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Heads and Cylinders All about your porting, compression, rings, cylinder and piston modifications to your bicycles engine

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  #1  
Old 07-05-2016, 05:35 PM
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machinegun4784 machinegun4784 is offline
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Default Cylinder wear

Here's some pics of my jug. What are we lookin at here? The worn areas are rougher feeling than the shiny areas.

http://motorbicycling.com/album.php?albumid=1947
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Last edited by machinegun4784; 07-05-2016 at 05:43 PM.
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Old 07-05-2016, 07:03 PM
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Default Re: Cylinder wear

We're looking at buying a new jug, and probably rings. What DO your rings looks like? They should be flat and nearly shiny too. What made you disassemble to begin with? Noise? Compression loss?
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Old 07-05-2016, 08:37 PM
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Default Re: Cylinder wear

Well, she kept quittin on me after about 20 minutes or so and wouldn't restart. I think I just ran it out of fuel, the second time, but the first time, it still had some in there. By the way, I bought the new speed carb-seems like it's using fuel up faster. Is it a bigger jet? If so, that means it should be richer, which I would prefer anyway.

Rings and piston look fine, machine marks are still there. Plug too. Everything's just black and oily as usual. Compression is a solid 150. This thing doesn't even have 100 miles on it. It seems sluggish, but I noticed a while back that removing the muffler cap really gives it a lot more power. I'm working on that problem as well. P/C clearance is 10 thou.

I already ordered a new jug yesterday. For 25 bucks, what the ****. So is it worn chrome or aluminum transfer? Did it get too hot?
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Old 07-09-2016, 11:28 AM
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machinegun4784 machinegun4784 is offline
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Default Re: Cylinder wear

Anyone? Am I talking to myself here?
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Old 07-09-2016, 05:56 PM
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Chaz Chaz is offline
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Default Re: Cylinder wear

I believe the nt speed and stock carb have the same size jet. The nt speed carb has a slightly bigger throat.
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Old 07-09-2016, 06:40 PM
crassius crassius is offline
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Default Re: Cylinder wear

the old speed carb had a smaller venturi - I have not measured the new model with pink filter (I usually just toss them)
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Old 07-10-2016, 07:02 PM
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Default Re: Cylinder wear

I just cannot tell from the picts.
"Sounds" like you scraped the chrome off. Heat can do that, so can too much fuel.
How many miles? What fuel/oil mix? What type oil?
Coud it be fine grit getting past the air filter foam?

Inquiring minds want to know.
I've got over 1000 kms on mine, 32:1 various oils but usually semi synthetic.
I suffered some damage early on from grit getting by the cheezy foam air cleaner.
Use a good thick foam filter now.

Steve
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Old 07-17-2016, 08:00 AM
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machinegun4784 machinegun4784 is offline
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Default Re: Cylinder wear

How can too much fuel damage the chrome? As I stated, I've gone less than 100 miles. Standard cheap oil, 32:1. I'm running premium-I don't know if i need to, the compression is 150 psi. I'm not sure what the comp ratio would be. I was running the crappy stock air filter. I ordered the cone type instead.
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