YZ85 Big Wheel Conversion Question

JR157
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27
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5/26/2021
Location
Camak, GA, USA
Edited Date/Time 6/15/2026 6:27pm

Anyone convert their YZ85 to a big wheel?

My son has outgrown his YZ85 with 17"/14" wheels. He's not really riding the wheels off the 85cc yet and I think he needs a lot more development before bumping him to a 125cc even though he's tall enough to ride one. I'm considering delaying the jump to the bigger bike and having him stay on the 85 but bump up the wheel size to what the YZ85LW version comes with, 19"/16" wheels.

I thought that was a straight forward swap but apparently Yamaha puts a different swingarm on the LW version in addition to just the wheels. I've read there can be clearance issues if you put the larger wheel on the existing swingarm so just curious to know if people have done this successfully and what the potential pitfalls are before dropping $500 on a wheel set.

I'd appreciate any advice. Thanks in advance

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El Capitan
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6/16/2026 7:45am Edited Date/Time 6/16/2026 7:53am

Not an answer to your question, but perhaps let him try a buddy’s 125 and see how he feels. Some kids do better once they move up. Sounds counter-intuitive, but I’ve seen it many times. Enjoy racing with your son—great memories being made! 

2
JMCR250
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Chesterfield, MO, USA
6/16/2026 2:56pm

I was in the same pickle with my son.  Getting too big for his regular 85, which he was getting better on, but still had not mastered, and needing a little more skill before going to the 125.  Had I readily been able to find a big-wheel kit for his CR85, I would have gone that way.  Since I could not, he was just a little oversized for an additional season on the 85 before he moved to the 125 the next year.  It confirmed my impression that a 125 is the perfect "move-up" bike for an improving and right-sized (but growing rapidly still) 85 rider!

1
MOTO557556
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Burtrum, MN, USA
6/16/2026 3:58pm

El Capitan is correct. Move to the 125 and do not look back.

The Shop

JR157
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Joined
5/26/2021
Location
Camak, GA, USA
6/16/2026 6:35pm

think I'm leaning more in that direction, (jump to the 125).  Just not a great time financially but it pretty much never is. I appreciate the advice

ikeG
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Location
Home, PA, USA
6/25/2026 2:43pm

I've noticed that yz85 big wheels utilize a linkage system whereas small wheel yz85s use no linkage.  Theres a chance that the bikes I've seen were different generations, im not sure.  Hard to imagine the same shock works both with linkage and no linkage

JR157
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5/26/2021
Location
Camak, GA, USA
6/26/2026 6:55am

24 YZ85 does use linkage

2
EAmato88
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Location
Egg Harbor City, NJ, USA
7/9/2026 4:58am
ikeG wrote:
I've noticed that yz85 big wheels utilize a linkage system whereas small wheel yz85s use no linkage.  Theres a chance that the bikes I've seen were...

I've noticed that yz85 big wheels utilize a linkage system whereas small wheel yz85s use no linkage.  Theres a chance that the bikes I've seen were different generations, im not sure.  Hard to imagine the same shock works both with linkage and no linkage

ALL yz85s use a linkage, since the beginning of the YZ85 they had a linkage.

1
EAmato88
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Location
Egg Harbor City, NJ, USA
7/9/2026 5:01am
JR157 wrote:
Anyone convert their YZ85 to a big wheel?My son has outgrown his YZ85 with 17"/14" wheels. He's not really riding the wheels off the 85cc yet...

Anyone convert their YZ85 to a big wheel?

My son has outgrown his YZ85 with 17"/14" wheels. He's not really riding the wheels off the 85cc yet and I think he needs a lot more development before bumping him to a 125cc even though he's tall enough to ride one. I'm considering delaying the jump to the bigger bike and having him stay on the 85 but bump up the wheel size to what the YZ85LW version comes with, 19"/16" wheels.

I thought that was a straight forward swap but apparently Yamaha puts a different swingarm on the LW version in addition to just the wheels. I've read there can be clearance issues if you put the larger wheel on the existing swingarm so just curious to know if people have done this successfully and what the potential pitfalls are before dropping $500 on a wheel set.

I'd appreciate any advice. Thanks in advance

I have extensive background in this area. You CAN use the short swingarm with big wheels, but its not the best route to go. Youll be force to run the chain adjustment in the extreme rearward position to clear the mud flap, and youre not doing geometry any favors. That being said, the big wheels DO NOT solve your problem. All youll be doing is giving the rider 1 extra inch of seat height and ground clearance, the rest of the bike is too small for him (IE the rider triangle). Its time for a 125, youll be doing him a favor.

2
JR157
Posts
27
Joined
5/26/2021
Location
Camak, GA, USA
7/18/2026 3:32pm
JR157 wrote:
Anyone convert their YZ85 to a big wheel?My son has outgrown his YZ85 with 17"/14" wheels. He's not really riding the wheels off the 85cc yet...

Anyone convert their YZ85 to a big wheel?

My son has outgrown his YZ85 with 17"/14" wheels. He's not really riding the wheels off the 85cc yet and I think he needs a lot more development before bumping him to a 125cc even though he's tall enough to ride one. I'm considering delaying the jump to the bigger bike and having him stay on the 85 but bump up the wheel size to what the YZ85LW version comes with, 19"/16" wheels.

I thought that was a straight forward swap but apparently Yamaha puts a different swingarm on the LW version in addition to just the wheels. I've read there can be clearance issues if you put the larger wheel on the existing swingarm so just curious to know if people have done this successfully and what the potential pitfalls are before dropping $500 on a wheel set.

I'd appreciate any advice. Thanks in advance

EAmato88 wrote:
I have extensive background in this area. You CAN use the short swingarm with big wheels, but its not the best route to go. Youll be...

I have extensive background in this area. You CAN use the short swingarm with big wheels, but its not the best route to go. Youll be force to run the chain adjustment in the extreme rearward position to clear the mud flap, and youre not doing geometry any favors. That being said, the big wheels DO NOT solve your problem. All youll be doing is giving the rider 1 extra inch of seat height and ground clearance, the rest of the bike is too small for him (IE the rider triangle). Its time for a 125, youll be doing him a favor.

Thank you for the great feedback. I appreciate that. Decided to hold off a few months and put him on a 125

2

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