ET2 Vespa build help - No top speed- Derbi Bullet
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Member
2004 Derbi Atlantis Bullet Piaggio engine et2
Joined: 14 Sep 2020
Posts: 13
Location: Ocean City Maryland
Mon Sep 14, 2020 3:57 pm quote
Hello Vespa enthusiasts! PLEASE HELP, I am doing something wrong... here is my set up: 2004 Derbi Atlantis Bullet - Vespa ET2 engine, 50cc stock cylinder, 17.5 Naraku electric choke carb with 34 pilot jet and 90 main jet, air brass restrictor still on , Malossi 2000 multivar variator with 5 gram roller weights, did not used the stiffer white contra spring since its 50cc, polini clutch with replaced green stiffer springs, stock air box with malossi red sponge inside, YASUNI R exhaust derestricted....and going only 46 miles an hour 🤦🏻‍♂️🤦🏻‍♂️🤦🏻‍♂️ PLEASE HELP!!!
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Granturismo 218
Joined: 04 Feb 2013
Posts: 6320
Location: NWAOK
Mon Sep 14, 2020 6:11 pm quote
You're drowning it in gas. Way too much main jet.
Member
2004 Derbi Atlantis Bullet Piaggio engine et2
Joined: 14 Sep 2020
Posts: 13
Location: Ocean City Maryland
Mon Sep 14, 2020 6:18 pm quote
What will your Jet suggestion be? Or just start lowering 88, 86, 84... I was advised to put From 5 gram to 6gram rollers and remove the brass metal between the air box and carb
Hooked
2003 Vespa ET2
Joined: 05 Apr 2019
Posts: 345
Location: Cambridge, MA
Tue Sep 15, 2020 6:13 am quote
try an 84 or smaller...take that brass restrictor out...

honestly you arent going to go much faster than 46 on a stock cylinder..maybe 50ish...how fast are you looking to go?
Member
2004 Derbi Atlantis Bullet Piaggio engine et2
Joined: 14 Sep 2020
Posts: 13
Location: Ocean City Maryland
Tue Sep 15, 2020 6:26 am quote
Thank you! I was advised from one of my scooter gurus to ad 6g rollers and remove the brass. Will let you know. I hope to get to 55miles, no more. If that doesnít work...I have a Polini small covered open air filter...will try that too. Then may start rejecting...
Hooked
2010 S50 Modified "Punkin"; 2003 ET4 150 "ISO"
Joined: 18 Feb 2017
Posts: 462
Location: Deepinnaharta, Texas
Tue Sep 15, 2020 6:29 am quote
Greetings:

The Holy Grail in 50cc scooters is to reach 50 MPH on 50ccs. You're pretty close as it is. Find a hill with a tailwind!
Member
2004 Derbi Atlantis Bullet Piaggio engine et2
Joined: 14 Sep 2020
Posts: 13
Location: Ocean City Maryland
Tue Sep 15, 2020 6:52 am quote
lol I am by the ocean on the east coast...no hills around here
Hooked
2003 Vespa ET2
Joined: 05 Apr 2019
Posts: 345
Location: Cambridge, MA
Tue Sep 15, 2020 7:36 am quote
that airfilter will take you there...you might need a jet larger than 84 though....do you have other jets just in case?
Member
2004 Derbi Atlantis Bullet Piaggio engine et2
Joined: 14 Sep 2020
Posts: 13
Location: Ocean City Maryland
Tue Sep 15, 2020 9:21 am quote
I have Polini kit 80-98...just tried polini filter with 90 brass on 44 miles 6g rollers🤦🏻‍♂️🤦🏻‍♂️🤦🏻‍♂️
Hooked
2003 Vespa ET2
Joined: 05 Apr 2019
Posts: 345
Location: Cambridge, MA
Tue Sep 15, 2020 9:28 am quote
try a smaller main jet with that filter...take the cover off that filter too...
Member
2004 Derbi Atlantis Bullet Piaggio engine et2
Joined: 14 Sep 2020
Posts: 13
Location: Ocean City Maryland
Wed Sep 16, 2020 7:02 am quote
Ok ...I tried yesterday many different combinations...open air filter or stock air box, 88,86 main jet, 5,6,7.2 gram rollers...I did end up with 5g , 86 main jet and stock box with brass on the carb 47 miles h With lowering the main jet size, everything seem to get better. I will try today 84 main jet. With lighter rollers I achieved the top speed of 47. Acceleration obviously itís not as good as behavior rollers six or 7.2 g. I will try today 84 main jet. With lighter rollers I achieved the top speed of 47. Acceleration obviously is not as good as the heavier rollers six or 7.2 g. I just wanna break that 50 miles an hour barrier thatís itÖ
Hooked
2003 Vespa ET2
Joined: 05 Apr 2019
Posts: 345
Location: Cambridge, MA
Wed Sep 16, 2020 7:29 am quote
definitely try the smaller main..

is it better at 7/8ths throttle that full or does it pull hard all the way?

that brass disc can act as a restrictor too...

