YZ250 Blaster Build Log
- Thread starter Tbrock77
- Start date
Fixed the carb today, found someone else to do my welding because my dads buddy backed out. Now I just have to wait for him to get some argon and we'll get it done.
On a side note, I'm interested in purchasing some white plastics for it. Partzilla carries them but I figured I'd post here and see if anyone has any BRAND NEW plastics that they were looking to get rid of. Brand new white plastics only.
I'm also in the market for a +4 roundstyle swing arm and axle carrier. Swing arm must be black and in good shape. I prefer the Axle carrier be black, white or silver.
Also looking for extended a arms. Black is a must, looking for +3. Must be built for blaster spindles.
I know there is a wanted section but I'm not desperately in need of these parts yet. If you happen to read this and have them, shoot me a pm. I will edit this if I am no longer looking for these parts.
On a side note, I'm interested in purchasing some white plastics for it. Partzilla carries them but I figured I'd post here and see if anyone has any BRAND NEW plastics that they were looking to get rid of. Brand new white plastics only.
I'm also in the market for a +4 roundstyle swing arm and axle carrier. Swing arm must be black and in good shape. I prefer the Axle carrier be black, white or silver.
Also looking for extended a arms. Black is a must, looking for +3. Must be built for blaster spindles.
I know there is a wanted section but I'm not desperately in need of these parts yet. If you happen to read this and have them, shoot me a pm. I will edit this if I am no longer looking for these parts.
I figure (and hope) once your frame is welded you will powder coat it. any additional parts (swinger and arms) could be coated at the same time to match exact colors to eachother
Oh yes, powder coating was part of the plan from the very beginning. I'm going to get all the welding done and unused tabs removed before doing it though. It'll be a little while after I get it running because I want to make sure it is all working properly.
The plan is white frame, white plastics, black a arms, black swing arm, white hubs, black nerf bars, black handle bars, black seat, black or polished aluminum wheels.
Consider frame gussets while you're at it. There's a good thread somewhere, maybe suspension, DIY.
Gussets are in the plans too, along with an extra support where the frames tend to bend a lot, right where the lower a arms bolts to the frame.
Dropped the cylinder off to get bored, should have it back within the next week. Classes start next monday so I'm just going to wait until then to fabricate the mounts since it'll be a lot easier to do it there.
Came into a lot of YFZ450 parts, already sold enough to make everything else free. I have a full set of front A arms, and one side spindle with brake set up, seriously considering fitting them to the blaster but I don't know how to go about doing it because of the suspension geometry. I know it'll make the blaster +6 wider, 3" on each side.
Came into a lot of YFZ450 parts, already sold enough to make everything else free. I have a full set of front A arms, and one side spindle with brake set up, seriously considering fitting them to the blaster but I don't know how to go about doing it because of the suspension geometry. I know it'll make the blaster +6 wider, 3" on each side.
Unfortunately no. My campus has a full machine shop but it's always busy, my professor asked the overseer of that program to cut out the mounts on their CNC but he hasn't done it yet. I talked to my professor yesterday and I'm going to simplify the design so we can just cut it out using our mill. As soon as I have the mounts in my hand it won't be any longer than a week until it's running.
Finally after months of waiting, I have the parts. My professor asked another professor (different than the one he originally asked) to cut the parts, he handed the drawing to one of his students and I had them the same day. They aren't perfect but they'll work. Now I just have to weld them on, cut and fit the pipe and mount the radiator. I should make progress with that this weekend.
So I did the same conversion to my blaster a few months back but with a cr250. Runs great the two times I have taken it out (deployment got in the way). I'm still in the process of dialing it all in. My blaster has a twist throttle on since I bought it and I just got used to it but with this extra power I decided to switch to the thumb. Sorry to backtrack the thread a bit but I have no idea what length of throttle cable to get it or even where to start with experimenting with it. Thanks in advance
Maybe this would work:
http://www.ebay.com/itm/Motion-Pro-...ash=item5d308a449b:g:DvMAAOSwd0BVzNFX&vxp=mtr
Might wanna start your own thread
http://www.ebay.com/itm/Motion-Pro-...ash=item5d308a449b:g:DvMAAOSwd0BVzNFX&vxp=mtr
Might wanna start your own thread
After a few months of no major progress I finally have an update.
The front engine mounts are in, and the engine sits perfectly.
The next step is making the FMF yz250 pipe fit. I'm also strongly considering sending my cylinder to be ported, I was thinking of sending it Ken along with 2 heads to be cut, 93 and 110. Opinions on his YZ work?
