Thanks to a quick shipment of spare parts from davipu, my cylinder head with the broken exhaust valve is now back together and ready to go. I lapped in both the existing intake valve and the new slightly used exhaust valve to make sure I had good seal all around on both of them. Put in a couple of slightly smaller buckets and all four buckets now have a nice fit. Can turn them with a finger tip as I always could on the 97 GS with 80k on it.
Soon as the new gaskets arrive I'll have engine back together and running again.
Don't think either myself or the first owner of the bike did anything to cause this failure. Suzuki screwed up on this one. Appearantly they must select fit these buckets at assembly and got the one exhaust valve bucket too tight and it held open the valve slightly till it warmed up a bit. Got away with it in warmer weather, but starting it on a very cold day caused it to hang open and crash. All the bucket bores in the head are in good shape and all about equal in size, just too big a bucket in the one hole.
I have never raelly noticed any tight buckets before. I have rebuilt several heads with parts from others and never had any problems with the buckets. This will be something that I keep in mind. Glad you got it fixed.
They have different sized buckets ??? well that's news to me ... anyway I have noticed that you can pull buckets out almost 3/4 of the way out easy and then they sorta get stuck ... and need serious pulling after that ... I thought that was cos they didn't want buckets flying out in case of valve float ... but might have been mistaken ...
Cool.
Srinath.
Quote from: seshadri_srinathThey have different sized buckets ??? well that's news to me ... anyway I have noticed that you can pull buckets out almost 3/4 of the way out easy and then they sorta get stuck ... and need serious pulling after that ... I thought that was cos they didn't want buckets flying out in case of valve float ... but might have been mistaken ...
Cool.
Srinath.
There's only one bucket size to order, but they have a small mfg tolerance range and the bore also has a small tolerance range and if they want to get a nice close fit w/o holding the parts to a expensive tight tolerance range, they sometimes use a select fit at assembly process. The put the bigger ones in the bigger holes and the smaller ones in the smaller holes.
If I had just ordered a new bucket, it might have been just as tight as the one I took out or it might have been a nice fit. I was lucky to have a set of four used ones to choose the two smallest ones from and get a good fit all around. :thumb:
Just like brake caliper pistons, they want to chicken and bind putting them in unless you are careful until you get a fair amount of engagement in the bore. Can be same coming out.
Yup I get it ... the buckets spin when motor is running ... so they wear to each other ... and even more specifically they wear to the part of the other piece that is right by them ... OK ... so if the bore has a small bump in it, it will wear a groove in the bucket ... making the thing hard to remove ...
Cool.
Srinath.