Oil Injection vs. Pre mix

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#1
I ride a street model kdx 200, with a oil injection system (handy when filling up at gas stations) I came to the thought of the oil injector squirting the oil into the intake, and not atomizing the oil like premix would. My thought is this would result in a less efficient "burn" or "combustion" therefor, less power. Should I try pre mix? 50:1 (I think I can run my oil pump dry without any damage)

Even though my bike has a 28mm (too small :) carb, some sort of dual wall KH 220 pipe, and a lowered exhaust port for tuning of tourque, I still am un able to lift the front wheel off the ground without a fair amount of pulling/weight positioning in my part.

I realise the front end shouldn't just "pop" up when ever you twist the throttle becaue it's only a 200 right!, but I would like some more "snap" to say the least.
That's where the pre mix idea came to be, but perhaps I'm way in left field here, I dunno.
-thinking about a fmf tourque pipe
-high tension carbon fibre reeds
The bike is a Japanese production '87 KDX 200 SR ('93 equivalent North American Bike)

Any imput would make my riding experience that much better!
Thanks again!
 

tedkxkdx

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#2
You can run premix in the gas and drop the oil can on the bike.
I would reconsider your ratio though since if you are doing street riding and running the bike at high rpm's you will want a 32:1 or more oil than that.
Remember that a lean almost ready to blow up bike will sound peppy and full of life and may even feel like it has more power. BUT it will seize since it lacks the oil to lubricate your crank and cylinder.
 
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#3
Originally posted by Yamablue
not atomizing the oil like premix would. My thought is this would result in a less efficient "burn" or "combustion" therefor, less power. Should I try pre mix? 50:1

The oil is not in there to "burn" --it's there to lubricate the contacting metal surfaces Keep the injection system -- your engine will work nicely with an effectively much higher ratio of fuel to oil. The heavier spray of oil is more likely to stay in the bottom end where it's needed instead of moving all around with the fuel/air charge. The only advantages of premix are: lighter weight [no pump] and, no chance of a pump malfunction.
Here in the USSA, a KDX with a pipe and 36mm carb will most definately lift the front wheel with just a "blip" of the throttle.
 
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#4
i've got a 1993 kawa X2 jet ski w/ a 650cc and when the oil injection quit working (i caught it quickly,luckily) i just started mixing 50:1 and its just fine. The only problem is a mixing inconvenience at the gas dock. Id leave the injection unit on for the sake of convenience if you ride it on the street a lot
 
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#5
I have a 1997 220 that I use on the street and have over 2000 miles on it and have had no problems using Walmart oil at 50 to 1. On the street you may be revving it a lot, but your not under a heavy load, most the time your under half throttle.I don’t know how many times I wish I had oil injection on it.
 
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#7
Thanks for the replies,
Yeah, I have a '79 Yamaha MX 175 (old school!) dirt bike with autolube as well. It works a treat and never have had a problem. As suggested I'll keep it!
-My compression and powervalve opperation is good. The bike has a 28 mm carb! Wouldn't this make the bike have unprecidented amounts of tourque?

I sometimes wish I had an USA, Can. version of the bike to compare with. I know the power is there, and the motor is capable of having the "ripping" power, but finding it takes time and money.

I realise an aftermarket expansion chamber "moves" the power characteristics around in the RPM range. Also, getting rid of the 2 wall pipe adds performance. The bike has a real good top end. Very noticeable to say the least. I would like a smooth transition from low rpm all the way to top rpms. (I assume that's what american KDX's are like)

I s'pose I gotta start somewhere. Break open the wallet and start with the pipe, reeds and perhaps carb.

Wouldn't putting a 35 mm carb on the bike lower the tourque output? I mean it pulls hard up top, I wouldn't want it too much harder, to say the least. Though, the thought of swapping carbs, gettin new air boots and somehow retrofitting the oil injection line into the boot has crossed my mind a couple of times. The problem is finding the carb...

Any more suggestions would be appreciated.
Thanks!
 

kmx125r

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#8
Hi Yamablue,

Greetings from Manila!

