Honda Shadow/Joker/SRX50 from 50cc -> big bore kit

This is the place to post your scooter builds; everything from stock Spree restoration to water-cooled drag bikes.

Moderator: Moderator

Post Reply
TheEnZo
Noob
Noob
Posts: 5
Joined: Tue Jan 17, 2023 4:34 am

Honda Shadow/Joker/SRX50 from 50cc -> big bore kit

Post by TheEnZo »

Ciao tutti,
Glad to meet you all.

I am more a Vespa guy, but i also have Honda Shadow 50cc - '97 restored but i need your help to manage to conversion to big bore kit.
Initial conversion to china big bore kit failed in ~ 1000 km due to soft seize.

New setup for this year:
- Pinasco kit with 47mm piston diameter.
- Pinasco head
- Ported intake case - already done previously.
- Leo Vince SP3 - Dedicated for Shadow/Joker 50cc - very rare i think. - mounted already
Question -
1.What carburator should i use and what main and pilot jet sizes ?
In this moment i have the original carburator that is very small.
2. What gear set should i buy for transmission, stock this scooter have a very short gear ration and the top speed at max RPM with the china 72cc was 60km/h. I want to go a little bit but , let say a top speed of 85km/h.

Thanks a lot.
Attachments
Picture 7.jpg
Picture 7.jpg (281.35 KiB) Viewed 2465 times
Picture 6.jpg
Picture 6.jpg (76.56 KiB) Viewed 2465 times
Picture 5.jpg
Picture 5.jpg (73.42 KiB) Viewed 2465 times
Last edited by TheEnZo on Mon May 22, 2023 2:11 am, edited 1 time in total.
User avatar
motormike
Moderator
Moderator
Posts: 5488
Joined: Wed Dec 29, 2010 10:58 pm
Location: Glasgow, KY

Re: Honda Shadow 50cc -> big bore kit

Post by motormike »

Here in USA, Honda never made a model called "Shadow" except in big motorcycles.
Your scooter is JDM. Sorry, can't help with info.
It would help if you will tell us the engine code.
RideRed
<Gyro S><MB5><Honda Navi><Helix><Sym Wolf><Yamaha Razz><Honda CH150 Deluxe>
"Live Large - Ride Small"
TheEnZo
Noob
Noob
Posts: 5
Joined: Tue Jan 17, 2023 4:34 am

Re: Honda Shadow 50cc -> big bore kit

Post by TheEnZo »

Hello,
Scooter is an autentic Honda product, is was sold also in USA with the name of Honda Joker SRX50 or SRX90. (50cc / 90cc ) - Made in Japan from what i know. Also mine is made in Japan , but there are few also made in Spain.
I am not to familiarly with Honda Scooters but the engine si similar to a Honda Dio 2 - 50cc.
Usually i buy parts for the engine and transmission that are made for Dio 2 - 50cc or Honda Bali 50cc.
There many copies of this scooter on the market made in Taiwan but all of them have 4 stroke engine vs 2 stroke on this one.

Couple of details that could help you to help me:
- vacuum actioned fuel pump
- mecanic oil pump for 2 stroke oil
- carburetor is Keihin PB12 or PB13 - with 2 stroke oil port above mixture screw and automatic cold start electrovalve

From my point of view the failure of china big bore kit was this small original carburetor that i tried to tune a lot and i have run with 97 main jet and 45 pilot jet on stock air filter box.
Usually the soft seizure appear when i let off the throttle ...

