrappydog...however I am lacking that initial acceleration I need to get in and out of a tight spot in traffic. I am new to this and I am learning as I go, having a GREAT TIME! ANY of your thoughts, suggestions, ideas, or criticisms are welcomed! Thanks CJ Attachments:
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Post by ctpgs on Apr 10, 2011 15:34:15 GMT -5
i would try the smaller jets and also try going back to the 5 gram weights 4 might be to light
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Post by edfr on Apr 10, 2011 15:41:29 GMT -5
Leave you jets alone it is running great, for more HUMP in the low to mid-range your weights are to heavy. Try what CTPGS said go with Lighter weights that will require more RPMS and keep the Belt down in the lower range for a longer period of time AS YOUR RPMS build up for your top end speed.
Lefty
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Post by D-cat on Apr 10, 2011 18:39:45 GMT -5
I don't see a BBK in that list. I would go down to 5g sliders and try a 92 jet (or if only with scrappy, try 90 and 95 and see which one is better).
I'm still retuning my carb for this season. I don't have a unifilter but it isn't stock either (dust filter only, you can see through it). B&S exhaust mod. I ran a 90 jet for yesterday and both my top speed and gas mileage went down, though it was mostly behaved. I'll rejet on the next sunny day.. playing the half game until I get it right.
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Post by edfr on Apr 10, 2011 18:48:30 GMT -5
Just re-read your thread, and I overlooked that you have a backfire when you let off the throttle. That means it is running LEAN and you probably have an Air Leak someplace. Check the Flange where it connects to the engine head. Sucking in air from there will always cause a backfire.
Lefty
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Post by chrisj9880 on Apr 10, 2011 20:03:46 GMT -5
First - THANKS for the Feedback! As I await a #88 and #95 jets to arrive via scrappy, I decided today to raise the float on the needle below the diaphragm (not sure exact term there). Not sure If I should have done this, but I Re-tuned the carb a bit, and it sounded better and seemed to run a bit better, however it was hard to tell with 25mph wind gusts. Did cruise in the 80 degree weather a bit and sucked down half a tank of gas. Not sure if this was the right thing to do, no more backfiring just a very muffled girgle when i let off WOT.
I will be back at it tomorrow afternoon and I will inspect the connections for air leaks (thanks lefty), and go back down to the 5g rollers I have.
I will update after re-jetting!
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Post by chrisj9880 on Apr 10, 2011 20:14:33 GMT -5
Should I consider a BBK? Any particular one? I am a very novice mechanic with this - is a BBK something I could do myself without too much risk of ruining my ride?
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Post by knitewolf on Apr 10, 2011 23:53:43 GMT -5
I agree with D-cat and Lefty Your just by looks and what I see of your build along the same build as mine I would have to double check the motor stamp. I would most likely go with the 88 main and the 5g rollers to start 6.5g may be the sweet spot I am still tuning mine but I have a fresh BBK I am breaking in so I am taking my time I am using a 6.5 and 8.5 combo at the moment but I will be changing things around a bit more Good take off and have not gone over 30mph yet but I want to wait till after break in to do so. As for the BBK they are in theory not hard to do just as long as you take your time and follow any and all directions. I would myself finish Tuning what you have and see what the end results are first then decide from there. I had a stock a VIP twin of my scoot blow by be today so I know I have a bit more tuning to do myself. Hope things pan out for you and enjoy the ride and work you have put it to it thats what Matters to me  |
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Post by chuckspeed on Apr 11, 2011 5:08:23 GMT -5
I have a smaller scoot body, but am at 43 on the level with just a CDI. I've started a thread on this called Jonway GY6 Build. I had the larger main jet in and it actually ran worse! Will do a swap on the rollers this weekend - hopefully - and may swap in a pipe if I have a chance.
Like others have said - there's no replacement for displacement. 45-ish is all you're gonna get for top end with external mods. To get torque, you're going to have to give up top end (read lighter weights) or go with a BBK. The BBK is the way to go - and if you do this, make sure to get the big valve head with a race cam.
The two things you want to do is increase displacement while raising the peak TQ point. Once you've accomplished this, you can tune the CVT to match the peak TQ to get the most bang for the buck. A scoot that runs out in the 50's is very realistic - and acceleration to match average cars on the street is possible, too. You need lots more displacement - a 72cc BBK gives you nearly 50% more - and the cam and head move peak TQ up about 20%. The shift means the engine is processing more combustible mix, which translates into more power!
Will you end up with a 150cc scooter killer? No - but you won't be embarassed by them, either.
