camshaft profiles

[micoulisninja]

I guess most of you might have considered a camshaft upgrade for more mid to top range performance but the "off-the-shelf" solution for a ready to bolt on webcam pair is quite expensive...

has anyone of you tried it yet or tried a reprofile ?? and if yes what results did you come up with ?? what timing did you choose and why ??

[Racer x]

Still waiting for someone to make cams. As far as I know custom grinds are the only option. I have toyed with adjustable cam sprockets some.

[micoulisninja]

Originally Posted by Racer x

Still waiting for someone to make cams. As far as I know custom grinds are the only option. I have toyed with adjustable cam sprockets some.

really ??

well since you are the top upgrade modifier I've seen (besides me, of course) I'm gonna give you a great tip... try reprofiling the intake cam to the oem KLR 250 single cylinder intake factory profile... gives only more lift but doesn't put strain on the valve springs... suggest anywhere from 104 to 106 degrees leaving the exhaust cam completely stock to both profile and timing values(if using full aftermarket exhaust system which I consider as a basic condition before this mod)...gonna need a bit fatter shims but nothing extreme... valve to piston clearance remains almaost identical to factory's and both low end torque and top end pwer are greatly improved... valve lifting and returning speed is of the same variable as oem's...

[Racer x]

I don't know how to reprogile. Is this something I can do myself or something a cam grinder would have to do.

[bdavison]

you'd have to get a machine shop to do it....unless you have a metal lathe, and a cam grinding attachment.

[Racer x]

I will look into cams over the winters break. I am going to put three motors together for a veriety of classes. Thanks for the tip. I will post up what I find.

[bdavison]

Also, racer....

Once you re-profile the cam, you have to harden it again. The grinding takes all the temper out of the steel, and makes it soft as butter.

Basically most re-profiling involves grinding down the base, and perhaps welding more material on the lobes, and re-shaping them, and re-hardening them for one of two reasons.
1. for more lift...the amount the valves open, or 2. duration...the time the valves are open. The idea being that you get more fuel/air into the cylinder faster. So they open farther, and stay open longer.

Their are a few caveats to re-profiling. Particularly on our ninjas. The shims being the main annoyance. When you re-profile the cam, it will need thicker shims...problem is the shims required are probably going to be outside available shim sizes, so I don't know what you'd do there.

The other annoyance is getting just the exact amount of re-profiling. too little...no change, too much, and the engine either wont run, or self-destructs.

The third problem, and one that most people forget is that when you reprofile the cam lobes, you are now hitting the valves harder, faster, and sharper than with the stock cam lobes. Considering that our little engines are turning tens of thousands of RPMs, its gonna be risky running a cam that beats the crap out of the valves like that. Also, because of the rapid speed of the valves opening and closing...if the valve springs cant keep up with cam you will get valve float, and the valves may not ever actually close before the cam smacks them open again.

Then of course you also have the risk of tangling valves on each other, bottoming out the valve springs (which would be VERY bad),and shoving a valve head into the piston.

I can tell you, reprofiled...you are probably only looking at a +/- 5mm TDC difference on stock cams in lift, before the engine just flat wont run or self-destructs. I don't really know, as there just simply isnt any data for these engines that I know of. You might be able to get kawasaki to give you some of their computer models, but I don't even want to think about what kind of strings you would have to pull to achieve that.

For most 250R owners, I'd say you would be out of your mind to even think about it.....
Considering what you are trying to do with yours, perhaps a change to the cams could get you a better top-end for your speed runs. As to how you accomplish this...best wishes man. Let me know how it works out.

[Racer x]

I have looked into cams before. I was in contact with a company called megacycle. http://www.megacyclecams.com/

They would do what ever I needed. I just have to figure out what that is. And the money bit.

