HajiWasAPunk

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Aug 5, 2005
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A beginner to C rider on new bike that's not a year old with the transmission oil changed every 2-4 hours of riding now has 2 broken teeth and needs the case split to fix all of this. Anyone know if there's anything that could be done to have prevented this or is this just the nautre of MX? Sprockets chains, tires, top ends I can live with but this is a major pain in the arse.
 

VintageDirt

Baked Spud
LIFETIME SPONSOR
Jan 1, 2001
3,043
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I figure my Maico 490 already had a week transmission. Then there was this double that I wasn't even close to clearing, and landing with the throttle closed probably caused the problem. It's been sitting in the garage, broken, for a whole year.
 

Masterphil

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Aug 3, 2004
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On your CRF?!?

If you are talking about your CRF, there is no f'n way you should have been able to break 2 teeth off since you got it. There is no way a less than one year old bike already wore out tranny parts. Sounds like a manufacturers defect to me. To answer your question. This is not the nature of MX. According to some, I beat my gearbox pretty good and have never had a single shifting problem.
 

HajiWasAPunk

Member
Aug 5, 2005
807
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Masterphil said:
On your CRF?!?

If you are talking about your CRF, there is no f'n way you should have been able to break 2 teeth off since you got it. There is no way a less than one year old bike already wore out tranny parts. Sounds like a manufacturers defect to me. To answer your question. This is not the nature of MX. According to some, I beat my gearbox pretty good and have never had a single shifting problem.

Sorry, this is on my son's CR85. But yeah he got it last November and started racing in January in the beginner class, just moved to C a month or so ago. It doesn't seem right to me either? He is power shifting (w/o the clutch) but isn't everybody in MX?! Crap, this is more than I wanted to tackle myself and the shop is talking 10-14 days to fix, :(

I'd love to find there was something I/we're doing wrong? Maybe, hopefully, this was a freak thing
 

Masterphil

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Aug 3, 2004
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Have you already taken it to the shop? Splitting the cases really isin't that difficult of a job as long as you have a manual, basic tools, a torque wrench, a flywheel puller, and a clutch holder or impact gun. Doing what you need done yourself will save you a lot of money. I'd pull the motor, tear it down and order whatever parts you need. You could have it ready by next weekend, as long as you can get your parts that fast.

A little OT, but when you say powershifting, do you mean:
1) Keep it pinned (no not touch the clutch) and shift while still on the throttle.
2) Let off the throttle only long enough to shift, then back on again.
3) Keep it pinned, tap the clutch and shift at the same time, still on the throttle. (This is what I do 100% of the time when track riding, otherwise I do #2)
 

HajiWasAPunk

Member
Aug 5, 2005
807
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Masterphil said:
A little OT, but when you say powershifting, do you mean:
1) Keep it pinned (no not touch the clutch) and shift while still on the throttle.
2) Let off the throttle only long enough to shift, then back on again.
3) Keep it pinned, tap the clutch and shift at the same time, still on the throttle. (This is what I do 100% of the time when track riding, otherwise I do #2)

We always do number 1. I swear I thought that's what everyone in MX was doing?
 

Masterphil

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Aug 3, 2004
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My bike doesn't like shifting like that(I have to push REALLY hard on the shifter), so I just keep it pinned and tap the clutch. It makes sure the bike stays on the pipe, too.
 

j32

Uhhh...
Jun 8, 2006
202
0
yea thats what i ment
any transmission will have problems if you keep that up -old -or new!!!!!!!!!
imagine the force on each tooth from it
and if not break it will bend the hell out of stuff


sorry i said "old kx" thats because i ride different ??i was 17 :nener: ,and had no brakes,had to slow down some how lol
-just a kid riding a big bore :cool:
 

HajiWasAPunk

Member
Aug 5, 2005
807
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Masterphil said:
My bike doesn't like shifting like that(I have to push REALLY hard on the shifter), so I just keep it pinned and tap the clutch. It makes sure the bike stays on the pipe, too.

My bike doesn't seem to fight shifting this way at all, but I've wondered what the potential damage is? I just don't understand well enough what's going on with the transmission and clutch. I had a guy at a shop tell me that at the right RPMs you don't have to shift a bike or car for that matter and I've never imagined doing this in a car?
 

darringer

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Dec 2, 2001
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Shifting under extreme load (pinned) without either a quick clutch pull or momentarily letting off the throttle is very hard on the transmission. Over time, the gear dogs round off a bit, and the gears don't fully engage. The end result is teeth break. Regardless of engine rpm, when shifting through the gears, the transmission main shaft and countershaft are spinning at different speeds, and without pulling in the clutch and/or letting off of the throttle to cushion the impact, there is a violent shock between the gears as they change speed.

A good example of this was when I was a kid racing my '74 cr125, I would shift as you described above. The bike would shift great, even under full throttle. Needless to say, until i changed my shifting technique, I got very good at splitting the cases and changing gears.
 

j32

Uhhh...
Jun 8, 2006
202
0
i have shifted cars that way as well ,never "on the throttle though" it wouldnt engage
-in side the tranny ? well spin the gears and try to engage them and youll see
it is verry hard on them
 

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