Arrow pipe on stock bore - what main jet to use?

Does your Spree/Elite already run great, and you're trying to make it quicker/faster? Need a monster motor swap? Discuss your ideas here.

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Sevyndaze
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Arrow pipe on stock bore - what main jet to use?

Post by Sevyndaze »

Hi all,

Topic pretty much says it, I started the engine build for my 2001 Elite by ordering an Arrow pipe from SSS. The original plan was to tear the whole thing down and do a BBK and an bunch of other stuff, but I am moving next month and won’t have time for all that until afterwards.

The transmission is tuned (variator, ZX, gears) but the motor itself is stock. I’m guessing I’ll have to play with the CVT a bit but my primary concern is what size main jet to put in the stock carb. I’m currently running an 80, any suggestions on what size to change to when installing the Arrow?
2001 Elite S (Derestricted)
Arrow Exhaust
Polini Variator
6.9g rollers
ZX Trans
1.5k Contra, 4k shoe springs
16/42 Gears
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Wheelman-111
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Re: Arrow pipe on stock bore - what main jet to use?

Post by Wheelman-111 »

Greetings:

It's possible nobody has ever installed that Exotic Exhaust on a stock bore, Ever. If you're using the stock airbox, you might just try the 80 that's in there now, but keep a close watch on the temperature. Variator weights can be lightened significantly to let the engine ring in harmony with the Arrow's high-RPM tune. 72cc Iron Polini Flash 9 uses the stock airbox and exhaust, and seems to like a 90. It's crazy, but with a 92 it practically falls flat on its face! So be aware that one jet size can make an enormous difference.
Wheelman-111
Most of my money is spent on scooterparts. The rest is just wasted.
"ISO": '03 Vespa ET4 Malossi187 74MPH
Flash 9: 2001 Elite SR Contesta 72 ZX Tran, 9:1 Gears, Stock Airbox/Carb/Pipe 58.8 MPH
Punkin: 2010 Vespa/Malossi S78, 61MPH
Sevyndaze
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Location: New Hampshire

Re: Arrow pipe on stock bore - what main jet to use?

Post by Sevyndaze »

Heh, I’m a pioneer! /s

Anyway, I’ll keep the 80 for starters as it does seem to run a bit on the rich side as it is. I’ll have to check what jet sizes I have but I think I have at least up to 90.

Temp wise, what should I look for/avoid?
2001 Elite S (Derestricted)
Arrow Exhaust
Polini Variator
6.9g rollers
ZX Trans
1.5k Contra, 4k shoe springs
16/42 Gears
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Wheelman-111
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Re: Arrow pipe on stock bore - what main jet to use?

Post by Wheelman-111 »

Greetings:

Kill it if it approaches 400F. at the cylinder head. I have a feeling that the tame Stock port timing won't be able to harmonize with the Arrow. It might even be slower than the stock pipe. Hope I'm mistaked.
Wheelman-111
Most of my money is spent on scooterparts. The rest is just wasted.
"ISO": '03 Vespa ET4 Malossi187 74MPH
Flash 9: 2001 Elite SR Contesta 72 ZX Tran, 9:1 Gears, Stock Airbox/Carb/Pipe 58.8 MPH
Punkin: 2010 Vespa/Malossi S78, 61MPH
Sevyndaze
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Posts: 114
Joined: Sun Jun 10, 2018 3:43 pm
Location: New Hampshire

Re: Arrow pipe on stock bore - what main jet to use?

Post by Sevyndaze »

That's about what I figured. I forget exactly where I set the limits but I think I set my trailtech warning light to come on yellow at a temp of 375 and red at 400 or thereabouts.

As far as the performance goes, I asked on the SSS Customer Support group on FB before I ordered. To quote Brandon, "Arrow on a stock bore rips!", so I am anticipating positive results :-)
2001 Elite S (Derestricted)
Arrow Exhaust
Polini Variator
6.9g rollers
ZX Trans
1.5k Contra, 4k shoe springs
16/42 Gears
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Meatball
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Re: Arrow pipe on stock bore - what main jet to use?

Post by Meatball »

I dont think theres anything about the stock bore that “rips”....but the Arrow pipe is certainly badazz. When you finally go Corsa you’ll see why....your biggest problems
will be trying to keep the front wheel down and trying to wipe the grin off your face. :D
I need to find some new haters...the ones I have are starting to like me.
Sevyndaze
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Location: New Hampshire

Re: Arrow pipe on stock bore - what main jet to use?

