Thanks to all of you for your advice.

Budget_89KDX · Post by **Budget_89KDX** » 07:19 pm Dec 02 2010

I just took the kdx out after doing the FMF pipe install and replaced the broken KIPS valve.All I can say is WOW this bike is like night and day!hard to belive that the kips operating correctly will make that much difference.I also used a topend kit from moose that's supposed to raise compression I don't know how much of a difference it alone made but the bikes a beast and I want to thank those of you who helped with advice.

Now if it would just hurry up and warm up again.I put on my riding gear that I use when riding my gixxer and it was still cold but man was it a blast!

kdxmaniac · Post by **kdxmaniac** » 07:55 pm Dec 02 2010

you may want to cheack your compression if you used the moose gasket.........i just put one on my ktm 300, and got 240 psi! i have to run race gas now........anything over 200psi need race gas to be safe.

Budget_89KDX · Post by **Budget_89KDX** » 08:16 pm Dec 02 2010

Really?

I hit 195psi before I tore it down.I rode it for maybe half hour today before work and I didn't hear any detonation and it fires up on the first kick.how much do these thin gaskets raise compression?

Where's the line drawn on compression and running race gas without getting detonation 200psi?I just use what the station has I think 87-89 octane and mix amsoil interceptor at 32.1 and would like to keep it that way.I'm using a forged wiseco piston if that matters?I know what detonation sounds like in a car I've had a few motors grenade on the spray but a two stroke may be a little difficult to recognize since they got that signature tinny rasp.please explain?

kdxmaniac · Post by **kdxmaniac** » 08:29 pm Dec 02 2010

you will hear the pipe ringing diff........and also, your motor will idle up and down{surge} when you crack the trottle hard, and let off quick"diff sound than lean!" .................the main reason you run race fuel is to cool the engine{hince, race gas burns colder}"detnation"
if i was you, i wouldnt run 87 oct on your motor when it was 195psi in the first place........as far as how much the gasket raises compression.......all motor vary, so youll just have to check it. i will tell you this tho.........your bike should run like a bat out of hell if its 210-230 psi.

Budget_89KDX · Post by **Budget_89KDX** » 10:29 pm Dec 02 2010

I think you're confused octane is a fuel resistance to burn not how cold it burns.to get a cooling effecte from fuel you would need to burn alchohol.

Just out of curiousity why is it a bad idea to run 87?is it because out of the box these kdx's have high compression?I'm confused?

I'm at work but when I get home ill do a compression check and report back.yea its running very well for a 200cc engine.I'm very impressed.I don't know which is more impressive the kips role in performance or that a 200cc engine can make this kind of power.

Velocity_Stack · Post by **Velocity_Stack** » 01:25 am Dec 03 2010

Since we are on the subject of compression, I thought I would ask a question for a better understanding in relation to our KDX engines.

In the 2-stroke jet ski world, our compression threshold to switch from 93 pump to race fuel is 185psi.

What is different, if there is a difference, that allows 2-stroke mc engines run a slightly higher compression on 93 pump gas?

I see a comment above that says "anything over 200psi should be race gas".

In addition, what is the correct method to check compression?

Again, in the jet ski world, we hold the throttle wide open as we turn the engine over, once at ambient temp and then again at operating temp to make sure we're not pushing the envelope as the engine temps climb.

Budget_89KDX · Post by **Budget_89KDX** » 02:32 am Dec 03 2010

210 psi.I just checked it.got 120 on the second kick with 210 by the 5th kick.

Post by **Julien D** » 06:58 am Dec 03 2010

210? jeeeze...

You're mostly right about the fuel octane. The higher octane is more stable. Running 87 with high compression could lead to detonation. The fuel ignites from compression before the spark gets a chance to ignite it at the proper time. So the piston is still in it's upward stroke as the fuel charge ignites.

Post by **fuzzy** » 10:48 am Dec 03 2010

It's more about head cc's and squish than psi (Of course a tight cc is going to be high on compression however). Maniac, you may find that a squish change could eliminate detonation at those head cc's. That's mostly what RB's head is all about. A better squish design while keeping the same fuel requirement.

Budget_89KDX · Post by **Budget_89KDX** » 02:41 pm Dec 03 2010

Yea I get how detonation occurs and what causes it but are these engines prone to this when u go upping the c/r?

Is 210psi something to be concerned with?I'm using a snap on gauge and I know its dead on.

kdxmaniac · Post by **kdxmaniac** » 03:51 pm Dec 03 2010

race gas does burn cooler,{not really motor temp cooler, but ignition cooler?}"dont burn as fast" for example, race gas keeps down on detnation..runs more effeciant....you can run 93 on 210psi, but i dont recomend it.....i always mix 1 gallon of 112 to 2 gallons 93-non ethonol.

kdxmaniac · Post by **kdxmaniac** » 04:21 pm Dec 03 2010

also when you use a thinner base gasket, you are lowering you ports on the cylinder, "poor mans port job"..........higher compression will give you more bottom-mid........and also the lower port timing will to.

Budget_89KDX · Post by **Budget_89KDX** » 08:28 pm Dec 03 2010

Well you got me a little concerned now.I don't want to waste money rebuilding this bike all the time.

What are the rest of you running for compression and still on the pump gas?nd I checked the local station and 89 is the highest they have.and most of the time I use 87.

What's the general opinions of an additive to raise octane?I know in the auto world you may get a half a point but we aren't talking about a poked and stroked small block ford on the spray either.I have to go about 30 mins for my 93 I use in the mustangs and gixxer.

Inda do you know where to get turbo blue any more?william street had the special pump off to the side years ago but that place has since closed.

Post by **Mr. Wibbens** » 08:33 pm Dec 03 2010

I've never checked mine since I rebuilt it

If it's not pinging I'm not gonna worry about it

Budget_89KDX · Post by **Budget_89KDX** » 08:57 pm Dec 03 2010

Mr. Wibbens wrote:I've never checked mine since I rebuilt it

If it's not pinging I'm not gonna worry about it

I kinda thought the same but better safe than sorry.

kdxmaniac · Post by **kdxmaniac** » 10:02 pm Dec 03 2010

i wouldnt run 210psi on 87 octane.........you might be alright on 93 non ethonol.........you might get by on 87, but like i said, i dont recommend it. all i know is non of the bike i have, and built for others, dont like 87, OR 93 WITH ethonol in it, "most gas has 10% ethonol"...

Post by **Mr. Wibbens** » 10:11 pm Dec 03 2010

What this deal with the Moose gasket?

sped66 · Post by **sped66** » 10:13 pm Dec 03 2010

Interesting. What would you say is the lesser of two evils... 87 octane straight gas or 93 octane w/ 10% ethanol?

kdxmaniac · Post by **kdxmaniac** » 10:16 pm Dec 03 2010

Mr. Wibbens wrote:What this deal with the Moose gasket?

the gasket is only .012 thick...........paper thin! most gasket are .020 thick.

kdxmaniac · Post by **kdxmaniac** » 10:18 pm Dec 03 2010

sped66 wrote:Interesting. What would you say is the lesser of two evils... 87 octane straight gas or 93 octane w/ 10% ethanol?

i couldnt tell you........i dont run eaither! i would guess 93 ethonol would be worse? i put some in my ktm 380, run like ****, pinging, and surgeing........changed it back to 93 non ehonol, went right back to running right.

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Thanks to all of you for your advice.

Thanks to all of you for your advice.