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Post by 49cctaotaothunder on Oct 14, 2017 7:11:23 GMT -5
Great forum and videos on youtube guys, I really like the forum. It is overwhelming the amount of info on this forum. I just ordered a new scoot and now want to try to tune it. I want to do the cheapest mods I can and see what happens first. I'm looking for starting torque and higher top speeds. I would like to do the following, but don't know exact sizes to order for things or if I even need them.
Here is what I'm considering: But what would you guys recommend ??
1) I'm going to use factory carb and adjust for now
2) What size jet should I try out in the carb
3) Open air filter
4) Weights Vs Rollers about what size and which one?
5) Clutch Springs (what size and are they needed)
Is there a restriction spacer on the variator of this scooter?
Down the road I may try a new carb and big bore kit
1) What size BBK is safe?
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Post by tortoise2 on Oct 14, 2017 10:22:58 GMT -5
Unless this is a liquor-cycle situation . . why did you order a 50cc scooter, knowing it is NOT compatible with your performance expectations? Not initially selecting at least a 125cc remains the most frequent regret! |
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Post by 49cctaotaothunder on Oct 14, 2017 12:01:22 GMT -5
I had a 50cc Honda spree (1984) back in the day. I had a 150cc for a couple years then sold it because I did not like paying for my motorcycle license and the hassle of inspection also it took up a lot of room. I miss having the ability to ride around on Sunday afternoons. So to answer your question it is a cheap way to ride and it won't take up as much space as my 150cc did. I own a small engine business, so I like tinkering with engines and this is the prefect way for me to fiddle around.
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Post by tortoise2 on Oct 14, 2017 12:44:02 GMT -5
like tinkering with engines and this is the prefect way for me to fiddle around The BBK aggravation factor is especially gratifying . . disabled on the side of the road with a shredded belt, and eventual bearing failure! |
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Post by cagiva4ever on Oct 14, 2017 15:18:13 GMT -5
.... 1) I'm going to use factory carb and adjust for now 2) What size jet should I try out in the carb . IF STOCK CARB pz18 ? pd18J , THEN DEPENDING OF YOUR ALTITUDE, #82 84 88 3) Open air filter. BIG NO NO. KEEP STOCK AND MODIFY AIRBOX INTERNALS IF NEEDED (BEING SHORT 10CM PIPE AND AIRFILTER PANEL THICKNESS. 4) Weights Vs Rollers about what size and which one? FOR STOCK 49CC NO BBK, 4,5GR TO 5GR 5) Clutch Springs (what size and are they needed) .STOCK SPRING IF STOCK 49CC Is there a restriction spacer on the variator of this scooter? HAVE A LOOK YOURSELF ,BECAUSE ITS CHINA THINGY, VARIES.. BUY PROPER NGK PLUG AND PROPER HT-LEAD, DO PARALLER EARTH CABLES, BUY A9 CAMSHAFT. .... replyes inside quote, i was lazy.............no intentional big caps |
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Post by 49cctaotaothunder on Oct 14, 2017 17:56:50 GMT -5
Okay thanks for the suggestions I'm just not sure what you mean about the air filter box. I know there is a restricter inside that can be removed. 3) Open air filter. BIG NO NO. KEEP STOCK AND MODIFY AIRBOX INTERNALS IF NEEDED (BEING SHORT 10CM PIPE AND AIRFILTER PANEL THICKNESS. Please explain 10Cm Pipe and panel thickness. Thanks Read more: 49ccscoot.proboards.com/thread/20148/thunder-50cc-simplest-cheapest-mods#ixzz4vWfXNwi9 |
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Post by lostforawhile on Oct 14, 2017 19:15:35 GMT -5
like tinkering with engines and this is the prefect way for me to fiddle around The BBK aggravation factor is especially gratifying . . disabled on the side of the road with a shredded belt, and eventual bearing failure! this is why you upgrade the crank and bearings instead of just slapping on the kit,if you can install the kit, you can learn to split the case and change the crank, these are no more complicated then a lawn mower engine |
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Post by lostforawhile on Oct 14, 2017 19:22:24 GMT -5
Okay thanks for the suggestions I'm just not sure what you mean about the air filter box. I know there is a restricter inside that can be removed. 3) Open air filter. BIG NO NO. KEEP STOCK AND MODIFY AIRBOX INTERNALS IF NEEDED (BEING SHORT 10CM PIPE AND AIRFILTER PANEL THICKNESS. Please explain 10Cm Pipe and panel thickness. Thanks Read more: 49ccscoot.proboards.com/thread/20148/thunder-50cc-simplest-cheapest-mods#ixzz4vWfXNwi9spend a few dollars and get a genuine Keihin carb, there is an entire post showing how to tell a real one from a fake, the cheap sealed carbs are pretty much crap, there is a lot of info on here showing how to tune them, but in general with the internal airbox restriction removed, and the four hole restriction removed, the best jet size seems to be an 86, it's best if it runs slightly rich, if you are running full out all the time, I'm waiting to try an 86 my self, but my stator crapped out when I was going to test it. Get an after market muffler, they are hiding converters in them now, and the design is horribly restricted  |
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Post by 49cctaotaothunder on Oct 15, 2017 8:22:33 GMT -5
Thanks for the reply. I have been researching. I read through the "real" carb thread and still do not know where to get a "real" one.
