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Ok, this is going to piss off some, anger others but just maybe help prove or clear up confusion amongst others!

I'm still very new at the vintage qvespa wrenching so I'm not claiming to know anything or dispute anything but I was sitting on the crapper the other day wondering if anybody is willing to, or has, taken a picture of their plug chop AND a picture of the tip as well.
I've heard it a zillion times if your reading the tip your an idiot. So if actual chop is they only way to really read your plug then the proof will be in the matching " tip " photos, right?
Good chop, bad chop whatever you get id love to see what the corresponding tip says.
I mean if your going thru the trouble of chopping and photographing your plug then one more pic should be easy enough.

I would think there might be some pattern that shows why you definitely can't read the tip and you must only go by the chop.

Anyway my legs went numb and almost had to call out for help to get off the crapper that day.
To much time on the porcelain thrown reading about chops is detrimental to your healh!
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So you're looking for correlating data between porcelain base color and tip color for tuning?

Having built and serviced close to 100 vintage 2t mopeds, scoots, and motorcycles, I can firmly tell you that there is no direct correlation. The tip will only read you what was happening in the last few seconds of the bike running, whether that's idle or WOT.

The base of the porcelain doesn't see the same amount of fuel wash and will give you a more homogenous view of how your tune is going.

This all said, when I'm tuning a fresh build I am not chopping up 6 plugs to check. I might cut one plug per build after my tune and time is set, just to check and make sure that it looks as it should.

CHT is the tool I use to help get me to the tuned/timed part without risking a 4-corner seize or some other catastrophy.
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Thank you for your info. I guess im just curious because I'm having such difficulties understanding my lean problem.

I have a P125x with Malossi 166 , 24/24e and sip road 2.o and a mazz race cut crank.

I live at sea level . I was just looking at my plugs trying to chase airleaks and what not.
I pressure tested after a rebuild, all good. I spray every square inch of my scooter with brakecleaner spray, I get no rpm change whatsoever!
My idle returns back almost instantly and no fuel in oil of course.
But my idle is never steady , it seems to search a bit.
My timing is 18 BTDC and I've messed around with my points gap from .30 to about. 55
Looking at my plugs I've never had a "rich " looking one
Jetting is , 120/BE3/135
SLOW CIRCUIT. 52/140 and or a 50/120 depending on the dal, lol. The best "looking" plug I've had was a faint brown more of a tan , dry plug.
Now thats doing WOT for about 15 seconds pulling a healthy grade and my big ass.

Today I went and got a new plug for my first chop , I read it has to be new, put it in but road about 2 miles on it before my WOT then clutch and kill.
I didn't bother to chop it yet because my electrode was as white as snow without one spec 9f darkness or carbon or burn or anything. Just a new plug with pure white on it. What am I doing wrong?
Funny thing is I've put alot of miles on what 8m thinking is a to lean scooter but I haven't had any problems with seizing, yet.

Here's the plug I pulled out of it to install new " chop" plug.
Ngk B7hs
Ngk B7hs
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Now this is one of the best readings I found on this subject (General, not 2 stroke specific):
https://www.crankshaftcoalition.com/wiki/Reading_spark_plugs

Your jets seem way too rich, picture is unfocused but seems lean at 1st glance, only a lurker here Razz emoticon
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PSMA wrote:
Now this is one of the best readings I found on this subject (General, not 2 stroke specific):
https://www.crankshaftcoalition.com/wiki/Reading_spark_plugs

Your jets seem way too rich, picture is unfocused but seems lean at 1st glance, only a lurker here Razz emoticon
It does seem a tad rich at 135 doesn't it? I can't figure it out. Some people say ride it and quit chasing it but until I have a full grip on what I'm doing in relation to the scooters reaction I can't leave it like this..
Anyway thanks Mr. Lurker😁
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Peeteboy2 wrote:
I was just looking at my plugs trying to chase airleaks and what not.
I pressure tested after a rebuild, all good. I spray every square inch of my scooter with brakecleaner spray, I get no rpm change whatsoever!
My idle returns back almost instantly and no fuel in oil of course.
But my idle is never steady , it seems to search a bit.
I'm not sure you have an air leak - can you record a video of the searching?
Peeteboy2 wrote:
Today I went and got a new plug for my first chop , I read it has to be new, put it in but road about 2 miles on it before my WOT then clutch and kill.
I didn't bother to chop it yet because my electrode was as white as snow without one spec 9f darkness or carbon or burn or anything. Just a new plug with pure white on it. What am I doing wrong?
That's the problem with the electrode reading - the tip will take a while to pick color up. Will do it quicker the more overrich or oily you are, but that's not desirable of course. Hold WOT for a while and do a plug chop or at least shine a light down at the base and squint and you'll start to see a smoke ring (if you aren't way too lean)
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Peeteboy2 wrote:
It does seem a tad rich at 135 doesn't it? I can't figure it out. Some people say ride it and quit chasing it but until I have a full grip on what I'm doing in relation to the scooters reaction I can't leave it like this..
Anyway thanks Mr. Lurker😁
Yeah, just a curious and a bit obsessive in the optimization of little things, as some chinese said "- man stumble on little rocks, not in mountains" Happy to find so much knowledge and real life experience on this forum, my #1 online reference for classic vespas … are you sleeping already? …

