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Discussion Starter · #1 ·
What's up Cam? I have some questions for you if you wouldn't mind answering. I have a 49cc x2 and I did alot of mods on it but I'm still looking to get more speed out of it without spending alot more money. So far I put a hp walbro carb on it which you gave me some advice about tuning it. I'm still having some issues with the carb tho. It'll stall on me once in a while and I'm getting some blue smoke from the exhaust. This bike sat for over a year and I fixed the problem with it when I first decided to fix it finally the other week. I know it has to get worked out and the carb still needs some minor adjusting. I also put on a fatty exhaust, boost bottle, 40t rear sprocket, saucer air filter, NGK BM6A spark plug gapped at .025, removed 1 of the roller weights and spaced them out into every other spot, velocity intake stack, replace the throttle cable and repainted it.

Well, my questions are what else can I do to get more horsepower/ speed? Right now I am using the stock roller weights and I don't even know what they weigh. I tried using metal stock in between the stock rollers which I saw online but I had better response and speed with just the stock 3. Do you know what the stock ones weigh and what weight should I try? I also read in one of your post that you were gonna put a 25t on your x2. How did that work out? should I go down to a 25t sprocket for more top end? What else could I do that won't kill my bank account? This is my x2
 

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for starters, the blue smoke is a good thing...LOL you have oil in the gas, which lubes the bearings in the engine since theres no oil in the Crankcase like a 4 stroke... then the rest of it gets burnt (its supposed to) and creates the blue smoke you are seeing
 

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If you havent done any power porting or compression bumping then the stock setting of 1 1/4" on the lowspeed needle will be too rich.....Plus i dont exactly like those UFO saucer type airfilters,,,Highflow foam UNI airfilter types are way better...The saucers are too restrictive at max revs and causes tunability problems.............

I run my X1 like i run my stand-up scooter,,,with pantyhose as a filter..The flow dont get any higher without being protected




The tuning process is a process of hit n miss..This involves moving the needles in small incriments til you get it dialed-in and exactly where you want it as far as takeoff power and topend screams............

Pulling the plug will tell you the symptoms of the problem practically and guide you which direction to go in rectifying the situation


Lean out the lowspeed needle a/f mix another 1/4 turn inwards and lower the idle when it raises up,,,,,,,,

Set the highspeed needle to 1 1/2

There is a l and a h casted into the carb body

You do know if you dont have the intake adapter for hp walbro the intake must be modded so the carb will work correctly

sparkplug is an NGK BPM7A gapped to .030".................025" is too tight of a gap and the BM6A plug is for reeded engines...

fuel is 93 octane mixed to 40:1 ratio...

put the roller weights back in as they were,,,just lighten the rollers a lil by drilling the hole a tiny bit bigger..a lil bit does a whole lot in centrifugal force........The way the trans works is the smaller pulley becomes the larger and vice versa,,,unvariated it goves nice bottomend takeoff ability,,,after adding alot of centrifugal torque the weights push the variator sheave out making the trans variate for obtaining higher topend speeds.....adding weights maqkes the trans variate early and makes you lose bottomend takeoff power.......too light and youll lose topend capabilities...............just right and youll get a nice 20-30ft rollout with nice bottomend takeoff then a variation which will slip ya right into topend screams in a very short distance.............

I have a 25 tooth on my X1 which has a 410 chainset,,X2 has a TF-8mm chainset...........My X1 goes a tick over 40...it has bumped up compression with the squish alot tighter than it ever was,,,windowed,,indexed,,lightened and polished piston,,polished the pin,bearing and bearing journal in the rod,,velocity ported the bottomend for max flow,,replaced the case bearings to higher quality plus ran metal polish through the bearings to remove any impurities and start the smoothing process alot less harshly,,ported intake with boost bottle nipple added,,homemade boost bottle,,ported exhaust and intake ports,,widened the transfer ports and matched them to the case,,fatty exhaust,,performance modded stock carb,,lightened flywheel,,added a rocket key to advance the timing,,gutted the electric starter,,lightened and modded clutches,,homemade velocity stack intake..modified trans to reduce friction and removed all the wiring and the battery to lighten the bike up by 5-6 lbs................
 

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Discussion Starter · #4 ·
Thanks for taking time and giving me all that info. I do have an intake adapter for the carb with all the gaskets and everything else from the boost bottle intake adapter all the way to the filter. I'll give it a go and let you know how everything worked out. I do have another question tho. I put 3 of the rollers back in every other slot. Should I keep them like that after I drill them out a little or add the 4th one back too? Thanks again bro
 

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Thanks for taking time and giving me all that info. I do have an intake adapter for the carb with all the gaskets and everything else from the boost bottle intake adapter all the way to the filter. I'll give it a go and let you know how everything worked out. I do have another question tho. I put 3 of the rollers back in every other slot. Should I keep them like that after I drill them out a little or add the 4th one back too? Thanks again bro

Put all 4 back...if you have a gram scale weigh all of them and reweigh after lightening........like I said a lil bit makes a big difference in centrifugal force.............Once you make more power the weights will add more force naturally...........
 

