No power??

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muffster
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Posts: 116
Joined: Sun Jul 24, 2011 5:41 pm
Xbox live gamer tag: muffinator233
Main scooter: LI 125 S3
Location: Bradford
Contact:

Evening folks.
iv'e been struggling to get my S3 running properly since rebuilding it. It's a 125/175, 22m jettex. At first it was a nightmare to re-start again after it had been running. But when started it would tick over nicely and ran ok as i rode it up and down the road without any flat spots.
Now after much fettling, 130 jet, air scoop off, air filter out, the scoot starts perfectly first kick evey time and ticks over nicely on the stand. But when i ran it up the road it had no power at all and it died.
So iv'e gone from poor starting but rode well, to perfect starting but runs dreafully with no power!
So it's left me completly puzzled, any offers on where i'm going wrong please folks?

Many thanks.

Muffster.
WINTERMODEL150
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Posts: 436
Joined: Sun Oct 17, 2010 5:31 pm
Main scooter: lambretta ld auto
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Hi,can you give us some more info please /what exhaust you running?,ignition set to?points or electronic?old engine or re-built?,150 or carb?

Regards

Dean
bristolmod
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Posts: 1741
Joined: Wed Jan 07, 2009 8:42 am
Main scooter: Lambretta TV175 S3- what else!
Location: Bali-Hai bar, Locarno Ballroom Bristol, 1967!- mines a Brown Split!!
Contact:

Main jet at 130 is way too big- you need to be around 118/123 dependant on tune, exhaust etc etc

Also, Jettex's are notorious for either working OK or not...........

I was running a 22mm Jetex on a standardish TV175 S3- ran well for a couple of years then started playing up for no reason- no amount of cleaning or swaping Jets etc would cure it so went back to an old 20mm Delly and it runs even better now!

Chris
Scootering since 1968.
muffster
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Posts: 116
Joined: Sun Jul 24, 2011 5:41 pm
Xbox live gamer tag: muffinator233
Main scooter: LI 125 S3
Location: Bradford
Contact:

More info. sorry folks, i should know better.
Ok, its a 175 conversion. 12v electrics. fast flow rear exit tap, using a filter. Rebuilt engine with all new seals, bearings etc. GP crank. Standard exhaust. On advice i changed the jets for a 50 and 130, also swapped the atomiser for a larger one. Afraid im not educated enough to elaborate on 'larger'. Using a 4% mix as per the book. I set the timing at 30mm from TDC. I cant remember what that equates to in degrees, and checked it with a strobe. 22mm Jettex. I am missing the clamp which connects the downpipe to the exhaust.

Hope this helps.

Many thanks.

Muffster.
lammy mark
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Posts: 65
Joined: Thu Apr 02, 2009 11:32 pm
Main scooter: Series 3 Special s type rep.
Location: Belfast
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As Bristol Mod has said, 130. Main is way too big. Drop it down to a 118 and see how that goes. I had a similar episode a while back. My personal experience with Jetex is they are hit or miss. I run my series 2 150 with one no problems, but i have " launched" one or two up the garage in the past lol.
bristolmod
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Posts: 1741
Joined: Wed Jan 07, 2009 8:42 am
Main scooter: Lambretta TV175 S3- what else!
Location: Bali-Hai bar, Locarno Ballroom Bristol, 1967!- mines a Brown Split!!
Contact:

yep- go back to a standard setting and work from there:-

Main 118
Pilot 45
Starter 50
Atomiser 5899/2
slide 7895/1 (could be 7895/2)
Airscoop- put back on!
Filter- use one!

Let us know how it goes

Chris
Scootering since 1968.
muffster
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Posts: 116
Joined: Sun Jul 24, 2011 5:41 pm
Xbox live gamer tag: muffinator233
Main scooter: LI 125 S3
Location: Bradford
Contact:

I know what you mean, i certainly feel like launching this one!! I'm not sure wether i would be just better off buying a better quality carb to get it running but i would like to get this one working and then understand why its giving me headache.
Anyway, i will put the original jets back in and see what happens. Not sure what size the atomizers are though, i don't think they have any markings on them. (will soon find out)
And removing the air scoop definately improved starting!?
I will report back later on today.

Thanks fellas.

Muffster.
Daggs
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Location: Addington Kent
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bristolmod wrote:yep- go back to a standard setting and work from there:-

Main 118
Pilot 45
Starter 50
Atomiser 5899/2
slide 7895/1 (could be 7895/2)
Airscoop- put back on!
Filter- use one!

Let us know how it goes

Chris

I've done the same upgrade as you Muffster. Except i used a Clubman exhaust. I have the same set-up as Bristolmod has posted but with a 122 main.
You also should fit a clamp to the exhaust/u-bend. Some people experience fuel flow problems with an inline filter.
Jetex get a lot of bad press, i'm not sure it's all justified. Once i've got them set right they've been fine and i've used them on three or four of my own scooters.
Timing should be 19* BTDC.
muffster
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Posts: 116
Joined: Sun Jul 24, 2011 5:41 pm
Xbox live gamer tag: muffinator233
Main scooter: LI 125 S3
Location: Bradford
Contact:

Ok all original jets back in, air filter in and air scoop on and it's sthe same.
Starts and ticks over fine but has no power under load when i took it up the road.
So i'm at a loss to explain why when i struggled to start it, it ran fine. Now it starts perfectly but won't run?? :wtf:

Iv'e got an in line filter in as a precaution and it has collected a lot of crap, and it did run fine with it on a couple of weeks ago.
What next, i'm clueless.

Muffster.
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RICSPEED
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Posts: 3334
Joined: Sun Jan 04, 2009 11:30 pm
Location: YORK

check the flow rate from that rear exit tap as there have been probs reported
Its in bits scooter club: www.facebook.com/groups/132415046859320
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