some random thoughts on spark plugs: every engine is different, no one-fits-all receipt you can find; plug chop is a must for main jet evaluation; CHT's are good things and can save your engine; or just forget and ride, maybe it won't break; if it isn't broken don't fix it; trust your mechanic (if not you), don't question everything
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Keep in mind I really don't have an ear for a good idle or even 4 stroking . Facepalm emoticon
Thanks guys

For some reason it won't allow me to attach my 7 second video
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Sounds pretty good to me, I heard the tickover change pace a little in there but unless there are other signs (which it sounds like there aren't based on your earlier post) I don't know if you should lose sleep over an air leak.
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Molto Verboso
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Non destructive plug chops have meaning yours is difficult to see clearly but the grey appearance indicates it could be lean. Is the hole at the bottom of the float bowl drilled? If it's not been increased to 2.0mm could be an issue. There is some belief there's a bottle neck with the hole at the bottom of the float bowl which leads to the jet gallery restricting flow for even a 135 main jet which seems large for your build spec.
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Sounds normal.

How many turns out is your mixture screw?
Try the edge of where the revs drop (warmed-up engine).
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xantufrog wrote:
Sounds pretty good to me, I heard the tickover change pace a little in there but unless there are other signs (which it sounds like there aren't based on your earlier post) I don't know if you should lose sleep over an air leak.
I agree but what I'm losing sleep over is it appears to run lean with a 135 main !
Seems way high to not be able to foul
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hibbert wrote:
Non destructive plug chops have meaning yours is difficult to see clearly but the grey appearance indicates it could be lean. Is the hole at the bottom of the float bowl drilled? If it's not been increased to 2.0mm could be an issue. There is some belief there's a bottle neck with the hole at the bottom of the float bowl which leads to the jet gallery restricting flow for even a 135 main jet which seems large for your build spec.
Well embarrassingly enough I tried drilling that hole on my other carburetor, hence the new carburetor!
I'm not sure I'm ready to spend another hundred and $135 on one of my mistakes again. Especially when I have not read anywhere on this form that anybody has been at a 135 and not fouling too rich you know what I mean?
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Ray8 wrote:
Sounds normal.

How many turns out is your mixture screw?
Try the edge of where the revs drop (warmed-up engine).
Will check it tomorrow regarding edge of rev drop but currently its 1 and 3/4 turns out.
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Peeteboy2 wrote:
Well embarrassingly enough I tried drilling that hole on my other carburetor, hence the new carburetor!
I'm not sure I'm ready to spend another hundred and $135 on one of my mistakes again. Especially when I have not read anywhere on this form that anybody has been at a 135 and not fouling too rich you know what I mean?
I'm slightly richer jetting with that on a similar setup, but my plug is nice and tan.. not white hot. Granted I'm on a Reed engine which should be richer than your rotary engine by default if all else is same.

110/be4/125 which is equivalent to 120/be4/136

24/24 carb with drilled hole. Malossi 166 mkii kit on 60mm mazz flowed crank heavy porting and exhaust widened. Port Timing 185/125. Ignition timing 19.5 degrees at idle on a vape variable ignition. Road xl pipe.

You might have too hot plug for that kit. I'm on br7es plug.

Edit: just saw your plug photo and you are using the wrong length plug. You are using short thread hs plug. The malossi 166 kit uses the long thread es plugs. Switch to b7es and recheck.

Also you need to be using premium gas on that kit. Not the cheap stuff. It affects the ignition and will cause issues if you use the lower octane stuff.
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Edit: just saw your plug photo and you are using the wrong length plug. You are using short thread hs plug. The malossi 166 kit uses the long thread es plugs. Switch to b7es and recheck.

