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Post by paydem on Nov 8, 2019 10:08:08 GMT -5
In process of buying a AC zuma as you called (we call it Yamaha Spy) but I would love to know how long I can travel if the engine is set up right, and how to prepare it for long term rides
(and also, how long can I go WOT if the engine is set up right? like not running too lean or hot)
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Post by Kenho21 on Nov 8, 2019 11:26:43 GMT -5
Until it stops.
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Rune 75
Scoot Enthusiast
Posts: 441
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Post by Rune 75 on Nov 8, 2019 11:52:07 GMT -5
Until you run out of gas.
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Post by tiny on Nov 8, 2019 11:59:04 GMT -5
I've ran two Vinos for 800km at almost WOT the entire trip. 1 engine needed to be rebuilt as piston gave out(stock piston & cylinder at 18k Km plus its second 800km trip) 75km after trip. The other 1 is still going strong.
Air Cooled 2strokes were ment to be thrashed strong as hell some of them is. Namely the Yamaha 2t.
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Post by 90GTVert on Nov 8, 2019 15:03:41 GMT -5
I can tell you that I've done 10 miles or more WOT before on AC setups on multiple occasions. I mean without letting off. Even here, I don't get into too many scenarios where I can go longer than that WOT. Could do it on the highway, but I don't want to spend that long on the highway on a small scoot anyway. That's anything from stock to 60+MPH modified stuff. If the setup is sound, temps should level out. If you've got a small carb, small jets, small stinger, issues with the shrouds or fan, ignition timing issues, etc... then you will run into trouble trying to push it hard. Anything from stock to sport and even into the midrace realm can take quite a bit if it's in a good state of tune with the right components. When you're talking about pure stock, then IMO they aren't worth having if any 49cc (2T or 4T) can't spend most of it's life at WOT because otherwise you're moving too slowly for me.
LC, to me, is largely about consistent performance all day and absolute max performance. I've put a lot of 8-12 hour rides on AC setups just fine. Switching to LC mostly made it so it ran the same 2 hours into a long ride as when it just started. Something I couldn't always say about AC. AC wins for simplicity though.
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Post by Zino on Nov 8, 2019 16:20:35 GMT -5
Jet it right and run temp gauge to monitor engine and you can run endlessly
6 months out of the year I ride to work basically wide open the whole way 20 miles .
The Temp gauge stays under 350 degrees .
I have a sport kits and a pipe .
When I was stock it could not push as many rpms and the temps would be in the 320 's
I have taken a couple hour trips I am the one that wears out or I have to fill up with gas .
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Post by paydem on Nov 8, 2019 17:19:12 GMT -5
My AC ran hot and for more than 10km's when it was jetted ritch on main jet (not sure about other settings though) and lost power so bad that I couldn't get up the hill.
On the other note, does an overheating engine loses power? And an overheated cylinder can still be used? (if there's no seizing marks)
And how does it work? Piston expands too much and starts grazing the cylinder, am I right?
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Post by 90GTVert on Nov 8, 2019 17:59:18 GMT -5
If you've got a dissimilar kit, aluminum piston and iron bore, then the piston will expand more than the bore and seize when it gets hot. The hotter it gets, the more everything tightens up and you will lose power. Plus if the whole engine is hot the heat will effect other things. Can happen with aluminum bores, but they are less forgiving. Less likely to seize and more likely to put a hole in the piston.
A lot of times a soft seize just scuffs things up. Don't even have to pull it apart. Just carry on once it's cool if you wish. Severity varies though.
If the engine is running rich and still very hot and overheating, you have another issue or it's not as rich as you think (or leaking). One thing that I've had happen is a fuel delivery issue. Engine tuned rich, but on long WOT it would lose power or seize. Turned out to be a float height problem where it ran low on fuel in the bowl when given enough time. Figured that out when I realized that smaller main jets allowed me to spend more time WOT before what I thought was a soft seize. Same thing can happen with other fuel supply issues, like with a clogged vent in the gas cap.
