My ninja losing power

[h_sandhu12]

Hi,

Usually when I ride on the highway I can go 110 km/h at 7 thousand rpm. However, since last week I have to rev the engine to 9 thousand rpm to do the same speed. My speed now at 7,000 rpm is about 95km/h. I called a couple shops and they said it was the clutch so I took apart the clutch and had a guy at a shop examine it for me. He said the clutch looks its in good shape. So my question is what else could this problem? This is my first bike so i'm really not sure what else to do. I would greatly appreciate any advice on this.

Background information:
- I put in new spark plugs
- I have a 15 tooth front sprocket with stock rear
- I've checked the chain slack
- My bike has 51,000 km on it and so I thought it might be valve adjustment issue but all the shops all I called said valves do not cause this kind of problem.

[SLOWn60]

How long have you had the bike for, Harman?
The clutch springs may have lost their strength but I'm curious how long you have been riding it for.

[Ghostt]

Did you recently changed the oil? And how long ago?

Also when did you go the sprockets? 9k @ 110kpm sounds a bit high for a +1/0 gears

The clutch itself is pretty bulletproof on these bikes, the weak link is the clutch springs, which are soft from the factory anyway, I recommend changing then out for some Barnett springs, etc...

SIDENOTE: valves need to be at least checked at service intervals, per Kawasaki.

[h_sandhu12]

I checked the springs and they measure at 1.5 inch which is the correct length according to the manual and there was no warpaze on the clutch played and the friction plates were the appropriate thickness were not burnt
I did an oil change at 49,287 km and and it is now at 51,789km. I used 5w40 fully synthetic oil with a k&n oil filter
I plan on putting 10w40 partialy synthetic in when I put the clutch back in.
I had the bike for two months now

[Abu_Mishary]

I would seriously recommend to change the clutch springs.

[Brother Michigan]

This is definitely a driveline issue (clutch, sprockets, chain) rather than a power issue and definitely sounds like a slipping clutch.

A silly question first, though; are you absolutely sure you are in the same gear as before? If your clutch isn't slipping, I can't think of any other way for this to happen.

[juliusmichaelhonrada]

Definitely no one mentioned the tires , so it must be a tire pressure issue .
Get the proper pressure thats in the manual

[cadd]

Did you use a motorcycle (JASO) specific oil when you did the oil change?

[h_sandhu12]

I just checked the tire pressure, the back tire was good but the front tire was at 34 PSI and the recommended is 44psi so I will fix that up
I'm not sure if the old oil was motorcycle specific but I can check the new oil before I put it in. Can putting non motorcycle specific oil cause clutch to slip?
And @Brother Michigan, I'm in the same gear (6th) lol
And just wondering what's the rationale behind changing the clutch springs even though they meet the requirement in the manual?

I really appreciate all the help, thank you very much

[juliusmichaelhonrada]

the increased rolling resistance on a tire with low pressure is enough to slow you down by 20 km/h

[CrazyCanuckGoat]

While you may have clutch issues with your mileage, I suspect a cdi issue. My 2012 with 15/44 gearing and a 140 rear tire is doing 7000 at 100 kph. That was with the stock cdi and now pregen cdi wired in. Not sure how your bike would do the same rpm at 110kph. Just food for thought.

[Ghostt]

Originally Posted by h_sandhu12

I checked the springs and they measure at 1.5 inch which is the correct length according to the manual and there was no warpaze on the clutch played and the friction plates were the appropriate thickness were not burnt
I did an oil change at 49,287 km and and it is now at 51,789km. I used 5w40 fully synthetic oil with a k&n oil filter
I plan on putting 10w40 partialy synthetic in when I put the clutch back in.
I had the bike for two months now

What brand oil? As others have stated some modern oils contain friction reduction additives, which will cause slippage. The favorite oil here is SHELL ROTELLA T-6 SYNTHETIC

A good example of wet clutch, and how oil effects it

Link to original page on YouTube.


Check your oil.


Personally I'd change the springs, they are weak, I recommend changing them anyway, as I consider this a preventive maintenance issue. It's easy and cheap to do, don't even need to drain the oil as long as you do the work with the bike on the kickstand. The angle is enough to keep the oil on the left side of the engine and away from the clutch cover.

[h_sandhu12]

from what I could find online Barnett makes good aftermarket springs that may help to reduce slippage. According to Barnett's online catalog the part number for the springs for 2008 ninja 250r is 501-45-04050. H/w when I was about to order this part on Amazon, Amazon told me part number 501-45-04050 would not fit in my bike. So, if anyone has used Barnett springs it would really appreciate if you could confirm if this is an incorrect or correct part...

