How long can "China doll" hold at WOT? Also, high altitude (+gear reductions and "too lean?")

Kehkou

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Hi, everyone!

I'm new, but I'll officially introduce myself once the sun comes up so I can take pics of my bike. But obviously I have a question, so, to reiterate, how long can an all stock 66cc "80cc China doll" on a 28-inch hold WOT (wide-open throttle). What do you guys feel is safe? It's actually really nice for a China doll; I had got a bad one, and when the seller sent the replacement, it was a significantly nicer shiny one; even the exhaust port was polished! They re-sent the entire kit to boot!
For your original answer, I ride mine about 13 miles straight WOT-- or close to it. My commute to work is first/last 2 miles city stop lights and the other 13 straight miles 2 lane farm highway. I treat every ride to work as a speed run.

Also, I ride in NM at 5,500'. I'm leaving the carb at stock while I break the engine, but for folks this high up, what's the best jet size for you. What's your experience with NT tuning a mile high? I'd like a baseline to start my 'experimenting' once the engine is fully broken in.

And thank you all for the heaps of knowledge I have already pulled from this site!
 

DAMIEN1307

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Also, I ride in NM at 5,500'
I'm pretty good with altitude adjustments etc, since I am at an altitude of 4500 ft.

Once you have it broken in, the NT will need to be at the leanest setting, (C clip at the very top notch on the needle valve with the stock #70 jet).

Also because of the high heat conditions, you should be running an NGK-BR8HS for the summer time, and when it gets cold up in Albuquerque, change it out to an NGK-BR6HS for the winter. The best plug gap for these on the CGs is .025....Throw out that junk "Z" series Chineseium plug...lol.

I also recommend getting rid of the stock air filter as it is too restrictive to breathe properly at altitude...I use this one below, and it is a direct fit as well for both the NT as well as the JRL BoFeng which is a much improved version of the NT and it also has the emulsifier tube installed with the jet that the NT does not have.


 

DAMIEN1307

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This is what I ride by the way.

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Kehkou

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I'm pretty good with altitude adjustments etc, since I am at an altitude of 4500 ft.

Once you have it broken in, the NT will need to be at the leanest setting, (C clip at the very top notch on the needle valve with the stock #70 jet).

Also because of the high heat conditions, you should be running an NGK-BR8HS for the summer time, and when it gets cold up in Albuquerque, change it out to an NGK-BR6HS for the winter. The best plug gap for these on the CGs is .025....Throw out that junk "Z" series Chineseium plug...lol.

I also recommend getting rid of the stock air filter as it is too restrictive to breathe properly at altitude...I use this one below, and it is a direct fit as well for both the NT as well as the JRL BoFeng which is a much improved version of the NT and it also has the emulsifier tube installed with the jet that the NT does not have.


Thanks for the info, @DAMIEN1307! A new plug and some 'real' fuel line is on my list. Lol "Chineseium"! Better than Sino-lite!

My kit actually came with a Beifong (where the hell is the tickler, lol) but she has plenty of breath until I get out of spark timing around 30 mph and get an extremely mild 'four-stroke' (I'm just at the WOT phase of break-in). You nailed the filter with that slim model; I had to trim the tentacles off my air cleaner to get it to clear the seat tube and install it after the carb was on the intake. I also had to bang the s*** out of my muffler with a mallet to get it to clear the pedal (off of the engine, of course). Chipped some of the paint off, but I'm happy with the results, looks kind of badass and no restrictions!

Edit: *whistles* She's a beaut! Love the chrome muffler and the wheels! I also have just one mirror there. How fast have you got her to?
 

DAMIEN1307

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Edit: *whistles* She's a beaut! Love the chrome muffler and mags! How fast have you got her to?
I just changed out the motor to what you see in the pics this Saturday...On its maiden "voyage" on Saturday, it took off like a shot going uphill at 40 MPH...This is a Phantom 85 motor with the BoFeng carby and an OZ reed valve in the intake, the exhaust pipe comes with it and has a 60mm exhaust port rather than a 40mm....A One piece jug, so no separate head, and it uses an improved magneto along with a Yamaha component CDI...It is also using a 36 tooth rear sprocket...This is a very fast and powerful bike and I have to be careful with it since it wants to pop wheelies...lol.

I do not have a clue what top speed will be, but if it starts out immediately hitting 40 going uphill with no effort, its gonna be something I will find out after break-in which ZTMoto sets at 310 miles running 20:1 ratio.
 

DAMIEN1307

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I also fabricated my own front motor mount as well as the rear caliper frame adapter out of 7075 T-6 military aircraft aluminum, and am using an aviation "Adel" clamp for the front brake caliper frame adapter.

IMG_0319.jpg
Fabricated Rear Caliper Adaptor IMG_0347.jpg
Another view of rear caliper adaptor.IMG_0350.jpg
Adel clamp holding front caliper adaptor to fork. IMG_0349.jpg
 

Kehkou

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Very impressive! 30 MPH kind of scares me what with the tar strips and all. My bike, I found outside my neighbor's with a "free" sign. It was pretty beat, but I fixed it up and it was a... bike for a while. The wheels are lies (they're nowhere near true) and it has no suspension. I like it because it is vintage, like a barn find. It has an '87 serial, which is a year before me, and Generals are pretty obscure; I think it was an offshoot of Redline, out of (PA?). It's a Catalina Plus 3. Don't worry, I'll post the web's first images of one (I've looked), albeit with a motor. It just has a coaster brake and internal gear (2-speed), and a front side-pull I took off another "free" bike.

I could tell instantly that those mounts were custom. I dub it the White Beach Cruiser; we both know why!;)
 

Sidewinder Jerry

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WOT can have 3 basic affects on the engine. Safe max operating rpm, over revving and engine strain. The ideal situation is to stay in a safe max operating rpm. On a single drive ratio this can be achieved through throttle positioning and pedal assist. If you're over revving then throttle back some; going down hill for example. Engine strain is caused when at WOT you still can't reach max torque rpm. This is where a multi speed bicycle gives you more ratios to pedal assist with. Engine strain can happen going up steep hills. Get a tachometer this'll let you know exactly what your engine is doing.

If you fortunate enough to have a shifter bike and tachometer then you can use multi gear ratios. When over revving at WOT up shift to a higher gear. When under engine strain at WOT down shift to a lower gear. This way you can always stay at the max safe operating rpm.
 

Kehkou

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The Duke City
WOT can have 3 basic affects on the engine. Safe max operating rpm, over revving and engine strain. The ideal situation is to stay in a safe max operating rpm. On a single drive ratio this can be achieved through throttle positioning and pedal assist. If you're over revving then throttle back some; going down hill for example. Engine strain is caused when at WOT you still can't reach max torque rpm. This is where a multi speed bicycle gives you more ratios to pedal assist with. Engine strain can happen going up steep hills. Get a tachometer this'll let you know exactly what your engine is doing.

If you fortunate enough to have a shifter bike and tachometer then you can use multi gear ratios. When over revving at WOT up shift to a higher gear. When under engine strain at WOT down shift to a lower gear. This way you can always stay at the max safe operating rpm.
Very good advice; thank you! I try not to overrev it, especially since it is new, and I usually promptly pedal it out if it starts to lug (like up a hill). But I weigh less than 100 so the bike hardly knows I'm there.

How about engine breaking braking? I do this both with the bike and my automatic-tranny 4wheelers (passenger cars). Will it wear the cylinder or clutch gears unduly?
 
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