Gearing question?

[R7]

Trying to keep a swap from dirt to SM simple and quick.
I have an 08 YZ450 that I use for some trail riding around the house and trackdays. When I get home from a trackday, I usually put the knobbies back on within a week or so.
The stock offroad gearing is 13/48 and I used a 14/42 for the SM stuff. 14/42 seemed fine to me at NHMS last fall and was OK at VIR in the spring. For offroad, I switched out the front to a 12 which helped a lot in the woods.
I'm swapping the bike now back to SM for the trackday next week and wanted to keep the 12 on the front, and found a new 38 rear from a KTM I had kicking around. Doing some simple math, the ratio seems very close if I use the 12/38 vs the 14/42, the 12/38 being just a bit lower. I guess my question is, is the smaller countershaft adding to much stress to the moving parts in the driveline? I remember reading in the past that a smaller countershaft adds stress to the driveline? I'm not to worried about it in the dirt because the tire is always spinning, there isn't much spinning going on at a trackday, at least not at my level of riding
Thoughts?

Thanks

[beet]

Beet thinks you will be happy. ratio is ratio as long as your set-ups good........ Like in the TL case you can only go so small front cause of the clearance chain swingarm

[KB]

Tully Most guys are running a 15 39 or 40 on those bikes if I recall correctly.

Not sure if this is of any help to you.

When I switch over the CRF back to Ice racing trim I run the stock dirtbike gearing. I have a ICE chain and a Track chain. Then it makes no matter what gearing you run as long as you have a chain for both.

You comng up for the classic???

KB

[R7]

I ran something in that area on my 04 YZ that was a 4spd, the 08 is a 5spd.
I have a 12,13,14,15, and 16, I guess I can just bring them all with me and adjust accordingly.

I also have 2 chains, one for dirt and one for SM. Just trying to avoid the front sprocket change.

I don't think I'll be up for the classic, but you never know

Tully Most guys are running a 15 39 or 40 on those bikes if I recall correctly.

Not sure if this is of any help to you.

When I switch over the CRF back to Ice racing trim I run the stock dirtbike gearing. I have a ICE chain and a Track chain. Then it makes no matter what gearing you run as long as you have a chain for both.

You comng up for the classic???

KB

[KB]

I ran something in that area on my 04 YZ that was a 4spd, the 08 is a 5spd.
I have a 12,13,14,15, and 16, I guess I can just bring them all with me and adjust accordingly.

I also have 2 chains, one for dirt and one for SM. Just trying to avoid the front sprocket change.

I don't think I'll be up for the classic, but you never know

You can crash in the loft of the RV.

[seth399]

hmm, not sure it would work out at Loudon but worth a shot if you can just bring the other sprockets. My 5speed crf I run 15/40.

The part about smaller countershaft is true with having more stress on the chain. I have no experience with running a 12t front but you will see more chain stretch running a 12t vs 14 or 15t front sprocket in general.

[R7]

I took the bike for a couple laps "around the block" today with the 12/38. It seems a bit low and there was a minor front wheel loft problem in all but 5th gear. I'm going to change the front to a 13 tomorrow and do another couple laps. If the 13 seems ok, I'll just order a larger rear for the offroad stuff so I still won't have to swap the front.
I'm also going to mess around with the jetting a bit tomorrow, seems to be running a bit lean