I have a friend that owns a valve train company. He said he would make me blanks .But Megacycle said they wanted to reprofile the original cams and would not work with blanks. It is just been on the back burner for a while. I have Carrillo rods already made and ARP studs . I just need to get the bottom end together and balanced before I can figure out how far and how long I can hold the valve open.I want to use 1mm larger valves also. Then I have to figure out spring pressure, after that I will do the cams. It is going to be a while.

[Somchai]

Eric, I really trust in your know-how, but designing cam shafts is a really difficult process.
Here you can find some already done for the ninjette (at webcamshafts you must select the ninjette):

http://danielcrowerracing.com/i-5935...cing-cams.html

http://www.beet.co.jp/english/kawasa...50r/index.html

http://www.webcamshafts.com/index_bl...le_search.html

The easiest thing would be ask them about the cams.

Wish you success.

What i forgot, maybe this article can help you a little bit also http://www.sportrider.com/features/1...ki_ninja_250r/

[thomason2wheels]

Originally Posted by Racer x

I have looked into cams before. I was in contact with a company called megacycle. http://www.megacyclecams.com/

They would do what ever I needed. I just have to figure out what that is. And the money bit.

I have a friend that owns a valve train company. He said he would make me blanks .But Megacycle said they wanted to reprofile the original cams and would not work with blanks. It is just been on the back burner for a while. I have Carrillo rods already made and ARP studs . I just need to get the bottom end together and balanced before I can figure out how far and how long I can hold the valve open.I want to use 1mm larger valves also. Then I have to figure out spring pressure, after that I will do the cams. It is going to be a while.

I hear what you are wrestling with. Why not focus on headwork and larger valves, that should improve both midrange torque and top end power. How much larger can you go before you run into interference issues? Computer modeling might help with defining cam profile limits, but i have no idea where you get access to the software or the computer to run it.

[Racer x]

When I oversize the valves I run into the side of the cylinder wall. Boring the engine. Helps with that and deshrouds the valves. I can do head work . But at this stage I will use stock cams and valves and let the nitrous do the work.
On a 14000 rpm engine the springs are the key. Bigger valves need stronger springs. Stronger springs have thicker wires. Getting the right spring pressure without binding the coils and not breaking is a can of worms I would rather not open.

[micoulisninja]

Originally Posted by bdavison

Also, racer....

Once you re-profile the cam, you have to harden it again. The grinding takes all the temper out of the steel, and makes it soft as butter.



well, yes !! but not if you do not exceed a limiti of about 5mm (0.2in.)



Basically most re-profiling involves grinding down the base, and perhaps welding more material on the lobes, and re-shaping them, and re-hardening them for one of two reasons.
1. for more lift...the amount the valves open, or 2. duration...the time the valves are open. The idea being that you get more fuel/air into the cylinder faster. So they open farther, and stay open longer.

Their are a few caveats to re-profiling. Particularly on our ninjas. The shims being the main annoyance. When you re-profile the cam, it will need thicker shims...problem is the shims required are probably going to be outside available shim sizes, so I don't know what you'd do there.




shims are of no trouble ! you can get up to 300 (stock used is 240-255 max) oem or fit up to 350 (max safety limit for a shim at 14k rpm) from other bikeswith same shim diameter (and there are plenty...)




The other annoyance is getting just the exact amount of re-profiling. too little...no change, too much, and the engine either wont run, or self-destructs.


well.... true in our cases , too !! I tried many profiles...can't do much about duration unless in a CR of 13,0 or more and even then got to be close to oem's (up to 5 deggrees more at 0.05") duration is easy stuff if staying in the safe limit of 5mm more (0.2") like I said before nd gives both low and high end torque but doesn't set fire on the road...however it is a big difference compared to stock...



The third problem, and one that most people forget is that when you reprofile the cam lobes, you are now hitting the valves harder, faster, and sharper than with the stock cam lobes. Considering that our little engines are turning tens of thousands of RPMs, its gonna be risky running a cam that beats the crap out of the valves like that. Also, because of the rapid speed of the valves opening and closing...if the valve springs cant keep up with cam you will get valve float, and the valves may not ever actually close before the cam smacks them open again.



that's why I only propose the KLR intake profile which is relatively mild, keeps same valve actuation speed both on lift and return....


