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Post by aspireman on Sept 18, 2015 12:53:51 GMT -5
Hi, I'm at a loss on what could be the problem with my 50cc ped. It's a Znen Aurora. I've posted here before. I've tinkered a lot and haven't gotten anywhere. I brought it in to the shop. This is what has been gone through.
Variator and weights seem OK. Not much of a change example for the typical acceleration response.
Secondary seems to work OK. I have ran it without the cover and the clutches seem to be working fine. I've tried a different secondary without any change.
Air filter cleaned.
New fuel filter.
The shop tried a different CDI with no change in performance.
Valves have been adjusted.
I've been trying different jetting, but so far no real change in performance. Right now I've tried 34 and 32 pilots and 78 and 80 mains. The others aren't marked, but I believe there are 82's and 85's.
Belt is new. No rear brake drag.
Oil and lower end changed.
I've checked for air leaks the cheap way by spraying carb and choke near hoses to hear of any changes in running. No changes that I have heard.
Mixture screw anywhere from 1 1/2 to 1 1/4 out. Not much of a change.
Anyway, the scooter seems to get to 20 on lower weights OK, but takes forever to get any faster. Down hill maybe 30. That was with 32 and an unknown main. Anything past 3/4 throttle gets boggy. No real acceleration. I switched to a 34 and 80 and it gets really boggy won't go past 10. 78 main boggs out 3/4 throttle bad. I've adjusted the mixture a bit, but no change there. The thing is is that it ran fine for months with the jetting it had and belt, rollers and tuning. And then it started acting weird. Any thoughts or suggestions?
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Post by Silar on Sept 18, 2015 13:02:02 GMT -5
Pull the carb and check the float. The reason I say this is because from what you have said, the jets have been changed quite a bit lately and it would be easy to accidentally bend the float tang.. Clean it while you have it out, or even just replace it. make sure the auto enricher is working right. If not, it may keep extra fuel going. Make sure you don't have an air restriction. If you have your factory airbox, try temporarily removing the air filter cover and the filter element and see if you still have the same problem.
Also, anything past 3/4 throttle should be the main jet.
One other thing I forgot to mention and it's something that seems to be constantly overlooked but so easy to fix. If you have a vacuum petcock, remove that crazy thing and go buy a manual one to replace it with. They are ridiculously prone to fail and will feed extra fuel into the intake causing what seems like a overly rich condition. It actually caused my scooter to only go up to 10mph and wouldn't go any faster... the diaphragm apparently tore inside the petcock allowing fuel to be sucked into the vacuum line..
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Post by aspireman on Sept 18, 2015 13:11:27 GMT -5
The carb is new. Less than 20 miles on it. I'll look into the other stuff.
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Post by aspireman on Sept 18, 2015 13:14:39 GMT -5
Do you have a link to the petcocks? Mine screws to the bottom of the gas tank. It's not inline.
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Post by Silar on Sept 18, 2015 13:20:27 GMT -5
Does yours have a vacuum line ran to it along with the fuel line coming from it?
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Post by aspireman on Sept 18, 2015 14:56:16 GMT -5
I just stuck in a 32 and an unknown main. Seems to running pretty good. I can twist full throttle and there's no hesitation. Speed is still down. 27 on a 1/4 mile. Can you upload videos or pictures on this forum? I have a picture of the petcocks and a video of how it ran.
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Post by Silar on Sept 18, 2015 15:08:01 GMT -5
I just stuck in a 32 and an unknown main. Seems to running pretty good. I can twist full throttle and there's no hesitation. Speed is still down. 27 on a 1/4 mile. Can you upload videos or pictures on this forum? I have a picture of the petcocks and a video of how it ran. I think so, but for video I usually just upload to youtube and link here..
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Post by aspireman on Sept 21, 2015 10:08:51 GMT -5
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Post by aspireman on Sept 21, 2015 10:09:40 GMT -5
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Post by aspireman on Sept 21, 2015 10:52:56 GMT -5
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Post by aspireman on Sept 21, 2015 10:55:40 GMT -5
Sorry about the double post. The first is my petcock. As I said it is connected to the tank. The next is a video of my run with it. Seems to run OK, but still kinda slow.
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Post by Fox on Sept 21, 2015 15:39:30 GMT -5
It's sure sounds like it's running pretty good. How heavy are the existing weights? What type of air filter you running? Are you sure your speedo is accurate?
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Post by aspireman on Sept 21, 2015 16:12:16 GMT -5
Should be 6 grams, maybe 4, but pretty sure 6. Haven't had time to change them. In the past when it wasn't running right it would bog down at full throttle. Speedo is correct. More so than my 150.
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Post by aspireman on Sept 21, 2015 16:13:05 GMT -5
Oh, and stock filter. Just cleaned.
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Post by Fox on Sept 21, 2015 16:58:30 GMT -5
If they are 4 gram that would make it take of fast but it would possibly lose top end from insufficient weight to fully counteract the contra spring with a load on the engine. They might seem okay with the scooter up on the stand with no load on the engine but that's not the same cause the engine is not loaded down with a rider and the weight of the scooter itself so it's free to rev up real easy so it's not a true assessment of the performance. I would suggest you find out for sure how heavy they are. So assuming they are 6 gram then you should be able to achieve 30-35 mph normally so if they are indeed 6 grammers, the top end bogging would point toward a jetting/air flow issue. You said you don't know what size jet you have so you can do some experimentation with air flow in hopes of maximizing the engines potential with the current jet. You can try removing the plug inside the snorkel or the small tube inside the air box cover to increase air flow. It may help since you swapped carbs. You can even drill holes in the cover to increase flow. If it gets worse with more air flow then go the other way and restrict air flow even more by partially closing off the intake snorkel. A piece of duct tape is good for testing purposes. This sometimes works on a carb with a smaller jet. There are a couple of posts in the library regarding increasing air flow in a stock air box. 49ccscoot.proboards.com/thread/2387/increasing-flow-virtually-stock-airbox49ccscoot.proboards.com/thread/1360/139qmb-airbox-mods-increased-flow
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