Cyclinder/head work in Auckland

**LTPC** · 25th September 2015, 15:20

Does anyone know any reputable companies in Auckland who have experience with cutting valve seats and honing dirtbike cylinders? Would any old engineering shop familiar with cyclinder head work be fine or am I better to find a motorcycle specialist? I'm doing a top end on my CRF450r but so far google hasn't given me any good leads...

**Akzle** · 25th September 2015, 16:39

http://www.bindons.co.nz/itemdetails...3-J/56222.aspx

http://m.supercheapauto.co.nz/Produc...e-Lapper/12551

**husaberg** · 25th September 2015, 18:11

Originally Posted by LTPC

Does anyone know any reputable companies in Auckland who have experience with cutting valve seats and honing dirtbike cylinders? Would any old engineering shop familiar with cyclinder head work be fine or am I better to find a motorcycle specialist? I'm doing a top end on my CRF450r but so far google hasn't given me any good leads...

Trust me its the better way to go.
http://www.bigborethumpers.com/newheads.html

**spanner spinner** · 25th September 2015, 20:24

CRF,s need a special finish if you are using the standard valves. The seats need to be cut with a diamond face cutter, if cut with normal valve seat cutter expect your new valves to last 15-20 hours tops. This is talking from experience as I have done more crf heads than I care to remember. I have also seen the results of the local machine shop cutting the seats with the wrong tools. If who ever you get to cut the seats looks at you blankly when you say diamond face cutter go some where else.

**spanner spinner** · 25th September 2015, 20:31

forgot to add DO NOT USE VALVE SEAT CUTTING PASTE ON CRF HEADS!!!!!! munted valves follow very quickly. also the inlet valves can't be faced as the hardened surface on the titanium so thin that any material removed removes the hardening and valve failure follows. If the inlet valves show any wear or problems new is your only option and replace the valve collets as I have seen destroyed motors from people reusing them and the bike firing the collets off and dropping a valve, instant engine destruction.

**LTPC** · 25th September 2015, 23:17

Originally Posted by spanner spinner

forgot to add DO NOT USE VALVE SEAT CUTTING PASTE ON CRF HEADS!!!!!! munted valves follow very quickly. also the inlet valves can't be faced as the hardened surface on the titanium so thin that any material removed removes the hardening and valve failure follows. If the inlet valves show any wear or problems new is your only option and replace the valve collets as I have seen destroyed motors from people reusing them and the bike firing the collets off and dropping a valve, instant engine destruction.

I'm replacing all the valves, springs, collets and seals. I just want to make sure the seats are done right so I don't end up with problems 10-15hrs down the line and it sounds like I definitely need to find someone who has experience with crf heads!