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Tunning of 125cc (GY6, 152MI) - do it by myself ?

 
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Igoritza



Joined: 09 Oct 2011
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Location: Serbia

PostPosted: Sun Oct 09, 2011 10:19 pm    Post subject: Tunning of 125cc (GY6, 152MI) - do it by myself ? Reply with quote

Ok, so here are couple of questions regarding my Scoot, but first the intro:

I'm having a Sprint FVision, Sprint is Serbian company that rebrands Chinese scooters, annd this model is most probably one of the following:

Giantco Fvision
Huatian HT125T-23
Jonway Astro

there is also a Boatian version of the same scoot with 125cc, but I havent found the exact name (would be appreciated if someone know, to tell me cause I really want to know the original design)

here it is, it's pretty much the same look with all of those brands:




Personal opinion: the scooter is AWESOME! the design is awesome, probably stolen from some Japanese brand scooter from early 2000's, but anyway it looks great. the comfortability is great, lots of space for both persons riding it. it runs really fine, except from the fat that max speed is 50mph (80km/h)

and, with that, I would like if one of you could tell me the following:


1. are there any stock parts that need immediate replacement due to the fact they are Chinese ? bad rollers, belt, anything that could compromise rest of the engine .. ? is anyone of you even familiar with this model ?

2. is there a complete list for 152QMI kit selection ?

3. is the exhaust on this model limited ? in terms of suffocating the engine, or is the stock exhaust ok ? I have read that many stock exhausts dont have enough space for the burnt exhaust to go "all out"

4. is it possible to modify the current Cylinder, in terms of putting the bigger piston in it ? no to kit it, but to put the cylinder on the lathe, and expand it for a bigger piston .. ? I dont know if I'm sounding like a complete lunatic right now, but I know this procedure to be done on the 50cc scooters, machining teh cylinder in order to putt bigger piston ..

5. would any of the 10-40w synthetic oils do the Job ? in the users manual it says to putt Motul in it, but I have a cheap supply of ENEOS Japanese synthetic Oil that should be one of the best oils in the world .. ?


6. most important -

I have read this thread: http://chinesescoots.forumwise.com/chinesescoots-thread4790.html

and, I see now what should be done, but I need to ask: is there anything in terms of performance that I myself could do, with a set of tools, for a start .. ?

I'm asking, cause I'm low on money right now, and I would like to experiment, and learn in the process, of 4Stroke engines, havent met with them ever.


thanks in advance. I'm alo doing a Paint job, I know how to do that, I have a professional air brush, and a supply of Polyurethane paint (the one that is putt on the newest cars, instead of Acrylic paint) so I'm gonna need your opinion on the color combination Smile



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Igoritza



Joined: 09 Oct 2011
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Location: Serbia

PostPosted: Fri Oct 14, 2011 3:19 pm    Post subject: Reply with quote

no one with any kind of comment ? Sad



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89newbie



Joined: 01 Mar 2011
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PostPosted: Fri Oct 14, 2011 3:34 pm    Post subject: Reply with quote

Looked the 152 qmi uo just general internet grab and it looks like its just a version of GY6125-150. Checked variator under listing of 152qmi and caption under it was GY6. Probably you can do most aything that the other gy6 engines work with. Great looking Bike Jonway is a clone in appearance.


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ROE



Joined: 13 Mar 2011
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PostPosted: Fri Oct 14, 2011 3:34 pm    Post subject: Reply with quote

5 days without a reply is unusual.
Not a 125 buff myself, so I can't help.
Perhaps if you ask your questions one at a time ?


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Igoritza



Joined: 09 Oct 2011
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Location: Serbia

PostPosted: Fri Oct 14, 2011 5:06 pm    Post subject: Reply with quote

Yeah ROE, you're right.

for starters - is it true that when changing carburetor values, you need to change a lots more stuff (air intake, rollers) ?

I heard from a local technician, that it is a tricky stuff to mess around with carburetor, and that is the most important thing to do when tunning.

is there any kind of a pics tutorial for tunning 125cc GY6 carburetor with instructions and such ?



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slawenm



Joined: 07 Sep 2011
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PostPosted: Fri Oct 14, 2011 7:55 pm    Post subject: Reply with quote

By valves if you mean the jets, then yes, by increasing your jet size your be letting in more fuel, so to match that you will need an increase in air intake.
(unless your already running pretty lean that is)

also after most tuning to the carb you've have to tweak the idle screw a little.



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BigCheeseStick



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PostPosted: Fri Oct 14, 2011 9:20 pm    Post subject: Reply with quote

I'd just like to say WOW! THAT'S A FREAKIN NICE SCOOT! Looks kinda like an older model BMW bike.

But read up on doing a full "PDI", change out the spark plug, oils, fuel filter and hoses and such. You'll be much happier down the road not having to endlessly "tinker" just to keep it running. There are several forums out there with some really good PDI's listed, and each one seems to have a thing or two another didn't.



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Igoritza



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PostPosted: Fri Oct 14, 2011 9:51 pm    Post subject: Reply with quote

@slawenm - I believe that current Air filter would suffice, cause it is extremely huge, in comparison to other 125cc I saw. My calculations is that there is more than enough air right now.

would be nice to see some pics, of how you increase Jet size, whole process. any pic tutorial out there ?

idle screw - gotta find out what the hell is that, Icon_lol4, I'm from Serbia, I speak good English, but technical terms are always a problem.


