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Old 03-09-2011, 05:10 PM   #1 (permalink)
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Default For ALL Z400 GURUS!! Starting problems...

I got 2003 kfx400 with a real puzzle. It will pop start and run hard, but will not start electrically. The starter spins freely if I remove the flywheel cover, the battery is 11.6volts (a little low, but I doubt that is the problem), all the gears on the flywheel have their teeth and spin freely. The larger starter gear behind the flywheel spins only one way, but to be safe I took of the starter gear out and saw no visible damage on the starter clutches, flywheel, the stator, or anything in the oil. When I push the start button, it sounds like that starter does spin but doesn't sound the same as my 03 z400. When I hooked up my compression tester, nothing, no compression. I took off the cylinder, the walls and the piston were in good shape with no scoring (plus it runs good if you pop start it).

What could it be??

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Old 03-09-2011, 05:17 PM   #2 (permalink)
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Did you check the valves?
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Old 03-09-2011, 05:25 PM   #3 (permalink)
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well if the starter is spinning and u have no compression it must not be fully engaging and locking into the flywheel to crank the engine right? other wise the engine would turn and youd have compression
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Old 03-09-2011, 05:26 PM   #4 (permalink)
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Valves? I thought since it runs good when you pop start it, valves would not be the issue.

Forgot to add, that it does sometimes start via start button, but that is if you ride for 30 minutes or more and the engine warms up a good amount..
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Old 03-09-2011, 05:52 PM   #5 (permalink)
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Quote:
Originally Posted by matty2299 View Post
well if the starter is spinning and u have no compression it must not be fully engaging and locking into the flywheel to crank the engine right? other wise the engine would turn and youd have compression
I kinda get the idea that somewhere its not engaging, but not sure where or how to properly diagnose it. I inspected the flywheel/starter gear assembly to the best of my knowledge and found no red flags.

When I took the spark plug out and cranked it, I did get puffs of air, but VERY WEAK (teaspoon of oil into the cylinder had no real affect on the compression).

Again, I do have some kind of movement when starting, but it sounds at a faster rate, and it doesn't sound like my Z,

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Old 03-09-2011, 05:57 PM   #6 (permalink)
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If it starts fine on a pop start and not by the starter it is always the valves. If they are out of spec using the starter wont be powerful enough. Pop starting it gives it more power for those valves that are out of spec to open up and that's why it starts. Its a very common problem on the z. Get yourself a manual, and a feeler gauge and check them out. Its pretty easy.
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Old 03-09-2011, 06:26 PM   #7 (permalink)
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Clearances should be,
Intakes: 0.10mm
Exhausts: 0.20mm
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Old 03-09-2011, 07:02 PM   #8 (permalink)
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Valve lash is too tight!

Read this.
Z400 Hard To Start Or Wont Start When The Engine Is Cold?
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Old 03-09-2011, 07:36 PM   #9 (permalink)
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I am so embarrassed. What a novice mistake

The intake was gone! absolutely no gap, so tight that when I tightened the cam holder in place, i couldn't even spin the damn thing

I guess a shim kit will be needed. Any possible damage that could have happened from this. When I took the shims off and tightened the cam in place it spins freely just like the exhaust one, but a tiny, tiny fraction with more resistance, almost non existent (with no signs of any scoring or any other visible damage) should this be a concern?

* this is like the time where I spent killing a battery or two not realizing that i was out of gas Lesson, always check the basics first lol..

Back to putting back the engine
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Old 03-09-2011, 07:49 PM   #10 (permalink)
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You might need to get new valves.
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Old 03-09-2011, 07:54 PM   #11 (permalink)
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You might need to get new valves.
Any way of knowing that before I order the shim kit?

I looked at the valves and did not see any gaps or light penetrating through..
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Old 03-09-2011, 08:16 PM   #12 (permalink)
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Here is the thought process. First off the stock valves have a coating on them that protects them from heat. When the quad is run with a dirty air filter, or the stock air filter leaks air, (Stock filters suck!) you pull air past the intake valves and "sand blast" the coating off the valves. The valves in turn get soft and cup. This means the bottom of the valves pull away from the stem, making them longer and don't seat correctly. So shimming the valves is a temporary fix. Additionally, the stock valves are a 2 piece design and have been know to separate and drop into the cylinder. This takes out the whole top end. Your best bet is to do a top end rebuild. New after market stainless steel valves and have the seats cut too. You can do a DRZe kit while your at it. You will be happy you did!

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Old 03-09-2011, 09:13 PM   #13 (permalink)
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some people might disagree with this method, but i would recommend doing the following (for saving some cash and possibly a lot of time):

buy a shim kit, reshim the valves, and run the quad.

if the coating is gone or the valves are otherwise damaged, they will get tight fairly quickly (or if damaged they will still not seal tight and the reshim will not change your current condition)

if it gets tight again quickly (10 hours or less of ride time) get some valves and think about a BBK or piston re-ring while you have it apart.

if not....go nuts and check them regularly as normal.
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Old 03-10-2011, 12:30 AM   #14 (permalink)
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The coating on the valves is not as thick as the valve clearance you lost... To make a long story short, you DO need new valves. If they lose clearance all the way to zero, the valve is junk.

Closely inspect the intake for leaks, but most likely the owner didn't service the air filter enough, and dirt ingestion ruined the intake valves.
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Old 03-10-2011, 02:34 AM   #15 (permalink)
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The coating on the valves is not as thick as the valve clearance you lost... To make a long story short, you DO need new valves. If they lose clearance all the way to zero, the valve is junk.

Closely inspect the intake for leaks, but most likely the owner didn't service the air filter enough, and dirt ingestion ruined the intake valves.
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