Technical Discussion Topics related to Technical Issues

High rpm problems

Thread Tools
 
Search this Thread
 
Old Jul 9, 2008 | 01:43 AM
  #1  
jonlun's Avatar
Thread Starter
Junior Member
Squid
 
Joined: Jul 2008
Posts: 22
jonlun is on a distinguished road
High rpm problems

I have some problems at higher rpm:s on my -97 Hawk. The bike just wont rev more than 6500rpm before it looses all power. I have checked the carbs for clogged jets but they seem ok. The spark plugs looks like it runs a bit rich. The set up of the bike is: Dynojet, KN-filter, Arrow slipons (originally from a -05 Suzuki gsxr 1000), modifyed airbox (Burnie Morgan). Main jets are #200, pilot jet #45. According to previous owner it ran just perfect with this set up. Any suggestions what it could be?
Old Jul 9, 2008 | 04:59 AM
  #2  
BeerHunter's Avatar
Slacker
Superstock
Superstock
 
Joined: Jun 2005
Posts: 489
From: San Antonio, TX
BeerHunter is an unknown quantity at this point
Have a look at THIS THREAD. You seem to be experiencing the exact same conditions. The "previous owner" is not always a trustworthy source for reliable information.
Old Jul 9, 2008 | 05:06 AM
  #3  
Gregw's Avatar
Senior Member
SuperBike
SuperBike
 
Joined: Jun 2007
Posts: 1,031
From: Los Angeles ish
Gregw is on a distinguished road
Yeah, for the mods listed the 200 main jet seems way big. Maybe the PO had a Harley and didn't realize motorcycles revved beyond 6000?
Old Jul 9, 2008 | 05:40 AM
  #4  
jonlun's Avatar
Thread Starter
Junior Member
Squid
 
Joined: Jul 2008
Posts: 22
jonlun is on a distinguished road
Well, it was actually the guy who built the bike from the start that told me that it ran ok with the set up used today. I wouldnt trust the PO even if it was a friend of mine. Anyway, I have ordered new main jets in a range of #175 to #185 so hopefully this will help. I have learned that the Dynojet needles wear out the jets which could cause my problems. The Dyno jet kit was mounted 8 years ago so....If that doesnt help I am thinkin of ordering new needles and main jet holders.
Old Jul 9, 2008 | 06:58 PM
  #5  
gboezio's Avatar
Senior Member
SuperSport
SuperSport
 
Joined: Dec 2006
Posts: 880
From: Victoriaville, Quebec, Canada
gboezio is on a distinguished road
Got to run pig rich at WOT, I run 180/185
I don't see how it could run with a 200 unless there a supercharger hidden somewhere
Old Jul 9, 2008 | 10:39 PM
  #6  
996er's Avatar
Member
Squid
 
Joined: Apr 2008
Posts: 34
From: Central Jersey
996er is on a distinguished road
I had the same issue on my bike when I got it. 2000 SHawk. Check all of the wires under the seat to the ecu. Check the battery Wires and Get some Sea Foam. Dump that stuff in your tank and say goodbye to the stumbles at high rpms. You can get it at any auto parts store for less than $10.00

If that doesnt work..the dude that jetted it did it wrong...
Old Jul 10, 2008 | 12:17 AM
  #7  
inderocker's Avatar
Moderator
MotoGP
 
Joined: May 2005
Posts: 2,708
inderocker is an unknown quantity at this point
I had the same issure when I got my first VTR. It had a 198/200 main jet combo. returned it to stock and all was well.
Old Jul 10, 2008 | 01:19 AM
  #8  
jonlun's Avatar
Thread Starter
Junior Member
Squid
 
Joined: Jul 2008
Posts: 22
jonlun is on a distinguished road
Got the ordered jets today so hopefully I'll find some time to mount them tonight. I've seached the bike looking for a super charger but so far I havent found any

I have drained the fuel tank this winter so it shouldnt be any water in there, but I guess it wount hurt to put in some carb cleaner or Sea foam.

