Possibly bent subframe on yz125

joeschmo
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19
Joined
8/14/2019
Location
Monroe, NC US
Edited Date/Time 12/5/2020 8:09pm
I am currently tearing down a new to me yz125 and noticed a few things that look off on first glance.

1. The first thing I noticed was that the subframe rails were spread out further than I expected at the top mounting location (photo 1). The previous owner had "solved" this by simply adding 3-4 washers to take up the slack but I want to address the actual issue.

It seems as if the subframe is bent but if I remove the washers and tighten down the upper bolt so that the subframe rails straighten out, it bends the support bracket between them.

Can anyone post up some photos of their subframes where they mount at the top of the frame for comparison?


2. The exhaust side plastics seem to be rubbing the exhaust due to their angle but from review, they seem to be in the correct location and the exhaust may be misaligned. I went over the exhaust hanger and it looks to be correct and unbent. The bike has the Polisport restyle kit currently and there does seem to be a small cutout in the airbox plastic to allow clearance but its still not nearly enough in the currently install.

From the couple photos I have seen of other bikes with the restyle kit, the exhaust should not contact the plastics nor airbox at all.


Has anyone seen these specific issues and if so, what was the solution? Thanks in advance.









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FGR01
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AZ US
Fantasy
1327th
12/1/2020 6:26am
Yeah it looks like the whole rear of the subframe got bent to the left. Put the rear fender and seat on. Compare the alignment of the fender and rear tire when viewed standing about 10ft behind the bike.
joeschmo
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Location
Monroe, NC US
12/1/2020 7:19am
Thats is what I thought as well but with everything assembled, it looks generally ok except for the silencer rubbing up against the plastics.



gklefev
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Goodyear, AZ US
12/1/2020 7:53am
Strange here is a shot of my 11YZ125 for comparison. Yours looks shorter then mine on the left side.

joeschmo
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19
Joined
8/14/2019
Location
Monroe, NC US
12/1/2020 7:54am
I am wondering if the previous owner could have used a '02-'04 subframe instead of '05+ to match the frame since the '02-'04 subframe was still aluminum and from looking at a few online photos, they were very similar and could explain the gap at the top frame mount bolt.

Anyone familiar with the differences in the '02-'04 and '05+ subframes?

The Shop

joeschmo
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19
Joined
8/14/2019
Location
Monroe, NC US
12/1/2020 8:08am
gklefev wrote:
Strange here is a shot of my 11YZ125 for comparison. Yours looks shorter then mine on the left side. [img]https://p.vitalmx.com/photos/forums/2020/12/01/462697/s1200_1AE45D2B_9C19_4147_BA64_F422413EA1F2.jpg[/img] [img]https://p.vitalmx.com/photos/forums/2020/12/01/462698/s1200_79674E18_6FB7_4228_B0ED_D651E89D9770.jpg[/img]
Strange here is a shot of my 11YZ125 for comparison. Yours looks shorter then mine on the left side.

I see what you mean. I grabbed a couple more of that mount on my bike.


12/1/2020 11:39am
I'd guess your subframe is tweaked slightly and has wore into the frame causing the wear in the right side frame mount and the subsequent gap on the left side.

Being a poor man and, poor people have poor ways, I'd just place a Stainless washer on the right side that is slightly thicker than the recess that's been created by the subframe wear to the main frame and closes the left side gap then pull the subframe over and bolt it up. Then you might try laying it on the right side and giving a few good foot presses around the left side seat bolt area and see if the silencer lines up a little better.



The damage is done to the frame and even with a new subframe it's still not going to want to bolt up correctly without a shim on the right side frame mount anyway.
12/2/2020 8:17am
The subframe does not look bend on the photos. The frame part is smaller than stock.

With the polisport restyle kit it will rub your exhaust. You need to cut a little more away.
joeschmo
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8/14/2019
Location
Monroe, NC US
12/3/2020 9:26am
Thank you to everyone who chimed in with their thoughts and photos. I ended up putting back in the washers that the previous owner was using on the left side of the frame to even that out and was able to shift the airbox a bit left so that I got a little more clearance on the silencer.

Its not perfect but I at least understand why its like that now. I will pick up a solid washer of the correct size to replace the stack of washer currently used and just ride it like it is as dishing out $700-$800 for a new frame and subframe is not worth it at this point.




JB500
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Granger, IN US
12/5/2020 8:09pm
joeschmo wrote:
I am wondering if the previous owner could have used a '02-'04 subframe instead of '05+ to match the frame since the '02-'04 subframe was still...
I am wondering if the previous owner could have used a '02-'04 subframe instead of '05+ to match the frame since the '02-'04 subframe was still aluminum and from looking at a few online photos, they were very similar and could explain the gap at the top frame mount bolt.

Anyone familiar with the differences in the '02-'04 and '05+ subframes?
This is interesting. I have both an 03 and just picked up an 06 yesterday for my next project. I may measure these two at that top mount to see if it’s any different. If nothing else, you have me curious now. I know these models share silencers from 02-21, as well as the plastic interchangeably, so interesting to look into a possible difference.

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