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Post by paydem on Nov 9, 2019 13:06:01 GMT -5
Another question... I've seen a guy do 700km trip all around the way on low 60's c stable on the temperature (Yamaha Aerox LC cooled), is that true? If so, does connecting it in different places can give a false reading?
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Post by paydem on Nov 9, 2019 12:27:03 GMT -5
The air shrouds are there for a reason. They help direct the cooling air flow around the cylinder So removing them would make it run hotter. No, I'm not talking about removing the shrouds. I'm talking about cutting them. i.ebayimg.com/images/g/0toAAOSwuMZZHZcq/s-l300.jpgSee these shrouds there? If I cut them out, would the engine run cooler?
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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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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 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 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 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 paydem on Aug 30, 2019 6:22:26 GMT -5
Sold my first scooter that I had for exactly 23 months. Definitely has been a journey, learned to do endless wheelies, circle wheelies and some other stupid stuff. Kinda sad to see it go but I need money for a car, so nothing much that I can do. Hopefully will buy one in the near future.
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Post by paydem on Aug 24, 2019 10:49:51 GMT -5
I have a CDI box that signs off at 6900 rpm in my pile,perhaps yours is restricted also? No, mine's not restricted. My only good guess as to what's happening is that my case is not hermetic (or leak-proof), because I've dropped the main jet by 10 and it still is rich up top. Probably crank seals, which I've installed, are leaking pressure and forcing a rich-mixture.
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Post by paydem on Aug 22, 2019 13:01:08 GMT -5
Changed main jet from 90 to 80. Top speed increased, rpm's now build all the way. Only at about top speed (50mph) it starts cutting down when I give it full throttle. I guess dropping down main jet size would help, but I don't have different jets. And yes, tuning that way will probably seize the piston, though I don't really care
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Post by paydem on Aug 21, 2019 14:15:33 GMT -5
Weird. Went today on a ride, it was a cold day. Could go WOT for as much as I wanted, the engine ran fine and didn't "misfire" - built rpm's all the way. I guess it's carburetor's settings that I got wrong, correct?
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Post by paydem on Aug 19, 2019 9:37:41 GMT -5
Errmkk,are you sure it,s engine related ?it could be the CVT overheating ? Geoff I'm pretty sure it's the engine. And when the engine is cold, it starts first kick everytime, but when it's hot I have to give it full throttle and kick it a few times to start it (doesn't matter how I set up the carb) so I guess it's the lack of compression. But why it wouldn't build rpm's is unknown.
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Post by paydem on Aug 18, 2019 8:28:40 GMT -5
minarelli horizontal 70cc air-cooled engine. when the top end was new it would max out at about 50mph. now it barely tops out at 43mph when the engine is relatively cold, and about 38mph when hot. I guess it's because I need a new piston.
Other problem which I couldn't figure out is, when I lift the wheel off the ground, and give it full throttle, the engine tops out at about 7000rpm (when top rpm should be around 10k), it other words, starts trailing, sounds like it cuts ignition (and at the moment when it cuts ignition, it puffs out smoke out of the exhaust) which I guess is unburnt fuel.
I've changed the ignition coil, spark plug, and the problem is still there. I would love to know if it's electrical or I need a top end refresh. Opinions?
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Post by paydem on Apr 9, 2019 10:50:51 GMT -5
that's strange. my rear drum brakes create much more drag and noise compared to discs. maybe the caliper's pistons doesn't return to their place and drags, or the caliper isn't centered with the disc? did you try to push the brake lever and then tighten the caliper bolts? check your pads, and also the spring that's on the brake cable. If the pads are thin or if the spring has gone soft you won't be able to adjust it properly, so to get brake pressure you have to adjust it all the way into the point where the shoe is dragging. the way i've adjusted it now the wheel can spin freely, any more and it starts dragging. i have to use two fingers to be able to stop. it makes noise when rolling, too. not sure, maybe I need to replace the pads. i've driven scooters with minarelli horizontal disc cases and the friction felt non existent, it stopped perfectly too.
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Post by paydem on Apr 7, 2019 10:53:37 GMT -5
All I had at the time was a 4" grinder/cut-off wheel :/ I've gotta nice Dremel tool now, but if I was gonna redo it id either do a conversion hub and keep the drum brake or I'd use an aerox case. To be honest, I've actually noticed a difference in Rolling resistance between the heavier disc brake bikes and the lighter drum brake bikes. My old prebug was way quicker off the line just cuz it rolled very easy, and it had front+rear drums. Drums have no rolling resistance compared to discs, that constantly drag the pads on the rotor. that's strange. my rear drum brakes create much more drag and noise compared to discs. maybe the caliper's pistons doesn't return to their place and drags, or the caliper isn't centered with the disc? did you try to push the brake lever and then tighten the caliper bolts?
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