>a link to the page I looked at for the Barnett online catalog (in case i made a mistake here) ...
http://www.barnettclutches.com/490/k...ja%20250r.html

[h_sandhu12]

Originally Posted by h_sandhu12

from what I could find online Barnett makes good aftermarket springs that may help to reduce slippage. According to Barnett's online catalog the part number for the springs for 2008 ninja 250r is 501-45-04050. H/w when I was about to order this part on Amazon, Amazon told me part number 501-45-04050 would not fit in my bike. So, if anyone has used Barnett springs it would really appreciate if you could confirm if this is the incorrect or correct part...

>a link to the page I looked at for the Barnett online catalog (in case i made a mistake here) ...
http://www.barnettclutches.com/490/k...ja%20250r.html

[Ghostt]

Originally Posted by h_sandhu12

from what I could find online Barnett makes good aftermarket springs that may help to reduce slippage. According to Barnett's online catalog the part number for the springs for 2008 ninja 250r is 501-45-04050. H/w when I was about to order this part on Amazon, Amazon told me part number 501-45-04050 would not fit in my bike. So, if anyone has used Barnett springs it would really appreciate if you could confirm if this is an incorrect or correct part...

>a link to the page I looked at for the Barnett online catalog (in case i made a mistake here) ...
http://www.barnettclutches.com/490/k...ja%20250r.html

I would trust the Barnett website over Amazon. As I have an addiction to Amazon I've noticed that while the this "fits your vehicle" isn't always right.

[DEFY]

Originally Posted by Ghostt

I would trust the Barnett website over Amazon. As I have an addiction to Amazon I've noticed that while the this "fits your vehicle" isn't always right.

The issue is that it is created for an original purpose and marked as such. However, it can usually be more universal then they think. That saying that size doesn't matter is incorrect, just check the dimensions and if its match-able it will do, usually (Unless its manufactured by a company who sucks at tolerances).

[InvisiBill]

Originally Posted by h_sandhu12

I just checked the tire pressure, the back tire was good but the front tire was at 34 PSI and the recommended is 44psi so I will fix that up

44psi is probably the max rating for the tire, not the recommended pressure. 34psi is closer to what people usually run. I think I'm using 32psi on my 500.

[RacinNinja]

Originally Posted by InvisiBill

44psi is probably the max rating for the tire, not the recommended pressure. 34psi is closer to what people usually run. I think I'm using 32psi on my 500.

This. If you read the tire it says MAX pressure at XXX load. If you're not running that load, run a lower pressure.

[h_sandhu12]

I don't have stock tires and it says recommended PSI when Cold is 44 psi
But yeah I ordered the springs, just gonna put in new friction plates as well b/c I don't want to have to open the clutch again
So now I wait for the parts ... Which sorta sucks since the weather has been so great lately and I can't ride

But thanks for all the help, when I put everything back together I'll let you know if it made a difference

[Ghostt]

Stock tires or not, 44psi is too much, you need to look at the vehicle recommend pressure, the tire pressure effects the handling of the bike.

Here's some helpful links, if you need future proof,

http://faq.ninja250.org/wiki/What_ti...hould_I_use%3F

A quote from that article

remember that the number on the tire is the maximum that you can put in, and not the recommended amount.

More helpful links about tires,
http://faq.ninja250.org/wiki/Tires

As far as the new friction plates go, it's your $$$, just remember to order a new clutch cover gasket.

You never answered the question about which oil brand and type you used last, as this might be the cause of the slippage.

Without any bias on oil brands or type, any 10w-40 to 20w50 rated JASO-MA/MA2 oil will do just fine.

Using an oil with friction modifiers, will cause problems with the clutch, no matter what kind of springs, plates, etc.. your using. Also the wrong oil can effect the starter clutch, as this to needs friction to work properly.

So before you go and replace parts, recheck the oil you used, unless you like wasting money.

Once again in case you missed it

Link to original page on YouTube.

Here's some information on the subject of oil,
http://faq.ninja250.org/wiki/Preferred_Brands

Quote from article

What they are really worried about is oil that is labeled Energy Conserving. Energy conserving (EC) oils are made to be more slippery than conventional oils, which may cause the clutch to slip on some motorcycles. If you put EC oil in your bike and do feel clutch slippage, just change the oil to non-EC; that should make the problem go away. Note that newer EC oils are labeled 'resource conserving'.

http://faq.ninja250.org/wiki/Engine_Oil

[h_sandhu12]

Thanks For the reminder Ghostt. I checked the old and new oils. The old one was 5w40 and new one is 10w40. Both were made specifically for motorcycles with wet clutches. The new one is JASO rated according to the label but I couldn't find any rating on the label of the old oil I used.
I watched the video too and read the article on tire pressure thanks for the information