..ok so i believe my primary gear  back of clutch basket has sheared Pn 525-16150-00-00i think this is due to an issue with timing and kick back on kick starting i think the bike is drifting out of time possible wear on crank shaft/flywheel
i had an issue with the idle gear shearing and rebuilt all was running really well until latest kick back problems
anyways it looks like the primary drive gear is part of the clutch basket assy
not having much luck in finding the part here in UK
will get it apart shortly to confirm this but initial thoughs are this is what has happened
anyone have any leads on this part or possible advice on a x-over part from a TY, different Dt years that would fit to broaden the serch pls?
thanks in adv

 

The primary drive gear is riveted to the clutch basket . I've never seen those rivets fail .
Rivets and rubber bushings are very likely available from Yambits .
Until you get it out you won't know exactly what parts are faulty .

If it's confirmed by "559" VIN to be a US 1976 "C" model, the clutch basket is "one year only" DT175 part in the USA. 

(The small primary kick start gear is part of the basket for the first time in 1976)

There is some evidence from posts here that possibly the "1G0" and almost certainly the (US at least) TY175 baskets are the same.  Nobody ever came back and confirmed that I remember and I'm in the US so I've never seen a 1G0 model and I don't know if overseas TY175's were the same as the US model. 

This link shows other potential US model matches.  www.partzilla.com/product/yamaha/525-16150-00-00

Shouldn't 'drift out of time' well not over advancing at least.
If points fiber heal wears over time the points get closer so retarding the timing.
But if its damaged the flywheel crank key then that another story & npossibility.
If it totaly sheared the key off then its unlikely to run if it's moved considerably. But could kick back very hard, yes!!.
One year had an advance mechanism on the points cam but if the weight spring broke i guess the worst is it'd stay on advance which wouldn't make it any worse than every other year with a fixed cam--fixed advance & 1.8 btdc timing.

thanks all
something going on with the timing as i time it corrcectly (with the cam advance open) and it runs great then will start to miss, next kick loads of smoke then runs fine again then kick back
can lap the crank and flywheel maybe check the advance return spring , its got new points rewired stator plate,good spark, idles well and plenty of grunt when running right, starts first second kick and idles well, will get it apart soon and updagte with some pics but intitial investigations look like the drive gear has completely failed and as its attached to the clutch basket looks like i need a new basket

If its not damaging or shearing off the key i wouldn't bother lapping it, not necessary.
Seems a bugger if you need a new basket when only the little gear is damaged.
Although non replaceable, "in theory", does the gear looked pressed on & driving into the clutch by a couple of dogs.
I've had those off & on, on earlier 175's, pressed off & on.
Had them off to grind a whisker off the dogs so it went on about 10 thou further.
Reason was to give the center spacer a bit of end clearance as the center hub was locking up when nut tightened.
Wasn't the best plan as tried to pickup on the bush extension pressing the gear back on but ended up with the right result.
Next one i just ground the flat of the gear end while in place on the basket to give clearance.
Pretty rough but think it was on an AG175 farm bike & did the job.
The old Ag's we sold a lot of so was always fixing them as the farmers literally destroyed them.

Just put the part number on google & this came up. Says DT100 but maybe the same--well, if part number is then it must be?

eBay item number:125958414730

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ok so its sheared the primary drive 
looks like it should be a replaceable part without the need to replace the basket but unsure if it is 
once i get it back together i will investigate the timing issue causing kick back
maybe lap the crank/stator 
check return spring on the advance cam
check points nipped up tight etc 
 

thats the badger!
the drive gear looks to be a replaceable part 
am based in UK so will have to check it ships to UK first 
thanks
JJ

The drive gear was never offered as a replaceable part for that basket.  Yamaha went to a smaller diameter transmission input shaft in 1976.

On the earlier models, 69 to 75, the kick gear was separate from the basket and just fit into the slots.  No common bushing through both.  I've wondered if an earlier gear could be grafted onto the 1976 basket?  You might have to press out the 1976 bushing and then press it back in...  and I seem to remember the kick gear was tack welded to the basket on the 1976 version