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DR177 kit installation

 
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Mr.FixIt
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Joined: 01 Aug 2018
Posts: 96
Location: York, PA, USA
Stella 2T

PostPosted: Sat Sep 14, 2019 2:35 pm    Post subject: DR177 kit installation Reply with quote

Might as well start a new thread on this.

DR177 kit from Scooter Mercato came in Thursday. I spend all evening doing the cleaning and prep work to bolt the kit in. No grinding, no cutting, just bolt on. I remembered to measure how much stud was sticking up above the head joint, so I just threaded them back in the same distance and used the torque wrench to finalize the installation. Added enough 2T oil to the fuel tank for an extra pre-mix for run-in.

I managed to sleep all night with anticipation of kicking her back to life this morning.

It was that easy after I re-attached the SITO+ exhaust. I dropped in the 112 Main Jet to start with. She fired up with a nice bit of smoke from all the assembly lubrication. A quick twiddle on the idle mix screw and she's idling nicely. I triple-checked the timing.

I would have been alarmed at the noise from the new cylinder, but I watched a few videos where others experienced the same thing, and they said that the DR kit is just loud at first and will eventually seat in.

I wanted to go down to the post office, but it started raining so I didn't get a test drive in yet.

More to come when I get a few miles on...

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johnk
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Joined: 03 Sep 2018
Posts: 163

2003 Stella 2T & 2012 Stella 4T

PostPosted: Sat Sep 14, 2019 2:52 pm    Post subject: Reply with quote

Nice work! I am really glad you got it working again.

I also like that the kit is "for agonistic purposes only."
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2003stellaDave
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Joined: 30 May 2017
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PostPosted: Sat Sep 14, 2019 8:58 pm    Post subject: Reply with quote

Cool. Keep us posted!
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Mr.FixIt
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Joined: 01 Aug 2018
Posts: 96
Location: York, PA, USA
Stella 2T

PostPosted: Sat Sep 14, 2019 10:52 pm    Post subject: Reply with quote

Well, gang.... the rain finally stopped enough to do additional testing.

The 112 main jet was silly rich. It was just soot on the plug.

I skipped over 110 and went straight to 108. Still sooty.

I went down to 106 with a hint of soot, but not a lot of go. It burbled like it was too rich.

I didn't expect to go less than that initially, so I was faced with a quandary. I didn't want to jump the whole way back to a 100 main with nothing in the middle to tune with. So the only thing to do was increase the air. (I'm able to strip the main jet out with my eyes closed at this point)

I "de-blued" the stock air cleaner and discovered it was fairly contaminated with oil in the white part too. So I cut all of it off. (its an adventure right?) I had plenty of UNI air filter foam in stock, so that was fitted to the air filter frame.

Now with a free breathing air cleaner the 106 main jet hesitates ever so slightly like its too rich, confirmed by a hint of soot on the plug on a short ride. So I threw the 100 main back in and went around the neighborhood. With the free-flowing air filter, it seemed about right. Its still in break-in so I can't hit the revs and see how she pulls. It putters around reasonably, with only a hint of soot. The problem is running 3% oil for break-in contributes to an oily plug. I haven't gone for more than a mile or so on each of the final test rides, so she's really not up to temperature.

I'm certainly not going to call it a final tune. I might not even attempt "final tune" till I get a couple hundred miles into break in. Its close enough for today and I need a beer. For "agnostic purposes only", I think I'll just be skeptical enough to believe that it needs more testing and tuning. Razz

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Mr.FixIt
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Joined: 01 Aug 2018
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Location: York, PA, USA
Stella 2T

PostPosted: Fri Sep 20, 2019 7:50 pm    Post subject: Reply with quote

Update.

The ride and tune testing continues on the DR177 & Sito+. As of today the present jetting is:

Stock 20/20 carb
55/160 idle, 160 air, BE3 atomizer and a 106 main jet.


4th gear and a good bit of throttle is just about right. Its still not broken in yet, so its not really peppy. I can cruise easily at 35-40mph on the flat. The 108 main jet was just boggy and wouldn't go.

