YZ 250 EFI

[GerbilGronk]

What's up with the injectors aiming downstream?

[Uniflow]

TMKIWI, certainly you can be the next to ride it, AFTER ME. Just got a call from Loyd ( Kiwi VMX ) today, seems Halcombe has just been canceled. Too much dust, too dangerous, they are worried someone will get hurt, fair enough. Could you pass this info on to anyone else you know planing to go to Halcombe. Thanks.
Stusmoke, because I have a YZ thats why, just because it's handy.
This post is a little confusing as I'm doing two projects, both on this post.

1   EFI standard YZ250, this will be first as all the parts are here now.
 
2  Make a 360 rotary valve engine ( EFI ) that fits in an 0010  YZF 250 frame. I call this a YZ360 VRV. ( variable rotary valve ) This engine has a 70mm stroke so can be re cylindered into a 250 if necessary. Maybe it might be competitive??? According to Wobbly's gas flow data on the cylinder, it should be good for between 60 and 70 HP, time will tell? I will definitely need help from other people ( Wobbly / Lozza ) to get this type of power.



 

[scottydog]

Awesome work uniflow! Think I seen your other bike out Maddix park a while back.
I started a EFI project for my YZ 144 but put that in the too hard basket for now.

Are you working out of a machine shop in Tauranga somewhere?
I ask as I need some bike(non motor type) parts CNCed up,

Scott

[2T Institute]

Cylinder isn't the problem the real problem is fitting the pipe of the necessary dimensions to get those BMEP levels. Rough dimensions would be 1100-1200mm long with a 140-145mm belly diameter.

[TMKIWI]

Just got a call from Loyd ( Kiwi VMX ) today, seems Halcombe has just been canceled. Too much dust, too dangerous, they are worried someone will get hurt, fair enough. Could you pass this info on to anyone else you know planing to go to Halcombe. Thanks.
 

****. I just paid my entry fee.
Bloody drought. " title="Angry" class="smiley">

[bigred1977]

a ha! i know who you are now!!! yes chris did tell me you were a whiz with the machining! certainly appears so too, yes we did have the problem of running crap off the bottom, it took some experimenting with different size injectors and also some trickery with injection timing, at one point we were injecting three times a cycle and then adjusting the obvious duty cyles, pulse widths, we did get a nice smooth transition, we luugged it as low as 500rpm then cracked it and it was nice, however as we both have experience, low volts stuffs the injection calculations big time, i had the calculations down for injecter size vs pulse width vs flow vs voltage drop threshold, when i scribbled it out, it explained exacly what was happening, very important. depending on what size injectors you are using and what draw the rest of the link will suck, i found the stock fuel pumps in the crf, yzf 450 which were set at 43 psi on the internal reg to be great, they only drew 1.2 amps at full throttle and at one point took a 1000cc injector to 95 percent duty!! pretty good i thought.
am looking forward to your project finishing mate, top stuff.
am interested to see what trigger wheel and cps you end up using? are you going to do a full stand alone with this 250/360 or are you going fuel only?
cheers mark.

[Stusmoke]

Wait on I thought rotatory valve was a four stroke thing?

[_X_]

i thought a rotary valve was in your heart. go figure.

[2T Institute]

You haven't ridden a real two stroke until you have ridden a rotary valve engine.

[Uniflow]

You haven't ridden a real two stroke until you have ridden a rotary valve engine.

Absolutely !!

[lauterbacher]

What you're doing is amazing, I have no doubt at all that the yz 250 will be phenomenal. especially when we know how much a yz 250 can put out under normal porting etc. Someone, were you folks are at needs to give you a 125 yz when you're finished up here with the 250. It would be nice to see a 45 horsepower 125 with an awesome power band. I also hope you can parlay this project into making some good money for you and your business.

[2T Institute]

If you wanted 45HP from a 125 you would just throw away a ****box YZ 125 engine, the RM 125 has the best cylinder,  only existing engine parts you would use is a crankshaft , gearbox and clutch. An enclosed belt driving a rear disc  with a variable length pipe would be a awesome engine.

A YZ 250 has about 35kW/ 48Nm torque to get more you need to rev them harder and a radicaly different pipe.

[lauterbacher]

I was'nt thinking of any specific 125 except I think of all the yz 125 that are out there and I think of someones potential profit if one were to be made and be available.
     Yes I remember your post of the aprilla 125 with the rear rotary valve and 54 horsepower.

[Uniflow]

What's up with the injectors aiming downstream?

Secret.    Nah, just this is the best way to fit them so as to miss the exhaust pipe. Also some car manufactures claim they get better air / fuel mixture / atomization pointing into the on coming air stream. I would prefer to have them point straight into the cylinder just above the transfer's but that is for the next engine with my own cylinder. Put my own injector lugs where I want them.

[Uniflow]

Awesome work uniflow! Think I seen your other bike out Maddix park a while back.
I started a EFI project for my YZ 144 but put that in the too hard basket for now.

Are you working out of a machine shop in Tauranga somewhere?
I ask as I need some bike(non motor type) parts CNCed up,

Scott

Yes probably, you don't see too many Bighorn Kawasaki's around these days. The day you would have seen  the Kawasaki the fuel pump split, it only ran for a short while.
I live in Hamilton, machine shop in the yard out the back of the house. Walk to work every morning. We already do a bit of work for Wobbly. Certainly I'm interested but we are very busy at the moment, your job might have to sit in line.