Technical Discussion Topics related to Technical Issues

cutout/lack of power at 7k rpms?

Old 08-01-2013, 06:14 PM
  #1  
Member
Squid
Thread Starter
 
Join Date: Apr 2012
Posts: 34
codybrown is on a distinguished road
cutout/lack of power at 7k rpms?

So I took the 2nd superhawk I bought out for a quick ride tonight, it feels faster than my other one, but when I bit about 7k rpm's it cuts out and loses power. It pulls great up to 7k, and runs great otherwise. All my tools are currently at work, my plans were to pull plugs and see what they look like. Any other ideas?
codybrown is offline  
Old 08-01-2013, 07:17 PM
  #2  
Senior Member
Superstock
 
cybercarl's Avatar
 
Join Date: May 2012
Location: UK
Posts: 397
cybercarl is on a distinguished road
Sounds to me like the timing is out by 180 degrees either that or the pulse generator is faulty. But as you say it feels faster than your other one this again suggests to me that the timing is out. As a side effect of being 180 out there is more low down power but you loose top. You will find that the rear cylinder fires, then the front one fires 90 degrees later. You need it to be 270 degrees later.

It's an easy fix, Just set the rear cylinder to TDC on the compression stroke, both cam lobes pointing upwards and inwards. Remove both cams, Now holding the cam chain so you don't loose it (get friend to do this) turn the crank 1 full turn anticlockwise until the RT comes back around again and refit the cams as before pointing upwards and inwards.

(:-})
cybercarl is offline  
Old 08-02-2013, 07:20 AM
  #3  
Senior Member
Back Marker
 
Stephan's Avatar
 
Join Date: Apr 2010
Location: Prague - Czech
Posts: 219
Stephan is on a distinguished road
size of main jets, depends on how sharp is the cut. If it is running, but just worse, then it could be.
Stephan is offline  
Old 08-02-2013, 08:28 AM
  #4  
Senior Member
MotoGP
 
7moore7's Avatar
 
Join Date: Jul 2010
Location: Phoenix, AZ
Posts: 3,867
7moore7 is on a distinguished road
Will it go above 7krpm or does it hit it like a rev limiter?
7moore7 is offline  
Old 08-02-2013, 05:53 PM
  #5  
Member
Squid
Thread Starter
 
Join Date: Apr 2012
Posts: 34
codybrown is on a distinguished road
I took the bike out again today. It will rev through 7k, I let off around 9k. After about 7k it starts bogging and cutting out, lurching a little bit. Up till about 7k it runs great and pulls hard.
codybrown is offline  
Old 08-07-2013, 05:51 PM
  #6  
Member
Squid
Thread Starter
 
Join Date: Apr 2012
Posts: 34
codybrown is on a distinguished road
Anyone?
codybrown is offline  
Old 08-08-2013, 12:50 AM
  #7  
Senior Member
SuperBike
 
Wicky's Avatar
 
Join Date: Sep 2008
Location: Essex, UK
Posts: 1,638
Wicky is on a distinguished road
Have you checked the timing as suggested earlier.
Wicky is offline  
Old 08-10-2013, 09:02 AM
  #8  
Junior Member
Squid
 
Join Date: Oct 2012
Posts: 2
brownhawk is on a distinguished road
I was having a similar issue and it ended up being my kick stand sensor. Previous owner did a hack job with the wiring so that when the bike was revved up the vibration would cause the bike to sputter and not accelerate. I bypassed the kick stand sensor and my problems went away.
brownhawk is offline  
Old 08-11-2013, 05:02 AM
  #9  
Member
Squid
Thread Starter
 
Join Date: Apr 2012
Posts: 34
codybrown is on a distinguished road
I haven't checked the timing yet. I bought this from the original owner and he has meticulous maintenance records. I've looked through them and the only thing I can see that has been done to the engine is cam chain tensioners.
codybrown is offline  
Old 08-11-2013, 08:02 AM
  #10  
Out of my mind, back in 5
MotoGP
 
Tweety's Avatar
 
Join Date: Nov 2006
Location: Skurup, Sweden
Posts: 6,109
Tweety is on a distinguished road
Originally Posted by codybrown View Post
I haven't checked the timing yet. I bought this from the original owner and he has meticulous maintenance records. I've looked through them and the only thing I can see that has been done to the engine is cam chain tensioners.
Which could easily cause the 180 degree out, if opened up and "fixed" the wrong way...
Tweety is offline  
Old 08-14-2013, 05:42 AM
  #11  
Junior Member
Squid
 
