I thought I'd update this thread with what worked.
The problem with starting was not caused by it being too rich, it's caused by it being too lean. I increased the pilot jet size and I haven't had a problem since. My jetting is now very close to a TV175 Series 3:
50 pilot
50 choke
108 Main (I may increase this to 110 after a plug chop)
5899-2 atomiser
5914-1 slide.
I'm running the kit throught an unmodified '63 airbox, with a GP scoop. Exhaust is a KBR clubman.
It's reasonable to assume it's too rich when it smells of petrol and there's petrol dripping out the carb as you're kicking it over for the umpteenth time, but the problem is actually it being too lean - fuel is not being burnt and is being sent back and flooding the carb.
Hopefully this will help someone who is experiencing the same problems - I certainly read a few threads when I was trying to sort mine. It's not taken more than two kicks to start it now, whether it's hot, warm or cold.
Lambretta jetting help please! 175 Li
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EddieStone
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- Main scooter: Lambretta Li 150
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EddieStone
- registered user
- Posts: 433
- Joined: Mon Aug 17, 2015 4:13 pm
- Main scooter: Lambretta Li 150
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Another update, finally feels like a scooter. First of all I fitted electronic ignition, the timing is strobed to 19 degrees.
It's been running really rich at low revs, the symptoms of which are hard to describe. 'Four-stroking' is what it's usually called, a better description is that it sounds like machine gun fire, accompanied by misfiring, general 'sounds like a box of spanners' and a tendency to have to rev it to get it to ride in town. Very unpleasant.
So I replaced the 50 pilot with the 48 and that made it better but not much. Put a 45 pilot in and that was better but not by much. Had a big effect on the mixture settings though.
Then I put in a leaner slide - one with a bigger cutout on the back of it. This completely cleaned it up and it really runs a treat. It's utterly transformed. Carb settings are now:
45 pilot
50 choke
118 Main (Did a plug chop WOT and it was a touch lean so i may increase this to 120 when i can find the jet)
5899-2 atomiser
5914-2 slide
I'v updated the thread because there isn't a lot of info of 175's with an Sh1/20, it runs nicely and I'm happy with the performance so far. Kit was cheap, but setting the carb is not easy. Hopefully this helps someone.
It's been running really rich at low revs, the symptoms of which are hard to describe. 'Four-stroking' is what it's usually called, a better description is that it sounds like machine gun fire, accompanied by misfiring, general 'sounds like a box of spanners' and a tendency to have to rev it to get it to ride in town. Very unpleasant.
So I replaced the 50 pilot with the 48 and that made it better but not much. Put a 45 pilot in and that was better but not by much. Had a big effect on the mixture settings though.
Then I put in a leaner slide - one with a bigger cutout on the back of it. This completely cleaned it up and it really runs a treat. It's utterly transformed. Carb settings are now:
45 pilot
50 choke
118 Main (Did a plug chop WOT and it was a touch lean so i may increase this to 120 when i can find the jet)
5899-2 atomiser
5914-2 slide
I'v updated the thread because there isn't a lot of info of 175's with an Sh1/20, it runs nicely and I'm happy with the performance so far. Kit was cheap, but setting the carb is not easy. Hopefully this helps someone.
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EddieStone
- registered user
- Posts: 433
- Joined: Mon Aug 17, 2015 4:13 pm
- Main scooter: Lambretta Li 150
- Contact:
Yeah, nice to get there in the end as winter draws near!
There's a bit of a splutter around 1/3 throttle so maybe a slightly leaner atomiser is needed, but it's great as it is. It'll get me to Woolacombe
There's a bit of a splutter around 1/3 throttle so maybe a slightly leaner atomiser is needed, but it's great as it is. It'll get me to Woolacombe