Thread: Ultra 250 timing mod.
12-04-2008, 01:36 AM #1
Ultra 250 timing mod.
Timing Advance Kit.
Saturday, August 23rd, 2008
Ah the much debated and my personal failure at testing it.
This is going to be a good and long one. It will incorporate the efforts of others and the product that are now coming to light due to recent information about it.
Let me start this with some of my personal history on it. The first place I ever saw this mod was in Guadeloupe while working on two 07 boats. One that wasn’t working to well had this mod in it. Closer inspection it seemed as if someone had filed away at the set pin location of the timing rotor. Well we played with it and during the race the boat had a total engine failure. So much for that.
The next time I saw something in regards to timing advancing was a product made by Speed Magic. They had it on the blog but was soon taken down and no more information was posted in regards to it. Talking with Macc Racing he had one and only one.
Doing my digging I found that several aftermarket companies stayed away from timing as it could cause serious engine damage if done wrong. Must have been the results I had encountered in Guadeloupe.
Well needless to say when it came up in the forums I was strongly against it, I not wanting to see alot of engine damage I challenged the modification. Short story is I was wrong. It took a certain person to visit me in Orlando to show me the errors I had been making. Thats right I was wrong, thats testing some times.
So lets get into the piece from Speed Magic and sold through MaccRacing and can be used on the Ultra 250, LX and 15 F motors.
Top pic is front side and the back side looks like this.
Notice that it puts the stock pick up on a slidable mount that allows for shifting to advance timing. The housing is notched to allow line up of notches to get to certain set points. 2 4 and 6 degrees are the preset points.
Kinda of pricey as I payed $250 for it.
Here is the stock cover.
Notice how there is no adjustment points.
Here is where it goes, mind you this is a 15F motor we were rebuilding but gives a good idea of the location we are talking about.
Next we will look at the other and much cheaper way to achieve a similar effect. Not a perfect calibration but vary close to it.
Look at this 15F motor and the location of the timing rotor. This rotor spins and the magnetic pick up can count the rotation that is then sent to the ECU for proper timing of the ignition system. ie when the plugs will fire. So advancing the timing could be done by relocating the pic up as Speed Magic does or by altering the rotor to allow it to rotate froward.
So lets do it.
Be safe and drain your oil first as if your doing an oil change. This will insure no oil spills under the motor.
Then you want to remove the timing rotor cover plate, “as I call it”. This can be done inside the boat and does not require the engine removed. I am using our 15F as a model. 4 x 8mm bolts hold on the cover
Under there you will find this. Notice the small amount of exposed set notch. Pink arrow #1 and the green circle #2 is the holding screw. The pink #1 is what we are going to alter to allow a small amount of rotation.
So to get that green #2 bolt off you have to hold the crank and that can be done at the coupler on the back side of the engine. You will see that the drive shaft has notched flat spots to hold it with a wrench.
Here are the simple tools needed to get the job done correctly.
Dremel, safety glasses, small vise, measuring tool that measures mm and a dremel bit. I used the dremel bit 9903 Tungsten Carbide cutter. Probably a bit to much bit but it made butter of the work.
I opted to buy a new rotor as to always have a stock ready to put back in. The part number is 21007-3744 from Kawasaki. If you bought a 250 then dont buy it from the dealer under your name. Trust me on this. Any parts you order to modify should be used under another name.
Once you have the rotor you want to take out a small notch to the left in the amount of 1mm to get approximately 6 degree’s of timing advance.
Here is me doing it to it. lol
Here is my measurement before and after cutting the rotor.
Here are some cut and not cut.
When reinstalling the rotor be sure to rotate the rotor toward the reverse level of the sky before tightening back down. This will ensure that the rotor is rotated in the direction necessary for advancing the timing.
Now for some results. 6 degree advancing gave my stock boat just out of the crate a gain from 7650 to 7890 and a 1.8 average speed gain on a bone stock machine. On my race boat with pulley kit I saw a 7750 to 8000 RPM gain and 2.1 mph gain. So I have been proven wrong. The timing advance works and in several races now we have seen no negative effects to motor. I have even bore scoped the cylinders to ensure no piston detonation signs are present.
Detailed information about this mod at 250xTech.com.
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