New cv carb setup jetting
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Cruiser
Joined: Jul 2013
Posts: 243
Likes: 6
From: Texas
New cv carb setup jetting
Here are some picts of the spark plugs. Does it look to you folks that I might have a front cylinder intake leak? Two picts are of the front plug (different angles) , 1 picts of the back plug. Back plug looks a little rich, front looks a little lean. What do you think?
I'm on my phone and can't see the pics that well, but that rear plug looks more like oil fouling to me.
You getting any exhaust smoke?
Edit. Never mind. I got a better look at it. What jets are you running?
You getting any exhaust smoke?
Edit. Never mind. I got a better look at it. What jets are you running?
Maybe a little, but it's hard to see. In any case, it doesn't look terrible, even if it is.
The rear, on the other hand really does look bad. Either crazy rich or burnt on oil.
Have you compression tested the motor?
How many turns on the idle jet screw? Stock needle?
The rear, on the other hand really does look bad. Either crazy rich or burnt on oil.
Have you compression tested the motor?
How many turns on the idle jet screw? Stock needle?
Last edited by 0maha; Jun 18, 2017 at 09:15 PM.
Thread Starter
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Cruiser
Joined: Jul 2013
Posts: 243
Likes: 6
From: Texas
Everything was fine until I swapped from butterfly to cv carb. I purchased an older intake and I think it is too short and I have a leak in the front cylinder. The back plug is not oil fouled it is rich. It looks like I might need to go a size smaller idle jet and main jet, and get the front leak fixed.
Intermediate
Joined: Dec 2010
Posts: 49
Likes: 12
From: Los Angeles
Are you using the stock air cleaner? I read somewhere that the front cylinder normally runs leaner than the rear one, and you jet the carb off the condition of the front plug, although your rear plug does look too rich. How does the bike run?
Thread Starter
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Cruiser
Joined: Jul 2013
Posts: 243
Likes: 6
From: Texas
Like I said in an earlier post, the bike was running great before the change over. I just did a compression test. Back cylinder 121, front cylinder 119. That was with an auto zone tester, they are notorious for not being accurate and reading low so I am happy with those readings.
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Yeah, the absolute number is less important than the fact that they are essentially the same.
I think you are on the right track thinking intake leak. Need to get that sorted before you consider jetting.
I think you are on the right track thinking intake leak. Need to get that sorted before you consider jetting.
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Thread Starter
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Cruiser
Joined: Jul 2013
Posts: 243
Likes: 6
From: Texas
Yes I am trying to find the part number of the larger intake seals harley makes. My intake looks a little short and I have read that harley made larger seals for that particular problem . Anyone have some suggestions?
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Joined: Mar 2010
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From: Honah Lee
The only time I have see a plug as clean as your front if it truly has the miles on it as the back one is either your rocker or pushrod on the intake valve is completely broken and the valve is not opening or you have not turned on the water injection on the back one. That is what a Z28 looked like that I overhauled a long while back....Go easy on the water, it's rough on starter housings...
Both my sets have 10K but my bike is FI I truly think you are maybe a tad lean but the back cylinder has a mechanical issue like a bad valve seal probably if compression matches front. Be sure to check with a good battery with the carb held Wide Open with the throttle.
Both my sets have 10K but my bike is FI I truly think you are maybe a tad lean but the back cylinder has a mechanical issue like a bad valve seal probably if compression matches front. Be sure to check with a good battery with the carb held Wide Open with the throttle.
Last edited by Jackie Paper; Sep 14, 2018 at 07:47 AM.