Thanks for the vidio. That's great .. build it & race it! ... Are those 250r's you're racing? Any racing R's will be 310 to 370.
yz 250 blaster
- Thread starter 240ice
- Start date
One is a trx 250r and im pretty sure the other one was a lt250r and yeah there pretty big, you can see in the vid they just pull away in the staights.
did you have to change the mount angle on the carb and did you have an issue with the kick hitting the frame?
Me and my bro did the punched over WR250 swap....its freakin crazy!!!
BTW
240ice- ur swap is freaking awsome and clean...gave me lots of ideas on how to re-do some stuff on our WR blaster.
No, we didn't change the mount angle on the carb and we had to take a little off the kicker to clear the frame.
Thanks and as far as the vibration issues we didnt have any after the crack but we have decided to sell it.
Crack what crack? I read the 1st and 3rd pages to see how awesome it was and to get an update why would you put so much time and effort to sell it?
We keep cracking the frame becouse vibration issues, look at page 8 the very first post you'll see the pic's.
I wonder how the YZ's ever manage without cracking their frames?
I have been running a KTM 250 SX in a Blaster and have no problems with frame cracking.
It is impossible to balance out all the vibrations on a single cylinder motor that does nearly 10,000 rpm, but the manufacturers have done a pretty good job. When we modify the chassis, we have to do our part too. We have to look to not create a stressed point. By using 3 (and even better the 4th) engine mounts we are spreading the torque load of the motor out through the chassis better and allowing the motor to become a stressed member, part of the frame. Having all the bolts tight keeps vibration movement and fatigue at a minimum, that is why I use Loctite almost everywhere.
I don't think the YZ250 motor is much different than the KTM 250. I ride all day and have no problems with vibration on the bars or the pegs. I think this is an exaggerated concern. The power of the internet forums tends to take one slight negative comment and blow it up into a major issue.
It's goin from 2 wheels to 4 that compounds the vibrations or a better word would be harmonics.
I can not speak on the smaller un-counterbalanced 2 strokes but the issue of the 465's, 490's, and 500's cracking frames is pretty well documented.
My mighty 400 has cracked the frame in 2 spots.
My next venture will be to take the 465 in my garage and stuff it into a new Blasty frame. I intend to add a 1/2" steel motor plate for my motor mounts to bolt to.
All in all the 400 blasty had a good run goin for 4 years strong.
I can not speak on the smaller un-counterbalanced 2 strokes but the issue of the 465's, 490's, and 500's cracking frames is pretty well documented.
My mighty 400 has cracked the frame in 2 spots.
My next venture will be to take the 465 in my garage and stuff it into a new Blasty frame. I intend to add a 1/2" steel motor plate for my motor mounts to bolt to.
All in all the 400 blasty had a good run goin for 4 years strong.
hate to hijack ... but ... PaulieB, can post pics or locate your crack locations? .. I'm gusseting my frame & would like to reinforce any likely weak spots. Been searching posts looking for frame break locations.
No problem buddy. The blasty is parked deep in the garage and it's hard to get a good pic but here you go sir.
The crack has rusted a lil making it easier to see the line.
There is an identical crack on the other side as well. General consensus is cracks will develope on the mounts, on the pipe, and factory frame welds.
Another issue I'm having with this frame is I can't get a good weld to hold where I broke the grab bar (serious wheelie). It will hold for a while and then crack again.
There is no stress on that area other then motor vibrations.
The crack has rusted a lil making it easier to see the line.
There is an identical crack on the other side as well. General consensus is cracks will develope on the mounts, on the pipe, and factory frame welds.
Another issue I'm having with this frame is I can't get a good weld to hold where I broke the grab bar (serious wheelie). It will hold for a while and then crack again.
There is no stress on that area other then motor vibrations.
Good post Paulie B, thanks.
Generally the smaller the engine the smoother it runs for various reasons.
Even at that I do confess to pipe cracks on my 125 from running long times
at high rpm. Also I do remember the older MX bikes (1980s, 1970s) did have
frame cracking problems too. I had a 1974 CR250 that had cracks
everywhere. So what we may be seeing in the bikes is design evolution
solving their cracking problems, whereas our Blasters may not be nearly so
evolved?
So far no frame cracks on the KTM 250 Blaster, but I am also up for info
on where they are most likely to occur so I can gusset this winter.
Thanks guys!
I had a 72 CR 250 that after the frame cracked the third time I parked it. Always thought it was from the stupid skid plate for the pipe. I just figured that it was the lightweight chro-mo frame. 40 yrs later I'm still learning.
i have the same kind of motor on my blastr...i got it already built...i have an exhaust leak right at the block though...is there any special kind of pipe i need to run ?
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