Lesson learned


15 replies to this topic
  • 450_gal

Posted April 01, 2008 - 09:37 PM

#1

Get a torque wrench.

Make sure everything, I mean, every little thing is torqued to spec.

Some of you may remember that I had some bike issues last week. Turns out that my cam cap was tightened too much and it caused the bike to jump timing and seize up.

  • grayracer513

Posted April 01, 2008 - 09:50 PM

#2

The cam caps are probably the single most critical torque point on the entire YZF engine. It is extremely important to be sure that you can seat the caps squarely without drawing them down with the bolts, to torque them evenly, in order and in at least 3 small steps.

Personally, I have always felt that 86 inch pounds with oiled bolts, as called for, is more torque than is required, and more than feels safe to me. So, I substitute 75-80 instead.

  • sirthumpalot

Posted April 02, 2008 - 02:33 AM

#3

Why do we always learn the expensive lessons the hard way. :bonk:

My opinion is get at least 2 torque wrenches. 1 for larger bolts (axles, etc..) and one for the smaller more delicate stuff (like cam caps, oil filter cover, etc..). The larger wrenches generally aren't accurate enough for the really delicate stuff, even if they adjust that low. Avoid the types that bend, they're very difficult to be dead-accurate with. Get a good clicker wrench. Avoid the $10 car store specials and get something good. Sears has some fairly decent wrenches for under $100. Once you have them, they do need to be calibrated on occasion.

Anyone can just slap things together and be lucky a few times, if you want good results every time then you have to be maticulious. Good luck! :prof:

  • grayracer513

Posted April 02, 2008 - 05:56 AM

#4

I own 3; one 1/4" flex beam, 0-120 in/lb, a 3/8" Snap-on digital (replaces a flex beam of the same size) 0-100 ft/lb, and a 1/2" Snap-On clicker for 30-150 ft/lb. Torque wrenches are most accurate in the center 70% of their range, which is why I own 3. Flex beam wrenches aren't as cool as clickers or digitals, but they are much less expensive, and very well suited to the home shop. If you have a used tool store in your neighborhood, it's a good place to look.

  • sirthumpalot

Posted April 02, 2008 - 06:00 AM

#5

If you get a used one (not a bad idea), be sure to have it calibrated before you rely on it. There are many services that do this, usually $20 or less per wrench. You'll get a report back that shows you exactly how accurate the wrench is at specific settings, and you'll be surprised at how the accuracy varries across the scale.

  • Racer808

Posted April 02, 2008 - 06:15 AM

#6

what is the cam cap? I would like to check mine now.

  • grayracer513

Posted April 02, 2008 - 06:21 AM

#7

The cam caps hold the cams into the heads, and do not need to be disturbed in any way unless adjusting the valves, replacing the timing chain, or removing the head. They don't loosen in service, and if you checked them for torque as they are, they would read as too tight, since they've settled into place. If you haven't had them off, don't fiddle with them.

  • Digger01

Posted April 02, 2008 - 07:22 AM

#8

Sorry about your bike:crazy: , I am about to open my 426 up to install the 450 cam and new cam chain, wish me luck.

I just went through this and bought an S&K torque wrench ($128). Sorry I dont have the model and price handy. But I first looked on that ebay site and then ended up ordering it from a tool supplier over the internet.

Sears doesnt guarantee their torques wrenches like their tools- I would get S&K, or one from another reputable comapany (do a google search).

Expect to pay over a $100.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • USED YZ426F

Posted April 02, 2008 - 08:09 AM

#9

You can get tools from local pawn shops also. I have purchased a lot of ratchets and wrenches (Craftsman, Husky, Snap-on) from pawn shops one or two tools at a time.
Obviously the selection varies greatly, but the prices are usually excellent. Don't forget going to the local flea market / swap meet also.

