The front sprocket and chain is a vital part of the system and of course turns at very high RPMs especially at speed .... its external and under load and its very close to your foot ...... now unless you ( meaning any member) have some solution or advice that equates to the sprocket and nut etc being installed as it came out of the factory, or with very little modification, then keep the backyard fixes to your own backyard The original poster here might have the knowledge and experience to differentiate between a safe fix and a dodgy one, but lets remember many people , including novice bike owners, may read this and use any advice given.
On a side note, I’m going to replace the chain aswel, does anyone know how many links? I counted 132 on mine. Just to confirm, I will need to buy a 132link 428 o ring chain?
428 chains come with 136 links, 520's 530's etc with 120. Generally you shorten as required, just don't cut them too short. And get a rivet link, clip links are rubbish
Most place's just stock the 136 link chain's as they can be cut down to fit most bike's, you can get them in 92, 104, 108, 112, 120 130, 132, 134, 136 links and a lot more depending on brand etc. DID 428 O'Ring 136L Chain $59 inc delivery https://www.ebay.com.au/itm/DID-Hea...ss/382548293693?hash=item5911a7b83d:rk:1:pf:0
That 15mm dia on the damaged thread is equal to 11/16" UNF which would be an easier die and nut to get.
Update. My new chain and rear sprocket have arrived, just waiting for my new front sprocket from litetek to turn up. Does anyone know the part number or where I can buy a new gearbox output shaft seal?? And is it difficult to replace?? Is it just a matter of digging the old one out and sliding the new one in?
The numbers are on the seal. Go to a bearing shop and ask for those sizes. Pull the bush from around the shaft and prize the seal out (clean area first) then using a large socket or pipe tap new seal in.
Thanks murdo, I’ll clean all the dirt n chain grease off the seal and see if it’s got some numbers on it
The New front sprocket from litetek turned up yesty arvo. Have I got it on the right way, the large flat side of the sprocket goes up against the bush and then the nut on the stepped side like in the picture?
Also I managed to order a new genuine gearbox output shaft seal from Yamaha and it was only $23!! However will take roughly 4 weeks to get here from japan I’m having abit of trouble removing the bush from the shaft so I can get the seal out, seems to be on there pretty firm, anyone else removed one before and had trouble?
The sprocket is on the wrong way around. It need's the raised flange on the back so it line's up with the sprocket. Are you going to weld the nut on again ?
Thanks, I’ll turn it around the right way. Yeah, I’m going to put a new output shaft seal in it while it’s apart and then I’m going to tig the sprocket to the shaft (a few tacks) and then tack the nut to the sprocket and then weld the nut to the shaft on the end. Definitely not my favourite outcome but it will get the bike back on the road and will be safe to ride for a few more years atleast.
The old sprocket was well worn out and it was welded. It looks like it had been on there a long while, even though it had the crappiest weld holding it on.
The drive axle is $299 new from Yamaha, but most place's list it as unavailable http://www.firstclassmotorcycles.com.au/partFinder/fiche/yamaha/1998/fzx25-zeal/transmission The output shaft seal is a 30 x 50 x6, you could try asking for one at a good bearing shop. The collar that sit's behind the sprocket look's like it's a slip on fit, may have a little rust holding it to the shaft?
Negative, I am not replacing the output shaft. My brain tells be I should but my wallet cannot justify it unfortunately.