Hi,
Thanks for the help fellas, much appreciated, I see what your saying about swinging on starter, but I've used the DT every week since last summer and have started it 99% of the time without incident, the one I bought from eBay, had a hard life I could tell that when I stuck it on, but as I hadn't much choice at the time, anyway after the lockdown ends Im going to see a lad I know about machining out the boss and welding a new spigot on, plus now Ill do my partzilla and eBay research. All part of the fun

cheers, stay safe

Don't forget the CMSNL website - it might show some European fitments for the part that you need (Partzilla only shows US).

For any part, after selecting "Yamaha", then "Motorcycle", type in the part number in the search box. They stock parts for some bikes that aren't on their model database (eg RD125DX).

Hi all,
i had the same problem, kickstart boss broke, while triyung to first start after restoration. Obviously this forged part has a construction failure, there should be a radius between the mounting shaft and the ring, but the Japanese made it a sharp edge. So all bosses will break soon- or later, the crack in the sharp edge will get bigger, Like 750kr1 wrote, only a small piece in the middle remains intact.
Good thing is, that the ´74 kick start assembly (boss and lever) fit on the 75-76 bikes, are much more solid. Negative: they don´t look not original.
So what to do? Welding is not an option, as welding doesnt go deep enough in structure and the welding itsself is a weak point again.
I decided for hard-soldering. For my lathe, i made a holder to screw the damaged boss-ring on, so i could turn a sack-hole into the ring exactly in the middle, where the broken Cylinder was sitting. 10mm deep, 16mm diameter, whats maximum not to bore through the teeth inside the ring. In the middle of the sack-hole a 3mm hole through the teeth, to let it breathe, while solderin.
Bought a 16mm 12.9 Screw on Ebay, the highest availble hardiness, From the shaft, i made a new cylinder, fitting 0,1mm gap into the sack-hole. Hard soldered into the hole with a silver solder with 420N/mm² stability.
After the soldering and shaft was cleaned up by sanding, i brought it to a chrome shop.
This is working now since 1000 Kilometers, i think it´s more solid than the OEM.
So don´t throw away your broken parts.

Find attached different levers. The left-one should be from a XT500 and the boss of our `75 DT´s fit, so i wonder if a kickstart boss of the XT500 would fit on the kickstart axle as well. In the middle is the lever of a ´74 model with bigger hole .
On the right is the origin ´75 lever.
Just a comparison...

75-76 DT400
75-76 DT250
75 MX250
75 MX400

That's all that show on the partzilla interchange table. They can be difficult to find.

Again, Yamaha uses parts on many models. They also suck at superseding parts in the lists. One main example is brake shoes. Many parts lists show the shoes as obsolete... but with a little detective work you'll often find they are still available and the same as a newer model.

Another problem is "finish"... or sometimes they just give it a new number for no apparent reason...

So here's the method I used to find if the kick boss might have fit other models. First, I looked up the part the kick boss spline has to fit... the kick shaft.



Note that I circled the 1976 YZ250... That caught my eye because the YZ250 is not listed in the list of bikes the 1975-76 DT250/400 kick boss fits... but with the same shaft, the splines would be the same and maybe the YZ250c kick boss would work?

Next step is to look up the other part the kick boss has to fit... the kick crank aka kick lever... I looked up the YZ250c...



What do you know? Shows it fits the YZ250 AND the 75-76 DT250/400!!! So why isn't the YZ250 shown on the DT250/400 kick boss list???

What you find there is the 583 part number.... and a list of dozens and dozens of bikes that kick boss fits!!! This is more like what I'd expect from Yamaha as they like to use common parts for many years and models...

And yes, the 75-76 DT250/400 is not on this list but again, that another flaw... superseded parts often get "missed"... it could be that the original boss was plated or painted and the new one has a different finish. I'm 99.99% certain it will fit... the only doubt comes from the same reasoning that led me on the hunt... sometimes there are errors in the lists. (Note the IT is shown too)




Here's the link to the dozens of models the 583 kick boss part fits... maybe you know someone with one of those bikes that you could check? If not, like I said, it's a fairly safe bet it will work. Maybe even a local shop or dealer will have one you could look at?

www.partzilla.com/product/yamaha/583-15621-00-00








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