Post by Sevyndaze »

Installed last night and test rode today.

Holy. Crap. It's like a whole new bike. WOT off the line and I'm going 30 in what feels like 2 seconds...acceleration is insane. If I slow down and then try to accelerate again its pretty boggy until it hits about 7k and then BRAAAAAAAAPPP....off like a rocket!

Didn't change the 80 jet and temps seemed fine. Topped out at around 300 during a WOT run where I hit just over 45, ambient temp about 60. Still, the top speed beats my previous by a few MPH and the acceleration is just ridiculous. I can only imagine how this thing is gonna pull after a BBK and full intake upgrade.

I suspect the slowness below 7k is because the variator weights are too heavy (8g rollers ATM) or the contra spring is too light (NCY 1K), or both. I'll probably try to mess with the rollers first since they are easier than changing out the spring. Watching the Dyno Shootout that SSS posted, the Arrow seems to like 9k (though this was with a ported Corsa).

I have an NCY 1.5k contra spring, and 5.6g, 6.9g, and 7.5g sets of rollers. Any advice from you gurus as to where I should start?
2001 Elite S (Derestricted)
Arrow Exhaust
Polini Variator
6.9g rollers
ZX Trans
1.5k Contra, 4k shoe springs
16/42 Gears
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Meatball
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Re: Arrow pipe on stock bore - what main jet to use?

Post by Meatball »

Try three 8g and three 6.9g...evenly spaced for weight balance of course. Think of your roller weight as a total of all six..youre now at 48g (6x8g)...go down from there. Drop too much and top will suffer.

Ive found that subtle roller weight changes make it easier to find your target. Keep a written log of weight used (and contra) and it’s reaction. Plan on trying a bunch of different combos before youre happy. Dont bother using rear belt cover till its dialed.

Trans tuning is fun and frustrating. Seems like Im still messing with mine for a small tweak once and awhile for rollers and launch engagement. Once you finally get it just how you want it...you’ll get a Corsa and start all over again.
I need to find some new haters...the ones I have are starting to like me.
Sevyndaze
Spree
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Posts: 114
Joined: Sun Jun 10, 2018 3:43 pm
Location: New Hampshire

Re: Arrow pipe on stock bore - what main jet to use?

Post by Sevyndaze »

So, update in case anyone is interested. Swapped my 8g rollers for 7.5. Helped the low-throttle bog but still present. Swapped out the 1k contra to the 1.5k and it’s a lot more responsive and acceleration is much smoother. Trans seems to be shifting around 8k and the low-throttle bog is hardly present, and is easily and quickly remedied by just giving it a little more throttle.

Top speed (per my trailtech) is about 46, and temps have creeped into the low 300’s. Wondering if maybe I should try a bigger jet since maybe it is running lean at the higher RPMs.
2001 Elite S (Derestricted)
Arrow Exhaust
Polini Variator
6.9g rollers
ZX Trans
1.5k Contra, 4k shoe springs
16/42 Gears
User avatar
Meatball
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Re: Arrow pipe on stock bore - what main jet to use?

Post by Meatball »

300 is cold...400 is seizure...target about 350-365 for happy burn. Mine creeps to 380 occasionally before I ease off...Either your main is too big or youre just not drivin it like you stole it. I beat the holy heII out of my scoots and the throttle is basically a toggle switch. I think they see wot more than any other throttle position. I dont build em to creep through town like a nancy boy. Get a Corsa and you’ll quickly wonder why you waited so long.
I need to find some new haters...the ones I have are starting to like me.
Sevyndaze
Spree
Spree
Posts: 114
Joined: Sun Jun 10, 2018 3:43 pm
Location: New Hampshire

Re: Arrow pipe on stock bore - what main jet to use?

Post by Sevyndaze »

I guess I must be running on the rich side then. In any case, I dropped my rollers to 6.9g and good lord I never thought a 49cc could accelerate that fast. Probably as good as it’s going to get for now, more updates to come after I install the BBK.
2001 Elite S (Derestricted)
Arrow Exhaust
Polini Variator
6.9g rollers
ZX Trans
1.5k Contra, 4k shoe springs
16/42 Gears
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