FI help please.


22 replies to this topic
  • zimak

Posted February 06, 2008 - 07:30 AM

#1

Ok so at work its called "fault isolation"...and I'm needing some on the pig big time.

Did a wet and dry compression test and its looking pretty clear that I have a problem in the valves somewhere.
Dont have a leak down tester so gonna break off the head today and try to figure this out.

Whats weird is I'm getting 120lbs w/o the decomp pulled in but 0lbs compression with it pulled.

I'll have it off here in the next hour so by the time I check up on the post here....where to start looking in my valve/head area?

  • crmc33

Posted February 06, 2008 - 08:38 AM

#2

shirley the idea of the decomp is you wont get much compression with it activated???

Im confused!

  • scalejockey

Posted February 06, 2008 - 08:50 AM

#3

Before you go to the trouble pop off the carb and exhast look in the ports at the valves faces.

  • Denn10

Posted February 06, 2008 - 08:53 AM

#4

WELL we will find out when he gets back with head all apart

  • scalejockey

Posted February 06, 2008 - 08:55 AM

#5

:busted:

WELL we will find out when he gets back with head all apart



  • zimak

Posted February 06, 2008 - 09:03 AM

#6

Ok decided to stop while I was ahead. Rechecked the valves again just to make damn sure and then waiting for the dealership to open.
Hate using them but not wanting to go get a leak down tester for $80 for one time use.
They just opened and have agree to let me pop in and do a fast test on her.

Oh as for the decompressor:
Manual says: Choke open, throttle full open, decompressor pulled 5-6 kicks should yield: 89lbs

Same as above but not decompressor and: 160lbs

I'm getting 0lbs and 120lbs which makes me think something in the decompressor system is hosed.

Loading up now, will post when I get back.

  • zimak

Posted February 06, 2008 - 09:04 AM

#7

Before you go to the trouble pop off the carb and exhast look in the ports at the valves faces.


Did that when I rejetted for the temp change yesterday and all looked a ok as best as I could tell with a surefire and a mirror.

  • cleonard

Posted February 06, 2008 - 09:41 AM

#8

I'm a bit confused here. Which year bike do you have?

What altitude are you at?

When you say decomp off do you mean that you backed off the valve clearance adjuster so the decomp will never open the valve?

In general you will not see a small leak that yields 120 psi. The valve is not quite seating perfectly. The best way to test is to spray some liquid, like carb cleaner, above the valve and see how much leaks through. Only a perfect valve will block it completely. A tiny amount usually seeps through a good valve. If a lot goes through it's time for a valve job.

  • Motosprtman

Posted February 06, 2008 - 10:31 AM

#9

I know it's kinda a backwards ? but what color is the plug? when compression is low you can get a oily black plug or a dry sooty black one. The color of the plug alone will tell the tale of low compression. This condition is also reffered to as BSPS "Black Sooty Plug Syndrome". Casued by incomplete / poor combustion as a result of low compression (everything else being correct, jetting, timing ignition etc)

  • zimak

Posted February 06, 2008 - 11:08 AM

#10

Ok got it figured out. Found a leak tester.
25% leak down at the rings.

Time for a fresh build!
Off comes the cylinder now.

Oh yeah sorry its a 2006. And when I was talking about the decomp I mean in the manual it says to hook up the compression tester and kick 5-6 times with the decompressor pulled. That should yield 89lbs. Alternately you can do the same w/o pulling the decompressor and should yield 160lbs.

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  • Denn10

Posted February 06, 2008 - 11:21 AM

#11

Ok got it figured out. Found a leak tester.
25% leak down at the rings.

Time for a fresh build!
Off comes the cylinder now..



Did you back off all the valves and lightly tap them to make sure there completely seated before doing leak down? I wouldnt say its exactly rings cuz you have no way on really knowing if the valves or rings are where its excaping. 25% is bad if you got a good reading for sure but that means you need head and cylinder rebuild.

  • zimak

Posted February 06, 2008 - 11:46 AM

#12

...Denn10 make sure I'm following you.
They rechecked my valves at TDC C-stroke and they were dead on. That means they werent being touched and there was gap between them....that should mean that the valves are closed all the way right? Nothing pushing down on them?

  • scalejockey

Posted February 06, 2008 - 01:12 PM

#13

If it is truly 25% past the rings i'm surprised that it didn't smoke like a mother-in-law.

  • martinfan30

Posted February 06, 2008 - 01:16 PM

#14

Sometimes they can hang open slightly on carbon. That would have shown on the test though.

  • Frank ZX

Posted February 06, 2008 - 01:29 PM

#15

Zimak,I think you should recheck everything.If your bike is a 2006,it's hard to beleave your rings are bad already,unless the bike has been abused,or has
60K miles

  • zimak

Posted February 06, 2008 - 01:47 PM

#16

Nah...there was an accident.
http://www.thumperta...ad.php?t=595630

Damn sure the rings. Taking the cylinder/piston and head in now to see what all I need to get on order.

Took pictures as I worked so will post those all later this evening.

  • zimak

Posted February 07, 2008 - 07:12 AM

#17

Ok so here is the piston and valves.

Got a new set of valve springs and piston/rings/gaskets on order now.

Posted Image

Posted Image

  • Motosprtman

Posted February 07, 2008 - 07:16 AM

#18

mmmmmmmmmmmm nice and oily, sure enough twas the rings a leakin. Valves look nicely seated.

  • zimak

Posted February 07, 2008 - 07:24 AM

#19

Yeah dropped off the whole set at my local motorbike shop since they have the precision tools to tell me for sure the good and the bad.

Valves are still spot on although they are suggesting I replace the valve springs since I have it all off and apart.

Cylinder isnt bad just needs a good honing.

New piston/rings and thats it.
Not too bad overall.

Fun part is earlier this week I rejetted the carb and adjusted the valves...first time I'd ever done either of those jobs.

Man this thing is easy to work on.

  • creeky

Posted February 07, 2008 - 10:15 AM

#20

New piston/rings and thats it.
Not too bad overall.
.



You are going to get a valve job, aren't you?





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