Hey all, My FZR's been running dodgy lately and I've determined the problem is due to low compression from leaking worn valves (clearances are correct). I've let the local Yamaha dealer take a look at it and they reckon they don't and no one around here will rebuild it. So my question is has anyone ever had there head / valves machined? If so where did you get it done and how much did it end up costing you? At the moment it's looking like it may be easier to just get another head or even an entire engine from a wrecker given there is some wear starting to show on the pistons & cylinders as well.
This will be quite a bit of money for such an old bike. If you're willing to fork it out that is. Otherwise, you can do it yourself <!-- s --><img src="{SMILIES_PATH}/icon_smile.gif" alt="" title="Smile" /><!-- s -->
Get a quote from an automotive engine reconditioners workshop like repco or who-ever is in your area. They do bike heads just the same as a car heads. At least then you can consider your options, (do i get a good reco head, or a suspect 2nd hand one)..
Only problem I see with taking it to a car workshop is sourcing any parts that would be needed. You would have to do all the leg work beforehand. As for anyone that thinks a backyard engine reco is a job for a learner, think again.
Are you on drugs?? I don't think I mentioned backyard boys or learners... I could be wrong, but I would assume most bike shops would sent the heads out to get done in a specialist workshop with all the correct gear. If it only needed valves ground, reseating and then the tops levelled off there would be no problem. If you needed guides thats a different story, but they still may be able to help. However the cost would have to be balanced against against the cost of a second hand head. Ring around bike shops and the other places and get an estimate for a valve job. Mention 16 valves.
No, no drugs for me. I was making the comments in reply to Katatonics "Otherwise, you can do it yourself". I didn’t want the majority of people / first timers having the idea that it is a reasonable option. I do remember people on this forum being told by certain bike shops that they wouldn’t do top end rebuilds for the FZR, why would anywhere else be different. Not to mention they would probably have never seen a head with such microscopic valves.
I've taken my head to places asking if they can do it (automotive engineers) and all of them (4 or so) said they didn't have small enough machining bits to do it. The last guy I tried said he had a mate who had the smaller bits he could borrow, but ended up not so true. But he did say my head was in great condition and if I just got some lapping compound I could rub down the seats and valves and she'd be almost 100% (was a bit over 80% based on vaccuum readings, he even showed me). I did try a dyno place on Stud Rd Wantirna South (can't remember the name) who run the national Suzuki Superbike Team. Unfortunately they were a little busy to play around with my head <!-- s --><img src="{SMILIES_PATH}/icon_sad.gif" alt="" title="Sad" /><!-- s --> No doubt they would have done a good job though <!-- s:rofl: --><img src="{SMILIES_PATH}/icon_razz.gif" alt=":rofl:" title="Rofl" /><!-- s:rofl: --> They did give me a quote but I can't recall what it was. <!-- s --><img src="{SMILIES_PATH}/icon_redface.gif" alt="" title="Embarassed" /><!-- s -->
Thanks for the responses guys. I've had the same problem as Bizz where all the engineering places I've tried are not able to do the job due to the valves being so small. The idea of getting some lapping compound and giving it a try myself seems to be the way to go at the moment. If that's not successful I guess I'll go back to hunting down another head or even complete engine. Something I've noticed when stripping down my head is it seems none of the valves have stem seals fitted. These engines are meant to have stem seals right? Does anyone know exactly how important they are?
Mine didn't seem to have stem seals either, apparently they were on there attached to the guides. Or maybe the guides themselves form a good seal with the stems? I'd say this was possible based on the tolerance of that gap and the viscosity of the oil. But I might be wrong. If you can get or have a vaccum gauge you can measure how good the valves are seating, you just have to make some sort of rubber seal between the port and guage.
