Drivability issue, Chugging 6-7k range...
04-20-2010 | 07:14 PM
#1
Thread Starter
Junior Member
Squid
Joined: Apr 2010
Posts: 13
Drivability issue, Chugging 6-7k range...
Hi folks,
I'm new to this forum and to the Hawk. I have a drivability issue, when I accelerate using full throttle it goes smoothly except it chugs a bit through the 6-7k range then is smooth through the rest of the revs. I find that if I back the throttle off a little through the 6-7k range than I can avoid the chugging but that’s no fun. The person I bought it from said that it was stock except for it has a K&N air filter and the stock mufflers were de-baffled. The bike has 24k on it and I don’t know the service history except for the basic maintenance I've done on it since I got it. I live in Flagstaff Arizona and we are at 7,000 feet and I wonder if the altitude might be causing a rich condition. I do get a bit of rapping from the exhaust while engine braking. the other problem I am having is it does not stay running after a cold start on a cold day, find myself having to crack the throttle open until it warms up. Hopefully this is easy for someone here because otherwise I'd just be left guessing, my guess would be the carburetor needs to be adjusted for the higher altitude but I am not confident of this. Also if anyone knows any quirks or things I should be aware of about this bike it would be nice to know. Thanks for your help.
-Chris
I'm new to this forum and to the Hawk. I have a drivability issue, when I accelerate using full throttle it goes smoothly except it chugs a bit through the 6-7k range then is smooth through the rest of the revs. I find that if I back the throttle off a little through the 6-7k range than I can avoid the chugging but that’s no fun. The person I bought it from said that it was stock except for it has a K&N air filter and the stock mufflers were de-baffled. The bike has 24k on it and I don’t know the service history except for the basic maintenance I've done on it since I got it. I live in Flagstaff Arizona and we are at 7,000 feet and I wonder if the altitude might be causing a rich condition. I do get a bit of rapping from the exhaust while engine braking. the other problem I am having is it does not stay running after a cold start on a cold day, find myself having to crack the throttle open until it warms up. Hopefully this is easy for someone here because otherwise I'd just be left guessing, my guess would be the carburetor needs to be adjusted for the higher altitude but I am not confident of this. Also if anyone knows any quirks or things I should be aware of about this bike it would be nice to know. Thanks for your help.
-Chris
04-20-2010 | 07:27 PM
#2
Out of my mind, back in 5
MotoGP
Joined: Nov 2006
Posts: 6,109
From: Skurup, Sweden
https://www.superhawkforum.com/forum...earchid=580846
I just did a search on the issues you mentioned... Not too surprisingly they have been discussed before... The K&N filter gives a increase in power in the top end but usualy leaves a big hole in the middle where it's really difficult to get the jetting right... Try reading a few of the already existing threads on the subject, and if you still have questions we'll help you out...
I just did a search on the issues you mentioned... Not too surprisingly they have been discussed before... The K&N filter gives a increase in power in the top end but usualy leaves a big hole in the middle where it's really difficult to get the jetting right... Try reading a few of the already existing threads on the subject, and if you still have questions we'll help you out...
04-20-2010 | 10:37 PM
#5
OCMD honorary member
Superstock
Joined: May 2007
Posts: 252
From: Olympia, WA
What's really funny is that you can take a bone stock superhawk and add a jet kit and the bike will run sooooo much better. They are just so lean from factory. The most noticable change with the aftermarket needles and a bump up from the pilots..... on a bone stock bike. I've known a few guys with superhawks and otherwise that drilled out the baffles and never got the bikes to run just right even with a jet kit. Either run stk mufflers or ones that were engineered the way they are for flow. If you have one that is drilled out and dialed in then you're lucky. It is also not to say that the carbs may need to be cleaned as well. The bike is not a spring chicken you know and who knows how long it sat with what gas in it for any period. Just enough deposits to effect running in the overlap of certian circuits but running good with the needle up and on the main. You are probably ok being that you don't have to run the bike with the choke part way on all the time, a tell tale but not always.