I use a temperature gauge to assist in tuning...trying to keep the temps between 195-210 really helps
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Granturismo 218
Joined: 04 Feb 2013
Posts: 6320
Location: NWAOK
Wed Sep 16, 2020 7:42 am quote
Try a 78.
Member
2004 Derbi Atlantis Bullet Piaggio engine et2
Joined: 14 Sep 2020
Posts: 13
Location: Ocean City Maryland
Wed Sep 16, 2020 6:50 pm quote
Ok . Just want to thank everyone in advance...I in counter another problem- twice. My starter clutch came out twice while riding with about 25 ml/h ... you can imagine the sound that came out from the clutch grinding into the teeth of the pulley. I thought that I blew up the engine!!! Just figured out that I am missing 2 little washers to keep it in place. It starts now without problem but I am not gonna try anything until I Figure that out...Then my plan is to keep lowering the size of the main jet. What I noticed - when I removed the brass on the stock air box or the Polini open air... scooter runs worst and loses about 2 ml/h!?!?? Thanks again. Will keep you posted. But if anyone comes Up with an idea or wants to share, please do so!

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Member
2004 Derbi Atlantis Bullet Piaggio engine et2
Joined: 14 Sep 2020
Posts: 13
Location: Ocean City Maryland
Wed Sep 16, 2020 6:55 pm quote
Missing number 4 washers...

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Hooked
2003 Vespa ET2
Joined: 05 Apr 2019
Posts: 345
Location: Cambridge, MA
Thu Sep 17, 2020 5:52 am quote
your variator nut is not all the way down.... you need to tighten it more...that plastic fan is tagging the side cover.....also be sure you use threadlocker on that nut or it will spin off

let me know if thats as far as it goes
Member
2004 Derbi Atlantis Bullet Piaggio engine et2
Joined: 14 Sep 2020
Posts: 13
Location: Ocean City Maryland
Fri Sep 18, 2020 6:37 pm quote
Yes the variator nut got unscrewed when the starter clutch hit the pulley ....and the plastic. Now its not ...but I have to figure out how to keep it in place without sliding out.
Member
2004 Derbi Atlantis Bullet Piaggio engine et2
Joined: 14 Sep 2020
Posts: 13
Location: Ocean City Maryland
Tue Sep 29, 2020 9:11 am quote
Finally! I Reached 59 miles an hour😳😳😳 I didnít expect that much. The main problem was the belt. I have replaced the original Piaggio belt with better Malossi kevlar belt that also was a Little longer. Assuming that this is better, opposite It made things worse after I found out I swapped and put the original Piaggio belt.

My final set up is (Will start with parts are replaced): 84 main jet, 34 pilot jet, Malossi 2000 Multivar (tried rollers from 4g to 7.2) ended up with the 7.2 for quicker acceleration, polini clutch with green springs, Yasuni R Black edition.

Stock: 50cc, Airbox with red Malossi sponge, Brass air restrictor left on the 17.5 Naraku carb... For some reason itís running better when the restrictor is on, stock contra spring on the clutch.

With this set up Iím doing 50-55 miles steady. I am at sea level.

My goal was to break 50, after I did 59 with 5 g rollersÖ I put the 7.2 g rollers and acceleration it so much better. I think Iím gonna put all the Fossett covers and enjoy it nowÖ Done with the tuning for now... until the Stage 6 MK2 🤣🤣🤣

Thank you all for the help and support!

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Member
2004 Derbi Atlantis Bullet Piaggio engine et2
Joined: 14 Sep 2020
Posts: 13
Location: Ocean City Maryland
Tue Sep 29, 2020 9:15 am quote
I forgot to mention, the bendix was broken replaced and it was all good.

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Member
2004 Derbi Atlantis Bullet Piaggio engine et2
Joined: 14 Sep 2020
Posts: 13
Location: Ocean City Maryland
Tue Sep 29, 2020 9:16 am quote
Night shot

72A58ABE-09B8-46E0-AD9E-B2308398819E.jpeg

Member
2004 Derbi Atlantis Bullet Piaggio engine et2
Joined: 14 Sep 2020
Posts: 13
Location: Ocean City Maryland
Tue Sep 29, 2020 9:18 am quote
Way too many pictures if anyone needs a picture of the parts I got let me know. Thank you again!

14DDE1FB-EFBF-46E1-BAB7-CDC65BBEA943.jpeg

Hooked
2003 Vespa ET2
Joined: 05 Apr 2019
Posts: 345
Location: Cambridge, MA
Tue Sep 29, 2020 10:49 am quote
hey there!...great job!....that pipe is the bees kneez...great pics
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