NSR250.net Forums Logo: Honda NSR 250 Forums, Classifieds and Service Manual in English. Covering All Honda NSR 250 MC16, MC18, MC21 and MC28 models
NSR250.net Forums

#
 
#
 
Performance Engineering

  • NSR250 Forums Index ‹ NSR250R Discussion
  • Members Content
  • Members Garage
  • Subscription
  • Transactions
  • FAQ
  • Search
  • Register
  • Log in

Power Struggle above 9k


Reply to topic   printer-friendly view
Page 1 of 2  Goto page 1, 2  Next Download Topic





kalnz44

 
Posts: 16
Joined: 06 Mar 2011

Location: New Zealand
    Send private message View user's profile
    Reply with quote  

Power Struggle above 9k

Sun Feb 26, 2012 1:22 am » Post: #1 » Download Post

Hi All,

3rd post of mine. Previous help has been amazing, so hoping you can help with my current issue that I have been wrestling with for the past month or so.
Doing some freshening up work on the bike(MC21SE 1993); carb clean(new kit), adjusted the floats to 12mm, RC valve adjustment + some general servicing.
Got the bike back together, started fine, warmed her up. Took her down the road for a test. RC adjustment seemed to do wonders for my mid range, no flat spots and great pull.
However, hitting about 9k the power staggered, seemed to have hit a wall..... Few more rides and same thing, but I noticed if I maintain WOT the revs will very slowly creep past the 9k mark...????
Could this be something to do with the float? too much fuel; float hight set to low?
Plugs look slightly black. Plugs are about a week old.
Aside from the wire splice, which I did this weekend, bike is stock.
Thanks for your time in advance, any other info needed just let me know.
Cheers
Kal
Back to top


Dmitry
Supporter - Titanium
Supporter - Titanium
 
Posts: 298
Joined: 25 Dec 2010

Location: New England
    Send private message View user's profile
    Reply with quote  

Sun Feb 26, 2012 2:54 am » Post: #2 » Download Post

Not sure about NSR but on my RG if it hits the wall like that it's rich.

I think since this discussion involves jetting is only for the members area?
Back to top


kalnz44

 
Posts: 16
Joined: 06 Mar 2011

Location: New Zealand
    Send private message View user's profile
    Reply with quote  

Sun Feb 26, 2012 3:29 am » Post: #3 » Download Post

That was my thought Dmitry. Adjusted the air screw, seemed to help a little; still some stammering at 9k. Thought the air screw only applied to low-mid range though?
Have not stepped into the jetting realm, carb is stock jetting.
Back to top


Dmitry
Supporter - Titanium
Supporter - Titanium
 
Posts: 298
Joined: 25 Dec 2010

Location: New England
    Send private message View user's profile
    Reply with quote  

Sun Feb 26, 2012 5:22 am » Post: #4 » Download Post

Pilot screw mostly affects idle however there is a small change through the entire range.
Back to top


Dana

 
Posts: 98
Joined: 24 Jul 2011

Location: Hachioji, Japan
    Send private message View user's profile
    Reply with quote  

Sun Feb 26, 2012 5:45 am » Post: #5 » Download Post

Your symptoms described my bike. I finally ended up swapping out my RC servo and cables with a spare and adjusted them, and she revs up smoothly.

Dana
Back to top


Neal

 
Posts: 900
Joined: 01 Mar 2009

Location: Scarborough
    Send private message View user's profile
    Reply with quote  

Sun Feb 26, 2012 6:19 am » Post: #6 » Download Post

And make sure that your battery is 12 volts at least or else this too will hamper you .
Back to top


nxrsr20

 
Posts: 919
Joined: 15 Jul 2007

Location: Sydney, Australia
    Send private message View user's profile
    Reply with quote  

Sun Feb 26, 2012 6:53 am » Post: #7 » Download Post

so any mods to the bike? If you change airbox, exhaust or the like then you need to rejet. Check the tuning section on how to read your state of tune.