Thanks for all help, I'll get back with the results as soon as the jets are mounted!
Old Jul 10, 2008 | 11:00 PM
  #9  
996er's Avatar
Member
Squid
 
Joined: Apr 2008
Posts: 34
From: Central Jersey
996er is on a distinguished road
supercharger...its in there some where right next to the loads of torque and hp!!!
Old Jul 10, 2008 | 11:04 PM
  #10  
jonlun's Avatar
Thread Starter
Junior Member
Squid
 
Joined: Jul 2008
Posts: 22
jonlun is on a distinguished road
ok, got the 180/185 jets installed and the bike runs much better but it still hesitates and studder at WOT. I'll try the stock jets today, getting really tired of taking the bike apart every second day!

Do you guys use the Dyno jet needles or the stock ones?
Old Jul 10, 2008 | 11:11 PM
  #11  
inderocker's Avatar
Moderator
MotoGP
 
Joined: May 2005
Posts: 2,708
inderocker is an unknown quantity at this point
Stock
Old Jul 11, 2008 | 03:26 AM
  #12  
gboezio's Avatar
Senior Member
SuperSport
SuperSport
 
Joined: Dec 2006
Posts: 880
From: Victoriaville, Quebec, Canada
gboezio is on a distinguished road
I run a DJ kit, needle installed @ 4th notch, You are running the same jets as mine but I don't have a K&N filter, witch improve breathing a lot, maybe your best setup is 185/190
Check your plugs to see if the carbon turned white, give it a few WOT pulls and it should put you on the right track.
Soot black too rich
Carbon that turned white, too lean.

I run 2 1/2 turn of idle screw and stock pilots, 48 I think, not quite sure
Old Jul 13, 2008 | 10:48 PM
  #13  
jonlun's Avatar
Thread Starter
Junior Member
Squid
 
Joined: Jul 2008
Posts: 22
jonlun is on a distinguished road
Went back to stock jets 175/178 and it runs better than with 180/185. It is now possible to rev it until it hits the rev limiter, but it still takes some convincing to get there. This has not been possible with the other settings. The idle screws are 2 1/2, pilot is #48 and needle on 4th notch, but these wount influence the high rpm, right? I've just ordered a stock air filter so I'll se if that helps.
Old Jul 14, 2008 | 12:36 AM
  #14  
inderocker's Avatar
Moderator
MotoGP
 
Joined: May 2005
Posts: 2,708
inderocker is an unknown quantity at this point
You should try the stock needles if you have those as well.

Is it possible that you have flip-flopped the emulsion tubes?
Old Jul 14, 2008 | 03:53 AM
  #15  
gboezio's Avatar
Senior Member
SuperSport
SuperSport
 
Joined: Dec 2006
Posts: 880
From: Victoriaville, Quebec, Canada
gboezio is on a distinguished road
What brand of jets you have, are they factory jets ?? It should like a bit more fuel than this, but you seem to go the right way tough.
Old Jul 14, 2008 | 11:39 PM
  #16  
jonlun's Avatar
Thread Starter
Junior Member
Squid
 
Joined: Jul 2008
Posts: 22
jonlun is on a distinguished road
Nope, I dubble checked the emulsion tubes (found a picture of them on this forum). Unfortunately the stock needles were lost some where in the chain of PO:s. Ordering new stock needles will be the next step if the new air filter doesn't help.

