Warrior YZ250 Engine Conversion

[Mathius]

You should be pushin bard to wrap it up reguardless, lol.

Well I did some work to it yesterday. We'll see if I can get some video up before "dmanabq" does? But his quad is more complete than mine.

You also have to remember that mine was a frame up build. I keep running into all kinds of little snags.

 

[dmanabq]

Thanks everyone. Bolt in? Yes once you make all new brackets from steel strap and cut the exhaust up then reweld it. The radiators may not be permanent but I had them so I used them. Believe it or not I started on this swap late Thursday and was riding it Sunday, so if you push lol you can get it done. I rode it this morning but the bald tires and gearing were holding it back. I need a 13T front in place of the 14T there now. Video soon I promise. PS vibes are less than a stock Banshee.:slayer:

 

[dmanabq]

I really hope you beat me Mathius I really want to see a 490 Warrior rock lol. I love that motor and now I love the Warrior chassis.

 

[Mathius]

I really hope you beat me Mathius I really want to see a 490 Warrior rock lol. I love that motor and now I love the Warrior chassis.

Ha ha ha.. :haha:

That's funny.
The YZ250 was actually my first choice as a motor for doing a swap, and I actually wanted to use a YFZ 450 chassis. For the more modern parts, and lighter weight. If I ever strike it rich, I still might build one?

I love the old school muscle of the air cooled big bores, and I have had my Warrior for years.. But I have to say that the Warrior chassis (especially the gen 1) is out dated, and kinda tough to find good parts for. Though they are a great look'n quad.
I more or less did this swap as a tribute to it's years of faithful service to me. :tup:

I still have a lot of work to do before I can post a video though.

 

[Mathius]

I was also gonna say that the reason the YZ250 runs so smooth is because it's counter balanced. Any Yamaha 2 stroke after 91' was counter balanced.
The early Banshee 350, 2 lungers weren't, and would shake you right off the quad.. Same thing with the old school 250's.
The Tri-Z 250 was an epileptic animal.. lol

 

[dmanabq]

So had a long trail ride yesterday and I discovered a weak link in the Warrior YZ. The stock 2.4 gallon fuel tank goes dry about 5 miles from the truck lol. This bike runs great otherwise. By friend was riding a banshee and I had to wait for him several times. With the gearing it has I can easily do 55 mph in 4th gear. I may need to change that though. I will get a video going as soon as I can.

 

[dmanabq]

P.S. It may just be me but this quad is a lot lighter than a Banshee now. I can easily load it into my truck by just picking up one side at a time. Last night (when his banshee broke down) we loaded his quad the same way and barely got it into the truck with two people.

 

[YAMAHAULER]

5 miles on 2.4 gallons of gas that can't be right espeicially for a two stroke 250 I push over 80 miles to a 100 per 2.4 gallons of gas with my 02 warrior pushing her hard

 

[dmanabq]

No after about 50+ miles or so I ran out. Sorry it was a joke about the little tank, I thought I would have a range similar to the YZ the engine came from. But my old YZ had a larger tank. Moral of the story was I had to walk several miles due to my bad reasoning skills lol. I must be bad at predicting fuel left in the tank.

 

[YAMAHAULER]

do 2 smokers suck more gas than 4 strokers? or am I missing something?

 

[88WarriorBoy]

yeah they usually burn twice as much fuel lol it just depends on riding style, weight, cc's, and much more lol

 

[dmanabq]

From my experience the two stroke use at least 50% more. Its the inherent problem of not having valves to stop fuel from exiting the cylinder before it has a chance to be burned. That and I was riding in a place were full throttle happens a lot but you never get out of second gear.

 

[bryanquad]

From my experience the two stroke use at least 50% more. Its the inherent problem of not having valves to stop fuel from exiting the cylinder before it has a chance to be burned. That and I was riding in a place were full throttle happens a lot but you never get out of second gear.

i have a yz426 on my warrior and it dont take long at all to run a tank of gas out of it . i dont know how may miles it will go but im lucky if i get to ride for 30 to 40 mims on a tank of gas .. what gears do you have on it ?

 

[dmanabq]

I have 13 tooth front and a 40 Rear with the stock YZ 250 case gears.

 

[Mathius]

I have 13 tooth front and a 40 Rear with the stock YZ 250 case gears.

Economy has a lot to do with the tune you have in you motor.. I've been tuning 2 strokes since I was 13, and there are so many variables it'll make your head spin!!
Just because it sounds like it's running good, and there's no sputter or bog. Doesn't mean that it's running properly.. The best way to tune your motor is with a few plug chops, different heat ranges of plugs, a handful of jets, and a days worth of your time.

You should be able to see a huge gain in topend performance, as well as economy if you do it right. :iagree:

 

[Mathius]

I thought I would share some findings with you here dmanabq.

Here are the gear ratios for a YZ250.

Primary: 3.00
1st: 1.93
2nd: 1.53
3rd: 1.28
4th: 1.09
5th: 0.92

Find a gearing calculator of your choice, and you can find out your top speed in each gear, the size of tires that might suit you best ect"..

 

[bryanquad]

I have 13 tooth front and a 40 Rear with the stock YZ 250 case gears.

i would put a 12 /42 on it to start with but you could need a 44 for the back .. my buddy has a yz 250 on a blaster i think he has a 44 on the back .. are they dont want to take off to good and that will use up some gas to

 

[bryanquad]

Economy has a lot to do with the tune you have in you motor.. I've been tuning 2 strokes since I was 13, and there are so many variables it'll make your head spin!!
Just because it sounds like it's running good, and there's no sputter or bog. Doesn't mean that it's running properly.. The best way to tune your motor is with a few plug chops, different heat ranges of plugs, a handful of jets, and a days worth of your time.

You should be able to see a huge gain in topend performance, as well as economy if you do it right. :iagree:

you are right about that to .. 2 strokes are very picky .. sometimes it is hard to get them right .. i hope you get all of the bugs worked out of it .. it should b a fast hybrid .. the best thing you can do is put it on a dyno that will take alot of guess work out of it .. do you have anything done to the motor

 

[dmanabq]

Stock everything on the YZ side. I know the gearing is close to the YZ overall gearing when you include the difference in tires. My wife tailed me in my truck on the way home and at 55mph I was pulling away from her. I never left Fourth gear, so I definitely think the gearing is too steep. I would be just fine with a pinned out in fifth top end of 60 mph. The engine runs well but could use alittle less fuel in the mid I think. I bet my fuel mileage problem is the gearing and the needle.

 

[dmanabq]

Okay got a video of it moving.