Loss of power on hills

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march10k
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Location: Hawaii

Loss of power on hills

Post by march10k »

My brand new Buddy 50 suddenly lacks power on hills. I thought it was just my imagination. But there’s this one hill on my commute... I always hit a red light right at the bottom. I was making 30mph up the hill from a dead stop, but today I noticed that I only got up to 20, so I guess this is for real. I’m right around 500 miles, and I got that first service at 208, and stayed off the throttle until then. I have been bad about keeping it under 75% throttle since the service, but I don’t run around with it wide open, either. It seems like it doesn’t get off the line very well, even on level ground. Any ideas? I’m taking it to the dealer the day after tomorrow.

I might ask them to put in slightly lighter rollers, since my commute is 6 miles of nothing but hills in 25 and 35mph zones, so I never really get above 40-45 anyway. But that’s separate from the problem I’m having.
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Stanza
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Post by Stanza »

Hmm, what octane of gas are you running? Did you fill the oil tank yourself, or did the dealership take care of that for you? In either case, which type of oil was used?

About that hill though...how steep is it? And if I'm reading this right, you're still hitting 40-45, given enough room?

It could be something simple, like the rear CVT pulley needing lubrication, so it moves smoothly through its high-low range.
march10k
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Post by march10k »

91 octane and silkolene, so no issues there. The dealership explained that the stock compression spring (they called it a ‘center spring?’) Softens from the listed 1000rpm to about 7-800rpm when broken in. They replaced it with a 1500rpm spring that they say will be good for 1000-1300rpm when it breaks in (about a thousand miles from now). Sure enough, with the new spring, I’m back to getting up to 30mph on that one hill! I guess the tradeoff is lower top speed, but my entire commute is 6.2 miles long, hilly, and exclusively in 25 and 35mph zones. I did notice that the bike is slightly less happy at 40-45 (it seems willing to go faster, but starts to sound like it’s over-revving somewhere around 50mph) than it was with the worn in stock spring, but that’s okay.
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skully93
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Post by skully93 »

I know different states use different methods to calculate, but you shouldn't need to go higher than the 87 Octane. Not that filling 30 cents more hurts the wallet, it just doesn't matter.
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Stanza
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Post by Stanza »

I find it a little strange that it would have suddenly gone soft though....Wouldn't a spring softening up have been a gradual process? I ask because you mentioned that it seemed to happen one day, vs a gradual decline in speed.
march10k
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Post by march10k »

As for the gas, I'm told that the jets are so tiny in a 50cc that you need all the detergents you can get. Also, compression is so high that lower octane increases the incidence of 'precombustion,' and we don't want engine knock. Just what I've been told, and, like you said, it's 30 cents a tank.

As for the spring, it was news to me, the bike actually felt like it got stronger around 70 miles, and the bike shop attributed that to the spring wearing in....now that it went weak at 500 miles, they attributed that to the spring wearing in. I can't see both being true, of course, but the proof is in the pudding.

I wouldn't say that it happened overnight. At minimum, it took a couple of days to be noticeable. I didn't mention it to anyone for a good week after I started to notice that something wasn't quite the same. I don't think it was a linear process, but it might have reached an inflection point or crossed a threshold where suddenly it was a noticeable issue for me.

With a new 1500rpm spring, I'm back to getting 30mph on that steepest hill. It also explains something else that was puzzling me. I wasn't convinced that the bike had issues getting off the line, but it was definitely weak from 20-35mph. If it was a matter of the spring doing what it does at 7-800rpm instead of the listed 1000rpm, that makes sense, I guess. And with the new spring, I do feel like it's soft from 30-40mph...which also makes sense if I'm comparing the new 1500rpm spring to the old 1000rpm spring. Hopefully, once this one is 'worn in' it will behave like a brand new stock spring, getting up that hill at the 30mph I expect, and not lugging between 30 and 40 like I'm now experiencing.
lovemysan
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Post by lovemysan »

The stock clutch sheave is designed to "lock" in over range at about 25mph. The increased spring pressure will delay this as you found out at a cost of top speed. There is another option. You can replace the stock clutch sheave with a straight ramped unit. Then I would going down to a 1000 or 1200 rpm(if you can find one) spring. You could also at that point reintstall the stock spring install the sheave, and lower the roller weights by half a gram. ALLLL that aside, the 1500 spring is a good compromise.

Here is a good moving demonstration of how it works. Be forewarned his conclusions apply to someone living in a flat area. Hills cause the driver to get stuck in overrange when you are forced to decelerate .
https://www.youtube.com/watch?v=FjVhtKaOH04

This one fits
https://ncystore.com/ncy-secondary-slider-dio-qmb
161cc big bore kit, NCY big valve head Hand ported, NCY transmission kit, jetted and tuned. I can port your cylinder head.
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