Then of course you also have the risk of tangling valves on each other, bottoming out the valve springs (which would be VERY bad),and shoving a valve head into the piston.



oem valve springs are good for a mild reprofile, have a limit of up to 1cm (0.4in.) more than stock cam's travel (for intake, exhaust is even more)
and can stand up to 1000rpm higher rev limit with that reprofiled cam I am using...I've been running that thing for 10000miles now and still works fine so far...



I can tell you, reprofiled...you are probably only looking at a +/- 5mm TDC difference on stock cams in lift, before the engine just flat wont run or self-destructs. I don't really know, as there just simply isnt any data for these engines that I know of. You might be able to get kawasaki to give you some of their computer models, but I don't even want to think about what kind of strings you would have to pull to achieve that.

For most 250R owners, I'd say you would be out of your mind to even think about it.....
Considering what you are trying to do with yours, perhaps a change to the cams could get you a better top-end for your speed runs. As to how you accomplish this...best wishes man. Let me know how it works out.

[micoulisninja]

Originally Posted by thomason2wheels

I hear what you are wrestling with. Why not focus on headwork and larger valves, that should improve both midrange torque and top end power. How much larger can you go before you run into interference issues? Computer modeling might help with defining cam profile limits, but i have no idea where you get access to the software or the computer to run it.

well, the thing is these valve springs can't cope with any extra weight of bigger valves and then it will be certain of having valve to valve clearance issues...

[Racer x]

I guess you mean valve to piston interference. And having valves that float or bounce off pistons is one side of the problem. That is a weak spring. The other side is to strong a spring that will lead to valve breakage spring brakeage and catastrophic engine failure. Figuring out the spring is the first step. Buying the spring hohoho . If a spring like I need is a shelf stocked item. Then they are 20 bucks each and I can buy the eight I need. Custom wound springs are 200 each and only sold in batches of 16 . Yikes that is over 3000 dollars for springs . You gotta pay to play with the big boys.

[Racer x]

There is still very little about cams out there. But there are cam sprockets available to adjust the timing. You can also grind the cam bolt holes to move the cams. You dont need to move the cam much to make a big difference.
I found this video.

Link to original page on YouTube.

[mgentz]

did anyone ever try out one of the cams mentioned? thoughts?

[Racer x]

I have the adjustable sprockets. Even a slight I mean slight adjustment either way makes a huge difference. Advance and the engine will crackle with detonation retard and the engine won't start. I spent weeks fiddling with them.

[fordendk]

Originally Posted by mgentz

did anyone ever try out one of the cams mentioned? thoughts?

I have the Nassert Beet cams installed. Getting 34hp on dynojet dyno now (other mods too of course). Torque curve is sweet and the cams seem to give the bike better pull in the upper rev ranges (above 9K). Like all small bikes it is the incremental mods that make the difference and not just one mod.

[bruce71198]

Originally Posted by Racer x

I have the adjustable sprockets. Even a slight I mean slight adjustment either way makes a huge difference. Advance and the engine will crackle with detonation retard and the engine won't start. I spent weeks fiddling with them.

Did you try adjusting them on the dyno ? Where the results favorable ? I can't imagine a small (+-4 degree) adjustment would change cylinder pressure enough to cause detonation.

[Racer x]

I never adjusted the cams on the dyno. But you are correct. 4deg adv on the closing of the valves will send cylinder pressure above 220psi and that requires race gas. Four deg the other way and the compression drops below 125 psi and the engine won't start.

[bruce71198]

If you degreed your cams do you remember where you set the center line ?