Also you need to be using premium gas on that kit. Not the cheap stuff. It affects the ignition and will cause issues if you use the lower octane stuff.
[/quote]


Ha, somebody finally caught it. Its weird that I missed that for so long. So I went and got a NGK BR8 es today, went to put it in and the top screw off nipple doesn't screw off so it doesn't fit my NGK cap!
WTF?
Plus I've been reading that running a short plug where a long plug is needed is going to foul up like crazy. So yes 8m going to try and get the correct plug in her tomorrow but I have no hopes of it helping in this situation.
I haven't read one person comment on the non screw off top part of the plug like I got today but yet I read a lot of posts where people ran that same plug,
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Peeteboy2 wrote:
Looking at my plugs I've never had a "rich " looking one
Jetting is , 120/BE3/135
First thing change the BE3 (lean) to a BE4 (correct). Then check your jets are sized actually as numbered. If you really have an AC120 and really have a 135, that plug should be totally black.
If it all checks out it's a fuel supply issue; tap, pipe, float bowl hole, fuel cap, etc
More to it than the hs plug.
But one thing your right about is it's not as it should be.
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swiss1939 wrote:
Also you need to be using premium gas on that kit. Not the cheap stuff. It affects the ignition and will cause issues if you use the lower octane stuff.
That's something I hadn't though, although I always use the best gas available.

Just one more thing concerning the carb float chamber bore to main jet stack, as it is referred again (above) that needs to be drilled larger. SI24/24E standard bore is 1.5mm, Scooter Center has a BGM SI24/24E all tuned up carb with a set of features for highly tuned engines ... the bore is 1.8mm, not 2.5mm! So I sent them my setup asking if I needed to drill the 1.5mm bore to make use of my main jet on my setup:
BGM 177, ported engine, filter drilled SI24/24E, Polini extended intake crankshaft and variable ignition, SIP Road 3, 55/160 and AC160/BE3/140

Their short and straight answer:
"you can expand them, but you don't have to."

Why do I always insist on opening cans of worms? Facepalm emoticon
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Jack221 wrote:
First thing change the BE3 (lean) to a BE4 (correct). Then check your jets are sized actually as numbered. If you really have an AC120 and really have a 135, that plug should be totally black.
If it all checks out it's a fuel supply issue; tap, pipe, float bowl hole, fuel cap, etc
More to it than the hs plug.
But one thing your right about is it's not as it should be.
Now everything I've read on this Forum tells me a BE3 is richer then a BE4, Thats why it gets so confusing.
But I have and will change to the BE4!

As far as fuel supply I don't know if a stock tap is the problem. I installed a stock replacement only because they didn't have a fast flow in stock..

If you can tell me not enough flow for my setup then fastflow it is!

So how do I check if my jet is actually sized as numbered?
I bought a kit from that scotterstore in Auza California or somewhere like that.
Can't remember the name.

I'VE checked the float bowl and its airtight. It doesn't seem to be sticking and if it was I would have a different issue wouldn't I?

So do I need to drill to the main jet, make it larger? Once again I've read on this forum a few problems that arouse from drilling it larger and overall it doesn't get talked about a lot. But, if I need to then I need to find someone that doesn't have the " Katharine Hepburn's" as I do. The more I concentrate the more my hands spazz out..

Fuel cap not an issue!
My pipe is clean as a whistle,,,

I may not know much but I do know this problem is so weird that it has to be something very simple im not seeing.
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PSMA wrote:
That's something I hadn't though, although I always use the best gas available.

Just one more thing concerning the carb float chamber bore to main jet stack, as it is referred again (above) that needs to be drilled larger. SI24/24E standard bore is 1.5mm, Scooter Center has a BGM SI24/24E all tuned up carb with a set of features for highly tuned engines ... the bore is 1.8mm, not 2.5mm! So I sent them my setup asking if I needed to drill the 1.5mm bore to make use of my main jet on my setup:
BGM 177, ported engine, filter drilled SI24/24E, Polini extended intake crankshaft and variable ignition, SIP Road 3, 55/160 and AC160/BE3/140

Their short and straight answer:
"you can expand them, but you don't have to."

Why do I always insist on opening cans of worms? Facepalm emoticon
So your suggesting I not worry about doing it?
Or atleast it won't hurt me 8f I don't expand it?
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Peeteboy2 wrote:
So your suggesting I not worry about doing it?
Or atleast it won't hurt me 8f I don't expand it?
I wouldn't go so far as "suggesting", I don't have the real knowledge and experience.
Remember I am *Mr. Lurker* ?

