08-18-2021, 11:37 AM | #1 |
Join Date: Oct 2020
Location: Long Island NY
Posts: 16
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Black Tar/Sticky in Intake
What's up guys. I'm having an issue with my motor. Let me give you a small breakdown of the backstory.
I was the one that changed their hawk into the Brat Bike (can be seen in "Videos and Pics." As you can see in the pictures, I put a pod air filter on the carb and removed the muffler from the exhaust. Now here's the problem I'm currently facing. Keep in mind, before the project, the motor ran fine with no issues. I changed the head gasket seal because the stock one was leaking. No big deal, easy swap. But ever since I put the pod and removed the muffler, I've been getting black buildup in the intake that ends up sticking to the inside of the carburetor and, after it sits a while, will seize the throttle up. Now my first thought was that I did not jet the carburetor and am running a Mikuni. To be honest, the bike runs great with no back fire and is very smooth. If the carb needed to be jetted, (which I know it probably still should), the bike would run like crap and very lean. Keep in mind this is the first bike I learned to work on and am still new to various variables when customizing. My first thought was that the gas was evaporating in the intake because the engine ran hot and the gas was too lean, thus creating an ethanol buildup in the intake. I don't believe this is the case. I believe that it is a valve adjustment. I think the valve either pre maturely opens or does not close all the way, so the explosion is getting into the intake, thus causing the black sticky tar in the intake and on the throttle. I did not have a tool to measure the space to ensure an accurate adjustment, but I did try to adjustment the valve as, (if this is the right way to say it), the highest setting, thinking that it will fully close and fully open. That did not work, and am buying a proper measuring kit. Does this diagnosis of the valve sound like the problem? I am pulling the motor off to: 1. Clean it, and 2. Inspect the valve. I'm hoping I did not do damage to the valve for whatever reason, but to be honest I might just buy a new hawk motor. Keep in mind that the valve might have been bad for 1000 miles (thats when the gasket started leaking), and now that the gasket is nice and sealed, all the extra pressure had to go somewhere, which was out of the bad valve. Thoughts? |
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08-18-2021, 11:53 AM | #2 |
Join Date: Jun 2021
Posts: 80
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So copy paper is about .005" thick. I'm not telling you setting the valve lash with copy paper is acceptable, but it'll get you in the ballpark better than eye or feel. Set it light enough to be able to drag the paper out without tearing.
It could be the oil used in the pod filter. |
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08-18-2021, 01:45 PM | #3 |
Join Date: Aug 2021
Posts: 4
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I think you main issue is using ethanol fuel. That shit will gum up any carb. What does the spark plug look like? That will give you an idea on if its lean or not.
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08-18-2021, 09:47 PM | #4 | |
Join Date: Oct 2020
Location: Long Island NY
Posts: 16
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Quote:
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08-18-2021, 09:48 PM | #5 |
Join Date: Oct 2020
Location: Long Island NY
Posts: 16
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Have not checked the spark plug, but I use 93 premium. The throttle in the carb is not gummed up on all sides, just the side that faces the motor. Inside the motor as well in the intake is all black and tarry when a finger goes down there. If its running lean, could that create the black gum? I was under the impression it only makes the bike run bad -- which when it runs, it runs great with no back fire and tops out at 70 mph.
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08-18-2021, 10:16 PM | #6 |
Join Date: Oct 2020
Location: Flower Mound Texas
Posts: 904
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By chance is your catalytic converter still on?
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2021 Tao Tbr7 - "Lucille" Mods so far- Brozz swingarm, 21" front rim (Bridgestone Tw302 rear/Dunlop D606 front tires), Digital gauge cluster, pz30b pumper carb, after market hand guards, aftermarket brake and clutch levers, round fold away mirrors, Fly handlebars shortened slightly, 13t front sprocket 2009 Q-link Legacy 250 1982 Suzuki GS1100ES - "Jolene" |
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09-07-2021, 08:29 PM | #7 |
Join Date: Oct 2020
Location: Long Island NY
Posts: 16
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Yea its probably still in the exhaust. Do you think that is the cause of the issue?
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09-07-2021, 09:54 PM | #8 |
Join Date: Aug 2020
Location: Australia
Posts: 1,393
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Out of curiosity does you PCV hose connect to inlet manifold by any chance? Is the gummy residue building up before or after the carb...
Is there an EGR system? if so the build up could be a combination of exhaust gas and crank case oil forming a black shmutz. |
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09-08-2021, 04:29 AM | #10 |
Join Date: May 2020
Location: San Antonio, Texas
Posts: 62
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Sludge in engine, sounds like dino oil.
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CSC RX4 2020 |
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09-08-2021, 06:16 AM | #11 | |
Join Date: Oct 2020
Location: Flower Mound Texas
Posts: 904
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On a car, if you run a rich air/fuel mixture or oily mixture for very long, it will eventually plug up a catalytic converter. Then you get severe back pressure and reversion.
__________________
2021 Tao Tbr7 - "Lucille" Mods so far- Brozz swingarm, 21" front rim (Bridgestone Tw302 rear/Dunlop D606 front tires), Digital gauge cluster, pz30b pumper carb, after market hand guards, aftermarket brake and clutch levers, round fold away mirrors, Fly handlebars shortened slightly, 13t front sprocket 2009 Q-link Legacy 250 1982 Suzuki GS1100ES - "Jolene" |
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11-19-2021, 08:11 AM | #12 | |
Join Date: Oct 2020
Location: Long Island NY
Posts: 16
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