Chris make sure you study up and go to the knowledge base section of this forum and play around with a few searches on the subjet. You'll probably go off on a tangent and find out all kinds of cool stuff about your bike.
I'd say start with the air cleaner as well.
Then the mufflers to something that is legitimate. Not stockers trying to be aftermarkets.
Best of luck.
Chris make sure you study up and go to the knowledge base section of this forum and play around with a few searches on the subjet. You'll probably go off on a tangent and find out all kinds of cool stuff about your bike.
I'd say start with the air cleaner as well.
Then the mufflers to something that is legitimate. Not stockers trying to be aftermarkets.
Best of luck.
04-21-2010 | 02:52 AM
#6
geezer
SuperSport
SuperSport
Joined: Jan 2008
Posts: 556
From: Honolulu
https://www.superhawkforum.com/forum...earchid=580846
I just did a search on the issues you mentioned... Not too surprisingly they have been discussed before... The K&N filter gives a increase in power in the top end but usualy leaves a big hole in the middle where it's really difficult to get the jetting right... Try reading a few of the already existing threads on the subject, and if you still have questions we'll help you out...
I just did a search on the issues you mentioned... Not too surprisingly they have been discussed before... The K&N filter gives a increase in power in the top end but usualy leaves a big hole in the middle where it's really difficult to get the jetting right... Try reading a few of the already existing threads on the subject, and if you still have questions we'll help you out...
You must be getting soft Tweety, you weren't harsh at all on the newbie...
04-21-2010 | 03:46 AM
#7
Out of my mind, back in 5
MotoGP
Joined: Nov 2006
Posts: 6,109
From: Skurup, Sweden
04-22-2010 | 01:20 AM
#9
Thread Starter
Junior Member
Squid
Joined: Apr 2010
Posts: 13
Cool, thanks for the input. I will swap the air filters around and see what happens. I have been debating if I am going to do anything with the carburetor jets. If indeed I’m getting a lean misfire perhaps a simple shim on the needles will help. It wouldn’t be hard to do while I’m in there setting the valve lash coming up.
05-02-2010 | 11:15 PM
#10
Thread Starter
Junior Member
Squid
Joined: Apr 2010
Posts: 13
to update, I haven’t been able to track down OE air filter yet. But last Saturday I had some time so I went ahead with the needle shim's. Why not, it’s easy to do and easy to undo. While I was in there I had a look at the rear plug, it was very black I was worried I may have been running rich after all, still I continued with the operation. When cleaning the carbs I noticed the air bleed tube on the rear carburetor was clogged, ah ha! I think it was fixing the rear carb that did it, it is so much better. I am sad that it wasn’t running as well as it could have been before placing the needle shims because I would like to know what that did on its own. It doesn’t seem to be running rich at this point, I will burn a tank of gas and inspect the plugs and go from there. I am much happier with the way it runs now, actually ecstatic, it’s like a new bike.
05-03-2010 | 01:28 AM
#11
Senior Member
SuperSport
Joined: Feb 2010
Posts: 667
From: NY State
05-03-2010 | 05:39 PM
#13
Thread Starter
Junior Member
Squid
Joined: Apr 2010
Posts: 13
If you remove the velocity stacks inside the air box you will see 3 small tubes sticking up on top of the carburetor not inside the bore. I believe those are air bleed tubes, also called emulsion tubes. The center one was clogged with "dirt". The purpose of these tubes is to pre-mix the fuel with air, Short version, allows for better atomization of the fuel. A clogged air bleed will cause a rich mixture and poor atomization.
05-03-2010 | 06:14 PM
#14
Senior Member
MotoGP
Joined: Sep 2006
Posts: 4,138
From: Austin, Tx
05-03-2010 | 08:17 PM
#16
Senior Member
MotoGP
Joined: May 2008
Posts: 3,451
From: San Clemente, CA
Don't try this at home with a running engine, at risk of singed eyebrows and mustache/beard.
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