pili
Scoot Enthusiast
Posts: 209
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Post by pili on Apr 14, 2022 20:42:22 GMT -5
I would think an 88 main will be way rich; the 46 pilot should be perfect with the needle raised. I run an 82 and have experimented with an 84 with no improvement; maybe a bit more bog if I give it full throttle at lower RPM. I would be surprised if the dealer has the jets in stock. It takes mine a week to order.
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Post by Zino on Apr 14, 2022 21:12:22 GMT -5
To give yourself peace of mind gets some bigger jets The 46 pilot is the the size of the vino pilot jet 5BM-14353-23-00.
I have used it with stock carb it richens up the whole throttle range .
I never found a Yamaha 88 jet that fits the stock carb So I used mikuni I f i could not find yamaha jets a 85-90 worked for mikuni.
For the yamaha jets a 82 or 84 worked for me .
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Post by chris7420 on Apr 14, 2022 22:40:49 GMT -5
I would think an 88 main will be way rich; the 46 pilot should be perfect with the needle raised. I run an 82 and have experimented with an 84 with no improvement; maybe a bit more bog if I give it full throttle at lower RPM. I would be surprised if the dealer has the jets in stock. It takes mine a week to order. Okay awesome, yeah the biggest they had was a 82 I got one of those
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Post by Zino on Apr 15, 2022 8:08:31 GMT -5
Is that 82 a yamamha jet part number 14T-14343-41-00 Jets are measured different ways some by flow some by size so one manufacture 82 is not the same as another's .
So a mikuni 82 and yamaha 82 are not equivalent.
I needed larger mikuni jet numbers to be equivalent to a yamaha
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Post by chris7420 on Apr 15, 2022 13:38:52 GMT -5
Yes that is the part number it’s the Yamaha jet. I have another question, the polini kit came with the base gasket for the cylinder, a exhaust gasket, and a green o-ring that fits into the cylinder head but no copper head gasket is that all that the polini kit uses as a head gasket or do I use the o-ring as well as a copper gasket? The old cylinder head just had a copper head gasket no o-ring. Here’s a photo - imgur.com/a/XOkbyXQ
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Post by Zino on Apr 15, 2022 18:19:56 GMT -5
The oring head is all you need i find they provide a better seal. here is a install guide by brett that shows the same polini kit being installed , 49ccscoot.proboards.com/thread/556
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Post by chris7420 on Apr 15, 2022 18:59:10 GMT -5
The oring head is all you need i find they provide a better seal. here is a install guide by brett that shows the same polini kit being installed , 49ccscoot.proboards.com/thread/556Oh yes thank you I read all that already but he showed the o ring and the copper gasket as well In his photos so I was confused and wanted to confirm. Thanks so much.
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Post by chris7420 on Apr 17, 2022 17:12:02 GMT -5
Got the kit all installed and the scoot all back together I rode it to store then to work today it runs good it has way more power and the engine has way more compression you can feel it when kickstarting it, goes 50-60kmh easily now at half-3/4 throttle I never went full throttle cause instructions said not to for first 500km’s to break it in. Also the engine is making a rattling noise now, when it’s just idling you can’t hear it but when you give it gas you start to hear it, it didnt make any abnormal noises with the old top end. Anyone have any ideas? I’m considering taking the top end apart to check everything but I don’t see what the issue could be. The idle was very high when I first started it but I adjusted it with the screw on the carb, I sprayed around the carb and cylinder and stuff with carb cleaner to check for air leaks but it seems good I’m pretty concerned about the rattling noise though
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Post by Zino on Apr 17, 2022 19:44:41 GMT -5
If you could up load the sound and pictures if you tear it down . That would help. I use a screw driver to locate problem area I take the handle to my ear and and the screw end i touch to the metal on the cvt I start at the back pulley and work toward the spark plug .With the scooter running I have someone lightly rev it I just work forward till I find the source of the sound .
If you tracked the noise to the variator area are all the rollers in good shape . If you have the same size rollers they are throwing out faster than when you had the stock cylinder.
If you have tracked it to the cylinder area .
The sport kits dont push squish that tight but try this first Check for detonation look at the fresh spark plug . Look for aluminum specs on the electrode . What octane gas are you running most of us run non ethenaol 87 octane or higher
Otherwise the next things require taking the head back off . Wristpin bearing was it new and the proper size . If it is yamaha oem that will work .
Rings are they snagging . Scuffing on the piston from piston slap.
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Post by chris7420 on Apr 17, 2022 20:34:34 GMT -5
Yeah I used a new Yamaha oem wirst pin bearing, and the first thing I tried is the screwdriver trick but couldn’t pinpoint where the sound was coming from. Ill take it apart again and take a look at the cylinder and the piston and I’m running 87 octane it does have ethanol in it is that bad? Thank you so much for the advice.
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Post by Zino on Apr 17, 2022 21:09:42 GMT -5
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Post by chris7420 on Apr 18, 2022 16:40:45 GMT -5
imgur.com/a/cDuoHt8There’s a video of the noise. When I first start the scooter and it’s idling high you can hear it but when the idle goes down you can barely hear it. It doesn’t seem to get worse with rpm’s though when I’m going 50-60 and the rpm’s are up I can barely hear it but when I’m taking off you and it’s idling high I can really hear it and it’s concering
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Post by Zino on Apr 18, 2022 17:04:11 GMT -5
What does the new plug look like ?
What spark plus is in there ? NGK BR8ES style is correct with the polini kit
I dont like that rattle either . I would take the cylinder apart and check for wear.
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Post by chris7420 on Apr 18, 2022 19:20:57 GMT -5
What does the new plug look like ? What spark plus is in there ? NGK BR8ES style is correct with the polini kit I dont like that rattle either . I would take the cylinder apart and check for wear. Yeah it never made this noise before the bbk, and yes I’m using the br8es it looks to be running pretty lean from the look of the plug. The cylinder looks good to me. Possibly some scuffs on the face of the piston and the cylinder head though, and possibly some wear on the bore just below the ports maybe. What do you think, here’s some photos. imgur.com/a/TgaAZVB
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Post by Zino on Apr 18, 2022 20:59:25 GMT -5
You have some brown on the plug. The mixture ring is brown 3/4 of the way around. With you running part throttle that plug is show casing the needle. I would drop it one notch So it richens that up. If you get the 46 pilot that would richen up the whole throttle range . Or You may need to jump to the 84 jet .
The cylinder walls look fine to me . I dont see grooves that are ground in .
Did you check squish ? 1 mm to 1.5 mm is where most sport kits run
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