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2006 Engine Troubles

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Hey guys, I have a 2006 RM-Z450 that I am working on for a friend and I am trying to get some kind of estimate together on what it's going to cost to fix it for him.  He dropped it off hoping that it just needed some jetting work because it seemed cold blooded when starting, idled high, and popped on deceleration.  He also mentioned that he thought it was using some oil.  Upon inspection, I found where the intake boot was separated from the airbox a bit.  This explains the lean running symtoms, and unfortunately the burning oil because I am sure it has been sucking dirt in there as well.  The bike lets out a small puff of smoke when you crack the throttle open and there is a faint smell of burning oil when you make a pass with the bike and then turn around and come back the same way.  The other thing that is alarming is the engine makes a strange back-and-forth spinning noise when you shut it off and the engine is coming to a stop.  Almost like the crank is going back and forth a few times.  There is no metal on metal noise when this happens  The engine also makes quite a bit of noise when idling like the cam chain is really loose or the valves have way too much clearance in them.  No bad noises or vibrations when riding the bike normally. 

 

My preliminary guess is that at a minimum it is going to take a piston, cylinder replate, valves, a cam chain, gaskets, and depending on the amount of dirt that passed the seats in the head may need to be ground.  Now come the questions:

 

1. Has anyone been down this road with this engine to know how the head will fair? 

2. Does this engine have Ti valves or steel, and how do they respond to steel valve conversions if they are Ti? 

3. Any ideas on what is causing the back-and-forth when the engine comes to a stop?

4. The parts diagrams for this bike show options for a K5, K6, or K7 configuration.  What is the difference and how do I know which one the bike is?

5. Local Suzuki shop has two stock pistons on hand for it.  The original part number is $138 and the updated one is $230.  Anyone know what the difference is?  visually they look the same other than one says ART on the bottom and one is a slightly different shade of grey.

6. Any aftermarket parts that are better than stock, or that I should stay away from with this engine during the rebuild?

 

It will be a couple weeks before I can actually tear into this project.  Just trying to get some info lined up ahead of time.  The bike will be used for casual riding so longevity and having a good starting and working bike are the main goals, not so much to increase performance.

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Well I did a little research and it looks like the valves are Ti in this bike so they will need to be replaced since it has been ingesting dirt.  And it looks like K5=2005 model, K6=2006, and K7=2007.

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I am doing a top end on my 05 and saved a lot of money getting parts off of ebay.  I found a wiseco piston kit with a top end gasket set for $90.  Once I took it all apart, the cylinder plating was ok, but I decided to send it off to Millenium technologies to have it plated $200.  To have the head machined is around $100 plus valves etc...You will have to do what I did and rip into it then buy the parts you need.  Thats cool you doing it to help a friend out.  Good luck with it.

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Well after putting it off for a couple months I finally got back to this project.  Tore into the motor and found that along with ingesting dirt, the following things showed up:

 

1. The cam chain was running loose from not adjusting the tensioner.

2. Tips of the lobes on the cams have lost their ground finish and are starting to wear.

3. Intake valves were slightly tight at 0.003-0.004", exhaust valves had excessive clearance at around 0.015".

4. I can push on the valve springs with my thumb and open them about 3/16".  These seem a bit soft to me?  Have to measure free length to see if they are in spec still.

5. Quick measurement indicates the cylinder is 0.003" out of round.

6. Piston compression ring has two different wear planes on it instead of one continuous shinny edge.

7. Wrist pin is rough and loosing its finish where it rotates in the rod, and consequently the rod end is rough.  No up and down slop between the wrist pin and the rod, but can rock the wrist pin side to side in the small rod end.

8. Crankshaft has 0.015" of axial play and will move side to side in the main bearings.  I would expect somewhere in the realm of maybe 0.005", but this seems a little excessive to me. Anyone know if this is correct?

 

I guess he will have to decide if he wants to fix it, sell it, or try to find a different motor now.

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