When you adjusted the rc valve, did you also give it a good clean?
Back to top


kalnz44

 
Posts: 16
Joined: 06 Mar 2011

Location: New Zealand
    Send private message View user's profile
    Reply with quote  

Sun Feb 26, 2012 8:02 am » Post: #8 » Download Post

No mods aside from the wire splice which was done today. Had the problem for about a month.
Gave the servo and pulleys a good de-grease, lots of gunk.
When i adjusted the RCs it took quite a bit to line them up. Any sign that the servo is on the way out? Apart from the obvious: no go.
Back to top


bushman
Supporter - Titanium
Supporter - Titanium
 
Posts: 650
Joined: 22 Aug 2006

Location: Espaņa
1991 Honda NSR250 MC21
    Send private message View user's profile
    Reply with quote  

Sun Feb 26, 2012 5:03 pm » Post: #9 » Download Post

How new/good is the battery?A bad battery can cause all sorts of symptoms.
Back to top


nxrsr20

 
Posts: 919
Joined: 15 Jul 2007

Location: Sydney, Australia
    Send private message View user's profile
    Reply with quote  

Sun Feb 26, 2012 7:31 pm » Post: #10 » Download Post

what about your battery voltage? Measure both when the bike is off & at idle.

When you say degreased your valves, did you reassemble dry or use a lube of some sort? Did you check your cable tension? How/why did you degrease the servo? It's a sealed unit so shouldn't get any gunk.

Have you checked continuity in the loom? Got the connector plugged in?
Back to top


Matt@TYGA
Supporter - Vendor
Supporter - Vendor
 
Posts: 1818
Joined: 15 Sep 2004

Location: In my office chair, in Pattaya, Thailand
    Send private message View user's profile Send e-mail Visit poster's website
    Reply with quote  

Mon Feb 27, 2012 2:43 am » Post: #11 » Download Post

Have you actually checked that the RC valve is opening fully at high rpm?
Back to top


kalnz44

 
Posts: 16
Joined: 06 Mar 2011

Location: New Zealand
    Send private message View user's profile
    Reply with quote  

Mon Feb 27, 2012 7:48 am » Post: #12 » Download Post

No disassembly of the servo. Only degreased the pivot points then a quick spray with crc. Battery seems to be holding charge. checked a few other posts and battery voltage is comparable.
Not sure how to check RC valve is opening fully at high rpm. help?
next step will be to check the loom.
my thoughts are still leaning towards rich mixture.
Had another look today: fuel tap out(little bit of debris on the mesh), plugs are changed, checked voltage.
Took it for a ride: still has a little stammer at 9-10k, but there is a flat spot now(new) at around 4-6.5k then boom, band kicks in like a horse. from idle to 6.5k, exhaust has a high pitched popping sound(not a back fire).????
Sorry for my lack of knowledge guys. passionate about this bike, but its a love/hate relationship.
Back to top


Dana

 
Posts: 98
Joined: 24 Jul 2011

Location: Hachioji, Japan
    Send private message View user's profile
    Reply with quote  

Mon Feb 27, 2012 11:08 am » Post: #13 » Download Post

kalnz44 wrote:No mods aside from the wire splice which was done today. Had the problem for about a month.
Gave the servo and pulleys a good de-grease, lots of gunk.
When i adjusted the RCs it took quite a bit to line them up. Any sign that the servo is on the way out? Apart from the obvious: no go.


Actually my servo would sound like it was moving when I inserted the key, but upon actually looking at it with the tank propped and engine running, me thinks it wasn't moving all the way. In fact, when I took off the cable pulley, it had some spots that felt like the gears inside wear stripped. Sure enough, I gently twisted the newer servo and there weren't any "free play" spots.

(I had also double checked to see that the RC valves were able to turn freely back and forth, and they were.)

Dana
_________________
2016 Husqvarna 701SM
2021 Husqvarna FS450 supermoto
2014 Honda CRF250R supermoto
1995 NSR250r MC28
Back to top


nxrsr20

 
Posts: 919
Joined: 15 Jul 2007

Location: Sydney, Australia
    Send private message View user's profile
    Reply with quote  

Mon Feb 27, 2012 6:58 pm » Post: #14 » Download Post

In your first post you said plugs were slightly black, are they wet and black or just black? If they are black and wet, then they are rich fouling and you need to make sure you carbs are setup correctly (so that means clean jets, emulsion tubes, air screws everything setup right).
Back to top


Neal

 
Posts: 900
Joined: 01 Mar 2009

Location: Scarborough
    Send private message View user's profile
    Reply with quote  

Mon Feb 27, 2012 7:39 pm » Post: #15 » Download Post

But could a electrical missfire contibute to black plugs beacause it is not burning the fuel Idea
Back to top


Reply to topic   printer-friendly view
Page 1 of 2  Goto page 1, 2  Next Download Topic

NSR250R Discussion

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You cannot download files in this forum

  • NSR250 Forums Index
  • All times are GMT
Powered by phpBB © 2001, 2005 phpBB Group


Hosted by NSR250dotNET © 2008 NSR250dotNET