Is the Glixal carb on Amazon any good (this is what I'm getting out of the carb thread)
Are the aftermarket exhausts louder than the stock? Is there a way to derestrict the factory muffler and keep it quiet? Thanks for any help.
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Post by jackrides on Oct 15, 2017 12:42:55 GMT -5
Airbox notes. There is an outer snorkle and an inner snorkle, their main purpose is reduce intake noise and that isn't a bad thing, but their small size is. Measuring the open area in each showed me that they each have about the same area as the carb venturi. I drilled open the outer one, still leaving 5 holes and removed the inner one. I feel that the venturi should be the smallest restriction in the intake tract. Went up 2 jet sizes, 3 might be better. In my climate there is a full jet size difference between summer and winter. (colder needs larger) The idle fuel jet should be fine tuned. There are posts on how to unplug the access. Change much earlier than specified and go to synthetic at 3rd change then should be good for every 1k miles. ADJUST valves at 1k miles. Check tire pressure weekly. Enjoy!
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Post by cagiva4ever on Oct 15, 2017 13:16:09 GMT -5
"humanshield" made topic, covers fake and tru 20mm carb. there is a 10cm long rubber pipe with square flange inside AirBox. to suit yours setup, test with and without it. 2-stage aftermarket airfiler panels exist, that Breaths-flows through better than stock oem 2-stage version. most aftermarket 139QMB zausts are loud, even with DB-killer in place. have alook at youtube for diff versions. stock oem 139QMB muffler(s) is a "Labyrinth" inside so to speak, there is some sample photos at web from dismantled-modded ones from "classic" version. and as a "lostforawhile" posted above for Round tubular shape1. like so, an sample from my fellow Finnish 139qmb hobbyist: www.mediafire.com/file/gcd61nizqx716n6/Kirurgiaa+Baotianin+pakoputkelle.pdfof course you need to Remove take out all SAC and EGR emission systems. any speed limiters inside CVT case and cdi's jumper wire if it exists....... regarding "rollers vs slider" , user feedback wins for Sliders (personally i dot have a set yet..) . but be aware that apparently there will be 1gr behaviour difference on them to Compensate, i.e 5gr rollers match 6gr sliders....Variable factors...... you bought/ordered brand new scooter ? if so, make sure it uses genuine NGK plug and quality HT-lead and resistor Cap. not chinese sparg plug and chinese metallic boxed resistor Cap. Route Paraller earth(s) wires if Stock is substandard....between engine and Frame, etc weak spots. Basic upgrades dont stop there, to make it better. diy sealing wire connector blocks is next step and sealing ign-switch bottom pinouts. for a "safer" bolt-on BBK size, use max 47mm diam bore or 44mm, as both can use stock 49cc head. buy A9 cam for it. Only go for bigger CC/bore when you have learned more about basics, after couple years...(compression issues, e-starter issues, crank durability issues, head variations piston variations, list is slong....and then to suit CVT for it all) |
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Post by 49cctaotaothunder on Oct 15, 2017 18:33:18 GMT -5
OKay, thanks for all the suggestions. Is there a brand or seller for the HT-lead and Cap? The scooter arrives tomorrow. I have been watching the youtube videos on the PDI, so I'm going to slowing go through everything (lots of electrical) right from the start. I will report back how things are going. Thanks again.
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Post by lostforawhile on Oct 15, 2017 18:42:25 GMT -5
I keep seeing things about the resistor plug, vs the non resistor, the only purpose of the resistor in the plug, is to suppress RF interference, since these scooters have no computers and no radio to interfere with, the resistor is not needed. The only reason you see them so often, is the NGK R plugs are so common
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Post by cagiva4ever on Oct 16, 2017 16:08:33 GMT -5
the ht-lead is common motorcycle size diameter. just choose good known brand manufac. i have Bosch, etc.
NGK makes good 5Kohm Cap 139qmb specific. google it and you see the NGK code for it.
yea choose NGK plug that has no build in R function. on 2t sportsbikes it R can ruin plug...........
dont either go iridium... NGK C7HSA iirc is most common 139QMB plug. double check, as its late night atm im knackered...
diff manufac plug comparison chart is never 1:1 on heat range, so stick with good known NGK.
most likely you need to take of CVT cover and Grease kicker parts and Bendix. also the e-start is dry inside, needs Grease for "bearing" end. and rear drum brakes expander axle...
if you do the e-starter motor, be very very carefull with the "phillips" head screws, they'r cheese soft... electro corroded ones 50-50 snap in 2 always. reason to upgrade for proper 8.8 strenght bolts.
china men speed up production line and often Leave out all Grease.....^^^^ only part they seems to grease is speedo drive. and littlebit for steering head bearings..
check carefully your steering head function (bearings). ... often 1 or some bearing balls are missing or are FLAT as new.
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Post by 49cctaotaothunder on Oct 18, 2017 18:18:05 GMT -5
Well I got the scooter everything is great with it except the main head lights. There are 2 head lights a right and a left, if I hit hi beam the right comes on if I hit low beam the left light comes on but not both at the same time. I'm thinking I flipped the wire connection when attaching the from light kit? I don't know how I would do that because all the clips are slotted I believe. I did not take it apart yet, but figured I would ask here. Thanks Guys!
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