kshansen
XS400 Addict
- Messages
- 265
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Not my fault must have been previous owner, that's my story and I'm sticking to it. But then the last owner did get the bike from me a few years back! He gave it back when his father in-law gave him a 1982 XS400. That father in-law would be my brother who got the 1982 XS400 from me!
Anyhow back to the title of this thread. The 1978 XS400 has some very weak threads on the right cylinder, takes maybe five minutes of careful work to get the plug started straight and screwed in the full way. I'm sure with little work one could easily destroy what is left of the threads.
After spending a good amount of time online some of it watching very poorly done Youtube videos I made two decisions. First I won't be doing a video of my attempt to install a thread repair. Second I was going to go with one of the solid bushing type kits as opposed to the spring like Heil-i-Coil kits. I have had very good luck in some very demanding applications using the Heil-i-Coil kits, but in an application with frequent install and remove like a spark plug the solid bushing type just seems a better choice.
The kit I have decided on is the OEM Thread Kit Part Number 25647. One thing I liked about this kit is that it has a knurled area at the top thread area and once it is screwed into the head there is a supplied tool that is used to slightly expand this knurled section into the head to lock it in place. One thing I did not like is the kit comes with three different thread insert, basically short medium and long. The long one looks right for the Yamaha. They do sell extra inserts Part Number 25648 but again they come in packages of three different lengths, two each this time. This was not a major put off for me as I know I have at least a couple lawnmower or snowblower engines that will need an insert some day. The kit I got was $29.99 and the six extra inserts were $11.99 from AutoZone.
I'm planning on doing the job in the next day or so and will try to get some good still pictures and post them a link to them.
Anyhow back to the title of this thread. The 1978 XS400 has some very weak threads on the right cylinder, takes maybe five minutes of careful work to get the plug started straight and screwed in the full way. I'm sure with little work one could easily destroy what is left of the threads.
After spending a good amount of time online some of it watching very poorly done Youtube videos I made two decisions. First I won't be doing a video of my attempt to install a thread repair. Second I was going to go with one of the solid bushing type kits as opposed to the spring like Heil-i-Coil kits. I have had very good luck in some very demanding applications using the Heil-i-Coil kits, but in an application with frequent install and remove like a spark plug the solid bushing type just seems a better choice.
The kit I have decided on is the OEM Thread Kit Part Number 25647. One thing I liked about this kit is that it has a knurled area at the top thread area and once it is screwed into the head there is a supplied tool that is used to slightly expand this knurled section into the head to lock it in place. One thing I did not like is the kit comes with three different thread insert, basically short medium and long. The long one looks right for the Yamaha. They do sell extra inserts Part Number 25648 but again they come in packages of three different lengths, two each this time. This was not a major put off for me as I know I have at least a couple lawnmower or snowblower engines that will need an insert some day. The kit I got was $29.99 and the six extra inserts were $11.99 from AutoZone.
I'm planning on doing the job in the next day or so and will try to get some good still pictures and post them a link to them.