But there are for sure forum members that have conducted experiments and can state for sure that, under certain circumstances, drilling the bore is a must. Maybe not for my setup or your setup?

Bottom line: I'm also in doubt, even more after SC answer. Maybe do a plug chop? but I've ride +500kms many times WOT, ignoring completely the subject, no problems at all ... logic tells me "stay steady", as they say "- Ignorance gives calmness" ... LOL
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i will say that every time i've messed around with jetting based on plug color it basically hasn't worked for me. i think the color issue is problematic because of the "chop vs tip" issue, it's problematic because on 2-strokes there's also burning oil "in the mix" that changes the coloration pattern, and synth vs dino, plug temp yadda yadda yadda blow my brains out it complicates what color to expect and where.

Of course I do think you can still make good sense of whether you are in the *ballpark* based on plug color. It shouldn't be a sooty mess, it shouldn't be bone white. But dialing it in to the final end points... over the years, and with the gentle patient nudging of more experienced members on here (for which I am eternally grateful), I've come around to the "seat of the pants" tuning approach - start with a crazy big jet, and work down based on how the engine actually performs, find the best behavior, and then bump it back up maybe 1 size for safety. I guess if I was building higher performance scoots for myself that might not wholly suffice and I'd bring CHT into the mix too, but my scoots are city drivers and country cruisers, not track demons
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Peeteboy2 wrote:
Will check it tomorrow regarding edge of rev drop but currently its 1 and 3/4 turns out.
On the exact same build/jetting as yours I was out close to 3 Spaco-thread turns.

If you want to give it a shot, ride it with a spanner/screwdriver in your pocket till it gets to temperature. Raise the idle speed a bit.
1/4 turns out at a time. Wait 5 seconds. Repeat until you hear the revs drop. 1/4 back in and ride it again. If you can live with it like that you'll see more color on your plug, if only for peace of mind. Much of the color on posted plug pics results from puttering around with that circuit in play.

Plug chop:

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xantufrog wrote:
i will say that every time i've messed around with jetting based on plug color it basically hasn't worked for me. i think the color issue is problematic because of the "chop vs tip" issue, it's problematic because on 2-strokes there's also burning oil "in the mix" that changes the coloration pattern, and synth vs dino, plug temp yadda yadda yadda blow my brains out it complicates what color to expect and where.

Of course I do think you can still make good sense of whether you are in the *ballpark* based on plug color. It shouldn't be a sooty mess, it shouldn't be bone white. But dialing it in to the final end points... over the years, and with the gentle patient nudging of more experienced members on here (for which I am eternally grateful), I've come around to the "seat of the pants" tuning approach - start with a crazy big jet, and work down based on how the engine actually performs, find the best behavior, and then bump it back up maybe 1 size for safety. I guess if I was building higher performance scoots for myself that might not wholly suffice and I'd bring CHT into the mix too, but my scoots are city drivers and country cruisers, not track demons
I'll say that after doing so many bikes, the only time I am doing a true plug chop is after break in period just to get a feel for the overall tune, or if during tuning I have a dead spot/gurgling spot I can't seem to tune out.

Most frequently I am tuning by feel, with CHT as a preventative against unseen mishaps. I typically pull CHT sensors from completed builds that aren't daily riders.
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I guess thats easy for you to say, you've never met me. I already screwed it up once, lol.
But I will give it a go. Thanks!
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xantufrog wrote:
i will say that every time i've messed around with jetting based on plug color it basically hasn't worked for me. i think the color issue is problematic because of the "chop vs tip" issue, it's problematic because on 2-strokes there's also burning oil "in the mix" that changes the coloration pattern, and synth vs dino, plug temp yadda yadda yadda blow my brains out it complicates what color to expect and where.

Of course I do think you can still make good sense of whether you are in the *ballpark* based on plug color. It shouldn't be a sooty mess, it shouldn't be bone white. But dialing it in to the final end points... over the years, and with the gentle patient nudging of more experienced members on here (for which I am eternally grateful), I've come around to the "seat of the pants" tuning approach - start with a crazy big jet, and work down based on how the engine actually performs, find the best behavior, and then bump it back up maybe 1 size for safety. I guess if I was building higher performance scoots for myself that might not wholly suffice and I'd bring CHT into the mix too, but my scoots are city drivers and country cruisers, not track demons
Well I 5hought i was getting close to getting a grip so I bought the correct plug today, NGK BR8ES WITH REMOVABLE NIPPPLE!
I had been running, incorrectly a NGK BR8HS.