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Discussion Starter · #8 ·
I don't have a scale but i'll try to pick one up from walmart or something. what weight should they be? what do yours weigh? just so I have an idea of what are I should be in. That's a pic of my bike but I haven't figure out how to enlarge it here yet. I only been on this site for a few days so far lol. Thanks
 

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Discussion Starter · #11 ·
Cam2, what's up? I weighed my roller weights last night and they weighed 6 grams. Should I still drill them out today? I'm gonna port the head and exhaust manifold today and polish the piston a little. Is there anything else I should do while I have that apart and the cvt? I'll cross drill the clutch plates. What about the timing key? I think it's stock is there anyway of hooking that up? Maybe polishing or grinding down a little. I don't have a spring but there is a lawn mower and bike shop by me. Maybe I can see if they have one. Should I go heavier with the spring or lighter? Thanks
 

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Cam2, what's up? I weighed my roller weights last night and they weighed 6 grams. Should I still drill them out today? I'm gonna port the head and exhaust manifold today and polish the piston a little. Is there anything else I should do while I have that apart and the cvt? I'll cross drill the clutch plates. What about the timing key? I think it's stock is there anyway of hooking that up? Maybe polishing or grinding down a little. I don't have a spring but there is a lawn mower and bike shop by me. Maybe I can see if they have one. Should I go heavier with the spring or lighter? Thanks
remove a quarter gram from each one.........

window the piston with 4 ports facing the two transfer ports

lighten the piston from underneath

widen the exhaust port 1/8 on each side

widen the intake port 1/8" on each side

open up the purge port to 1/8"

taper port the exhaust port

taper port the intake port

port match the intake to the intake port

widen the transfer ports 1/8" on one side each..

polish the pin,,pin bearing and rod bearing journal......

index the piston on the exhaust side

yamabond down the head to bump compression,,give yamabond 24 hours to dry before putting the engine to use....

lighten the flywheel

add a rocket key to advance the timing 10 degrees

lighten and mod the clutches

add a hp clutch spring[heavier]

mod the exhaust

add a boost bottle setup
 

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Discussion Starter · #13 ·
What do u mean by index the piston on the exhaust side? Everything else I already pretty much did
 

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What do u mean by index the piston on the exhaust side? Everything else I already pretty much did
Put the head onto the bottomend with the piston installed onto rod but without rings.....roll the engine down to BDC..youll notice the piston top is like a speedbump to the port

mark both sides of the port and then between those two lines take a file and shape the piston top so it has less interferrence inside the port at BDC...........

Did ya happen to take any pics of what you did along the way in this project.?
 

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Sorry to hijack thread but forum will not allow me to post new thread. I am new to pocket bikes and my neighbor just gave me his old beat up bike. I fixed everything but have a few questions.

What oil and ratio should I use? I have heard ratios from 40:1 - 60:1

What sparkplug and gap should I use? I tried this but couldn't get the bike started and finally when it did it did not run right and the plug came out white hot. "sparkplug is an NGK BPM7A gapped to .030".................025" is too tight of a gap and the BM6A plug is for reeded engines..."

Can I use regular unleaded gas? 88 Octane?

What speeds should I be looking for? I got it upto 24 mph. I weigh 190 lbs

What maintance should I be doing on the clutch?

How tight should I have the chain? It seems like I have to keep tightening it everytime I ride.
 

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Discussion Starter · #16 · (Edited)
Cam2, no I didn't and i ended up breaking both piston rings putting the head on. First i broke the lower one then when I took the head back off to get the pieces out the other one broke. ugh!! Well i'm gonna order the boost port piston kit from pocketbikeparts.com for $29 and it comes with everything & its already ported too. I guess the rings where to brittle from being so old atleast it'll all be new now. I won't have to file it then right? And I'll take pics soon cause it's all still apart. I couldn't drill the rollers, so should i just get lighter ones? and should I get a new clutch too, or just get a hp spring? I already crossed drilled the clutch. The only other thing I have to get is the rocket key, everything else I have and did. Drilled, polished, ported. I already have an hp carb, filter, boost bottle, fatty exhaust. I am having a problem with my kill switch tho. I tested the switch & that seems to work. I think it's that little solenoid or whatever it is thats not working. what is that little box called that it connects to? Can I run it with one piston ring? only about a 1/4 inch broke off, the rest is still on the piston & it's the top one? Or will I lose to much compression?
 

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Discussion Starter · #17 ·
Leenover, Cam2 said to use 40:1 with 93 octane but I would say to start off go with 32:1 which is normal. I use super and it works fine. The plug should be gapped at .30 and ur right. bpm7a is for a normal bike without a reed & bm6a is for reeded engines. Read the posts from Cam2 to me and it'll give you some ideas about the clutch. He's been helping me cause I'm new to this too.
 

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Cam2, no I didn't and i ended up breaking both piston rings putting the head on. First i broke the lower one then when I took the head back off to get the pieces out the other one broke. ugh!! Well i'm gonna order the boost port piston kit from pocketbikeparts.com for $29 and it comes with everything & its already ported too. I guess the rings where to brittle from being so old atleast it'll all be new now. I won't have to file it then right? And I'll take pics soon cause it's all still apart. I couldn't drill the rollers, so should i just get lighter ones? and should I get a new clutch too, or just get a hp spring? I already crossed drilled the clutch. The only other thing I have to get is the rocket key, everything else I have and did. Drilled, polished, ported. I already have an hp carb, filter, boost bottle, fatty exhaust. I am having a problem with my kill switch tho. I tested the switch & that seems to work. I think it's that little solenoid or whatever it is thats not working. what is that little box called that it connects to? Can I run it with one piston ring? only about a 1/4 inch broke off, the rest is still on the piston & it's the top one? Or will I lose to much compression?
Post up a link on the piston youre getting...I have a feeling youre buying a piston for a reeded engine............You can just get new rings.....

I was able to drill my rollers..I used a reamer tool and held the rollers with a pliers in a paper towel...........You can also grind them shorter to reduce weight...

You can get lighter rollers...The GY6 scooters have roller weights aswell and will work in the CVT on the X2 but the roller kit isnt cheap.....

Disconnect the wire coming from the fancase/coil...........disconnect the wire coming from the throttle starter pushbutton from the harness.........connect those two ends together and you have a new killswitch...................Good Luck
 
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