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Old 04-06-2020, 06:11 AM
DirtyDogs446 DirtyDogs446 is offline
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Default Top end issues

So these are all the parts I have installed on predator 212 billett flywheel and rod 18lb valve springs set lash at .003 as recommended mod2cam got a tourque converter with juggernaut driver performance high flow exhaust and air filter and mikuni 24mm flatslide carb. The engine does not want to idle unless you have it around 4000 rpms. Once you start getting to top end it stutters for some reason. Spark plug is black with a little black smoke while idle. Engine and all parts brand new sorry no pic of tourque converter and juggernaut driver. I just feel like it also should be faster then it is and the stuttering more at the top end is annoying any help would be great
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Old 04-06-2020, 06:44 AM
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Did you tune the carb after you installed it?
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Old 04-06-2020, 07:16 AM
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Sounds like its running super rich. I would try tuning the carb like anickode suggested. It wont want to idle until you lean out the fuel mixture
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Old 04-06-2020, 07:25 AM
DirtyDogs446 DirtyDogs446 is offline
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Originally Posted by Wilson_Engine_Shop View Post
Sounds like its running super rich. I would try tuning the carb like anickode suggested. It wont want to idle until you lean out the fuel mixture
I tried and tried and it was almost like it did not do much no matter what I tried it seemed like it was still getting to much any suggestions? Do I need a racing head something that can handle the gas coming in if so any suggestions
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Old 04-06-2020, 07:25 AM
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Yeah, those flat slide carbs are pretty generic. Especially if you didn't order from someplace like GPS or BMI as being set up already for a predator. They'll typically need tuning right out of the box.
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Old 04-06-2020, 08:45 AM
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Is the choke closed (or stuck closed internally)? Which side of the carb is the pilot adjustment screw (intake side or motor side). When you're adjusting the pilot are you making very small adjustments and allowing up to 30 seconds for it to take affect? Picture the pilot screw as a clock face with 12 hours, adjustments should be 1-2 hours small. As others have said chances are it needs to be set up for your application right out of the box (by re-jetting it) but I thought I'd help do some troubleshooting. I'd also ditch that spark plug and put a NGK single electrode in, less hassles in the long run and easier to read.
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Old 04-06-2020, 11:47 AM
DirtyDogs446 DirtyDogs446 is offline
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Quote:
Originally Posted by anickode View Post
Yeah, those flat slide carbs are pretty generic. Especially if you didn't order from someplace like GPS or BMI as being set up already for a predator. They'll typically need tuning right out of the box.
I ordered it off nrracing.

---------- Post added at 01:47 PM ---------- Previous post was at 01:44 PM ----------

Quote:
Originally Posted by Brianator View Post
Is the choke closed (or stuck closed internally)? Which side of the carb is the pilot adjustment screw (intake side or motor side). When you're adjusting the pilot are you making very small adjustments and allowing up to 30 seconds for it to take affect? Picture the pilot screw as a clock face with 12 hours, adjustments should be 1-2 hours small. As others have said chances are it needs to be set up for your application right out of the box (by re-jetting it) but I thought I'd help do some troubleshooting. I'd also ditch that spark plug and put a NGK single electrode in, less hassles in the long run and easier to read.
I'll have to check on the carb but pretty sure it was fine the silver screw you speak of is on the air filter side. Also no jets go smaller then the 15 that comes in it. So I put the stock predator carb on it fired it up and it would barely idle if i very lightly featherd the gas but as soon as I would push down the gas in it it would die right away. Is that a lack of gas? If so if I order larger jets and new e tube would that work for now
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Old 04-06-2020, 06:46 PM
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I was helping a guy with a similar carb recently, he didn't update us so your guess is as good as mine if my advice helped. There's alot of info there, you should have a read

http://www.diygokarts.com/vb/showthread.php?t=43028

Also make sure that when you put the slide in the carb that the needle actually went down into the emulsion tube/needle jet, mine didn't once and because of the spring I didn't notice!
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Old 04-06-2020, 11:07 PM
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Quote:
Originally Posted by Brianator View Post
I was helping a guy with a similar carb recently, he didn't update us so your guess is as good as mine if my advice helped. There's alot of info there, you should have a read

http://www.diygokarts.com/vb/showthread.php?t=43028

Also make sure that when you put the slide in the carb that the needle actually went down into the emulsion tube/needle jet, mine didn't once and because of the spring I didn't notice!
Thank you I appreciate the info. I got a few jets on the way for the stock carb that has no fuel air adjustments also I have a stock carb I ordered off line with adjustments that my buddy is tuning up I will update when i try each out
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Old 04-06-2020, 11:26 PM
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Sounds good and good luck!
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Old 04-07-2020, 08:45 AM
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Is it possible that it’s a methanol carb?
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Last edited by Flyinhillbilly; 04-07-2020 at 08:46 AM. Reason: I kant spel
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Old 04-07-2020, 09:05 AM
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Quote:
Originally Posted by Flyinhillbilly View Post
Is it possible that it’s a methanol carb?
That is an excellent point. Methanol carbs are jetted about 30% richer, aren't they?

The picture does specify gas, which means they probably also carry alky carbs. Maybe they sent the wrong one?
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Old 04-13-2020, 06:29 PM
DirtyDogs446 DirtyDogs446 is offline
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Quote:
Originally Posted by anickode View Post
That is an excellent point. Methanol carbs are jetted about 30% richer, aren't they?

The picture does specify gas, which means they probably also carry alky carbs. Maybe they sent the wrong one?
So I moved clip on needle to make more lean and it's running pretty **** good now thanks for all the help
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Old 04-13-2020, 06:39 PM
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Glad to hear it!
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