Now with this details i hope that somebody have some suggestions for me.
Attachments
Picture 10.jpeg
Picture 10.jpeg (53.81 KiB) Viewed 2445 times
Picture 9.jpeg
Picture 9.jpeg (56.77 KiB) Viewed 2445 times
Picture 8.jpg
Picture 8.jpg (126.57 KiB) Viewed 2445 times
Tunis

Re: Honda Shadow 50cc -> big bore kit

Post by Tunis »

Hello,

I also own a Honda scooter like yours but I must admit that your scooter is nicer than mine.
User avatar
Wheelman-111
Moderator
Moderator
Posts: 11319
Joined: Wed Oct 22, 2008 5:09 pm
Location: Deepinnaharta, Texas

Re: Honda Shadow 50cc -> big bore kit

Post by Wheelman-111 »

Greetings:

The red - on - Chrome scooter in the pics above appears to be a Chinese machine sold as the "Venice 150" among probably many other names. That is no Honda as far as I can tell. The only badging I could see in your pictures is stamped on the belt cover, which also looks like no Honda I know of. Honda does tend to place its name on cowls, saddles, etc. A close-up of that belt cover name could convince me otherwise.
Wheelman-111
Most of my money is spent on scooterparts. The rest is just wasted.
"ISO": '03 Vespa ET4 Malossi187 74MPH
Flash 9: 2001 Elite SR Contesta 72 ZX Tran, 9:1 Gears, Stock Airbox/Carb/Pipe 58.8 MPH
Punkin: 2010 Vespa/Malossi S78, 61MPH
SoftheartedLibra
Noob
Noob
Posts: 1
Joined: Sat Feb 25, 2023 1:37 pm

Re: Honda Shadow 50cc -> big bore kit

Post by SoftheartedLibra »

Wheelman-111 wrote: Sun Feb 19, 2023 10:21 am Greetings:

The red - on - Chrome scooter in the pics above appears to be a Chinese machine sold as the "Venice 150" among probably many other names. That is no Honda as far as I can tell. The only badging I could see in your best fat burner for men pictures is stamped on the belt cover, which also looks like no Honda I know of. Honda does tend to place its name on cowls, saddles, etc. A close-up of that belt cover name could convince me otherwise.
Yes I think you are right. Red scooter appears to be a Chinese machine to me also.
Last edited by SoftheartedLibra on Fri May 19, 2023 7:09 am, edited 1 time in total.
User avatar
Meatball
CB900F
CB900F
Posts: 2320
Joined: Sat Jun 04, 2016 10:45 am
Location: seattle

Re: Honda Shadow 50cc -> big bore kit

Post by Meatball »

Chonda
I need to find some new haters...the ones I have are starting to like me.
User avatar
Wheelman-111
Moderator
Moderator
Posts: 11319
Joined: Wed Oct 22, 2008 5:09 pm
Location: Deepinnaharta, Texas

Re: Honda Shadow 50cc -> big bore kit

Post by Wheelman-111 »

Greetings:

Quoth MeatBall:
Chonda
Tha's funny rat thar1 :)
Wheelman-111
Most of my money is spent on scooterparts. The rest is just wasted.
"ISO": '03 Vespa ET4 Malossi187 74MPH
Flash 9: 2001 Elite SR Contesta 72 ZX Tran, 9:1 Gears, Stock Airbox/Carb/Pipe 58.8 MPH
Punkin: 2010 Vespa/Malossi S78, 61MPH
User avatar
motormike
Moderator
Moderator
Posts: 5488
Joined: Wed Dec 29, 2010 10:58 pm
Location: Glasgow, KY

Re: Honda Shadow 50cc -> big bore kit

Post by motormike »

Wheelman-111 wrote: Sun Feb 19, 2023 10:21 am Greetings:

The red - on - Chrome scooter in the pics above appears to be a Chinese machine sold as the "Venice 150" among probably many other names. That is no Honda as far as I can tell. The only badging I could see in your pictures is stamped on the belt cover, which also looks like no Honda I know of. Honda does tend to place its name on cowls, saddles, etc. A close-up of that belt cover name could convince me otherwise.
If you google search the Honda Joker, you'll find images of said model that correspond with the OP's claim.
RideRed
<Gyro S><MB5><Honda Navi><Helix><Sym Wolf><Yamaha Razz><Honda CH150 Deluxe>
"Live Large - Ride Small"
TheEnZo
Noob
Noob
Posts: 5
Joined: Tue Jan 17, 2023 4:34 am

Re: Honda Shadow/Joker/SRX50 from 50cc -> big bore kit

Post by TheEnZo »

Hello all,

Below you will find couple of pictures that will prove that this is a genuine Honda scooter and not a Chinese clone.
Now couple of details about the build:
- Pinasco BBK with 48.5mm piston ( Since my kit was a NOS one found on shelf , i didn't get the rings for the piston and took me a while till i found them)
- Pinasco head that come with the kit.
- I have the original Keihin PB carburetor with 16mm diameter exist
- LeoVince SP3 exhaust.
- Original air box with original air filter.

