Max RPM on a stock 150 Stella 2T?
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Member
2005 Stella 2T, 2014 Stella 125 Automatica
Joined: 20 Jul 2018
Posts: 39
Location: NY, NY
Wed Feb 06, 2019 11:27 am quote
I have recently installed a temp gauge and tachometer on my stella to better understand my jetting before I upgrade the head on my scoot. I am aware that I have been extra cautious with the jetting keeping it what I think is slightly rich at 118 main jet for 32F day. A couple days ago, I finally ran it for an hour or so with the new gauges on to see what my baselines were.. and found that I could never get the RPM over 5000 even on a mile or so on a less busy highway area. Max speed at about 50mph and engine temps were consistently 180F only getting up to about 200F after that mile on the highway (45F +/- day in NYC). So today, I swapped the 118 main jet which was slightly rich for 32F day, for a 116 main jet, and was able to rev up to 6500 possibly more, never went on the highway, and temps were 200F consistent, max 220F.

After looking at the manual, I see that it gets peak power at 5500 RPM stock. This led me to wonder if that should be the max at stock or if it is just the peak power range with excess RPM available. What is the max RPM for a stock engine? Anyone have specific details?

My engine and carb is stock, but I do have a SIP Road XL pipe, and Boyesen reeds. Carb idle jet 140/45 main stack 140/be1/116.
Member
2005 Stella 2T, 2014 Stella 125 Automatica
Joined: 20 Jul 2018
Posts: 39
Location: NY, NY
Wed Feb 06, 2019 11:37 am quote
I think I've answered my own question.. because of the SIP Road XL pipe, my scoot max RPM is now at 6500 over the 5500 stock.
Hooked
'04 Stella 2T GB150 '15 Genuine Roughhouse 50 '17 Kawasaki Versys 650
Joined: 08 Jun 2012
Posts: 342
Location: Philadelphia
Wed Feb 06, 2019 11:43 am quote
I've always held back at 60000 rpm. asking for more is asking for trouble.

I also try to keep it under 320F max.
Member
2005 Stella 2T, 2014 Stella 125 Automatica
Joined: 20 Jul 2018
Posts: 39
Location: NY, NY
Wed Feb 06, 2019 12:06 pm quote
Roaringtodd, do you see a drastic difference in running temp based on ambient temperature of the day? I'd imagine on hot summer days what is currently at 200-220f engine for a 42f day would probably be up in the 250-275f temps on a 95f day due to the ambient difference.
Banned
2:6
Joined: 11 Jan 2007
Posts: 7357
Location: San Francisco
Wed Feb 06, 2019 1:19 pm quote
Mechanical limits:

Piston will be over stressed above 9400rpm

does the Stella have 2mm rings like the stock P150?
if so, they will start to flutter ~7000 RPM

stock it runs out of power before this, but keep it in mind as you start to modify.
Member
2005 Stella 2T, 2014 Stella 125 Automatica
Joined: 20 Jul 2018
Posts: 39
Location: NY, NY
Wed Feb 06, 2019 7:13 pm quote
I assume so, haven't taken it apart yet. Good info on the mechanical limits!
Addicted
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 993
Location: London UK
Wed Feb 06, 2019 8:48 pm quote
Easiest way to check a main jet is do a long WOT run like you did. Then take the plug out and see what colour it is.

How high the rpm will go and where the max power is, are two different things. An average 2 stroke will typically do at least 1000 rpm over the max power rpm.
Hooked
59" Allstate
Joined: 03 Aug 2018
Posts: 126
Location: TC Florida
Thu Feb 07, 2019 5:02 am quote
RoaringTodd wrote:
I've always held back at 60000 rpm. asking for more is asking for trouble.

I also try to keep it under 320F max.
That would be something worth hearing
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