The front engine mounts are in, and the engine sits perfectly.
The next step is making the FMF yz250 pipe fit. I'm also strongly considering sending my cylinder to be ported, I was thinking of sending it Ken along with 2 heads to be cut, 93 and 110. Opinions on his YZ work?
You will have NO problem with the stock YZ250 power output, at least initially. If the engine works good, leave it alone and only work on the swap. You will have wheelies on command at any speed and no hill will bog this motor. The gearboxs are very narrow ratio in these MX motors, and the quad weighs 100lbs more than a bike, so you need to keep the powerband as wide as possible in a quad.
The pipe is crucial.
Start with a proper YZ250 pipe for this engine (ideally a broad rpm pipe like stock) and do everything to keep the same lengths. Cut and rotating the pipe is preferable to get the bends. The other option if you have to bend it is to cut a wedge out of one side and weld it back in opposite.
Just noticed the rubber mount. I would recommend against rubber mounts. Better to keep the motor rigid with the frame to minimize vibration. YZOtis has worked on this in the past. A head stay would also reduce vibes, but is had to make a good rigid one on the Blaster.
I had to weld a header flange in so I could get the pipe on and off the assembled Blaster.
Also note wedge cut at neck.
The pipe is critical to the success of your swap, for power, power delivery and mechanical reliability. Worry about engine mods after you get all the bugs out of the stock setup.
Most of the heat blueing on this pipe is from removing a dent. Note mount at bottom.
Wedge cuts (2) were under engine, hardly visible.
My KTM Blaster is reliable enough to take on weekend 100kms long exploring camping trips.
Starts and idles well, great fuel mileage and will run slowly with other quads if it has to.
Good arguments for keeping the stock porting. My other KTM bike will run on 87 octane if needed.
This 250 still needs 93 and will be detuned to run on backwoods available 87 if I ever have to open the engine.
My muffler sticks out too far, drags when doing wheelies. Try to keep it tucked in.
Below, Look carefully near the bottom of the engine and you can see the wedge cut.
Again. muffler could have been tucked in and protected better.
I owe YZOtis huge thanks for his help in the success of my swap.
Steve
The pipe is crucial.
Start with a proper YZ250 pipe for this engine (ideally a broad rpm pipe like stock) and do everything to keep the same lengths. Cut and rotating the pipe is preferable to get the bends. The other option if you have to bend it is to cut a wedge out of one side and weld it back in opposite.
Just noticed the rubber mount. I would recommend against rubber mounts. Better to keep the motor rigid with the frame to minimize vibration. YZOtis has worked on this in the past. A head stay would also reduce vibes, but is had to make a good rigid one on the Blaster.
I had to weld a header flange in so I could get the pipe on and off the assembled Blaster.
Also note wedge cut at neck.
The pipe is critical to the success of your swap, for power, power delivery and mechanical reliability. Worry about engine mods after you get all the bugs out of the stock setup.
Most of the heat blueing on this pipe is from removing a dent. Note mount at bottom.
Wedge cuts (2) were under engine, hardly visible.
My KTM Blaster is reliable enough to take on weekend 100kms long exploring camping trips.
Starts and idles well, great fuel mileage and will run slowly with other quads if it has to.
Good arguments for keeping the stock porting. My other KTM bike will run on 87 octane if needed.
This 250 still needs 93 and will be detuned to run on backwoods available 87 if I ever have to open the engine.
My muffler sticks out too far, drags when doing wheelies. Try to keep it tucked in.
Below, Look carefully near the bottom of the engine and you can see the wedge cut.
Again. muffler could have been tucked in and protected better.
I owe YZOtis huge thanks for his help in the success of my swap.
Steve
Last edited:
Thanks for the info!
The goal with the pipe is to keep it one piece and model it after the stock blaster pipe with the curves and it must mate to the stock style silencer. The radiator will be mounted in the front as of now.
I was only thinking of porting because the motor is not together yet and it's on a brand new bore and piston. 93 is readily available by me, and I would run it with this motor all the time anyway, some people have said they get pinging with 93 so that was another reason I wanted to get a head cut for 93. 110 is also available but I would only use it if I wanted that power boost.
The goal with the pipe is to keep it one piece and model it after the stock blaster pipe with the curves and it must mate to the stock style silencer. The radiator will be mounted in the front as of now.
I was only thinking of porting because the motor is not together yet and it's on a brand new bore and piston. 93 is readily available by me, and I would run it with this motor all the time anyway, some people have said they get pinging with 93 so that was another reason I wanted to get a head cut for 93. 110 is also available but I would only use it if I wanted that power boost.
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