@BigCheeseStick - I already changed oil, and air filter sponge. I heard that quality hoses are a big deal. hitting the shop tomorrow, to buy some parts spark plug for starters.



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89newbie



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PostPosted: Fri Oct 14, 2011 10:45 pm    Post subject: Reply with quote

Easiest thing to remember is the engine breathes. Just like us, what goes in has to come out. If you modify the carb by a jet change you have to look at the exhaust because it will restrict what you did at the carb. Vice Versa. Read here and you will learn most ins and outs. Best thing you can do now is a good PMI, which means check everything, tighten everything as needed, replace fuel lines as needed in general make sure all is good at this point. Be sure to drain the crappy Chinese oil and rear end grease, replace these with good known brands. Also remember the Chinese oil/grease and fuel qualities are not as good as ours. Valves have to be run in on these bikes, good adjustment at the factory changes to tight adjustment as we run them because the tappets are hardening the stems as the engine runs and the hardening results in closer gap thus starting problems appear as the engine breaks in. I dont know for sure but I have read the valve seats are just the aluminum head and break in time results in the valves creating a harder head surface to seat against simply from heat and wear. That also causes the valves to get out of spec. Enjoy the bike it is beautiful Icon_thumbs_up


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89newbie



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PostPosted: Fri Oct 14, 2011 10:50 pm    Post subject: Reply with quote

Igoritza wrote:
@slawenm - I believe that current Air filter would suffice, cause it is extremely huge, in comparison to other 125cc I saw.

would be nice to see some pics, of how you increase Jet size, whole process. any pic tutorial out there ? Pull it up on you tube lots of tut's on carbs. Check scooter sights for technical specs to find more

idle screw - gotta find out what the hell is that, Icon_lol4, I'm from Serbia, I speak good English, but technical terms are always a problem. Idle adjustment screw is the screw that increases or decreases idle speed on the crank the throttle cable actuates. Idle mixture screw is on the side and usually has a small cap on it. The big cap is mixture when away from idle.


@BigCheeseStick - I already changed oil, and air filter sponge. I heard that quality hoses are a big deal. hitting the shop tomorrow, to buy some parts spark plug for starters.


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Igoritza



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PostPosted: Sat Oct 15, 2011 12:13 am    Post subject: Reply with quote

thanks 89newbie! great stuff!

I just got back from a ride. had a devilish increase in power - tried out of fun, some russian gasoline additive .. 60 mph, suck on that chinese people! Icon_lol4

I'm not gonna do that in the future, cause I guess it burns the shi* out of piston. Only tried with one litre (1/4 gallon)

I'm going to post some pics tomorrow, from Photoshop, Need new paintjob, cause I'm going to reinforce plastics. gonna need your opinion on the color combination.



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89newbie



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PostPosted: Sat Oct 15, 2011 1:25 am    Post subject: Reply with quote

Igoritza wrote:
thanks 89newbie! great stuff!

I just got back from a ride. had a devilish increase in power - tried out of fun, some russian gasoline additive .. 60 mph, suck on that chinese people! Icon_lol4

I'm not gonna do that in the future, cause I guess it burns the shi* out of piston. Only tried with one litre (1/4 gallon)

I'm going to post some pics tomorrow, from Photoshop, Need new paintjob, cause I'm going to reinforce plastics. gonna need your opinion on the color combination.
Yep years ago ran Avgas in bikes and trucks and cars Icon_lol4 guess who had engine problems. Seriously I would run premium till its broken in burns better and engine runs cooler, no matter what the reports to contrary say.


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Scootaloot



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PostPosted: Sat Oct 15, 2011 3:37 am    Post subject: Reply with quote

Youtube is your friend!

Just type in "GY6" in the search window followed by the part your interested in ("jets", "valves", "fuel lines").


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89newbie



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PostPosted: Sat Oct 15, 2011 10:22 am    Post subject: Reply with quote

Igoritza wrote:
thanks 89newbie! great stuff!

I just got back from a ride. had a devilish increase in power - tried out of fun, some russian gasoline additive .. 60 mph, suck on that chinese people! Icon_lol4

I'm not gonna do that in the future, cause I guess it burns the shi* out of piston. Only tried with one litre (1/4 gallon)

I'm going to post some pics tomorrow, from Photoshop, Need new paintjob, cause I'm going to reinforce plastics. gonna need your opinion on the color combination.
Icon_rofl2 Vodka???


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Igoritza



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PostPosted: Sat Oct 15, 2011 1:26 pm    Post subject: Reply with quote

Icon_lol4, dunno how it's called, it says something like - "pojacivac benzina" which translates to: petrol enhancer

Was just hanging out with a friend, He has 2000 Scarabeo. it is also 125cc, but DAMN is that scoot fast! accelerates like crazy, goes over 120km/h.

Now I see how much could 125cc produce. it is a big pitty that GY6 in my scoot cant produce at least 80% of that power.

that's it, the tunning became necessary. I'm gonna crank it up for real.



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