Hi all, 

Just picked up another DT100 and I came across a weird thing that I've never come across before...

I will put the bike into neutral...kick it over..and as I am kicking it over it pops into gear. 

The only thing I can think of is I'm putting it into a false neutral and when the internals start spinning it pops back into gear...I seem to have found proper neutral and it no longer does it, but it's still concerning and I wanted to hear your guys' thoughts.

Thank you!

Long time no see!

Yes, you might have had it in a false neutral... like between 2nd and 3rd instead of 1st and 2nd.

There's also a detent ball and spring behind the neutral switch... not as likely to be missing as on the bigger bikes but I have seen it.

Heya! Good to be back. Life has a funny way of getting really busy all of a sudden. Still into these bikes though, don't think I'll ever not be Been doing some trials events on my TY175, finally getting around to mating a modern DT175K/L top end onto my '81 cases, and just today rekindled my passion to get my DT100 finally up and running again. My original DT100 frame is bent out of shape in the cradle area by the previous owner...I had purchased an incomplete RT100 to do a cradle swap but it was challenging to find someone to help me do that (welding working and such). This new DT100 pretty much solves that issue, and now no frames need to get chopped up!

Thank you for the insight! I will definitely check behind the neutral switch because I know for a fact the previous owner had that off at some point..

Welp, this is an unpleasant find, and somewhat worrying. The side to side play seems excessive but not abnormal for bikes that have been abused for 40+ years...but what about the in and out play? What could be the cause of it?

youtube.com/shorts/tPuL3iuLghM?feature=share

Don't panic. It's typical of that useless setup that yamaha used on a lot of small models from "74 on. No oil in there & should be grease. Think if i had one i'd fit a grease nipple somewhere in the cover. Shaft is short & goes to a linkage to the shaft proper that goes through to the other-side. There's a seal in the case in there where the proper shaft protrudes into small case. probably a washer has been left out or maybe one each end but no harm done & they flog out the case terribly. Seal in the little case two but with shaft up & down it'll be doing little if anything.

That looks exactly like the RT100 setup.

You got a slight bit of wear in the outer chamber casing and are probably missing some shims from the outer shaft.

If you can get a new case and shim the outer shift lever, that will cure it.  Easy fix.  Don't lose the top hat from the pivot though.

I used to fill the entire chamber with grease once I swapped the outer casing.

It does show a washer #6 & #6. Others have repaired & bushed the outer case.
I'm not sure about the inner one but maybe could build the shaft up & bore the case--which is the main crankcase in there.
None of that will make it operate any better & just feel less sloppy.
TYFAN from UK on here will be along with a cure as TY175 have the same setup.
www.partzilla.com/catalog/yamaha/motorcy...974/dt100a/shifter-2

Outer cover is still available at CMSNL. Part number is 4371541901

38 Euros.

www.cmsnl.com/yamaha-dt100-1975-usa_mode...rshifter_4371541901/

Dang, thanks for the reassurance and the quick replies guys! I'll probably get a new cover on order and in the meantime inspect to make sure the assembly has all the required bits and pieces. My 5am brain did not realize that piece wasn't part of the main half-case.

Blimey 38 Euros sounds pretty tough, but i can't find a cheaper one with my limited search ability. Think we're limited to what we can see here.
One here a bit cheaper & if you go to the parts pic showing the rest of it i think i saw an Oring that mist fit in a groove around the edge rather than gasket--if its available--plus the two washer if available.
www.partzilla.com/product/yamaha/437-154...0f9449e1c123211db292
As for 5am, the only 5am i have is if the cat starts clawing the bed [feed me] & if no response she jumps on me lol.
Then again we did 5am starts to assemble new Yamaha farm bikes in the late "60's with Landscout YG1T's. They were going out the door faster than we could assemble them. Workshop was too busy to assemble them 8am to 5pm so was a bit of a pay bonus incentive to do early starts when needed. We all got good at un-crating & assembling plus pre-delivery check ready to go out the door.
photos.app.goo.gl/ojvbEychcDFY8vg4A