  • Ga426owner

Posted April 02, 2008 - 11:15 AM

#10

This is the 4th YZF450 06-08, that I have heard this happening to. One happened at a track a few weeks ago, happened over a table top and rider was injured. I agree that people are not properly torquing these caps down.......expensive mistake...geez even a Husky Torque wrench is better than nothing

  • todds924

Posted April 02, 2008 - 04:10 PM

#11

I own 3; one 1/4" flex beam, 0-120 in/lb, a 3/8" Snap-on digital (replaces a flex beam of the same size) 0-100 ft/lb, and a 1/2" Snap-On clicker for 30-150 ft/lb. Torque wrenches are most accurate in the center 70% of their range, which is why I own 3. Flex beam wrenches aren't as cool as clickers or digitals, but they are much less expensive, and very well suited to the home shop. If you have a used tool store in your neighborhood, it's a good place to look.


I can't seem to keep batteries in my snap on digital for very long...the damn things always going dead.......I prefer my flex head snap on clickers much more.

  • 642MX

Posted April 02, 2008 - 04:19 PM

#12

So, I substitute 75-80 instead.


This is excellent advice. I've always done it just like Grayracer suggests and I've never had a problem.

  • 642MX

Posted April 02, 2008 - 04:22 PM

#13

Get a torque wrench.

Make sure everything, I mean, every little thing is torqued to spec.

Some of you may remember that I had some bike issues last week. Turns out that my cam cap was tightened too much and it caused the bike to jump timing and seize up.


Don't feel bad. We've all torn something up from not following the procedures. With that said, be sure to torque your oil drain bolts with a torque wrench too........ don't ask me how easily they strip when over-tightened. :prof:

  • Chad76

Posted December 01, 2008 - 02:13 PM

#14

G'day all. Did a search and found this thread. I am trying to get to the bottom of something. I had my valves checked by a store for I thought I would leave it to the experts. They checked the valves and made one valve adjustment. After this work the first ride I took it out for a ride the bike felt really flat with no bottom end. The engine also would just cut on me when cruising along in no particular gear. After 30k I decided to turn around for I knew something was not right. Since this ride I took it to a different store for I thought the jetting might be playing up. They had a look and I mentioned another place had just checked the valves just recently. They re checked the valves and said all 3 inlet valves clearances needed changing, centre valve had zero clearance. The inlet cam was out by 1 tooth. The cam journels had damage for the cam shafts were not sitting right resulting in burring of the journals to the point that the buckets could not be removed. They said that the previous shop who had just recently checked the valves had not tightened the cam caps down correctly reulting in the cam shafts to damage the journals. Is it possible to not screw down the caps correctly causing the cam shafts to damage the journals? I have since spoken to the first store and they said it is impossible to incorrectly install the cam caps resulting in this damage. Any ideas?

  • grayracer513

Posted December 01, 2008 - 02:24 PM

#15

I had my valves checked by a store for I thought I would leave it to the experts. They checked the valves and made one valve adjustment. After this work the first ride I took it out for a ride the bike felt really flat with no bottom end. The engine also would just cut on me when cruising along in no particular gear. After 30k I decided to turn around for I knew something was not right. ...(the second shop) re checked the valves and said all 3 inlet valves clearances needed changing, centre valve had zero clearance. The inlet cam was out by 1 tooth. The cam journels had damage for the cam shafts were not sitting right resulting in burring of the journals to the point that the buckets could not be removed. They said that the previous shop who had just recently checked the valves had not tightened the cam caps down correctly reulting in the cam shafts to damage the journals.

Is it possible to not screw down the caps correctly causing the cam shafts to damage the journals? I have since spoken to the first store and they said it is impossible to incorrectly install the cam caps resulting in this damage. Any ideas?

Yes it is possible, and it happens all too often. The cam caps are very sensitive to incorrect torque, and must be torqued in the proper sequence, and to the proper torque value. If this isn't done, the bore will be distorted. No distortion can be tolerated, because the clearance is only about .04mm to begin with.

The faulty cam timing was either from incorrect assembly, or could have occurred as a result of seizing the cam. Any experienced Yamaha tech will vouch for this, and a search here will turn up several examples of the same thing.

  • Wiz636

Posted December 01, 2008 - 02:29 PM

#16

Is it possible to not screw down the caps correctly causing the cam shafts to damage the journals? I have since spoken to the first store and they said it is impossible to incorrectly install the cam caps resulting in this damage. Any ideas?


Yes, it is absolutely possible to install the camshaft caps incorrectly and cause damage to the journals. They need to be torqued very precisely and in correct order...probably the most critical of all torque specs on the bike.





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