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UTC

Member
2012 s150 ie, 1997 px150
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Location: philippines
 
Member
2012 s150 ie, 1997 px150
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Location: philippines
UTC quote
Hello guys. Its my plug too lean? My px seems to run fine. No loss of power or what. Just installed a SIP race pipe. Currently have a cast iron 177 polini and a 24.24g carb.

my current jetting:
idle jet: 50/100
air corrector: 120
mixer: be4
main jet: 120

Will be putting a vespower ignition next week also. Any tips would be much appreciated. Thanks!
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@chandlerman avatar
UTC

Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate
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Posts: 9489
Location: Nashville

137 Days Since Last Explosion
 
Lucky
@chandlerman avatar
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate
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Posts: 9489
Location: Nashville

137 Days Since Last Explosion
UTC quote
You may be a little lean. Try a 125 main jet and see if it still revs cleanly.
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UTC

Member
2012 s150 ie, 1997 px150
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Posts: 30
Location: philippines
 
Member
2012 s150 ie, 1997 px150
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Posts: 30
Location: philippines
UTC quote
chandlerman wrote:
You may be a little lean. Try a 125 main jet and see if it still revs cleanly.
I actually just put the 125. Will be riding it later. If it still has that color plug, it means i have to tweak the air mixture?
@chandlerman avatar
UTC

Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate
Joined: UTC
Posts: 9489
Location: Nashville

137 Days Since Last Explosion
 
Lucky
@chandlerman avatar
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate
Joined: UTC
Posts: 9489
Location: Nashville

137 Days Since Last Explosion
UTC quote
benedicto15 wrote:
I actually just put the 125. Will be riding it later. If it still has that color plug, it means i have to tweak the air mixture?
The 120 AC is already about as rich as you want to go. You'll need to drill the carb's float passage to get any benefit from a main jet over 125, though.

Are you 100% certain you don't have an air leak?
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UTC

Member
2012 s150 ie, 1997 px150
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Posts: 30
Location: philippines
 
Member
2012 s150 ie, 1997 px150
Joined: UTC
Posts: 30
Location: philippines
UTC quote
chandlerman wrote:
The 120 AC is already about as rich as you want to go. You'll need to drill the carb's float passage to get any benefit from a main jet over 125, though.

Are you 100% certain you don't have an air leak?
125 will be my max MJ. Will double check for air leaks! I already have the compression tool. I will update you!
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Member
2012 s150 ie, 1997 px150
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Posts: 30
Location: philippines
 
Member
2012 s150 ie, 1997 px150
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UTC quote
Compression test reads at 105 psi.
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@grumpnut avatar
UTC

Hooked
'58 VBA
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Location: Chico CA
 
Hooked
@grumpnut avatar
'58 VBA
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Location: Chico CA
UTC quote
Compression is one thing. Air leaks are another.
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UTC

Member
2012 s150 ie, 1997 px150
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Posts: 30
Location: philippines
 
Member
2012 s150 ie, 1997 px150
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UTC quote
Grumpnut wrote:
Compression is one thing. Air leaks are another.
Incase of an air leak, will the compression go down and not steady?
@mjrally avatar
UTC

Veni, Vidi, Posti
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 61 Ser 2, 65 Silver Special, 90 V5N 50, 01 ET2, 2015 HD Road Glide Special
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Veni, Vidi, Posti
@mjrally avatar
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 61 Ser 2, 65 Silver Special, 90 V5N 50, 01 ET2, 2015 HD Road Glide Special
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Location: Oceanside, CA
UTC quote
benedicto15 wrote:
Incase of an air leak, will the compression go down and not steady?
No. That's just your gauge losing pressure.

IF you have an air leak, it's introducing air into the combustion chamber from a few possible places. Either the carb gasket, the carb box gasket, the cylinder head, base gasket, exhaust stub (p200), or engine seals.

Try this test- when riding, pull the choke out. If the engine runs better, you need to tweak the jetting OR you have an air leak. If the motor runs poorly, your jetting is fine and you need to ride more.

How many miles did you ride before you took the picture of the spark plug? Maybe do 20 miles and see what the color of the plug is. A true plug chop is where you ride at a certain rpm and kill the ignition. Then remove the spark plug, cut the threads and look at the base of the insulator. My 20 mile idea isn't exactly a plug chop, more to just see how the jetting is big picture.
@ray8 avatar
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Molto Verboso
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Molto Verboso
@ray8 avatar
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UTC quote
MJRally wrote:
cut the threads and look at the base of the insulator.
With an otoscope you can avoid the work/trashing a new plug.

$20 otoscope/ear cleaner from Amazon. Snap off the scraper tool.
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@roland87 avatar
UTC

Molto Verboso
'13 LML Star 200, '81 50 Special, '81 P 150 X, '87 PK 50 Nuova, '84 PK 50 S
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Molto Verboso
@roland87 avatar
'13 LML Star 200, '81 50 Special, '81 P 150 X, '87 PK 50 Nuova, '84 PK 50 S
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Location: Ukraine. Kyiv.
UTC quote
benedicto15 wrote:
Compression test reads at 105 psi.
Seems low. According to Polini manual it must be 150 PSI.
Even my used DR with Malossi head shows 163 PSI.
@subetherbass avatar
UTC

Ossessionato
1997 Italjet Formula 125, 2 matching N.Z. '69 VBC Super, 177cc Racer, VespaCross Bodge, Puch SRA150, Piaggio Zip 100! & others
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Location: Australa, Mate
 
Ossessionato
@subetherbass avatar
1997 Italjet Formula 125, 2 matching N.Z. '69 VBC Super, 177cc Racer, VespaCross Bodge, Puch SRA150, Piaggio Zip 100! & others
Joined: UTC
Posts: 4729
Location: Australa, Mate
UTC quote
105psi... that's not compression, that's squish?

I dunno what I'm talking about, but it seems way too low
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