Good afternoon - new around here, but I hit on this topic on a mostly dead thread a couple days ago. Thought I'd start a new topic for general commentary/advice.
First thing - this is on a 2013 Vespa LX 50 4T 4 Valve. Full disclosure - bike had sat for the better part of the last 18 months up until about a week ago, so I am fully aware that this problem is probably of my own making.
Symptoms: Bike electric starts very well and idles down after about 60-90 seconds of running - first time, every time. No issues there. From a cold start I am able to accelerate the bike to full (albeit restricted) speeds - about 39MPH indicated on the speedo. After running it like this for about 3-5 minutes, there is a lag or a hesitancy for the bike to accelerate - but will eventually open up. But after this - 1-2 minutes running with the lag/hesitancy - the bike no longer wants to accelerate beyond 7-10 MPH indicated - essentially stalling at wide open throttle. I can get her to move forward ONLY with very deliberate, minimal jockeying of the throttle. I surmised that is was a fuel flow issue, so I started at the fuel - moved to the carb, and worked my way back from there. I don't suspect that the auto-choke has failed, as it does start well and idles down in a well mannered fashion - but I could be off-base in this assumption.
I have competed the following remedial actions to get her running right again:
- Removed old fuel, replaced with fresh 93.
- Ran with SeaFoam
- Cleaned large and small fuel jets (72 and 35 respectively)
- Inspected and tested the fuel line
- Inspected and tested the fuel tap vacuum line
- Replaced the fuel tap - was concerned that the diaphragm may have been compromised.
- Cleaned Air Filter
So far, nothing from the above has corrected the condition I am experiencing. Beginning to go a little greyer as a result.
If anyone has experienced similar symptoms and can recommend actions beyond what I have already completed, I would greatly appreciate it. For now - I'll just sit on my hands. I have other projects to attend to, but I'd love to get her up and running soonest. Many thanks, in advance!
-JP