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@stuarttiainen avatar
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Hooked
PX232, Super221, Rat PX200, Rally 221MHR
Joined: UTC
Posts: 188
Location: Brisbane, QLD
 
Hooked
@stuarttiainen avatar
PX232, Super221, Rat PX200, Rally 221MHR
Joined: UTC
Posts: 188
Location: Brisbane, QLD
UTC quote
Hey Ho (let's go!!)

So just finished putting together a 221 sport on OEM cases, no porting, standard SI24 with main jet upped to 130 and a 50/120, drill jet stack to 2mm, fast flow tap, Mazzuchelli K2D 60mm crank and 210 sport top 1.5 gasket, 0.9mm QK, SIP road 2.0, ducati ignition timed to 18deg.

This is a standard sort of build that I've done a fair few of but normally I'd use the SIP 60mm 115/4 cranks but they were not in stock. So the scooter goes well when you're getting up it but seems to flood when you're putting up a hill in a higher gear, say third, and just feels like it's flooded. Plug is sooty and black after a ride, telling me rich. Also, trying to warm start it, it needs full throttle and chugging and eventually, it will clear up but plug isn't wet still, just sooty.

I've changed plug, CDI, tried different jetting combinations, including smaller idle, but still has that bog is still there. My thinking is that it could be the timing on the crank... K2D has a 138/6 which might be pulling too much fuel in for such a tame setup?

Any ideas?
top of piston is pretty sooty.
top of piston is pretty sooty.
plug is lighter than it looks, but that soot doesn't ring true.... surely needs to be a bit of moisture around there?
plug is lighter than it looks, but that soot doesn't ring true.... surely needs to be a bit of moisture around there?
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Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
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Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4599
Location: London UK
UTC quote
Pretty sure it's just the jetting. Main jet is too big. AC is too small. And for this set up, pilot jet no smaller than 55/100.
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Hooked
PX232, Super221, Rat PX200, Rally 221MHR
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Location: Brisbane, QLD
 
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@stuarttiainen avatar
PX232, Super221, Rat PX200, Rally 221MHR
Joined: UTC
Posts: 188
Location: Brisbane, QLD
UTC quote
Jack221 wrote:
Pretty sure it's just the jetting. Main jet is too big. AC is too small. And for this set up, pilot jet no smaller than 55/100.
Thanks for popping your head in Jack221.

160 AC BE3 and yeah, 130 main, with a 50/120. What jetting do you think for a start?
UTC

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4599
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4599
Location: London UK
UTC quote
Stuarttiainen wrote:
Thanks for popping your head in Jack221.

160 AC BE3 and yeah, 130 main, with a 50/120. What jetting do you think for a start?
Firstly this set up needs an UN-DRILLED air filter. Air box lid, filter and bellows need to be fitted at all times.

I would start with AC120 at the biggest. 55/100 at the smallest. 04 slide. And on this, a BE3.

To set the main jet, begin with the 130MJ (you already know this splutters but still worth a check), ride up a medium, 3rd gear hill, at exactly 1/2 throttle, reduce the MJ size until the spluttering goes away.
When you get this far the jetting is at the 'roughed out' stage.
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Hooked
PX232, Super221, Rat PX200, Rally 221MHR
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Location: Brisbane, QLD
 
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@stuarttiainen avatar
PX232, Super221, Rat PX200, Rally 221MHR
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Location: Brisbane, QLD
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You'd think it would be easy to find an undrilled filter, everybody wants/uses drilled ones!! Luckily I had one in my stash. So 120AC/BE3/130MJ, 55/100... bogs terribly but at least the plug is now showing wet instead of sooty which, I'm not sure, good or bad thing.

Bogs and dies, not idling, not really ridable at this set up stage?
Forum member supplied image with no explanatory text
Forum member supplied image with no explanatory text
UTC

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4599
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4599
Location: London UK
UTC quote
Stuarttiainen wrote:
You'd think it would be easy to find an undrilled filter, everybody wants/uses drilled ones!! Luckily I had one in my stash. So 120AC/BE3/130MJ, 55/100... bogs terribly but at least the plug is now showing wet instead of sooty which, I'm not sure, good or bad thing.

Bogs and dies, not idling, not really ridable at this set up stage?
Looks rich now. Reduce the main jet until it's ridable? See where it ends up but would expect it to settle before 120.
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Hooked
PX232, Super221, Rat PX200, Rally 221MHR
Joined: UTC
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Location: Brisbane, QLD
 
Hooked
@stuarttiainen avatar
PX232, Super221, Rat PX200, Rally 221MHR
Joined: UTC
Posts: 188
Location: Brisbane, QLD
UTC quote
Jack221 wrote:
Looks rich now. Reduce the main jet until it's ridable? See where it ends up but would expect it to settle before 120.
Thanks Jack. The rains are here in Brisbane now, once there's a patch of blue I'll give that a run and report.
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@stuarttiainen avatar
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Hooked
PX232, Super221, Rat PX200, Rally 221MHR
Joined: UTC
Posts: 188
Location: Brisbane, QLD
 