The #200 jets are Dynojets and the #185, #180, #178 and #175 are Honda factory jets. I'm getting quite confused that the bike runs better with the stock jets than 185/185 with the modifications done. When seaching the forums for suggested settings, the 185/180 seems to be the best. Might be that the Dynojet needles are worn out? The air/fuel mixture should be different with dynojet needles than with stock needles since the dynojet needles have a "neck" at the tip, right?
Old Jul 15, 2008 | 07:46 AM
  #17  
inderocker's Avatar
Moderator
MotoGP
 
Joined: May 2005
Posts: 2,708
inderocker is an unknown quantity at this point
Originally Posted by jonlun
The #200 jets are Dynojets and the #185, #180, #178 and #175 are Honda factory jets.
Just as long as the jets have the little "k" symbol, you're good.
I'm getting quite confused that the bike runs better with the stock jets than 185/185 with the modifications done. When searching the forums for suggested settings, the 185/180 seems to be the best.
My bike runs way better with stock jetting than with the Factory jet kit that was installed
Might be that the Dynojet needles are worn out?
That's a possibility as well...
The air/fuel mixture should be different with dynojet needles than with stock needles since the dynojet needles have a "neck" at the tip, right?
No, the mixture screw is for fine tuning the idle circuit only
What is this "modified air box (Burnie Morgan)" that you speak of in your first post. From my experience, there is a lot of r&d into late model motorcycle air boxes and they are better left alone.
Old Jul 15, 2008 | 10:59 PM
  #18  
jonlun's Avatar
Thread Starter
Junior Member
Squid
 
Joined: Jul 2008
Posts: 22
jonlun is on a distinguished road
Well it is actually the air filter rather than the air box that has been modified, http://www.burniemorgan.com/firestorm/airfilter.html

This was done by the PO so I can't say if it had any effect or not. I've just picked up a stock air filter so hopefully I will find some time to install it before the weekend, than I can tell you if the mod did any difference.

The air/fuel mixture should be different with dynojet needles than with stock needles since the dynojet needles have a "neck" at the tip, right?
No, the mixture screw is for fine tuning the idle circuit only
Ok, it wasn't really clear what I ment. What I was trying to say is that the ammount of fuel thru the jet should increase if Dynojet needles are used since the diameter is smaller than on the stock needles, meaning that the jetting is depending on the type of needles used, correct or not? Someone?
Old Jul 16, 2008 | 03:42 AM
  #19  
RK1's Avatar
RK1
Senior Member
MotoGP
 
Joined: Aug 2007
Posts: 2,547
From: Way Out West
RK1 is on a distinguished road
Keihin jets are designed to work with Keihin needles. Dynojet jets are designed to work with Dynojet needles. Mixing jets of one make with needles of another is asking for a headache. Also, Keihin jets and Dynojets with the same number are NOT the same size and do not flow the same volume of mixture.

My advice based on personal experience? Use the OEM air filter, Dynojet 175/180 mains, Dynojet needles on 5th position.
Old Jul 16, 2008 | 03:47 AM
  #20  
gboezio's Avatar
Senior Member
SuperSport
SuperSport
 
Joined: Dec 2006
Posts: 880
From: Victoriaville, Quebec, Canada
gboezio is on a distinguished road
Maybe the guy choked the airflow, reducing the need for fuel and believed that his 20hp air filter mod was in need of big fuel
Old Jul 16, 2008 | 03:54 AM
  #21  
RK1's Avatar
RK1
Senior Member
MotoGP
 
Joined: Aug 2007
Posts: 2,547
From: Way Out West
RK1 is on a distinguished road
Originally Posted by gboezio
Maybe the guy choked the airflow, reducing the need for fuel and believed that his 20hp air filter mod was in need of big fuel
That makes sense to me 'cause, 1) there's been such thing as a 20 hp filter mod since about 1986, and 2) #200 mains don't make sense at all without major engine mods, a race air filter and free flowing full exhaust system.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
amhsraptor
Technical Discussion
10
Sep 17, 2010 06:25 AM
uchi
General Discussion
15
Sep 15, 2009 02:11 PM
luv2insanity
Technical Discussion
11
Aug 31, 2008 08:05 AM
bob4pres
Modifications - Performance
15
Jul 25, 2008 10:38 PM
DRIVEN2MADNESS
Technical Discussion
6
Jun 14, 2008 05:27 PM




All times are GMT -7. The time now is 03:16 AM.


Top

© 2026 MH Sub I, LLC dba Internet Brands



When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.