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Post by paydem on Nov 8, 2019 18:08:58 GMT -5
If you've got a dissimilar kit, aluminum piston and iron bore, then the piston will expand more than the bore and seize when it gets hot. The hotter it gets, the more everything tightens up and you will lose power. Plus if the whole engine is hot the heat will effect other things. Can happen with aluminum bores, but they are less forgiving. Less likely to seize and more likely to put a hole in the piston. A lot of times a soft seize just scuffs things up. Don't even have to pull it apart. Just carry on once it's cool if you wish. Severity varies though. If the engine is running rich and still very hot and overheating, you have another issue or it's not as rich as you think (or leaking). One thing that I've had happen is a fuel delivery issue. Engine tuned rich, but on long WOT it would lose power or seize. Turned out to be a float height problem where it ran low on fuel in the bowl when given enough time. Figured that out when I realized that smaller main jets allowed me to spend more time WOT before what I thought was a soft seize. Same thing can happen with other fuel supply issues, like with a clogged vent in the gas cap. So, if I have my AC engine jetted perfectly or too rich, I can go WOT for as long as I can? (iron/aluminum bore) |
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Post by Zino on Nov 8, 2019 18:14:30 GMT -5
Short answer is Yes .
10 kms is not a long run .
It takes about 3-4 kms wot just for me to get to peak temps .
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Post by repherence2 on Nov 8, 2019 20:38:28 GMT -5
Get a cylinder head temp gauge and keep it below 350°f and you should be safe.
Be careful on too rich. I tried to jet my oko 28 with fat jets because most setups i read about ran jets from 130-150. So i bought a full range of jets from 130-160 and tried all of them. When the jets were 140 or greater on my engine, it actually ran hotter on my engine. Without my temp gauge, i would have never known that it was getting hotter.
I ended up running a 125 main on my 94cc. I could hold WOT for as long as i wanted to at 350°f.
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Post by paydem on Nov 9, 2019 6:07:20 GMT -5
Since I don't have a temperature gauge, should I run it until it stops? Then it seized/hot seized, I guess. But if it's not reacting to throttle well and the power is way down, should I stop? That's an AC engine we're talking about.
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Post by Zino on Nov 9, 2019 9:17:25 GMT -5
I dont run my scooter when its not running right .
What jet are you running and what carb?
Do you have multiple jets so you can adjust it even closer ?
Check to see if you have a exhaust leak.
Take a gloved hand and a rag While the scoot is running plug the exhaust if your scoot Kills quick you are good if it keeps running you have a leak and will go lean and over heat .
Check for air leaks around the carb and intake manifold while the scoot is running check by spraying starter fluid at around the intake If the idle speed changes that is here you have a leak .
You also can check the same way at the head gasket with the starter fluid .
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Post by ryan_ott on Nov 9, 2019 9:35:12 GMT -5
I’ve done a lot of decent rides on my old AC setup. Some just under 200 miles others for 4-6 hours at 50mph plus. I was running a Polini cast, C16 and 21mm. Jetted right you can run in the 280-320 range for miles on end. Run a temperature gauge.
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Post by paydem on Nov 9, 2019 10:24:00 GMT -5
I dont run my scooter when its not running right . What jet are you running and what carb? Do you have multiple jets so you can adjust it even closer ? Check to see if you have a exhaust leak. Take a gloved hand and a rag While the scoot is running plug the exhaust if your scoot Kills quick you are good if it keeps running you have a leak and will go lean and over heat . Check for air leaks around the carb and intake manifold while the scoot is running check by spraying starter fluid at around the intake If the idle speed changes that is here you have a leak . You also can check the same way at the head gasket with the starter fluid . I’ve done a lot of decent rides on my old AC setup. Some just under 200 miles others for 4-6 hours at 50mph plus. I was running a Polini cast, C16 and 21mm. Jetted right you can run in the 280-320 range for miles on end. Run a temperature gauge. You people are awesome, thank you. Such a good information on my next build. Also, can I test crank seals without pressure testing it first? And what temperature should be at an LC engine, 50 or 70cc? I heard AC can take more heat (partly because of it's lower compression) am I right? Sorry if I'm bothering y'all with these questions, just something to keep in mind. My friend has a 2-stroke that's not running well and I'd love to buy a 2-stroke scooter/dirtbike soon, so I'd like to ride it atleast 100 miles WOT if jetted right and running right..... Also, would minarelli (or other) AC engine would run cooler if the shroud's vents are removed? AND if I do long wheelies, on minarelli AC that I had I sometimes sort of run-out of fuel, so should I somehow tilt the carburetor leftwards so in the long wheelies it stays vertical?  Sorry, just high thoughts... |
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