Modern Vespa

I have fitted a malossi 172 kit on my vespa T5 and now test riding it and trying to get the the right jet in it. 120 main jet. Standard carb. Simonini racing exhaust. Timing standard. NGK B9ES spark plug. Test ride 1. Ride it for 30 minutes then cut it off to check to the spark plug. Video of when starting up the scooter after checking the plug.https://youtu.be/U6JOogz4Ok8

Plug chop should be done at a single sustained throttle position. For example try WOT in 3rd and see what it looks like. Then you know which throttle position needs work.

Looks really slow, like jetting is lean.

Id expect it to ride faster than you are in the video.

Not sure what you mean Bud. I was told to ride around to get it hot so i did for 30 mins then ride at 40 mph then switch off the engine then chack the plug.

I got a 120 main jet in it at the moment. I have 118, 120, and a 125 main jets to play around with. I tried it with 125 yesterday but it ran shit and with the 122.

I forgot to add the mixture screw is two turns out

Holding it even at 40 mph was holding it in a single throttle position. Without marking throttle position you don't know which one.

Here's a little reading.

The Plug Chop Thread

Yeah I don't think it's just your main jet… it just seems lean from setting off to you accelerating…

It's like it's struggling to get up to speed.

First off, Simoninis are shit. Even the stock T5 exhaust is better. I run mine with a SIP XL and a 125 main. Every other jet is stock T5…

ok il get changed my exhaust. Any other exhaust you recommend.

Needs a bigger pilot jet. 55/100, probably.

I will change it tomorrow. Thank you.

All are standard apart from the 120 main jet

Filter standard. No heart drilled out

It rides ok from 30 upwards but less it's like it's abit in high revs. I will add more videos of the test ride when I was stuck behind a slow driver doing 20 to 25

The little jet 50/100 needs to be a 55/100. Problem is they don't sell them anywhere that I know of.
If you buy one of these
https://beedspeed.com/products/carburettor-jet-dellorto-9892-long-idle-jet?variant=10568184856619
And cut 9 mm from the top and saw in a new screwdriver slot, it will work.

Edit: That filter is drilled. The un-drilled ones have no holes in the heart area.

I found one in my old bits but I will see if it's the same size later

Can see the 55 but not the 100. If it's a 55/160 it will be worse than the 50/100.
If it is a 55/100 then great 👍

it's a 55/100. I have cut it to the size you said and went out for a ride. I video it with better audio. I will upload it soon.

Todays test ride 1. Stripped and cleaned carb. 120 main jet. havent changed the exhaust yet waiting to get the money togeather to buy one. Audio is better in this video

Test ride 2 9-10-23. Cut to size and installed little jet 55/100 and went on a test ride.

Lower throttle now sounds good. Definately not weak but not far away from correct. Spluttering at the transition but don't worry about that for now.

Next test. Wide open in second gear. This will check the main jet. Put in a 122 main jet. Check that it doesn't rev out fully and has a nice wet splutter. If not up the size to 125 (and so on) and try again. Once you get this wet splutter at wide open in second gear we will know what to do next.

Ok I will change the jet to 122 then go back out on it and full throttle in 2rd then change the jet to 125 and go back out and test it again. I will video it so you can hear it. I haven't got any more jets the highest I've got is 125 but I will order some more. The timing is standard is that ok or does it need changing. Someone said to change it.

Went to go out to test ride it but had problems starting it. Had problems before. When I put the malossi kit on over a week ago I changed the fuel pipe. Today I had the tank out to check if the fuel tape filter was blocked but it seems ok but the pipe looked like it kinked. I check the to see how long the pipe was and it was 27 3/4 of an inches long. Tomorrow I will put it back together and go on the test ride.

After putting the tank back it wouldnt start. I tested the spark plug and found it was no good. Thats two plugs ive used in the last two week.
I had another plug and put that in and it started so i went on a test run.
Main jet changed to a 122.
After the traffice light and not long after turning left I put it into full throttle in 2rd.
I did the same in the same places two times in the video.

That's the colour of the plug after riding around town for 25 minutes. BR8ES. 122 main jet

Its clearly too rich on 122mj but did you try 125mj? Which jet size makes it full splutter decides what to do next.

No I'm going to put a 125 in shortly then test ride. I will order two more jets after if need too

I doubt you will need any bigger jets. The 122 sounds rich already but just want to check with the 125.

Ok bud il have a coffee then il get into it.

Only interested in the wide open in 2nd gear. With the 125mj it's going to be really rich at mid rpm. Ride through that rpm as quickly as possible.

125 jet full throttle in 2rd.
I cut the vidoe down.
I hold up to figgers when i do it the first time full throttle in 2rd then i do it not long after when i turn left.
Sound is low. The lens with the mic muffer have broke so i have to use another one.
It ran crap with the 125 jet in it.

Spark plug after the test ride with a 125 jet

Well that confirms it. Your mj should be 120 at the most. Try 118 and suddenly open the throttle full, as the power starts pulling. See how it feels. If it bogs (pauses before going) it might need bigger or a different atomiser.

ok I will try it tomorrow bud

For the benefit of the readers, how did this go?

Hi bud sorry I haven't been out in it since down to health problems but I will be out on it next week so I will update things on here. I haven't forgot about the site. All info does help others so I always come back on here to let everyone know.

Update. Im back I am available to sort it out now. I went out yesterday but the wind was bad on the mice so the video I did was crap. The scooter seem to run ok with the 118 main jet but it just feels abit like it was in high revs a little. When I come back I did an oil change but I found out the oil what come out was very low so I put new oil in. I haven't seen any oil leaks over the months so it didn't leak on the floor. I started it up and I noticed it's smoking more so it's sucking oil into the casing where the crank is I bet so I've ordered a new gasket set and I will change it very soon. I only put a new sip gasket set on last year but I don't think I used gasket sealer so I have ordered some to use this time.

I went round the block today to get my clutch setting right. Smoking a bit when I started out witch I expected. It's not boging when I pull the throttle back. Can't get the clutch set up right tho. I put a cosa 2 clutch in but I can't get it right. I will put up another post about that problem. Ordered the gasket set so hopefully I will have them by the weekend then il get it done.