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Post by origjoker on Jun 8, 2013 8:29:53 GMT -5
Hey guys, I have an odd problem that started about a week ago. Normally my scooter is capable of 55mph and sometimes a bit more depending on wind etc... but all of a sudden one day I was struggling to hit 51-52. This went on for a couple days so I started off by doing a valve adjustment and new fuel filter then tried my spare CDI, Coil and Plug all separately so I could pinpoint if it was one of them. No changes at all changing any of this. Now is where it gets strange.... The next day I filled my tank at Mobil (91 octane) and BAM! 55mph again just like before....Must have been a batch of bad gas... This lasted about 2 days and the problem was back so that ruled out my bad gas theory. I thought maybe it was a fuel tank vacuum problem, Maybe bad gas cap or vent valve so I loosened the cap and it did not help either. Went to a different gas station and filled up again, Now it's back to 55mph....!!! This is my scoot: itistheride.boards.net/index.cgi?action=display&board=50ac&thread=1710&page=1All emissions junk removed and the only things left would be vacuum or fuel pump? I thought it could be belt or clutch slippage also but that should happen more consistently. It's also a noticeable lack of power from about 30mph up when it's happening, It just doesn't have quite the pull that it normally does. This is my first actual problem with it in 3200 miles so I am not greatly concerned yet just wondering what it could be? Thanks in advance guys!!! |
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Post by scootnwinn on Jun 8, 2013 9:42:39 GMT -5
I think the belt could be the issue. But the fill up cure is what makes you wonder. Is there anything in your tank that could be blocking the flow and then when you fill up get blown of the outlet? If that is the original belt you are close to its service limit...
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Post by origjoker on Jun 8, 2013 10:17:37 GMT -5
Original belt was tossed at 1100 miles and swapped for an Ebay Gates fake, I opened the cover and cleaned out the variator real good a couple weeks ago and everything looked fine. Drilled some cooling holes in the variator cover too.
There could be something in the tank, Haven't checked that but it doesn't only run good at fill ups. It does run fine about 1/2 the time when I don't fill up, It just seems like right after I filled it both times it ran good the next 3-4 times I drove it.
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Post by indymoped on Jun 8, 2013 15:39:23 GMT -5
If you find that after fill ups is the only thing in common with being able to not struggle to get to top speed I would start there. Check the tank for any sort of debris that could be clogging it. Also this is very far fetched but could the weight of having more fuel in the tank be helping cover up a worn out petcock valve? Maybe try bypassing the petcock if it is externally mounted...
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Post by origjoker on Jun 8, 2013 15:57:42 GMT -5
It is external, It's bolted to the frame below the tank...My only scare there is then I would be 100% gravity fed and that could vapor lock the engine. I was planning to buy a Mikuni pump anyway since the stock ones are unreliable but I want to track down this bug first before I just start throwing $$$ and parts at it. All the other parts I used were spares already so it hasn't cost anything but time so far.
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Post by indymoped on Jun 8, 2013 20:56:52 GMT -5
You won't vapor lock the motor or hurt anything as long as you don't leave it sitting with the petcock bypassed. If you don't want to have to switch the hoses around every time you shut the scoot off get an inline shut off valve.
As far as the petcock the stock ones in my experience anyways have always been very reliable so that is why I have my doubts that your petcock is casuing the issue but it never hurts to check.
Also I wouldn't go out and buy a Mikuni unless it turn out yours is bad.
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Post by origjoker on Jun 9, 2013 0:58:24 GMT -5
Yeah, I don't want to buy the Mikuni unless I know it will fix the problem for sure. I may snag a $4 shut off valve and try that, I'm not sure if it will feed properly if it's bypassed though. The bottom of the tank is a bit below the carb level so it may not gravity feed correctly. I drove it about 30 miles today and both ways 52 mph max, It just has less power through the whole range when it's acting up. It has to either be fuel related or my clutch/belt slipping though...I plan to take apart the clutch assembly this week and scuff it up real good with some sandpaper anyway.
Still has me puzzled though...
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Post by prodigit on Jun 9, 2013 3:01:04 GMT -5
Could be a variety of things,
1- Bad weather, too much humidity in the air will reduce performance, low pressure will make you run richer.
2- Wind against. Sometimes the wind goes against you on a certain road. Not enough to notice, but if you have a 5-10MPH wind against you, while on another day it's in your back, you could easily see a 5MPH speed difference.
3- A high pressure (sunny) will make you run leaner, but also will make your tires deflate somewhat (pressure can drop by a few PSI). Deflated tires cause drag, that can be translated to slower top speed and acceleration.
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Post by indymoped on Jun 9, 2013 10:53:37 GMT -5
The bottom of the gas tank is below the carb? Did you move the gas tank from the factory location? As far as I know the "fuel pumps" we have are nothing more than a valve that opens and shuts with vacuum and I don't believe they create any pressure to actually "pump" the fuel.
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Post by origjoker on Jun 9, 2013 12:07:23 GMT -5
prodigit - I don't think wind/weather are the problem, It's been pretty cool and dry here lately and only a couple days where it was pretty windy. Last night was low wind and nice and cold out and I still struggled to hit 52.
indy - I checked today, Tank is a bit higher that the carb inlet. I am going to yank the line and run it direct on the way to work tomorrow and see what happens. Pulled the carb today and gave it a good bath, It was pretty clean and took it for a test drive after with same speed issues.
Thanks for the replies! Will update tomorrow after work (hopefully with good news ;D)
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Post by origjoker on Jun 9, 2013 14:53:13 GMT -5
Ok, quick update...Yanked fuel pump and took it apart, Everything looked fine so I reassembled and checked my vacuum lines going to it and to the carb and they are both great also. Next is clutch/belt and fuel tank I guess....grrrrrr
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Post by geh3333 on Jun 10, 2013 16:39:59 GMT -5
I removed my fuel valve as i like to call it. I put an actual fuel shutoff valve on instead. I usually leave the valve open. The carb float will shut the flow of gass off, ive never had a vapor lock prob the stock fuel valve is worthless.
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Post by jerseyboy on Jun 10, 2013 16:59:58 GMT -5
I removed my fuel valve as i like to call it. I put an actual fuel shutoff valve on instead. I usually leave the valve open. The carb float will shut the flow of gass off, ive never had a vapor lock prob the stock fuel valve is worthless. WOW,, So we can just put a regular petcock on these,,then just plug up the vacc line at the manifold?? If so,,that would be cool,,one less thing to go wrong... |
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Post by geh3333 on Jun 10, 2013 17:32:21 GMT -5
That is correct just plug the vac line i used an extra cvt cover screw. I have heard of others doing the same thing. Will not hurt anything. I also used a heavier 1/4 inch fuel line with actual scew clamps , much more reliable.
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Post by jerseyboy on Jun 10, 2013 20:55:01 GMT -5
[replyingto=geh3333]geh3333[/replyingto]I wont have anymore vacuum lines,,I bet all that extra vacuum will make the motor run even better yet.
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