Intake wearing into head? What now?


31 replies to this topic
  • Gadsen

Posted January 10, 2006 - 09:29 PM

#21

...i wonder if head "assembly" includes the valves and everything else?...


No, it will be a bare head, except the caps with bolts and guides. Thats about it!

  • Gadsen

Posted January 10, 2006 - 09:32 PM

#22

That's what I figured. I ordered a new head from the TT store... ~$450, along with new valves & all.

The Exhaust valves haven't moved at all ... It only has 3k miles on it so I'm going to just rebuild the intake side.

- Ryan


Perfect fix Unky! :applause: Might as well do it right. I suspect it may come with stem seals, but as for valves, just install the new ones, and dont forget to remove the small shim from under the valve springs. Usually stick to the head and you wont even know its there. You can reuse all the springs, keepers etc.

  • tntmo

Posted January 11, 2006 - 11:13 AM

#23

This is a pretty common wear point on these bikes. I had a small ammount of wear like that on my bike too, did some searching on this forum and there were some other threads covering it. Yours looks a lot worse than mine did. I cleaned it up and am just keeping an eye on it for now but will be replacing it down the road. Good luck.

  • unkle_george

Posted January 11, 2006 - 01:25 PM

#24

That can also be caused by overtorquing the caps.
They only want about 70-75 ft/lbs or so... that spec is critical.


I had a local shop rebuild the top end for me and I know they didn't use a torque wrench when they put it back together. Some of the head bolts were stripped.
:bonk: They're not in business anymore. : (


Cause of death:
Incorrect torque on the cap bolts
Overheating from the blown head gasket.
Me not keeping an eye on things. :applause:

- Ryan

  • CycleWriter

Posted January 11, 2006 - 02:07 PM

#25

I had a local shop rebuild the top end for me and I know they didn't use a torque wrench when they put it back together. Some of the head bolts were stripped.

Cause of death:
Incorrect torque on the cap bolts
Overheating from the blown head gasket.
Me not keeping an eye on things. :applause:

Like I said, any one thing done improperly probably wouldn't have caused this, but in conjunction with one or two other conditions being present... A torque wrench is essential on these engines. I can put an Evo Harley engine together by feel and have it last, but on a bike like this I wouldn't even think of skipping the torque specs or procedures. The tolerances are just too tight to play with.

  • jbrooks26

Posted January 11, 2006 - 02:20 PM

#26

That can also be caused by overtorquing the caps.

They only want about 70-75 ft/lbs or so... that spec is critical.



WHOA!!!!! :bonk: You had better re-read that one. 70-75 ft/lbs will snap these bolts or pull the threads out of the head. The manual calls for 7.5 ft/lbs. Just don't want someone reading this and trying to torque these babies to lug nut specs. LOL, I am sure it was a typo. :applause:

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  • BIGMatt

Posted January 11, 2006 - 02:28 PM

#27

WHOA!!!!! :bonk: You had better re-read that one. 70-75 ft/lbs will snap these bolts or pull the threads out of the head. The manual calls for 7.5 ft/lbs. Just don't want someone reading this and trying to torque these babies to lug nut specs. LOL, I am sure it was a typo. :applause:


Yeah thats what I thought! Good catch! 7.0 to 7.5 ft-lbs, is 85 - 90 inch-lbs. That might be the confusing part. The head studs don't even see 70 ft-lbs!

As far as repair options, get estimates for over boreing the cam saddles and caps and installing journals, like what is used in V8 crankshaft bearings. But it kind of all depends on how bad/deep the damage is now. Any repair should be a PRECISION machined repair, not a dremmel job.
Then use LOTS of assembly lube! And even pre fill the oil galleys before startup, and pour oil all over the whole cam assembly too!!

  • WheelsUp

Posted January 11, 2006 - 03:43 PM

#28

:applause: Oops... ya.... I meant 70-75 inch-pounds. Good catch.
I believe spec actually IS 7 or 7.5 ft/lbs, but common practice is to stop short.

  • xr_man

Posted January 12, 2006 - 01:26 AM

#29

what about getting the head welded and the lot linebored true again ??

  • ncampion

Posted January 12, 2006 - 07:05 AM

#30

Hard to understand how you got that much wear on the bottom of the cam bearing. All the force on that bearing is towards the upper cap bearing. What does the cap look like?

  • unkle_george

Posted February 02, 2006 - 08:37 AM

#31

Adding on what I know now for the next guy with cam journal wear.

After I got all the parts I recieved a mail back from Engine Dynamics LLC saying they could repair my old head for ~$95. edco@enginedynamics.com If anybody wants a repaired head for a few hundred less then a new one, I'd be glad to sell it.

The cam caps were worn about as much as the head. The strangest thing is, the intake cam was only worn near the lobes and only about half way around. It was almost like it was out of balance. (I replaced it because of the wear)

- Ryan

  • Boss302

Posted July 23, 2006 - 01:07 PM

#32

I just took my engine apart after checking the intake valve clearance and finding none. I have the same type damage to my cam journals and cap that you had. My engine has about 2000 miles and has never been over-heated or low on oil.

I am very surprised to see what looks like oil starvation in the journals. When I was checking the clearance, I noticed that the far right front cam cap bolt was loose. This is the first time this engine has ever been apart. I can only infer that it was loose from Yamaha and that the constant up and down hammering has caused mushrooming, which resulted in oil loss from the journal, and subsequent heat build up and bluing. This is definitely a manufacturing/assembly fault. There is no reason for the cam cap bolt to be loose....ever.

Now, how to fix!




 
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