OP
UTC

Member
PX210
Joined: UTC
Posts: 12
Location: Scotland
 
Member
PX210
Joined: UTC
Posts: 12
Location: Scotland
UTC quote
I recently completed a 758 mile round trip in the UK. My GTS ran great and as I was about 20 miles from home, it started to pulse/ surge at low speeds. Give it the beans and she was smooth.
Gave my friend a lift from Glasgow, and again at low speeds she idled at the lights, then died, off and on again and away we went. Someone at a rally told me it was the variator, well I've just changed it , brand new pulleys inner and outer. Took her for a spin and still pulses or surges. Help required please 😳🤔🤔🤔🙄
@steelbytes avatar
UTC

Veni, Vidi, Posti
2019 GTS300 HPE SuperTech 66,000km
Joined: UTC
Posts: 6796
Location: Batmania aka Melbourne, Australia
 
Veni, Vidi, Posti
@steelbytes avatar
2019 GTS300 HPE SuperTech 66,000km
Joined: UTC
Posts: 6796
Location: Batmania aka Melbourne, Australia
UTC quote
Just too be clear, is it struggling when idle AND when riding at low speeds (but still fast enough that they clutch hasn't disengaged) or is it just one of these two scenarios?
@caschnd1 avatar
UTC

Grumpy Biker
1980 Vespa P200e (sold), 2002 Vespa ET4 (sold), 1949 Harley-Davidson FL
Joined: UTC
Posts: 5573
Location: Sparks, Nevada, USA
 
Grumpy Biker
@caschnd1 avatar
1980 Vespa P200e (sold), 2002 Vespa ET4 (sold), 1949 Harley-Davidson FL
Joined: UTC
Posts: 5573
Location: Sparks, Nevada, USA
UTC quote
When the engines revs vary up/down at low throttle (idling at a stop, or cruising under low throttle conditions) the first thing I'd look for is an intake leak. Perhaps a crack in the rubber tube connecting the throttle body to the engine. Low throttle conditions present the highest vacuum in the intake manifold between throttle body and engine and small leaks can present themselves. This causes the engine revs to seek up/down.

-Craig
@miguel avatar
UTC

Veni, Vidi, Posti
2009 GTV250 (Gone), 2003 Inder trailer (also gone), 2001 BMW R1100RT
Joined: UTC
Posts: 5707
Location: Santa Cruz California
 
Veni, Vidi, Posti
@miguel avatar
2009 GTV250 (Gone), 2003 Inder trailer (also gone), 2001 BMW R1100RT
Joined: UTC
Posts: 5707
Location: Santa Cruz California
UTC quote
Could also be a dirty/clogged air filter. Whenever my small tractor starts surging at idle, it invariably is cured by changing or cleaning the air filter.

Miguel
OP
UTC

Member
PX210
Joined: UTC
Posts: 12
Location: Scotland
 
Member
PX210
Joined: UTC
Posts: 12
Location: Scotland
UTC quote
G'day,
I'm sure it's a throttle issue, when it starts up, she sometimes idles quite well, most times though she seems to struggle on idling. Another forum , person said I should clean the throttle body and especially clear a hole that controls slow idle. I'm still in the dark with these 4 stroke machine and their complex build, give me a PX any day.
Tomorrow, I'll remove the air filter and put in a new one and check for any splits near the ECU.
I'm allowed to say G'day as I lived in OZ for 24 years!!!!! :
Cheers
@guzzi_gal avatar
UTC

Ossessionato
Gigi, '13 GTS 300ie Touring
Joined: UTC
Posts: 2874
Location: Phoenix, AZ.
 
Ossessionato
@guzzi_gal avatar
Gigi, '13 GTS 300ie Touring
Joined: UTC
Posts: 2874
Location: Phoenix, AZ.
UTC quote
caschnd1 wrote:
When the engines revs vary up/down at low throttle (idling at a stop, or cruising under low throttle conditions) the first thing I'd look for is an intake leak. Perhaps a crack in the rubber tube connecting the throttle body to the engine. Low throttle conditions present the highest vacuum in the intake manifold between throttle body and engine and small leaks can present themselves. This causes the engine revs to seek up/down.

-Craig
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