OP
@daz9tt avatar
UTC

Hooked
T5 Classic 152. GTS 300ie Supersport.
Joined: UTC
Posts: 199
Location: Northumberland, UK.
 
Hooked
@daz9tt avatar
T5 Classic 152. GTS 300ie Supersport.
Joined: UTC
Posts: 199
Location: Northumberland, UK.
UTC quote
Hi all. My GTS 300 has developed a rattle noise and loses power. The noise is constant from idle all up through the rev range.
The power feels quite normal on acceleration but now tops out at 61mph and feels like its hitting the rev limiter, with some hesitation felt.

I had a remap done early last year at Tasso in Edinburgh and it will hit a genuine 80mph on GPS easily, so this is way down at top end.

My mechanic has checked belt/rollers. Valve clearances ok and no play on big end and timing marks set correctly.
However, when revving his strobe shows the timing all over the place.
He's going to take cam out today to check but wondering if anyone has had same or any idea what to look at?

Thanks.
@steelbytes avatar
UTC

Veni, Vidi, Posti
2019 GTS300 Supertech E3 60,000km
Joined: UTC
Posts: 5701
Location: Batmania aka Melbourne, Australia
 
Veni, Vidi, Posti
@steelbytes avatar
2019 GTS300 Supertech E3 60,000km
Joined: UTC
Posts: 5701
Location: Batmania aka Melbourne, Australia
UTC quote
rattle at idle on/off the stand?
rattle revving on the stand (w abs turned off)?
rattle on left near cvt?
rattle on right near water pump?
rattle under seat storage / pet carrier?
does the rattle change pitch or volume?
did it develop suddenly or did it gradually appear and get worse?
can you make a video of it rattling?
UTC

Member
Joined: UTC
Posts: 33
Location: Belgium
 
Member
Joined: UTC
Posts: 33
Location: Belgium
UTC quote
Does your GTS has a decompression valve in the cyl-head?
Another issue that causes the symptoms, like 'timing all over the place', and stalling at high revs, is a defective crankshaft sensor, but that doesn't has a rattle as a result.
Forum member supplied image with no explanatory text
OP
@daz9tt avatar
UTC

Hooked
T5 Classic 152. GTS 300ie Supersport.
Joined: UTC
Posts: 199
Location: Northumberland, UK.
 
Hooked
@daz9tt avatar
T5 Classic 152. GTS 300ie Supersport.
Joined: UTC
Posts: 199
Location: Northumberland, UK.
UTC quote
SteelBytes wrote:
rattle at idle on/off the stand?
rattle revving on the stand (w abs turned off)?
rattle on left near cvt?
rattle on right near water pump?
rattle under seat storage / pet carrier?
does the rattle change pitch or volume?
did it develop suddenly or did it gradually appear and get worse?
can you make a video of it rattling?
Visited my mechanics workshop today and unfortunately he has various bits off the enging so cannot run it to make a video.
He's ordered a rocker arm as there was markings on it so suspects it could have something to do with it.
If not that then will continue trying to diagnose.
@jakem avatar
UTC

Addicted
Vespa Sprint Sport S 125cc
Joined: UTC
Posts: 661
Location: Brighton, England
 
Addicted
@jakem avatar
Vespa Sprint Sport S 125cc
Joined: UTC
Posts: 661
Location: Brighton, England
UTC quote
Not completely relevant to your query, but how much power did you gain with the remap? Was the remap in addition to other engine mods?
OP
@daz9tt avatar
UTC

Hooked
T5 Classic 152. GTS 300ie Supersport.
Joined: UTC
Posts: 199
Location: Northumberland, UK.
 
Hooked
@daz9tt avatar
T5 Classic 152. GTS 300ie Supersport.
Joined: UTC
Posts: 199
Location: Northumberland, UK.
UTC quote
JakeM wrote:
Not completely relevant to your query, but how much power did you gain with the remap? Was the remap in addition to other engine mods?
An extra 3-4hp. Doesn't sound much but it makes a difference. I wanted some extra punch at top end for overtaking vehicles that sit at an awkward speed. Standard can keep up but not get past.
So happy with result.
Only mods were DR Pulley rollers and opened up the air filter box to fit a sock filter over the intake.
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