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Post by mainepeace on Apr 11, 2011 15:35:04 GMT -5
Well I think a turbo and an EFI conversion will give a huge power increase. Probably too much for the stock crank though.
Greg
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Post by D-cat on Apr 11, 2011 19:48:26 GMT -5
I know of a couple projects working on that for 150 GY6 but not for 50, don't know why. EFI and an O2 sensor input would sure make my ride tuning easier. I too wonder though if a stock crank could handle a turbo for very long.
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Post by mainepeace on Apr 11, 2011 23:10:03 GMT -5
I came across a link earlier for EFI for 50cc scooters: www.ecotrons.com/Small_Engine_EFI_kit.htmlReading the install manual it seems to be a very straightforward install. Fairly simple. Just replace the intake manifold and carburetor with the new EFI assembly, install a fuel return line, hook the system into the 12v electrical system. Could possibly install in about 30 minutes. Also it's programmable from a PC through the serial or USB port. Curious to see how well it works. If I had some extra money floating around I'd be tempted in buying one. Greg |
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Post by D-cat on Apr 12, 2011 8:33:54 GMT -5
Good find. $300 seems to be a fair price for that complete of a kit (exactly what I am talking about and more), but I can't justify dropping that on a running 50cc that I purchased for $400. This would make sense for a brand new bike or a project bike with a new engine (or at least top end). A winning lottery ticket would help. >D On a 150+cc I could see it being worth it at any time.
I wonder if it has on demand switching between economy and performance modes (like normally economy but goes into performance automatically at WOT like many cars do). That alone would improve its value.
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Post by mainepeace on Apr 12, 2011 11:58:54 GMT -5
From the info it has a switch that will go between two different programs while running. So, at the light you can switch to HOT ROD mode... It shuts off fuel when coasting. It can also be custom tuned via the PC.
I'd consider it more for reliability and fuel economy. There might be a little more power from the timing advance and better ignition profiles, but the real advantage will be the cold starting and the savings of fuel. It also comes with a wideband O2 sensor. With a 20 degree temperature difference from day to night it makes tuning the scooter much easier.
It's also probably not that difficult to remove from a scooter if you decide to sell it. Just patch a few holes with screw blanks.
In itself the $300 won't be returned except after 400 tank fillups. But think of the more immediate throttle response and the better emissions overall.
I figure I'm saving at least $500 per month without having a car payment, insurance, or weekly gas fillups in the $60 range. I'll have to really see if I can scrounge together the $300 or so.
Greg
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Post by D-cat on Apr 13, 2011 7:24:24 GMT -5
I kind of have a similar thought, but I am still paying over $200 /mo on a mini-van, and as you pointed out, some 400 tanks to see a return has the brakes on.. it is still a 50 after all. OTOH when a top end eventually becomes necessary in which I would want to replace that piece of garbage stock carb I run anyway, the investment starts making a little more sense.
I did ask for a couple specs from them and I liked the responses I got. One was the 2 profile switch you just mentioned. The other I asked was about the rev limit, which I was told is user programmable and the limit is over 16k (which is well above what any sane person would want to set it to), so the user really does have the ability to do some serious economy (/ city legal) vs high performance tuning. This definitely beats out any carb out there, but whether I can justify the estimated 4x cost of a carb for the gained features is still in the air, but definitely up for consideration. I do like this kit's specs, completeness, and flexibility; that was an excellent find.
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Post by larrball on Apr 13, 2011 8:30:40 GMT -5
I thank another benefit for some would be by installing one of the EFI kit's you have a better understanding on how they work.
With that said, if you where to ever have the opportunity to get a scooter that had EFI you would have a heads up on any repair that may be needed with that scooter.
Just my .02
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Post by oscar on Apr 13, 2011 11:48:11 GMT -5
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Post by chrisj9880 on Apr 14, 2011 9:48:51 GMT -5
This morning I finally was able to install the #95 jet, and after making adjustments I think I have found the right one! Top speed verified at 47mph on flat road! I do plan to play with the roller weights to get the right combination to give me a little more pickup from idle, I will update if any progress is made there.
I did check for air leaks as suggested after installing the new jet. No air leaks found however with carb in tune I am no longer getting a backfire or gurgling sound after letting off WOT.
Just a recap of my specs;
1p39qmb 4 stroke
#95 main jet
UNI air filter
Stainless Glass Pack Performance Exhaust
Racing No Limit CDI (Orange one from scrappy)
HP Ignition Coil (Orange from scrappy)
NGK Spark Plug
Kevlar Drive Belt
7g Performance Roller Weights
Thanks to you ALL for you input!
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