Hooked
@stuarttiainen avatar
PX232, Super221, Rat PX200, Rally 221MHR
Joined: UTC
Posts: 188
Location: Brisbane, QLD
UTC quote
Jack221 wrote:
Looks rich now. Reduce the main jet until it's ridable? See where it ends up but would expect it to settle before 120.
Spot on Jack. Down to a 122 which seems pretty good. Still rich down low but, bogging has pretty much disappeared. Any suggestions to clear it up a little?
UTC

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4599
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4599
Location: London UK
UTC quote
Stuarttiainen wrote:
Spot on Jack. Down to a 122 which seems pretty good. Still rich down low but, bogging has pretty much disappeared. Any suggestions to clear it up a little?
Been doing this a while. If you ride along at 3000rpm and gently feather the throttle, how does it feel, rich or hesitant?

How many turns out is the mixture screw?

Sound recording would help.
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@stuarttiainen avatar
UTC

Hooked
PX232, Super221, Rat PX200, Rally 221MHR
Joined: UTC
Posts: 188
Location: Brisbane, QLD
 
Hooked
@stuarttiainen avatar
PX232, Super221, Rat PX200, Rally 221MHR
Joined: UTC
Posts: 188
Location: Brisbane, QLD
UTC quote
Jack221 wrote:
Been doing this a while. If you ride along at 3000rpm and gently feather the throttle, how does it feel, rich or hesitant?

How many turns out is the mixture screw?

Sound recording would help.
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@stuarttiainen avatar
UTC

Hooked
PX232, Super221, Rat PX200, Rally 221MHR
Joined: UTC
Posts: 188
Location: Brisbane, QLD
 
Hooked
@stuarttiainen avatar
PX232, Super221, Rat PX200, Rally 221MHR
Joined: UTC
Posts: 188
Location: Brisbane, QLD
UTC quote
Jack221 wrote:
Been doing this a while. If you ride along at 3000rpm and gently feather the throttle, how does it feel, rich or hesitant?

How many turns out is the mixture screw?

Sound recording would help.
Mixture screw, two turns out. To be honest, it's feeling pretty good all round now after riding it for a while... thoughts?
UTC

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4599
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4599
Location: London UK
UTC quote
So this is AC120/BE3/122MJ 55/100
Doesn't sound so bad. Possibly lean a bit. Might be just between jet sizes. If you go to 125, is it definitely too much? Either way decide on the MJ, then adjust the mixture screw again. Put the idle screw in all the way and the mix screw over 4 turns out. If the pilot is big enough, it should be no more than a fast idle, like 1600 rpm. Close the mix screw until it suddenly speeds up. Adjust idle to 1000 or less. I like less as it's better for the gearbox.
Seems like it's riding fine. How's the plug chops look?
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@stuarttiainen avatar
UTC

Hooked
PX232, Super221, Rat PX200, Rally 221MHR
Joined: UTC
Posts: 188
Location: Brisbane, QLD
 
Hooked
@stuarttiainen avatar
PX232, Super221, Rat PX200, Rally 221MHR
Joined: UTC
Posts: 188
Location: Brisbane, QLD
UTC quote
Jack221 wrote:
So this is AC120/BE3/122MJ 55/100
Doesn't sound so bad. Possibly lean a bit. Might be just between jet sizes. If you go to 125, is it definitely too much? Either way decide on the MJ, then adjust the mixture screw again. Put the idle screw in all the way and the mix screw over 4 turns out. If the pilot is big enough, it should be no more than a fast idle, like 1600 rpm. Close the mix screw until it suddenly speeds up. Adjust idle to 1000 or less. I like less as it's better for the gearbox.
Seems like it's riding fine. How's the plug chops look?
The 122 that I've settled on just felt nicer than the 125, with 2 turn mixture. Plug is sooty and black, not wet, but yeah, as You said (and I thought) it's riding fine, and sounds normal... a little bit 4 stroking a low/light throttle but I'm counting that as needs for high speed roll off.
UTC

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4599
Location: London UK
 
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: UTC
Posts: 4599
Location: London UK
UTC quote
Open the mixture screw to 2.5 tuns and do that same video again. I think I hear something slightly lean.

Plug colour off full temperature (only a fast long run), is irrelevant. When non stock, dark brown or matt black on an 8+ plug around town, usually means pretty good.

Where's the timing at? Squish?
OP
@stuarttiainen avatar
UTC

Hooked
PX232, Super221, Rat PX200, Rally 221MHR
Joined: UTC
Posts: 188
Location: Brisbane, QLD
 
Hooked
@stuarttiainen avatar
PX232, Super221, Rat PX200, Rally 221MHR
Joined: UTC
Posts: 188
Location: Brisbane, QLD
UTC quote
Jack221 wrote:
Open the mixture screw to 2.5 tuns and do that same video again. I think I hear something slightly lean.

Plug colour off full temperature (only a fast long run), is irrelevant. When non stock, dark brown or matt black on an 8+ plug around town, usually means pretty good.

Where's the timing at? Squish?
So the sooty black is around town, aggressive(ish) riding with a BR8EIX plug, squish is at 1mm with a strobed 18deg.
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