I started the engine based only on the oil pump and no premix added.
Runs quite decent till it warm up and ones is warmed up is felling like low compression engine. ( Today i will measure the compression at cold and warm)
This Keihin PB come original with:
- 85 main and 35 pilot jet
Since i am not willing to destroy also this kit by soft seize i change the main to 98 and pilot to 45 , problem is that is running to rich at wot on standstill lots of smoke (unburnt fuel) and if I let idle more than 2 minutes it will flood and stop. Needle clip is in mid position , and in the moment is sound and run with no / less smoke between 1/2 and 2/3 of acceleration.

Any suggestion how to jet this carburetor in my situation.
Attachments
Picture 3 - engine view.jpg
Picture 3 - engine view.jpg (104.75 KiB) Viewed 2031 times
Picture 2 - case model and number.jpg
Picture 2 - case model and number.jpg (113.25 KiB) Viewed 2031 times
Picture 1 - vin number.jpg
Picture 1 - vin number.jpg (151.5 KiB) Viewed 2031 times
TheEnZo
Noob
Noob
Posts: 5
Joined: Tue Jan 17, 2023 4:34 am

Re: Honda Shadow/Joker/SRX50 from 50cc -> big bore kit

Post by TheEnZo »

Second part of the pictures attached below:
Attachments
Picture 7.jpg
Picture 7.jpg (102.47 KiB) Viewed 2031 times
Picture 6.jpg
Picture 6.jpg (130.99 KiB) Viewed 2031 times
Picture 5.jpg
Picture 5.jpg (188.28 KiB) Viewed 2031 times
User avatar
Meatball
CB900F
CB900F
Posts: 2320
Joined: Sat Jun 04, 2016 10:45 am
Location: seattle

Re: Honda Shadow/Joker/SRX50 from 50cc -> big bore kit

Post by Meatball »

Needs more air…bigger carb, intake and pod filter. Thats a much bigger slug than stock so it needs a supporting cast. Its breathing through a straw. Also need a temp gauge for tuning to avoid damage.
I need to find some new haters...the ones I have are starting to like me.
TheEnZo
Noob
Noob
Posts: 5
Joined: Tue Jan 17, 2023 4:34 am

Re: Honda Shadow/Joker/SRX50 from 50cc -> big bore kit

Post by TheEnZo »

Hello all,

For the moment i am stuck with a issue of flooding the spark in idle and then engine stops.
I drove it a little bit couple of times, then i took a compression test and at cold a i had 130psi. I decided to take the head gasket off, but was not notable, then I mill couple of times from the head till i get a squish off 1.1mm. This raised the cold compression to 150 psi.
Also i have change the followings:
* main jet from 98 to 92
* pilot jet from 45 to 42

It runs ok with with throttle from 1/4 to 1/2 i didn't pass 1/2 , and at constant 1/2 it brings me up to around 45-50km/h. If i stop the scooter keeping my hand in gas at 1/2 the spark plug will be brown. If i am coming to a stop and let idle for 1-2 minutes it will start to run lower and lower in rpm with lots of unburnt fuel coming from exhaust till engine stal. If this happens , then is very very hard to start it again, but very hard.
For the moment i order a chines copy of an Keihin PB 19mm style carburetor. ( I think my carburetor some how is bad)
Any other suggestions regarding this issue ?
What other carburetor should i buy , most likely i have to change the intake with different style on carburetor side ?
Post Reply