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I've only put 150 miles on my 450k1 since i got it running and for the last two rides I've been unable to shift down into first, or find neutral while I'm on the road.

I can shift smoothly up and down (as far as second) and back up and back in the shed I can roll the wheel slowly and find first.

So before I start messing around, any thought as to where I might look first?
I can't imagine it's the shift forks, but what do I know
First gear on the counter shaft?
shift drum stopper, neutral stopper drum? If that's as far as I have to go into the engine i'd be very happy.

Thanks,
Adam
 

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I think I would look at the shift drum first. Look at the pins on the outside of the shift drum where the shift shaft pushs/pulls to move the drum. There is a phillips screw that holds the outside assembly in place (you'll have to first remove the clutch) and you can pull that off to examine the pins. One of the pins might be bent and not allow the shift shaft to pull/push it far enough. Or, one of them might even be broken.

From what I've seen, the rollers are probably loose but I don't know if that would keep it from actually shifting into first.
 

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perhaps your clutch is not fully disengaging?? could be keeping it out of nuetral and first, and explains why it shifts with the engine off..
 

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Like Mike says, you have to pull off the clutch and examine the end of the shift drum, that's normally where the problem is.
Or else the shift shaft itself, which can get bent - either anywhere along the lengthy shaft that runs from the shift lever to the other side of the engine, or the engaging "teeth" on the articulated arm.

However, be advised that there was a known shift fork/tranny gear problem with early 5-speeds (most common in K1-K3) that required replacement of a couple of countershaft gears and a shift fork - normal symptoms for that were difficulty shifting into/out of 2'nd gear, and jumping out of 2'nd gear. The probelm was essentially corrected by K5, and only appears rarely after that point.

Sounds like your problem may be on the end of the shift drum, though. Study the fiche or the manual drawing to see how it all goes together.

Unfortunately, the vast majority of 450 drums have that phillips screw "staked", and can be really difficult to remove. Avoid using a manual impact on it, as it's possible to deform the crankcases, or even break them - generally you have to remove the drum entirely and put it in a vice, which means split the cases. Normally it's not required to remove it at all.
The following photo shows a staked screw head....




The photo below shows the area in which the detent roller works, and can get really worn in there......



In the photo below, the pencil indicates the detent roller "pin", which can get all worn and loose.
Combine worn areas in the previous photo with a worn out roller pin, and you'll have problems shifting.
More typically, it's just the detent roller itself that causes problems.



The articulated end of the shift shaft engages the "pins" which insert into the end of the drum. They can usually be pulled out easily once you have the phillips screw and the little plate it holds on removed. Less frequently, they can get bunged up, but that's unusual unless you've really been trying to force it into gear - usually you'll mess up the shift shaft itself before that happens.

The neutral detent roller is a non-issue for the most part, it has a very strong spring, and is not critical. It "snaps" into the "notch" indicated in the photo below.


If all that stuff looks up to snuff, then you may have to get into the tranny/shift forks themselves........
 
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