O-tuning V5A for my elder son (hot french recipe inside)
Posted: Tue Mar 31, 2015 9:41 pm
Hi folks back to the bench with a new project: building my elder son first vespa. He is close to 15 and really deserves her. I mean it. A nice boy, brilliant at school, no drug nor R'nR; I found a V5O in a rather fecking condition but with the precious V5. Complete resto and safe full hydraulic conversion scheduled.
He wants her in a deep black rendition.
For the engine I found a 50 with a 4 gear box. No sign of bad treatment but obviously engine has been previously upgraded with a kit (case ported).
My goal is to give him a close to standard engine with more guts and fun to ride. So let's go for a o-tuning session. No kit or unaffordable special tuning part. French pig became awful mutterficker, so discretion and original specification are much appreciated....
Standard timings are:
T: 94°
E:134°
I: 90+40= 130°
guess what? Those timings are very close to those on a standard Solex: A pain....
with a 2,5mm packer I'll get:
T: 114°
E: 158° with a small grinding amount (1,5mm up)
BD:22°
I: 150°
very conservative timings indeed. But quite enough for a newbie on the vespa scene.
I keep the SHB 16/16, standard air filter and a banana exhaust. Siproad banana is too expensive and high Rpm tuned to match a so small and torqueless engine.
delivery service:
a standard 38,4mm barrel with its 2 obstructed main ports and exhaust as small as your thumb tip. Broouuu, that sucks a lot...
Barrel is ready for a boost port conversion. The 2 ring pegs leave only place for one large port, no way to get 2 boost ports there.
beginning of the digging job:
exhaust port cleaned up a bit:
Slightly nicer:
A bit more difficult: digging a boost port each side of the exhaust
Keep in mind that the thickness of the wall is 5,5mm no more....
Moviluty is your friend:
crank obviouly finely balanced!! a shame.
After a little operation it gives 105-45=150°
This pic shows perfectly the main prob with this small bore cylinder: a huge step is facing the gaz flow in its way up to the transfert: Pas bien du tout!
better!
slowly things are looking better:
last step:
He wants her in a deep black rendition.
For the engine I found a 50 with a 4 gear box. No sign of bad treatment but obviously engine has been previously upgraded with a kit (case ported).
My goal is to give him a close to standard engine with more guts and fun to ride. So let's go for a o-tuning session. No kit or unaffordable special tuning part. French pig became awful mutterficker, so discretion and original specification are much appreciated....
Standard timings are:
T: 94°
E:134°
I: 90+40= 130°
guess what? Those timings are very close to those on a standard Solex: A pain....
with a 2,5mm packer I'll get:
T: 114°
E: 158° with a small grinding amount (1,5mm up)
BD:22°
I: 150°
very conservative timings indeed. But quite enough for a newbie on the vespa scene.
I keep the SHB 16/16, standard air filter and a banana exhaust. Siproad banana is too expensive and high Rpm tuned to match a so small and torqueless engine.
delivery service:
a standard 38,4mm barrel with its 2 obstructed main ports and exhaust as small as your thumb tip. Broouuu, that sucks a lot...
Barrel is ready for a boost port conversion. The 2 ring pegs leave only place for one large port, no way to get 2 boost ports there.
beginning of the digging job:
exhaust port cleaned up a bit:
Slightly nicer:
A bit more difficult: digging a boost port each side of the exhaust
Keep in mind that the thickness of the wall is 5,5mm no more....
Moviluty is your friend:
crank obviouly finely balanced!! a shame.
After a little operation it gives 105-45=150°
This pic shows perfectly the main prob with this small bore cylinder: a huge step is facing the gaz flow in its way up to the transfert: Pas bien du tout!
better!
slowly things are looking better:
last step:
