Kawasaki Ninja 250 - New Thread, 12/2008

[BigBikeBKK]

For all those wanting to hot up their Ninjas, JE Pistons is now offering 12.0, 12.5, and 13.0:1 pistons. Cost is some 335 USD. This is an increase of 0.4-1.4 over stock...

Cool Dave!

You gonna hot up your Ninjette?

Let us know how it goes.

Happy Trails,

Tony

[dave_boo]

Cool Dave!

You gonna hot up your Ninjette?

Let us know how it goes.

Happy Trails,

Tony

Until I can get a solid month home, anything this drastic is on the back burner. I don't trust the local monkeys who own a (mismatched) set of wrenches......

[CanInBKK]

For all those wanting to hot up their Ninjas, JE Pistons is now offering 12.0, 12.5, and 13.0:1 pistons. Cost is some 335 USD. This is an increase of 0.4-1.4 over stock...

Hey Dave, quick question. What performance increase would you expect from this kind of mod? I understand that the pistons will increase the compression ratio....but really what does increasing the compression ratio do for performance? (is it something like a turbo?) Also by increasing the compression with pistons won't thiseffectively decrease the displacement (longer pistons but same diameter results in higher compression but less displacement even at the bottom of the stroke)? Am I way off base here?

[Jake1]

Hey Dave, quick question. What performance increase would you expect from this kind of mod? I understand that the pistons will increase the compression ratio....but really what does increasing the compression ratio do for performance? (is it something like a turbo?) Also by increasing the compression with pistons won't thiseffectively decrease the displacement (longer pistons but same diameter results in higher compression but less displacement even at the bottom of the stroke)? Am I way off base here?

The higher the compression the greater the explosion, the greater the explosion the more power you're creating

I'm sure others will elaborate further

[dave_boo]

Hey Dave, quick question. What performance increase would you expect from this kind of mod? I understand that the pistons will increase the compression ratio....but really what does increasing the compression ratio do for performance? (is it something like a turbo?) Also by increasing the compression with pistons won't thiseffectively decrease the displacement (longer pistons but same diameter results in higher compression but less displacement even at the bottom of the stroke)? Am I way off base here?

Well, looking at this article where they used 13,5:1, had head work and oversized (1,5mm) valves, they were able to net 10,31 HP (40%) over the stock carb'd engine.

There is a forumla to figure out the efficiency, and generally you can assume it will give you the same increase in power. It is as follows:

E=1-(1/R^k-1)

R=compression ratio

K=adiabtic expansion of air (figure 1,4)

Using that, the efficiency of an 11,6:1 engine is going to be approximately 62,5%. An 12,0:1 engine is going to be 63%. So if we apply the same 1,5% increase you can expect approximately a half a horse power by going up to the aforementioned size. Going all the way out to 13 will get you to 64,2% efficiency, and maybe up to 33,6 HP. Note that this is inexact and is assuming you don't change ANYTHING else; otherwise those calculations fly out the window.

Increasing the compression ratio means more power. Greater compression means that for the same charge of air, you can get more force out of it--the greater it is compressed, the more it wants to expand upon combustion.

The displacement is not changed. The reason that the compression ratio is changed is because the diameter of the piston nor the stroke of the crankshaft has changed. It does seem counter-intuitive at first glance, but consider the point that compression ratio is figured by how much volume there is at the bottom of the stroke versus how much there is at the top of the stroke. While you do lose a simdgen of volume at the bottom of the stroke due to the extra height of the piston, the real magic happens at the top. Since a little loss of volume there is a HUGE change, it more than out-weighs the loss in volume from the bottom of the stroke. If you want to see it in numbers, think of it this way (using 250R sized piston); we have a piston that is 62,0x41,2mm. That means that it has a volume of 124,4 cm³ at BDC. Now, ran up to TDC, you're going to end up with a volume of 10,7 cm³. If on the other hand, you added a fraction of a milimeter to the dome of the piston (shooting for 12,0:1 compression ratio), your BDC to the end of the stroke will be essentially equal (since you'll take away nothing from so much space) and your TDC will equal 10,3 cm³.

Also consider the fact that expansion ratio (the exact opposite of compression ratio; compression ratio is measured from BDC to TDC and expansion ratio is measured TDC to BDC) plays a major role. If you have 12x the pressure of BDC, it takes longer to get back to the pressure that BDC represents (when you first turn it over it should be one Bar, but there's residual pressure when running from the last power stroke). The lower compression ratio looses power more quickly through the stroke because it doesn't have to 'dump' as much pressure as quickly. This builds power and actually increases efficiency.

One thing to note; if you do increase compression ratio it doesn't hurt to increase your duration on the cam. At lower RPM range this can actually be counterproductive because the speed of the air flowing in is greatly countered by the force of the air in the piston being displace on the compression stroke (the cam won't allow the valves to close before BDC is passed). However, at higher RPMs, the increased duration allows air to be available for a greater length of time (important since at say 10k rpms your intake valve is opening 42 times a second--it's actually open 0,024 seconds each time versus the 6 openings/second and 0,16 seconds that it is open at idle), and since the speed of the air is greater it overcomes the losses experienced at lower RPM levels.

Cooler air is also important; if you go with a higher compression ratio, find a way to get the coolest air possible. Also look at your cooling system's thermostat. Being in Thailand, there probably isn't much need for one unless you live up in Chiang Mai. Removing the sucker can bring your head's temperature down and help reduce the chance of detonation from using a higher compression ratio. From what I've read, every 10 degrees (F) you reduce your coolant's temp is another 1/4 ratio higher you can run without worry of detonation. There was a board member who had his valves coated on the VFR he runs for that same reason.

Back when I fooled around with building up cars I didn't like domed pistons; the domes actually get in the way of quick mixing of the air/fuel mixture. Also, the flame had to travel around/over the dome rather than straight across the piston as a flat-top allows it to. Playing around with the cams (above the duration) and thus timing is recommended. Higher compression ratio makes it a bit harder for the plug to fire (granted the little bit we're talking about here isn't that bad) requiring you to advance the timing so that the plug starts firing before TDC is reached; not exactly sure if the Fuel Injection Ninja has the same-same timing advance as the carb'd version, but the service manual I have states that the ECU controls the timing from 10^o BTDC to 35^o BTDC.

The other good thing is that Thailand is humid. So when ambient temperatures increase, you can expect some help from the humidity in the air charge preventing detonation.

I hope this brief primer helps you understand.

Edited August 10, 2009 by dave_boo

[soihok]

Why would you want to mess about with it?

If you want more power, just get a bigger bike.

I understand that its cheap and legal, but come on guys.

Lets start stripping down Honda 150,s also.

Its like you are 15 again.

Sorry for any insult,,,not intended,,,

R1 anyone?.............now you are talking

[thaicbr]

"Why would you want to mess about with it?"

Because you can!!!!!!!!

Why live in Thailand and not the USA, Europe or the UK.

Because you can!!!!!!

simple formula really.

[engrin]

Looking for a secondhand ninjaette, please pm with details of said ninjette for sale

[dave_boo]

Why would you want to mess about with it?

If you want more power, just get a bigger bike.

I understand that its cheap and legal, but come on guys.

Lets start stripping down Honda 150,s also.

Its like you are 15 again.

Sorry for any insult,,,not intended,,,

R1 anyone?.............now you are talking

Wow, yet another clueless person. Any old Tom, Dick, or Harry can go and buy an R1. Not all of them can get dirty trying to extract more power out of a little engine.

Add in the fact that in certain areas (say the Mae Hong run) the R1 would probably be struggling to keep up with the Ninjette and there isn't anywhere that the R1 can go that the other can't and I don't see the problem. How many more foreigners are killed in Thailand, or elsewhere, on a 'real' motorcycle rather than the little 250?

The "Its like you are 15 again." was an intended insult......but having read your previous postings it is just par for the course for you.

[Bard]

I found the "Why would you want to mess about with it?" amusing.

Look at bike owners in general.

Lot of them mod the bikes, most popular is exhaust to make more sound and power, powercommanders, suspension and the list goes on and on.

I previously owned a 250R and it's a cracking little bike cheap and good fun to ride. If I kept it I would buy racetech fork springs tho to avoid the nosedive on it. But I did mod mine when I had it with exhaust obviously.

Why fiddle with the bike, because it's fun.

I got a 600 now and I fiddled even more with that because it's fun, if I buy a literbike I will fiddle with that because it's fun.

The little Ninja has proven itself Tony toured up and down to Chiang Mai from Bangkok and everywhere with his, Simon did Pattaya Chiang Mai with his, and me and him both played on Bira with them when we had them, a realistic laptime you can achieve if you fix the suspension would be around 1:20 I see lot of much bigger bikes doing worse than that... (rider skills)

Granted on a fast road it's lacking power, but for twistes it's a fun bike. Obviously a 600 will crush it in everything, but literbikes don't always do it in the twisties. For the money it's a hel_l of a bike in Thailand, end of story and if people enjoy fiddling with there bikes, they do it out of satisfaction for doing the mod, and to get difference in the bike (which you did)

People on Harleys probably do more than anyone else on there bikes, people with R1's I know have Powercommanders, Exhaust systems, quick shifters and you name it. Why would anyone criticize someone because it's a smaller bike for doing the same?

[CanInBKK]

<snip>

There is a forumla to figure out the efficiency, and generally you can assume it will give you the same increase in power. It is as follows:

E=1-(1/R^k-1)

R=compression ratio

K=adiabtic expansion of air (figure 1,4)

Using that, the efficiency of an 11,6:1 engine is going to be approximately 62,5%. An 12,0:1 engine is going to be 63%. So if we apply the same 1,5% increase you can expect approximately a half a horse power by going up to the aforementioned size. Going all the way out to 13 will get you to 64,2% efficiency, and maybe up to 33,6 HP. Note that this is inexact and is assuming you don't change ANYTHING else; otherwise those calculations fly out the window.

<snip>

I hope this brief primer helps you understand.

Hey Dave, that was actually a very insightful read. In theory I guess the displacement loss would be minimal - if the piston was a little taller making the compression at the top 12:1, at the bottom of the stroke the displacement lost would be 12x less....quite minimal.

[soihok]

Why would you want to mess about with it?

If you want more power, just get a bigger bike.

I understand that its cheap and legal, but come on guys.

Lets start stripping down Honda 150,s also.

Its like you are 15 again.

Sorry for any insult,,,not intended,,,

R1 anyone?.............now you are talking

Wow, yet another clueless person. Any old Tom, Dick, or Harry can go and buy an R1. Not all of them can get dirty trying to extract more power out of a little engine.

Add in the fact that in certain areas (say the Mae Hong run) the R1 would probably be struggling to keep up with the Ninjette and there isn't anywhere that the R1 can go that the other can't and I don't see the problem. How many more foreigners are killed in Thailand, or elsewhere, on a 'real' motorcycle rather than the little 250?

The "Its like you are 15 again." was an intended insult......but having read your previous postings it is just par for the course for you.

Wow, what a touchy guy.

Then again I,ld be touchy if I had a 33 brake horse 250.

Look...apologies all round, I have been modifying bikes since the early 80,s and while this gives great satisfaction it is no substitute to simply getting a better bike.Suzuki X7 has the same power as the Kwak 250 more or less and that was 30 years ago.

Ok it handled like a donkey .

Bike = feedom=up to you to do with it what you want....we will all agree on this.

Go do what you want.....its your choice

[dave_boo]

Wow, what a touchy guy.

Then again I,ld be touchy if I had a 33 brake horse 250.

Look...apologies all round, I have been modifying bikes since the early 80,s and while this gives great satisfaction it is no substitute to simply getting a better bike.Suzuki X7 has the same power as the Kwak 250 more or less and that was 30 years ago.

Ok it handled like a donkey .

Bike = feedom=up to you to do with it what you want....we will all agree on this.

Go do what you want.....its your choice

Touchy yes; however not for the reason that you surmise.

I'm not ashamed that I have a bike that only produces 33 BHP, in fact I'm quite happy with the 'lesser' bike I own that only produces 20 odd (the CBR 150R). I'm touchy that you have the hubris to come into a thread and spread your bilious inanities. Your attempts to equate a 30 year old 2 stroke of the same displacement and horsepower are ridiculous. The NSR 150 produces nearly the same horsepower as both these bikes; so why was the X7 so far down on power?

I do agree with your last two sentences though; however why couldn't you have that attitude before posting previously?

[monkeyofdoom]

Looking for a secondhand ninjaette, please pm with details of said ninjette for sale

I will be selling my 2009 green 250R with about 3500 km on the clock when I move up to the new Ninja 650R, but not for a few weeks or even months. What are 250Rs going for at the moment? Engrin, how much are you expecting to shell out?

Edit:

Never mind, looks like around 100000-130000 at http://classifieds.thaivisa.com/?act=searc...amp;x=0&y=0

Edited August 12, 2009 by monkeyofdoom

[soihok]

The NSR 150 produces nearly the same horsepower as both these bikes; so why was the X7 so far down on power?

Because its 30 years ago mate.

Look I can see where this is going and there is no point taking this any further.

I wish you all the best and if we were to meet I,ll buy the beers.

I,m bikeless at the moment sadly (decided not to import my VMax so I sold it ),,bought a new Fino for the wife last week,, but thats about it for now.

So I,m happy for you that you have decent wheels to get about on.

New job on the way at the end of the year....KTM SuperDuke is calling.

Cheers

Edited August 12, 2009 by soihok

[Bard]

I'll PM you next time I tour up to Korat soihok, and I'll take you up on the beers, hope that you keep it even tho I got a 600?

LOL

[engrin]

Looking for a secondhand ninjaette, please pm with details of said ninjette for sale

I will be selling my 2009 green 250R with about 3500 km on the clock when I move up to the new Ninja 650R, but not for a few weeks or even months. What are 250Rs going for at the moment? Engrin, how much are you expecting to shell out?

Edit:

Never mind, looks like around 100000-130000 at http://classifieds.thaivisa.com/?act=searc...amp;x=0&y=0

Depending on the addons/mods the price range above is what I can pay! Send me a PM when you're ready!

[Bard]

PM tuktukracer he has one for sale full exhaust system and power commander installed, he might still have it for sale engrin

[engrin]

will do! thanks Bard!

[Weeble]

The NSR 150 produces nearly the same horsepower as both these bikes; so why was the X7 so far down on power?

Because its 30 years ago mate.

Look I can see where this is going and there is no point taking this any further.

I wish you all the best and if we were to meet I,ll buy the beers.

I,m bikeless at the moment sadly (decided not to import my VMax so I sold it ),,bought a new Fino for the wife last week,, but thats about it for now.

So I,m happy for you that you have decent wheels to get about on.

New job on the way at the end of the year....KTM SuperDuke is calling.

Cheers

Yes - as mention in previous blog - i had a Kawaski KH250 S1 - (30 years ago) -simlar power simlar top speed now with the Ninja getting same feeling - I was 17 then young foolish best bike i could get at the time flat out everywhere - Now old, Knackard but just as foolish - its great!!!

[dave_boo]

For those interested, PM me and I'll shoot you a service manual of the carb'd Kawasaki Ninja 250. I understand that there's some differences, but considering that the majority of us aren't set up to do fuel injection system work it really shouldn't matter.

[engrin]

I'm part of the Ninja club, wahoo! Fun bike, fast, so light and easy to control.

Where would you guys recoemmend I get the Area P from and also what Benzyne number would you recommend. I'm running 95 now. (sorry but hard to search TV for the info required!)

Also, how often should I change oil/filter.

I bought the bike second hand with 3000km on odo.

[dave_boo]

I'm part of the Ninja club, wahoo! Fun bike, fast, so light and easy to control.

Where would you guys recoemmend I get the Area P from and also what Benzyne number would you recommend. I'm running 95 now. (sorry but hard to search TV for the info required!)

Also, how often should I change oil/filter.

I bought the bike second hand with 3000km on odo.

Welcome to the club.

I haven't found anything on the fuel grade to be used; I simply use Shell 92. Area-P I believe can be obtained overseas; there is a shop that offers various exhaust (and other bits and bobs) that is on the west side of Bangkok. Here's a thread on the local (Thai only I'm afraid--but pics and prices come through) Ninja board that describes his offerings.

Oil is changed yearly or at 1 000, 12 0000, 24 000, 36 000, and 48 000 km. This comes from the service manual:

Recommended Engine Oil

Type: API SE, SF or SG

API SH, SJ or SL with JASO MA

Viscosity: SAE 10W - 40

Capacity: 1.3 L (1.4 US qt) (When filter is not removed)

1.6 L (1.7 US qt) (When filter is removed)

That seems like an excessive amount of time between changes; more frequent changes will not hurt anything.

[JonnyF]

I have the Area P quiet core carbon exhaust and got it from areapnolimits.com

The exhaust is great, noticeable performance gain and sounds great without sounding over the top. Import duty was about 5000 baht because Area P refused to mark it as a gift.

Dave, I'm pretty sure there's a service at 4000 in addition to the ones you mentioned i.e. 1k, 4k 12k and then every 8k after that. Mine was done at 4k in any case. I'm sending it for it's 3rd service next week at 11k because I agree that 8k seems quite a lot considering the high revving nature of the engine.

Kawasaki told me to use 91 so that's what I've been using with no issues.

[NinjaGladiator]

Not sure if I'm allowed to drop an ad in here but I will get it on the classified as well.

I'm selling my 250r 7,800km of good memories and 3 oil changes later. Read back over my posts to get some idea of it's history. Inc. a faultless 800km round-trip to last years CMBW, with her-in-doors and all the luggage that goes with it, it took the mountain ranges without a struggle.

I'd like around the 105k for her (149k brand new) and it's her birthday tomorrow (1yr old)

Call me on 0845 125 025, the bike is reg'd in Udon Thani with a No.1 plate.

...Looks like I can't attach pics - something about being deemed pornographic by RT police.

Getting more like China every day.

If you want pics emailed get in touch

[engrin]

Is there an alternative to the Area-p that is cheaper and works just as well?

Also, anyone know where to get cheaper engine guards? They are charging 4,000 at Kawa in Pattaya.

[dave_boo]

I have the Area P quiet core carbon exhaust and got it from areapnolimits.com

The exhaust is great, noticeable performance gain and sounds great without sounding over the top. Import duty was about 5000 baht because Area P refused to mark it as a gift.

Dave, I'm pretty sure there's a service at 4000 in addition to the ones you mentioned i.e. 1k, 4k 12k and then every 8k after that. Mine was done at 4k in any case. I'm sending it for it's 3rd service next week at 11k because I agree that 8k seems quite a lot considering the high revving nature of the engine.

Kawasaki told me to use 91 so that's what I've been using with no issues.

Two items; first I also think that's a ridiculous amount of time between oil changes--however that's what the service manual calls for. Second, I meant benzine 91 not 92.

Not sure if I'm allowed to drop an ad in here but I will get it on the classified as well.

I'm selling my 250r 7,800km of good memories and 3 oil changes later. Read back over my posts to get some idea of it's history. Inc. a faultless 800km round-trip to last years CMBW, with her-in-doors and all the luggage that goes with it, it took the mountain ranges without a struggle.

I'd like around the 105k for her (149k brand new) and it's her birthday tomorrow (1yr old)

Call me on 0845 125 025, the bike is reg'd in Udon Thani with a No.1 plate.

...Looks like I can't attach pics - something about being deemed pornographic by RT police.

Getting more like China every day.

If you want pics emailed get in touch

Sad to see another Ninja leaving our group, but that's a hel_l of a price and will make someone happy.

Is there an alternative to the Area-p that is cheaper and works just as well?

Also, anyone know where to get cheaper engine guards? They are charging 4,000 at Kawa in Pattaya.

Faddy is offering an Area-P knock off for 250 USD.

[thaicbr]

If you look on the ninja250 thailand forum you will find a DBS system for 7,000b

here ya go. http://www.ninja250thailand.com/board/index.php?topic=2249.0

[Jake1]

Has anyone been able to get a discount at all on their new 250r purchases? or free gifts? I'm thinking about picking one up next month and I'd like to know if I'm able to negotiate at all.

I still may take the kiniyow route and purchase a 150 though

[BigBikeBKK]

Has anyone been able to get a discount at all on their new 250r purchases? or free gifts? I'm thinking about picking one up next month and I'd like to know if I'm able to negotiate at all.

I heard about a guy who recently bought 4 ER6n's and got a FREE Kawasaki Ball Point Pen!