OP
@badblackbishop avatar
UTC

Member
2020 GTS 300 HPE Touring
Joined: UTC
Posts: 13
Location: Sacramento California
 
Member
@badblackbishop avatar
2020 GTS 300 HPE Touring
Joined: UTC
Posts: 13
Location: Sacramento California
UTC quote
Two days ago I was on my 2020 Vespa GTS 300 HPE Touring riding on California Highway 580 eastbound when the throttle got stuck completely open. Because it was night time I did not want to lose my lights (and for other reasons) I used the kill switch once I was on the shoulder. I called AAA and had it towed to my mother's house where I am able to work on it. In the morning I inspected the throttle cable and it's components and noticed many of them were quite dirty (I just made it passed 30,000) and after carefully cleaning and lubricating the throttle cable at various points it no longer stuck.

Once the throttle cable issue was resolved I started the maintenance that I had originally planned to do, change the belt, rollers and oil. While changing the rollers I noticed that several of them where in terrible shape, in fact the worst I had ever seen. I have attached a picture of them for your viewing pleasure. I was wondering if using the kill switch caused this serious damage to the rollers and does using the kill switch damage the engine?

The reason I ask is that after doing the maintenance I took my Vespa for a test drive and discovered that it would not go faster then 42 mph and I had my check engine light on. After breaking out my code reader I learned that it was the O2 sensor that was producing the error code. I was wondering if a bad O2 sensor would cause the dramatic reduction in speed and did using the kill switch cause the problem.

This is only the second issue I have ever had with my GTS 300 the first issue was the Immobilizer antenna going bad and that was a real simple fix. Hopefully this will be the same.
Rollers
Rollers
@motovista avatar
UTC

Veni, Vidi, Posti
GT 2.4
Joined: UTC
Posts: 8741
Location: Watts in OK
 
Veni, Vidi, Posti
@motovista avatar
GT 2.4
Joined: UTC
Posts: 8741
Location: Watts in OK
UTC quote
At least one of those appears to be a Polini roller weight. What weight and size are they and are they in a stock HPE variator? What does the variator look like? Based solely on the appearance of the rollers, I would have a good look at the tracks of the variator and likely consider replacing it. The wear marks on them are very unusual, in terms of the chunk that was worn off a couple of them. Are the rollers the same weight or did someone alternate two different weights?

Using the kill switch won't affect the rollers. And it definitely won't do that. I've broken a speedo cable, zip tied the throttle so it was mostly open, and used the kill switch when I didn't want to run into the back of cars. It gets you home, and doesn't affect the rollers.

the O2 Sensor won't affect your top speed. The ECU doesn't pay attention to it after 6K rpms.

Have you ever run it very low on oil?

If your throttle cable is sticking and you needed to oil it to get it to work again, you likely should replace it. There's a good chance that the part that stuck frayed the cable, and it might let go completely next time. Has the cable already been replaced? It sounds like this is either a flood bike, or the cable was replaced by someone who didn't have the patience to route it properly. Is it a salvage title bike?
⚠️ Last edited by Motovista on UTC; edited 1 time
@steelbytes avatar
UTC

Ossessionato
2019 GTS300 Supertech E3 55,000km
Joined: UTC
Posts: 4918
Location: Batmania aka Melbourne, Australia
 
Ossessionato
@steelbytes avatar
2019 GTS300 Supertech E3 55,000km
Joined: UTC
Posts: 4918
Location: Batmania aka Melbourne, Australia
UTC quote
Wow those rollers! Sure i usually have some minor flat spots by 10,000km but ... Suspect it cracked and broke rather than wore

Previously I've unplugged my o2 sensor and still ridden at over 100kph. (If you do this it will idle high).

And the throttle cable ...

Have you been letting Gremlins ride you scoot?
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