2005 suzuki rmz450 smokes after installing valves

[doctordirt]

This is the 2nd motor where I've installed Kibblewhite exhaust valves and after about 5 hours of running they would burn oil through the exhaust guides. First motor was 05 rmz 250 and now the same problem with a 05 rmz450. Whats up with that?

 

[Rich Rohrich]

The obvious questions that come to mind are :

- If you used the original guides, how many hours of running time have they seen?
- Did you size the exhaust guides for the new valves?
- Did you verify the stem seal to retainer clearance at full lift including a margin for error in case the engine is over-revved?
- What stem to guide clearance did you set the new valves at?
- What method did you use to measure valve stem to guide ID clearance?
- Did you replace the stem seals when you changed valves?

One last thing, are you sure the oil burning is coming from the exhaust guides? The exhaust don't as a rule of thumb have much of an issue with oil leakage given the pressure differentials between the port and the crankcase. Intake valve seal leaks are far more common.

 

[doctordirt]

I replaced the valves due to hard starting because the valve face was cupped, fixed the hard start problem, but now sucks oil through the exhaust guides. Reason I used Kibblewhite valves was due to the cheaper cost, by about half. My machine shop guy thinks its due to steel vs. titanium causing a heat transfer problem. Yes I measured and used new seals. My machine shop fixed the problem on the rmz 250 , he knurled the exhaust guides, how this fixed that problem, I don't know.

 

[Ol'89r]

Reason I used Kibblewhite valves was due to the cheaper cost, by about half. My machine shop guy thinks its due to steel vs. titanium causing a heat transfer problem. Yes I measured and used new seals. My machine shop fixed the problem on the rmz 250 , he knurled the exhaust guides, how this fixed that problem, I don't know.

You need to find a new machine shop guy. Knurled guides may work for your grandads chebby but the tolerances on your RMZ are a whole lot closer than that. Find a good motorcycle machine shop or race shop that knows what they are doing. If your machine shop guy knurled your guides, he does not know what he is doing.

Also, if you used the stainless Kibblewhite valves, you should have also used the titanium spring kit like you are supposed to do. Without the spring kit, you are asking for trouble.

 

[doctordirt]

spring kit....ok, Thanks

 

[Ol'89r]

If you used the stainless valves, they are heavier than the ti valves. They require a stiffer spring or they can float. If you do not have the proper clearance and the correct springs are not used, the spring collar can hit the valve seal and damage it. Once the seals are damaged, they will pass oil.

It is VERY important to use a machine shop that knows this stuff.

Like Rich asked, how did you measure the clearance between the guide and the valve? And what was that clearance? Did you check your spring pack? Did you check the clearance between the spring collar and guide seal?

If you read the instructions that come with the Kibblewhite valves and spring kit, they spell out very clearly what needs to be done.

 

[Rich Rohrich]

If the head has new stainless valves with the OEM valves springs then my guess would be valve float causing the retainer to bang on the stem seal and tear it up when the valves float.

Make no mistake, as 89r pointer out the valves will definitely float with that combination. When they float the valve will loft over the cam losing contact with the nose of the cam (max lift point). When that happens the momentum the valve has developed will keep it moving open past it's normal lift point till something stops it. Sometimes it's the spring retainer banging into the valve stem steel, sometimes the spring will just coil bind (which breaks springs), but usually on the exhaust valve it's the piston that will eventually make contact with the valve.

When you float the valves they lift higher than they should and they don't seat when they should, which effectively retards the cam timing.

The piston chases the exhaust valve closed near TDC and if the exhaust valve doesn't get settled on the valve seat in time you end up with the exhaust valve closer than normal near TDC and they'll eventually hit the piston.

If all you did was tear up a stem seal you got really lucky. Putting the correct valve springs in the engine seems expensive at first but it's very cheap insurance in the long term.

I think I peed my pants from laughing when I read the knurled guide reference. :)
It's always good to see lawn mower trained machinists getting into the high rpm race engine business. :whoa:

A new machinist would be a wise investment as well. :cool:

 

[BSWIFT]

I think I peed my pants from laughing when I read the knurled guide reference. :)
:cool:

It's now time to clean the Coka-cola off of my monitor and keyboard!