log
Scoot Junior
Posts: 19
Location: Oregon
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Post by log on Apr 15, 2024 19:21:17 GMT -5
Ok so I just replaced the intake gasket but it's still leaking. Anyone have any ideas?
To clarify, the intake was leaking during my first leak down test, and I figured it was because I made the gasket from cardboard. I just replaced the intake gasket with oem and it's still leaking.
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Post by aeroxbud on Apr 16, 2024 4:30:02 GMT -5
Is it leaking from the gasket surface?
You can use a thin coating of RTV to help with sealing. If your having trouble.
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gi
Scoot Junior
My motto is 'Runner & Roll'
Posts: 5
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Post by gi on Apr 16, 2024 4:49:02 GMT -5
Yeah I am hopeful I can get it to run better. I want to reintroduce the oil pump, as the previous owner had disconnected it, so that will be the next task. What do you think the breather is for? Having a hole in the oil filled transmission doesn't seem like a good idea to me. Good to hear you managed the replacement of the oil seal. About that breather, as the guys have said, that is for the gearbox ventilation. There will be no oil going into the cvt, but is necessary to help the gearbox to not get pressurised. You it really bothers you, remove the hose (#25) and leave the other part hanging somewhere next to the shock absorber mount. Sorry for the late reply but I've being pretty busy at work. |
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log
Scoot Junior
Posts: 19
Location: Oregon
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Post by log on Apr 16, 2024 13:11:29 GMT -5
Is it leaking from the basket surface? You can use a thin coating of RTV to help with sealing. If your having trouble. Ok that sounds like a good idea I will try that. As far as I can tell, it's leaking between the gasket and reeds, or cylinder. I have never used RTV before. Is there a specific type, or brand that would be good for this application? I see permatex black on google. Is that a good one?
Good to hear you managed the replacement of the oil seal. About that breather, as the guys have said, that is for the gearbox ventilation. There will be no oil going into the cvt, but is necessary to help the gearbox to not get pressurised. You it really bothers you, remove the hose (#25) and leave the other part hanging somewhere next to the shock absorber mount. Sorry for the late reply but I've being pretty busy at work. Ok that makes sense. |
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Post by aeroxbud on Apr 16, 2024 14:55:44 GMT -5
You need the automotive formula RTV. Petrol, oil and temperature resistant. Any automotive store should sell it.
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log
Scoot Junior
Posts: 19
Location: Oregon
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Post by log on Apr 18, 2024 19:56:30 GMT -5
Ok so I fixed the intake manifold leak with RTV, and did another test. It still has a leak somewhere but its really slow, so I figured it was good enough to start riding and trying to tune the carb. I started with a 95 jet and went all the way up to 115. Performance seemed to improve after the 95, but pretty much remained the same to the 115. Max speed was like 35mph which was pretty sweet, but every size I tried, after a few laps in the parking lot at WOT, the scooter would bog down. I figured it was still too lean so that's why I kept moving up jet sizes, but they all bogged at WOT after a few laps. Any ideas?
I will add that the scooter has stock carb, but previous owner removed the airbox, so I am running a pod filter. I am mixing gas because I can't find the oil inlet on the carb. I think it was snapped off? I will also say that stock jet is 83.
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log
Scoot Junior
Posts: 19
Location: Oregon
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Post by log on Apr 20, 2024 12:36:08 GMT -5
I took the carb apart again and fully disassembled and blasted with air. I tested the float height and it was either 13 or 14mm, which is out of spec. Would this cause my issue with bogging after riding at WOT for a few minutes? While I was in the carb, I put in a 90 jet, but haven't tested it yet. I feel like I might have been going overboard with the jet size last test. I tested compression while the engine was warm and it was at spec. And the last thing, I removed the exhaust and attached a heat gun to smoke the oil out, and then filled it with oven cleaner.  |
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log
Scoot Junior
Posts: 19
Location: Oregon
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Post by log on Apr 29, 2024 21:05:25 GMT -5
I started the tuning process from scratch. Following the guide on the website. I started at a 90 jet and up to 115 in increments of 5. Performance seemed to improve at 105. 105-115 seemed similar. I inspected the plug and it seemed the same after every jet. I exhausted all available jets, so i drilled out a size 70 jet to ~118. Same results as previous. My next size drill bit was a 0.145mm, so I drilled the 70 jet to 145. Same results as previous. I was hoping for a rich condition but I don't think I ever achieved that. The 145 seemed way too big but it still seemed lean. Am I being limited by the carburetor? Hopefully somebody has some thoughts on this. I took a photo of the plug at the end of the tests. I compared the plug to some online images and I think that it looks lean, but I'm no expert.
The plug was new and gapped to spec. I should add that I replaced the float needle and got similar measurements as before. I wasn't holding it at 45 degree angle so I think that's why it seemed low.
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log
Scoot Junior
Posts: 19
Location: Oregon
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Post by log on Apr 30, 2024 19:52:31 GMT -5
Today I did more tests.
I took the engine out again and did another leak down. The engine is air tight. Turns out the leak was the tester. Threw some hose clamps on and was good.
I removed the main jet and did a test run. The mythical rich condition was achieved and confirmed with sound and wet plug.
I then tested various jets and found that the sweet spot is somewhere between 0.158mm and 0.175mm.
These jet sizes seem ridiculously large for a stock 50cc. I understand that the carb is intended to get less airflow with the airbox.
Will a bigger carb allow for more fuel, less air? Maybe the stock carb was specifically designed for the low air flow? Any thoughts?
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