[Racer x]

I should have. But I did not measure anything. I installed the sprockets. Moved them around some tested for interference and measured compression. After a week of pulling the valve cover and dozens of combinations.
I put the stock gears back in. It seemed a can of worms I did not have time for.

[tubarney]

Originally Posted by Racer x

I should have. But I did not measure anything. I installed the sprockets. Moved them around some tested for interference and measured compression. After a week of pulling the valve cover and dozens of combinations.
I put the stock gears back in. It seemed a can of worms I did not have time for.

I would say the only real way to test it would be with a dyno. Trying to calculate these things would be almost impossible without some serious software. Camshafts have to be the most complicated part of the 4-stroke engine. You can't gain something in 1 area without effecting another. Its all about compromise with these things. You basically need to find what works best for your particular type of riding.

Say with the intake, You can increase scavenging but hurt intake closing time; or the other way round. The exhaust is similar.

You will find kawa engineers have set the timing up pretty much spot on for the type of riding that the majority of people who buy it will do.

Also, if you take the duration of stock cams for example, they have set them up to give as much top end as possible whilst still keeping it street-able. The main reason it makes all the power above 8k whilst still be able to be ridden comfortable in a car park or something similar.

[Racer x]

Yes this is a very complex area. At this stage in the world of the 250 ninja there are four camshaft choices.
1 beet cams
2 custom cams . from web mega cycle others
3 the adjustable sprockets
4 two intake cams . Gives the exhaust 1mm more lift.

I don't know what sort of specs the Beet or custom cams have. I understand it a little . But have just been waiting for someone else to do the work.

[Somchai]

The difference in cams of the Ninjette



I'll try to describe: A very important factor for an optimum engine operation is the proper valve opening time.
With a 'sharper' camshaft (like the left one from the pre-gen), the flanks were made ​​steeper, so the valves are opening faster and also closing faster.
The tip of the cam is wider, so the valves remain longer fully open, which causes a 'pulling' into the cylinder and facilitates a better and more gas exchange at high revs.
With a very radical camshaft the valve overlap can be so extreme that the engine will stutter while idling.
And always keep in mind, that this way is not the best for emission-control.

[Racer x]

The first gen engine had rocker arms and the new engine is shim under bucket. I wounder how much difference that makes to the cam profile.

[red26]

So, which one is the better camshaft? The pre gen or the 08 version? I'm still new on these things

[Racer x]

The cams are not interchangeable. The new cams are shim under bucket . The old engine was rocker arm.

The intake cam on 2008 + motors have a little more lift and are I terchangable.

[red26]

Thanks racerx, I do have another intake cam so I'm thinking to put 2intake cams. Any drawback on that?

[mgentz]

The intake cam in the exhaust helped him on the bottle but not by itself.

[fast1075]

As a note, I exclusively used Web Cam for all my drag bikes. I will say prices have gone up a bit since I last bought something from them, so have BigMacs.

On their site, they list complete lift, duration, and centerline specs, you just have to click on the grind number to open a new page.

On the question about the different profiles between pre gen and new gen cams, and how different is the duration. I ask this question. How wide is the contact pad on a rocker compared to the width of a bucket? I don't know, but I bet someone can figure it out, and the affect geometry has on duration.

as for valve springs, you might want to see if APE has any. I am not real enthused about Ti retainers as long term use items because of their tendency to shatter after XXXX number of cycles, but for a race only application, they may be ok. And technology advances in metallurgy may make them more durable than they used to be. You may need them for stronger springs just to keep weight down.

I would carefully check the centerlines of the stock cams and see how that compares to the Web Cams. On my 650 I picked up considerably by degreeing the cams. On that note, the TINIEST change in cam position cam actually be many crank degrees. Remember the crank turns at twice the speed of the cams. That is why I use the largest degree wheel I can get to get best resolution.

As a rule, intake centerline defines the power peak, exhaust defines the peak width, of at least it did on my much longer stroke Kz engines. Your result may vary.