Join Date: Aug 2013
Location: Slovakia
Posts: 1
bizivtr is on a distinguished road
Hallo, I have the same problem. Power lost between 7 and 8 rpm under load 5th, 6th gear, but I feel it also on every gear. If i go over 8, then it rews to red without problems. Till 7 and over 8 it runs great.
Checked timing ( FT - FI, FE outside with head, then turned CCW 270 degreess to the RT and RI,RE outside with head), sparks ok, carb cleaned, everything stock only open cans, airfilter has 3.000 km.
What could it be? What should i check?
bizivtr is offline  
Old 08-14-2013, 06:32 AM
  #12  
Senior Member
Superstock
 
cybercarl's Avatar
 
Join Date: May 2012
Location: UK
Posts: 397
cybercarl is on a distinguished road
OK guys, symptoms of the timing being out 180 are as follows:
The bike will rev to 7000 with no issues at all but once it gets to 7000 it will either behave like a limiter and not go any further or start to stutter and get a bit jittery, feel boggy and slowly rise, very slowly start to go higher up the rev range. Please note at idle when you rev the bike it will go past 7000 fine but you rev needle may not rise and fall as fast as usual. This issue will only occur while riding the bike so needs to be road tested. You will have more power below 7000 than usual as being out 180 gives you more power low down at the sacrifice of the top end but as soon as you hit 7000 the problems will be felt.

It's not as if the timing is wrong as such and the bike will run without causing any damage and if you remove the cam covers the timing marks will all line up as they should. the issue is the relationship between one cylinder firing and the next, how much the crank turns between firing pulses. One cylinder fires and then the other 90 degrees later when you want it to fire 270 degrees later.

This does not mean that you should just automatically think that the timing is out 180 degrees as everything else should be ruled out first. ie pulse generator, fuelling issues, electrical, but it's an issue to be aware off if nothing else can be found. There's no reason why you can't give it a try, it will either make things better, in which case it was for sure 180 out or it will put the timing out 180 and makes things noticeably worse. In which case you just put it back and search for other possible cause to your issues.

(:-})
cybercarl is offline  
Old 08-14-2013, 04:35 PM
  #13  
Senior Member
Back Marker
 
WhOrD's Avatar
 
Join Date: Sep 2012
Location: California
Posts: 133
WhOrD is on a distinguished road
I was thinking perhaps something was wrong with my bike also......SO:

I went out and rode my friends 2005 ZX10R.........

End Result:

Our bikes may have been fast in 1998, then again 320HP was considered FAST in 1998 for a car.....

I think of the VTR as a Mustang versus an S2000...

The Mustang has a ton of torque but dies out ~80mph...the S2000 has HP but crap torque and comes to life at Higher speeds in the upper RPM band....

My biddies 2005 ZX10R was sick, and it felt just as fast and felt like it had as much torque as my 98 VTR.....that is life.

Just don't tell my buddy I spent LESS than HALF of what HE spent for HIS ZX10R.
WhOrD is offline  
Old 08-14-2013, 05:02 PM
  #14  
Senior Member
Superstock
 
cybercarl's Avatar
 
Join Date: May 2012
Location: UK
Posts: 397
cybercarl is on a distinguished road
LOL your comparing a V Twin to an IL4 they are both two totally different animals. The last time I rode a ZX10 I thought my VTR had more pull doen the bottom, it wasn't until I got the revs up on the ZX that it went like a rocket. It didn't feel like a rocket but the speedo got to triple figures faster than it felt.

(:-})

Last edited by cybercarl; 08-14-2013 at 05:05 PM.
cybercarl is offline  
Old 08-15-2013, 10:03 AM
  #15  
Out of my mind, back in 5
MotoGP
 
Tweety's Avatar
 
Join Date: Nov 2006
Location: Skurup, Sweden
Posts: 6,109
Tweety is on a distinguished road
Originally Posted by WhOrD View Post
Our bikes may have been fast in 1998, then again 320HP was considered FAST in 1998 for a car.....
320HP has never ever been fast... It's not the amount of Hp, it's how you use them...

The VTR was never intended to be super fast... It was never a race replica bike, or a super sports bike... In 98 (97 really) it was a sport tourer... A fast touring bike that you could use for everyday riding, as well as chucking it into a corner fast...

So the fact that it can hold it's own against 16 year younger bikes, is a true testament to how good it actually is...

And don't be fooled... With a little work done, it's still properly fast... More than fast enough to beat the pant's of a lot of the newer bikes...
Tweety is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
chemomche
Technical Discussion
8
11-13-2012 12:26 AM
05xman
Technical Discussion
2
07-24-2011 02:18 PM
dani p
General Discussion
11
07-08-2009 11:00 AM
supermarto
General Discussion
15
11-28-2007 07:56 PM
EngineNoO9
Technical Discussion
9
12-22-2005 01:06 PM


Thread Tools
Search this Thread
Quick Reply: cutout/lack of power at 7k rpms?


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.

All times are GMT -7. The time now is 03:18 PM.


© 2019 MH Sub I, LLC dba Internet Brands