I do have a US version AND an SR version of a KDX, but they're both 250s. The SR is a 1992 (F2) and the US version is a 1993. Like your SR my SR has a small carb, 32mm vs. 38mm for the US version.

I'm not sure about the 200SR, but my 250SR has a different power valve set-up than the US version. The SR only has the two side valves while the US version has the two side valves and the main "center" valve.

The US version definitely rips compared to the SR, but remember the SRs were manufactured to be street ridden, too. They are more mildy tuned. In fact, a US version piston will not work on the 250SR version even though they have the same bore AND stroke. The wrist pin location is different.

I have recently spent a good bit of time jetting my SR correctly. It came from Kawasaki with a 148 main, a 42 pilot, and a #5 slide in the 32mm Keihin. I put in a set of Boyesen reeds, and finally settled on a 142 main and a 38 pilot, with the clip in the top (most lean) needle position. She runs quite nicely now, pulls like a tractor off idle and will run out very nicely on top. I'm quite happy with her now, for a street legal dirt bike that is!

I don't think the snap that you're looking for will be found by trashing the oil injector. You have to face it, your SR version will not run like a US version without swapping some parts, bigger carb, cylinder (if your SR only has two power valves), etc. etc... and make it an US version!

I ran a "test" to check my gas-oil mixture once on my SR... I made sure the oil pump was adjusted as per factory specs, topped off my gas tank, added my 2T oil until it filled the tank, and went for a ride (about 75 miles). After my ride, I filled both my tanks to the same pre-ride level (measuring the fluids I was putting in) and I came up with an average of 68:1 gas to oil. Interesting...

I love my SR, it is smooth and mild on the street and still offers a good ride when the pavement ends! Maybe hang onto to your oil injector, get your jetting right (if it's not already), and add a set of reeds. If you need more snap than that affords you... get a US version and be done with it.

For what it's worth... stay in touch, fellow KDX SR owner!
 
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#9
Most oilpumps will pump less oil at idle and lots at high RPM(makes sense).I'm sure my next comment will open much discussion.Oil lubricates and draws the heat from the piston to the cylinder then the cooling system by making a perfect seal from piston ring to cylinder wall.Outboard marine engines,high reving model airplane engines etc make maximum power with ratios at 10 or 15 to one.Obviously in day to day running this is not desireable , fouling plugs, smoke and the terrible emmisions.
Opti and other oils with high ratios(100:1)came to be from chainsaws and guys cutting all day.If your breathing smoke from the next guy or your own saw it can be sickening.
Oil and ratios is a highly technical topic, generally speaking the smaller and higher reving a motor is, the more oil it needs(oil migration).
Often friends and I will duke it out on the Opti 100:1 verses my preference of Klotz at 32:1, sometimes the arguements are intense.
So does less oil make more power? I would say no.Keep your pump, these guys who put these things together are pretty smart and make motors that withstand a wide variety of applications.
There are some good websites on this topic,I find it interesting, most people will read it to go to sleep.
 
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#10
I have an old 89 KDX200 SR (or 'F' model as we call it down under).

I'm a little concerned at your comment about lifting the front!

OK, I haven't ridden it for awhile as its my 2nd bike, but as far as I remember it would lift the front wheel in 3rd gear with a tug on the bars!

Are you running really high gearing (eg - 14 tooth front???).

Maybe your jetting needs cleaning up ...... doesn't sound right.
 
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#11
No, my gearing is 13 47. And I want more speed! I think Kawi screwed up by not making first gear taller and 6th smaller. And the bike would run all right with a wider ratio transmission anyway!

I wouldn't gear anymore towards tourque. (although it's an easy fix I know!)

Pretty sure my jetting is stock, but the bike runs real good, and haven't replaced a plug in the longest time (good brown color too)

I think I need a KX 500 LOL!
(no seriously! I have a problem with power! Can't get enough VRRROOOMMMM)
 

Fibb

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#12
Yeh Yama,

I know what you mean ... more power, more often.

Although, I have got a more powerful bike, and everytime I hit the dirt, it rides me, cleans my filter, wrings me out and basically leaves me hanging out to dry.

Its great to try and get the most out of one of these little mosquitos - much more fun, much less tiring.

Fibb