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1998 Superhawk - Fueling to Vacuum Issues

Old 02-22-2017, 03:42 PM
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1998 Superhawk - Fueling to Vacuum Issues

New here. Recently purchased a 1998 Superhawk for dirt cheap and trying to get it running (first carbed bike). Original issue was crank but no start whatsoever. It is stock other than full PAIR blockoff/delete and some sort of aftermarket air filter.

My first task was removing carbs and doing a thorough cleaning. They have stock 45 pilots, front needle has a #4 washer, rear needle has stock washer + a #4 washer. Front mixture screw is at 2.5, rear at 2.25 turns out. TPS is set to 500 ohms.

I put it all back together (after remembering the vacuum hose connects to the rear of the petcock...not the bottom) and it fired right up with choke.

***It will idle all day with full to half choke but it will occasionally sound like its lightly misfiring/popping out of the exhausts. Push the choke all the way in, and it will idle for a few seconds then die out. Any amount of throttle input (with choke or none) will produce severe hesitation/RPM drop and more pronounced misfiring.

Pretty stumped here as other than replacing the 45 with 48 jets, its pretty spot on to what all the carb tuning threads on here recommend. Any recommendations?

I do have this vacuum line open that I have no clue where it connects to...it T's off near the rear brake pedal.
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Old 02-22-2017, 10:40 PM
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Where does the other end of the hose connect? If that vac tube is connected to fitting at the base of the front carb manifold it needs to be plugged ( or remove the hose and cap the fitting. That fitting is used for synchronizing the carbs.
As far as the jetting and air filter go there are lots of threads in this forum 8541 Hawk's is as good as it gets.
Let us know how it comes out.
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Old 02-23-2017, 04:26 AM
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Other end connects to a T fitting all the way down near the oil pan on the right side, near the brake pedal.

As for hawks thread, thats where i got this setup...minus 48s. Ive read for days and have no clue which way to go now.
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Old 02-23-2017, 04:48 AM
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Where do the other legs of the T go?

Welcome to the forum.
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Old 02-23-2017, 05:58 AM
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Second on the welcome.
Do what CaryDG suggested. Also make a decision on the auto CCTs.
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Old 02-24-2017, 12:16 PM
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Not diving into manual CCTs until I get this thing running (if it will ever). But i hear you on them. Wonder how they lasted for 34k miles.

Interesting find. The disconnected vacuum line apparently connects to nothing on either end of the T. One end ends next to the oil filter, and the other goes under the coolant bottle somewhere and is connected to nothing either. So who knows why thats there.

As for trying to get it running so it wont stumble badly with any amount of throttle input, where do i start? Ive sprayed starting fluid around all possible air leaks, and found no RPM rise. All vacuum lines seem good or capped off properly. Do i go back to OEM needles and mixture screw settings?
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Old 02-24-2017, 12:41 PM
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What's going on your bike on the front cylinder's vacuum plug / port? Is it open i.e the hose is disconnected from it, or does it have a small allen bolt sealing it.



Here in the UK as well as for carb balancing it can be used (using the T fitting) to also run an automic chain luber device (Scot Oiler)
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Old 02-24-2017, 12:47 PM
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Not diving into manual CCTs until I get this thing running (if it will ever). But i hear you on them. Wonder how they lasted for 34k miles.
Don't leave it too long - The first auto CCT failure of Spring has arrived as regular as clockwork...

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Old 02-24-2017, 12:47 PM
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Small allen bolt.

Cant even use the throttle so manual CCTs are the least of my worries at the moment. Funny thing is I just replaced/upgraded my F4i CCT and TCT on my Honda S2000...must be a Honda design thing

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Old 02-24-2017, 03:30 PM
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Well, after taking off the air box again, it appears the front carb is dribbling out small amounts of fuel even when the bike is shut off. Guess I did something when cleaning the floats...time to open them up again apparently.
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Old 02-24-2017, 06:32 PM
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Why are the carb breather vents capped? There should be a pair of hoses from those running up to the space between the carbs. The maint manual is available in the knowledgebase section of the forum for a picture.
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Old 02-24-2017, 07:27 PM
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PAIR delete? Has TBR block off plates.

Edit: See what you mean now. Apparently, I need to purchase a few inches of hose to run back to the middle area of the carbs. Oversight on my part, good catch.

Last edited by [email protected]; 02-24-2017 at 07:33 PM.
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