I'll do it tech support style first,
2012 Vespa GTS 300 SS
Dr Pully Sliders at 12k miles
Belt change at 12k miles
up to date oil changes
Akropovic Exhaust at 14k miles "does not backfire under normal riding"
Mike's Airbox Mod at 17k miles
I am a bigger guy, 350lbs.
Bike has almost 20k and has always performed flawlessly. Went on a 120 mile ride yesterday, cruising 55 mph through the country, stopping every 15-25 miles to check out little towns, take pictures and what not, not a demanding ride by any stretch of the imagination.
Twice during the ride the check engine light popped on for 5-7 seconds and then went off, never ran funny or anything. This happened a bit around 16k miles, turned out to be one of my battery posts was loose.
The last 20 miles though things went weird. Bike started shuddering on take off, smooth, fast, didn't matter. Around 7 mph the bike would shudder hard then smooth out.
Also, during that 20 miles, the bike started backfiring violently anytime I was decelerating. Now with the pipe, I've always been able to leave a tiny bit of gas during deceleration and get a little pop or two if i didn't let go of gas all the way. But this was anytime i tried to coast it started popping VERY loud, enough that I was worried it was hurting something. So I kept some gas on to do a bit of a powered stop and keep the thing from barking so loud.
Right before the 20 mile problem there was a 5-10 min section stuck on 2 blocks of stop and go, got the bike hot enough to turn the fans on a few times. But it always cooled back down and stopped, then later when i was having the problems, I was moving fast enough to keep the temp down.
I've seen some mention of brake clean for the shudder, and possible needing the clutch roughed up. Could that clutch issue somehow be causing the back firing though?
Curious as to what people think?
Thanks for the listen.
UM... Road trip picture from the ride so its not all doom and gloom.