I put another 5 or so miles on the old plug today ending with a 20 second WOT. Didn't chop it just pulled it and put in glove box.
Installed correct plug and ran about 4 miles, ending with 20 second WOT, clutch grab ignition kill .

Here's the pics of both plugs. I didn't bother chopping the new one cause I can see down to the base of this albino plug. Now im even more confuseded
Forum member supplied image with no explanatory text
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@peeteboy2 avatar
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Hooked
1980 P125x 2002 Bajaj Chetak
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Location: Southern California, but Crete is where my heart is!
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Oops , old one here
Forum member supplied image with no explanatory text
@psma avatar
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125 GTR 1977, 50S 1975, GTS 125 Supertech 2021
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You already did the hard part

What I see is the correct plug now, correct 19mm reach, looking very lean, apparently. I would cut off the threads and check if you have a dark ring on insulator base, 2 to 3 mm…

If it's white then you're definitely lean

Ps: and btw, you NEED a fast flow tap
@kowalski avatar
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2005 Stellalossi 177 Fe
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UTC quote
Your Malossi 166 uses a short reach plug. For NGK, it uses a B8HS. B9HS for extreme conditions. Get that long reach plug out of there asap.
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Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
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UTC quote
Facepalm emoticon think your head is for hs plug. Put the short reach back in. See the dirty line on the threads of the es?

As said, drill the carb by hand. Between 2.1 and 2.5mm is ok. There is a whole spectrum of info on the subject but this gives the best reliability once up over 15 bhp.

You need a fast flow tap. I like the SIP 2.0 with reserve position. Take it apart when be you get it and check its smooth and debris free.
@greasy125 avatar
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Weird 80's Vespas & Cool Vintage Lambrettas
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you need a full reset. and you're going to have to change stuff/spend money for the right parts to get this dialed in.

fast flow tap
drill carb
get the right jet stack and a handful of mains
buy some set drills (or a gauge set, or both) with a pin vice.

confirm that your fuel line is correct diameter and length
confirm that your vent in the tank cap is clean and clear, hell, even open it up

run the correct plug for the application. B7 is too hot, ES is the wrong reach

are you running a spaco or dellorto? does it have the *correct* jets-- some came with T5 jets. what air filter are you running? is it drilled?

you have to be specific, otherwise you'll just be chasing your ass.

having run what you're running, you'll likely wind up in the mid too upper 120's and a you'll want a B8 or 9 plug depending on the type of riding you're doing. adjust your timing accordingly, and if you don't have a degree wheel get one.

tons of great info here to follow up on.
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@peeteboy2 avatar
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Location: Southern California, but Crete is where my heart is!
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greasy125 wrote:
you need a full reset. and you're going to have to change stuff/spend money for the right parts to get this dialed in.

fast flow tap : WILL GET!
drill carb : WILL DO
get the right jet stack and a handful of mains : I HAVE A SET OF MAINS FROM 115 TO 138,
I HAVE A 190 , 150 AND 120 MIXERS ,
IDLE JETS I HAVE A 55/160, 50/120 AND A 52/140

buy some set drills (or a gauge set, or both) with a pin vice. : ORDERED A NEW SET OFF AMAZON!

confirm that your fuel line is correct diameter and length : PURCHASED AND INSTALLED FROM SCOOTERWEST 1 MINTH AGO

confirm that your vent in the tank cap is clean and clear, hell, even open it up : VENT IS CLEAN QND CLEAR!

run the correct plug for the application. B7 is too hot, ES is the wrong reach : LOL, WILL INSTALL MY NEW NGK BR8HS!

are you running a spaco or dellorto? : NOT SURE PURCHASED 2 MONTHS AGO FROM SCOOTERWEST

does it have the *correct* jets--: HOW DO I KNOW THE CORRECT JETS? ALL JETS ORDERED WERE ORDERED FOR AN SI24/24E


some came with T5 jets : ?????
. what air filter are you running?
is it drilled?
NOT SURE THE BRAND BUT THE HEART SHAPE ABOVE THE JETS IS DRILLED. APPEARS TO BE FACTORY HOLES!

you have to be specific, otherwise you'll just be chasing your ass.

having run what you're running, you'll likely wind up in the mid too upper 120's and a you'll want a B8 or 9 plug depending on the type of riding you're doing. adjust your timing accordingly, and if you don't have a degree wheel get one.
TIMING CHECKED 17 TIMES , AT 3000 RPM IM ABOUT 19 BTDC AND 18 AT IDLE. POINTS GAP CURRENTLY SET AT .35

tons of great info here to follow up on.
AGREED BUT FUNNY ENOUGH IM FINDING ALOT OF CONFLICTING ADVICE ASWELL. IVE SPENT CLOSE TO 8 HOURS TOTAL ON THE CRAPPER READING EVERYTHING I CAN FIND ON THIS FORUM!