Here's the issue. Part throttle just tootling down the road it has a burble to it. I don't know how to describe it. It hesitates and is not smooth. As soon as I add more throttle and she starts to pull it smooths out. Pulling the choke strangles the engine so its still not too lean.

Now I'm not sure what to change to get the mid-range corrected. Confused

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Christopher
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Joined: 11 Nov 2019
Posts: 6
Location: Rochester Minnesota
2007 Stella 150

PostPosted: Mon Nov 11, 2019 11:40 am    Post subject: Reply with quote

Did you ever get the jetting figured out? Curious what you ended up with. I just bought a Stella with the same setup.
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Mr.FixIt
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Joined: 01 Aug 2018
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Location: York, PA, USA
Stella 2T

PostPosted: Mon Nov 11, 2019 12:40 pm    Post subject: Reply with quote

The weather turned cold, so I haven't come to a final conclusion with enough miles for break in. It is between 106 and 108 Main Jet.

The 106 gives good pickup and pulling torque, but hasn't yielded a brown plug color. It does bog down when I pull the choke, so not overly lean.

The 108 seem a bit doggy in general like it is too rich. I'm considering a 107 Main Jet. If I drive by the Cylinder Head Temperature gauge, I can reach 280'F without really pushing hard (with this cold weather). That's making me think it might still be a little on the lean side, OR its still tight and not broken in properly.

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Christopher
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Joined: 11 Nov 2019
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Location: Rochester Minnesota
2007 Stella 150

PostPosted: Wed Nov 13, 2019 2:28 am    Post subject: Reply with quote

I want to try one of these, should be able to get a really good idea of the jetting for each stage.

https://www.plxdevices.com/PLX-Wideband-O2-Air-Fuel-Ratio-Sensor-Modules-Gauges-s/125.htm
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Mr.FixIt
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Joined: 01 Aug 2018
Posts: 96
Location: York, PA, USA
Stella 2T

PostPosted: Wed Nov 13, 2019 7:21 pm    Post subject: Reply with quote

Its nice to be able to put a number on something and chart it out. The wide-band lambda sensors are power-hungry to keep the internal heater warm. I bought a system like this 15 years ago to try to measure the emissions of a natural gas Caterpillar G3406 engine that I was working on. The results were less than exciting. I ended up not using it, and it was an expensive failed experiment.

That's not to say that this newer unit wouldn't work. I imagine it would require fairly steady-state conditions to get a good measurement.

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Christopher
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Joined: 11 Nov 2019
Posts: 6
Location: Rochester Minnesota
2007 Stella 150

PostPosted: Thu Nov 14, 2019 12:22 am    Post subject: Reply with quote

I was thinking about feeding it with its own battery while tuning. Also need to hook up an.oscilloscope and see.how noisy the power really is. I could add a capacitor as a filter to the positive lead if needed.
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Mr.FixIt
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Joined: 01 Aug 2018
Posts: 96
Location: York, PA, USA
Stella 2T

PostPosted: Tue Nov 19, 2019 5:04 pm    Post subject: Reply with quote

The #108 main jet was totally dogging on me last night when I took her out to the gas station for some Ethanol-Free. She didn't want to climb any hills. I put the #106 main jet back in which yields about the right performance.

So how hot should I let the CHT reading get (measured with the ring under the spark plug)? What's a good alarm threshold? Am I playing with fire exceeding 280°F and not really pushing it?

(edit)
According to http://www.vespalabs.org/wiki/vespa-tuning/gadgets/cylinder-head-temperature-gauge
Quote:
Roughly a Vespa engine will run at between 320F and 380F, different engine set-ups will run different temperatures



Apparently I have to re-torque the case bolts again, she's dripping gearbox oil. (grumble grumble)

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Christopher
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Joined: 11 Nov 2019
Posts: 6
Location: Rochester Minnesota
2007 Stella 150

PostPosted: Wed Nov 20, 2019 2:01 am    Post subject: Reply with quote

Those temperatures are about right, from my studying. I have been working on tuning my 50cc scooter with a 70cc big bore kit that turns 11,000 RPM. I've been using a cht gauge and shooting for around 320, I read to stop at 350.

This is where I get my information from.

http://49ccscoot.proboards.com
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