[russ Jolly]

im not an expert on this by far but unless you missed some thing while changing the gears it might not be mechanical. Could it have something to do with your ignition at such high rpm?

[Christian Hubbell]

I just went through this with my kart.  I was getting a false neutral in 5th gear and the motor would zing and not put down power.  There are two different main shafts for the different years of a cr125, I thought I had the wrong one but this wasn’t the case.  If you search this site for “5th” and the old ekarting news forum you can find the part numbers.  Take a closer look at your gears again, I thought mine looked pretty good but they were indeed rounded on the dogs.  It was expensive to fix but no issues with the new pieces installed.  Personally, I think there is too much gear play on the secondary shaft  and thought about adding a shim to help hold it in gear but decided against that.  Check that there is a lot of space for the shift rod next to your  seat too, I saw marks on my seat and it was flexing in fast lefts and pushing on the shift rod while on power (bad).

[Donnie Leonard]

Christian you are right on the money with the rounded dogs.  I called Mike over at shark shifter and he explained it all to me and you pretty much echoed what he told me.  My shifter rod has no play in it and is super tie and doesn’t flex in either direction.  With the case separated I looked at the spacing in the gears and it all seems pretty good nothing to excessive.  I did take a closer look at 5th and the other cluster and it looks like I need to replace some gears.  When I was talking to Mike I had him send me the parts needed to correct this as he had them in stock and could ship out that same day.  I should have the parts Thursday and will compare them once its all apart.

 

I think to help reduce gear wear I am going to send out all gear box internals to have the REM treated by Taylor Race Engineering (isotropic finishing).

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