IVE HAD TWO PEOPLE ADVIZE A BE4 IS RICHER THEN A BE3 BUT IN THIS FORUM THERE IS A COMPREHENSIVE WRITE UP ABOUT JETTING IT POINTS OUT IN NO UNCERTAIN TERMS A BE3 IS RICHER THEN A BE4.
AS AN EXAMPLE IS ALL IM SAYING.
I SWEAR THE MORE I "LEARN " ABOUT VESPAS THE DUMBER I BECOME.. I CANT AFFORD MUCH OF THAT
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1980 P125x 2002 Bajaj Chetak
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UTC quote
PSMA wrote:
You already did the hard part

What I see is the correct plug now, correct 19mm reach, looking very lean, apparently. I would cut off the threads and check if you have a dark ring on insulator base, 2 to 3 mm…

If it's white then you're definitely lean

Ps: and btw, you NEED a fast flow tap
Back to the shorty, lol. Damn I feel stupid
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@peeteboy2 avatar
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Hooked
1980 P125x 2002 Bajaj Chetak
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Location: Southern California, but Crete is where my heart is!
UTC quote
Kowalski wrote:
Your Malossi 166 uses a short reach plug. For NGK, it uses a B8HS. B9HS for extreme conditions. Get that long reach plug out of there asap.
Thanks Kowalski!
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@peeteboy2 avatar
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Hooked
1980 P125x 2002 Bajaj Chetak
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Posts: 151
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1980 P125x 2002 Bajaj Chetak
Joined: UTC
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Location: Southern California, but Crete is where my heart is!
UTC quote
Jack221 wrote:
Facepalm emoticon think your head is for hs plug. Put the short reach back in. See the dirty line on the threads of the es?

As said, drill the carb by hand. Between 2.1 and 2.5mm is ok. There is a whole spectrum of info on the subject but this gives the best reliability once up over 15 bhp.

You need a fast flow tap. I like the SIP 2.0 with reserve position. Take it apart when be you get it and check its smooth and debris free.
Thanks Jack221. Will be drilling and fast flowing aswell and of course the correct plug will go back.
Not the sharpest tool now am I? Tool, yes.
@kowalski avatar
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2005 Stellalossi 177 Fe
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@kowalski avatar
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The information to set this kit up is out there. I would start with Malossi's installation manual attached. Your kit is the 31-4093. As I interpret the manual, your baseline is:

Timing-18 degrees BTDC
Idle Jet-52-140
Main Jet-122 (with cut crank)
Air Corrector-140
Mixer Tube-BE4
Sparkplug-B8HS (B9HS for extreme conditions).

It is not necessarily where you will end up, but it is a safe place to start.

The more interesting question is whether you really want a Malossi 166. In its day (note the 2003 date on the manual) it was known for cheap, high rpm horsepower at the expense of low rpm grunt. If you see yourself as a boy-racer out to win the stoplight grand prix, this is your kit. If you see yourself loping along the country roads, not so much. Personally, I would make the effort to dial this in, but a lot of people would not.
@swiss1939 avatar
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@swiss1939 avatar
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UTC quote
Kowalski wrote:
Your Malossi 166 uses a short reach plug. For NGK, it uses a B8HS. B9HS for extreme conditions. Get that long reach plug out of there asap.
The malossi 166 mk2 head uses a long reach. Specifically this is what is mentioned for the same part number in my manual which is the MK2 kit: denso w24es-zu which is a long reach plug.

https://www.densoproducts.com/denso-4032-w24es-zu-platinum-u-groove-spark-plug

So if you don't know which kit you have, the best way to tell is to take your head off and check to see if the short plug sits inside the hole and doesn't come out to the edge of the plug hole.. or if the long reach plug sticks out too far from the hole.

I've confirmed on my mk2 head that the long reach plug is correct.
@swiss1939 avatar
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@swiss1939 avatar
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UTC quote
Here is an old post on my malossi 166 mk2 thread with photos of the short reach plug in the MK2 head which is too short and the long reach which sits flush with the edge of the plug hole and is correct.

https://modernvespa.com/forum/post2344029#2344029

You need to figure out which version head you have first before you progress, so that you use the correct length plug.
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