Yz250 swap
- Thread starter Blaster118
- Start date
make 100% sure you line the sprockets up. if the rear carrier bearings are shot, replace them before you do anything and the same for the swingarm pivot tubes. if either of them move around, your wasting your time lining anything up. you will need to make all your motor mounts. with the mounts cut out, you can move the motor up or down for better pipe placement. the pipe will be the hardest part to fit. the radiator is also a tough fit. mine fit into the frame just right. just made an upper mount and welded it to the frame. than used the stock blaster fender brace mounts to mount the lower part of the rad. I want to do a 250 some day. not sure when.
Thanks .. I and going to be ordering preety much all new parts for the bike new a arms new swing arm shocks every thing I going to get all of that first and than start getting tho motor in place . And has any one used a single radiator as opposes to the double like on the yz
I was planning on using bushing on the motor mounts to help with that idk if any one has had any luck with doing that
if your motor has the rear facing head stay, you need to make a mount for that and use it. i am running a single tank radiator on my build. it is up inside the frame. only thing i need to do different, is have someone modify the filler neck. it needs to be cut off and relocated. i can't weld aluminum so i didn't do it. i need a new tank since mine is bent. when i order a new one, i will get it modified. i did a 125 swap, you can check out my pics for any possible ideas.
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Make the type of motor mount that bolts to the frame and motor, and use some type of rubber bushings.
Do a 79 yz 250 and you don't need a rad..
If you do a old air cold motor then it will look almost stock!
IMHO .. the YZ gear set isn't a wide enough ratio for a 4 wheeler .. to get some low speed grunt you sacrifice top speed & if you want a decent top speed the bike is scooting right along at idle in 1st .. lotsa clutching on trails .. we change sprockets & chain going from trails to dunes .. the Blaster 6sd is perfect with it's super low 1st
I don't have the ratios for newer YZ'S. I used WR gears cuz 1st is a bit lower than the Blaster 2nd and 5th is a bit higher than Blaster 6th. WR 5th is like overdrive. The YZ is taller in 1st than the Blaster 2nd and lower in 5th than the Blaster 6th. To me the WR gear set seemed better suited for a quad. Guess it depends on what you want. Anyway, sumthin to think about with the WR/YZ swap.
Here's sum numbers to give you an idea of the difference between the Blaster, YZ and WR gearboxs.
Gear Ratios
---- Blaster --------- 89 WR250 -------- 90 YZ250 -------- Tri-Z
1st 34/11 (3.091) -- 32/14 (2.285) -- 31/15 (2.067) -- 30/14 (2.142)
2nd 31/14 (2.214) -- 29/17 (1.706) -- 29/17 (1.706) -- 28/16 (1.750)
3rd 25/15 (1.667) -- 24/18 (1.333) -- 22/16 (1.375) -- 26/18 (1.555)
4th 20/16 (1.250) -- 21/20 (1.050) -- 22/19 (1.158) -- 24/20 (1.200)
5th 19/18 (1.056) -- 21/25 (0.840) -- 23/23 (1.000) -- 22/22 (1.000)
6th 19/21 (0.905) ------ N/A ----------- N/A ------------- NA ------
I don't have the ratios for newer YZ'S. I used WR gears cuz 1st is a bit lower than the Blaster 2nd and 5th is a bit higher than Blaster 6th. WR 5th is like overdrive. The YZ is taller in 1st than the Blaster 2nd and lower in 5th than the Blaster 6th. To me the WR gear set seemed better suited for a quad. Guess it depends on what you want. Anyway, sumthin to think about with the WR/YZ swap.
Here's sum numbers to give you an idea of the difference between the Blaster, YZ and WR gearboxs.
Gear Ratios
---- Blaster --------- 89 WR250 -------- 90 YZ250 -------- Tri-Z
1st 34/11 (3.091) -- 32/14 (2.285) -- 31/15 (2.067) -- 30/14 (2.142)
2nd 31/14 (2.214) -- 29/17 (1.706) -- 29/17 (1.706) -- 28/16 (1.750)
3rd 25/15 (1.667) -- 24/18 (1.333) -- 22/16 (1.375) -- 26/18 (1.555)
4th 20/16 (1.250) -- 21/20 (1.050) -- 22/19 (1.158) -- 24/20 (1.200)
5th 19/18 (1.056) -- 21/25 (0.840) -- 23/23 (1.000) -- 22/22 (1.000)
6th 19/21 (0.905) ------ N/A ----------- N/A ------------- NA ------
