CV Carberator Jetting 1340 EVO ,previously modified
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CV Carberator Jetting 1340 EVO ,previously modified
Hello,
I have a 98 fatboy that I'm rebuilding.
It has 1340 Evo. So far I have found some mods in the engine, and the carb. Engine had stage 1 atleast, will pull heads soon.
The Carb had been rejected with. #48 Pilot and 185 Main..My CVP carb kit recommend #46 and #185 for stage 1.
I'm wondering if this bike had alot more done to use that pilot jet? Bike ran pretty good, but it sat for a long time..a decade.. so I knew there was a deep clean needed. i was right, lots of ethanol build up. Accelerator pump rusty and coated in Ethanol. And jets.
So the mixture screw was 3.5 to 4 turns out with this #48 jet. The Plugs showed about normal color..Front was mainly white after 1k miles and the rear was a little blacker. So I'm assuming mixture was close. But possibly would need a larger jet, as 3.5 plus turns suggests it.
I will Pull heads tomorrow to get more info on this mystery. But if anyone has a some info regarding this l, i would appreciate it.
Im thinking that the carb being so dirty it is not running even close to its potential. But it it generated decent power..but not like it was as modified as it is. I'm might put the #46 in and see how much mixture it's asking for after my build..or leave the 48 or go larger now.lol
it's just 48 seems like it would be for larger motor or highly modified..
I have a 98 fatboy that I'm rebuilding.
It has 1340 Evo. So far I have found some mods in the engine, and the carb. Engine had stage 1 atleast, will pull heads soon.
The Carb had been rejected with. #48 Pilot and 185 Main..My CVP carb kit recommend #46 and #185 for stage 1.
I'm wondering if this bike had alot more done to use that pilot jet? Bike ran pretty good, but it sat for a long time..a decade.. so I knew there was a deep clean needed. i was right, lots of ethanol build up. Accelerator pump rusty and coated in Ethanol. And jets.
So the mixture screw was 3.5 to 4 turns out with this #48 jet. The Plugs showed about normal color..Front was mainly white after 1k miles and the rear was a little blacker. So I'm assuming mixture was close. But possibly would need a larger jet, as 3.5 plus turns suggests it.
I will Pull heads tomorrow to get more info on this mystery. But if anyone has a some info regarding this l, i would appreciate it.
Im thinking that the carb being so dirty it is not running even close to its potential. But it it generated decent power..but not like it was as modified as it is. I'm might put the #46 in and see how much mixture it's asking for after my build..or leave the 48 or go larger now.lol
it's just 48 seems like it would be for larger motor or highly modified..
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It sounds like you have a massive vacuum leak, a #48 jet and 3.5-4 turns out should be running dead rich with black plugs.
John
John
Last edited by John Harper; Apr 9, 2025 at 01:23 PM.
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Well it was tuned like that with the original owner..it sat for 10 years..then I just did the maintenance stuff..3 hole, etc..sprayed the carb..and it rode pretty decent for 1k miles. Small rocker box leak got me taking everything apart..lol
but I have not touched the carb til now. I did find the vacuum tube going to the tank was eroding and not connected properly.
but I have not touched the carb til now. I did find the vacuum tube going to the tank was eroding and not connected properly.
Last edited by Ciddvicious; Apr 9, 2025 at 06:34 PM.
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I did notice when removing the carb, that the Intake rotates pretty easily. I'm going out to garage to pull head now.
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To late now as you probably already pulled the head, but the way you descibed how it ran is screaming "dirty and gunked up carb internals".
You can't really determine anything regarding the carb until you completely disassemble and clean it. The slow jet (and it's passage) and the tiny holes in the emulsion tube are the first thing to clog up from letting the bike sit. They are the smallest holes. Then comes the transfer ports, those get clogged up as well.
So my point is, once your done with the cylinder head, put it back together, make sure the bike runs like before you pulled the head, then take the carb completely apart and clean it.
Make sure every hole, port, passage, and orifice is clean and clear. Carb spray in a port and look for where that spray cleaner comes out. Thats the only way to know that port or passage is clear. Do that with everything. Inspect the diaphragm for holes. Probably need a new accelerator pump diaphragm and mini O-ring also. Careful when working near the accelerator pump diaphragm, there is a small one way check valve in hidden passage that is easily lost, you have been warned. Replace the two intake manifold seals, and the carb to manifold seal
This link is a sportster related link but sportys used the same carb. The info is very detailed:
https://sportsterpedia.com/doku.php/techtalk:evo:carb02
You can't really determine anything regarding the carb until you completely disassemble and clean it. The slow jet (and it's passage) and the tiny holes in the emulsion tube are the first thing to clog up from letting the bike sit. They are the smallest holes. Then comes the transfer ports, those get clogged up as well.
So my point is, once your done with the cylinder head, put it back together, make sure the bike runs like before you pulled the head, then take the carb completely apart and clean it.
Make sure every hole, port, passage, and orifice is clean and clear. Carb spray in a port and look for where that spray cleaner comes out. Thats the only way to know that port or passage is clear. Do that with everything. Inspect the diaphragm for holes. Probably need a new accelerator pump diaphragm and mini O-ring also. Careful when working near the accelerator pump diaphragm, there is a small one way check valve in hidden passage that is easily lost, you have been warned. Replace the two intake manifold seals, and the carb to manifold seal
This link is a sportster related link but sportys used the same carb. The info is very detailed:
https://sportsterpedia.com/doku.php/techtalk:evo:carb02
Last edited by Yankee Dog; Apr 10, 2025 at 12:04 PM.
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Thanks YankeeDog,
I have already pulled carb apart. I will soak and clean all the metal parts. I have a complete rebuild kit from James amd a performance kit from CVP.
I will definitely clean every passage before reassembling. Thanks for the advice!
I have already pulled carb apart. I will soak and clean all the metal parts. I have a complete rebuild kit from James amd a performance kit from CVP.
I will definitely clean every passage before reassembling. Thanks for the advice!
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Current state of rebuil
I received my andrews ev27 cam. In the instructions it says for 90 up evos, to use a #48 to #50 pilot jet, and 190 main. I'm guessing that's why my carb has a #48 in it, from previous cam installer following a cam manufacturers recommendations. Make some wonder if the #46 i put in will be enough..