• There has been a recent cluster of spammers accessing BARFer accounts and posting spam. To safeguard your account, please consider changing your password. It would be even better to take the additional step of enabling 2 Factor Authentication (2FA) on your BARF account. Read more here.

How do I fix this cam cap? (pics)

E

electric!sheep

New member
Joined
Jun 30, 2005
Location
SF Bay Area
Moto(s)
Kawasaki KLR650
LESSON #1: ALWAYS CHECK YOUR VALVE CLEARANCES! If you're not sure if the previous owner of your vehicle had them checked and adjusted, do it yourself ASAP. The consequences of doing otherwise:

camcap2a02.jpg


camcap37fe.jpg


camcap142e.jpg


So these are all machined surfaces, which means I can't replace the cap without replacing the cam, and I can't replace the cam without replacing the head, which costs $750. The crack seems fairly minor, and it ends in solid metal on either side (tapering towards the edge of the groove), so could I have the top welded to add some strength? I assume the top of the cam cap makes no difference to anything? I know of someone who ran their KLR650 without the cam cap end (that little side portion below the crack), and they're apparently OK. But I don't even have the option of snapping it off.
 
Sorry, but this is an honest question. I still don't understand why you can't just replace the cap. Can someone explain this to me?
 
wannabe said:
Sorry, but this is an honest question. I still don't understand why you can't just replace the cap. Can someone explain this to me?
Click to expand...

The head and cap are line bored together at once, so they match. Each one is different ever so slightly.

Another cap will be off, meaning the hole may or may not be true when you switch caps.

Its like switching around main or rod caps on a block....you just dont do it.

That being said, some people have done it in the past, with good results.

If I was to replace just the cap, I would install the new/used cap and plastigauge the top cap and sides. If it was in spec, run it.

The correct way is to get a head.
 
+1 for the above. I have done it. But I wouldn't do it on a race motor. You can't fix it.
 
here is what to do:

* order a new cap or ge one from a salvage yard.
* make sure that the cap fits well on the cam diameter. (use some fine emery to open it up)
* put it together and ride the daylights out of the bike.


if the cam decides to roach, you are out the same money that you would have been if you did the correct fix (head and all) right now.

go for it.


ps. welding on a part like this is just stupid. even if you can get the thing straight again (ha), the temper will be lost and it will function like play-dough.
 
You can replace a main cap, rod cap, or cam cap. You just need to have the head line-bored to make sure the journals are round again. Any competent machine shop should be able to do this in a few hours.

I've had to replace a main cap on an engine before, and it was near impossible to tell the difference between the original and the replacement.

I want to say it was $80 to get my V8 line bored, so I would imagine a head wouldn't be more expensive than that.
 
wilit said:
You can replace a main cap, rod cap, or cam cap. You just need to have the head line-bored to make sure the journals are round again. Any competent machine shop should be able to do this in a few hours.
Click to expand...

My knowledge of engines comes from my Clymer's manual. Could you explain to me what it means to have the "head line-bored"? Where would these "journals" be? How does this relate to putting in a new cam-cap? In fact, I'd probably need to replace both (in/ex) of the left cam caps, since they come flexibly joined by the oil supply tube. I'm not sure how to separate it.
 
pvd said:
here is what to do:

* order a new cap or ge one from a salvage yard.
* make sure that the cap fits well on the cam diameter. (use some fine emery to open it up)
* put it together and ride the daylights out of the bike.


if the cam decides to roach, you are out the same money that you would have been if you did the correct fix (head and all) right now.

go for it.


ps. welding on a part like this is just stupid. even if you can get the thing straight again (ha), the temper will be lost and it will function like play-dough.
Click to expand...


I would strongly advise against trying to "force" it to work. You aren't seeing the bigger picture- if the cam decides to "roach" like you say, do you honestly believe the bike will gently shut itself off and announce that it is finished???? Fuck no dude! The fucking thing is going to seize bigtime and endanger the rider's life. Especially if he's winding it up to the limit. If you've ever seized a motor, you know what I'm talking about. If you haven't seized a motor, take it from me- you don't want to know what it's like. You can punch a hole in the block and pour hot oil all over yourself and the rear tire.

This is fucked up advice.

Dumb idea.

Bad idea.

Don't do it.

I'm pretty pissed off now because of the burglary, but I have to say that sometimes I see some pretty shortsighted advice being dispensed with no regard to safety. Fixing things on the cheap can work-sometimes. But these are complex machines with a huge downside potential if something is done half assed. What's less expensive- a Home Depot hack repair or a trip to the hospital? Internet advice is free and you get what you pay for.

Please don't listen to the witchdoctors.
 
Last edited:
Basically what they will do is take the cam cap mill a few thousandths off the flat part of the cap and bolt it onto the head. By taking the material off the bottom of the cap, it will make the journal (the round hole the cam sits in) an oval shape. The bolt the head down into a line-boring machine so it can't move. Then this long drill like thing (set to the diameter required by the manufacturer) goes through all of the cam journals (5 I'm guessing on your head?) and makes them round again.

Here's a picture of a line boring maching boring out some main journals on an inline 6 (looks like).

fbore.jpg
 
wilit said:
Basically what they will do is take the cam cap mill a few thousandths off the flat part of the cap and bolt it onto the head. By taking the material off the bottom of the cap, it will make the journal (the round hole the cam sits in) an oval shape. The bolt the head down into a line-boring machine so it can't move. Then this long drill like thing (set to the diameter required by the manufacturer) goes through all of the cam journals (5 I'm guessing on your head?) and makes them round again.

Here's a picture of a line boring maching boring out some main journals on an inline 6 (looks like).

fbore.jpg
Click to expand...

Oh god. That would require me to send everything to a shop, which would probably involve more cost and effort than getting a new head shipped in. I can install one myself. My KLR is a single cylinder so I suppose I have 4 cam journals?

Can I have a machine shop just match the "new" cam caps to the old ones?
 
Whoops, didn't notice you had a KLR. Yes, you will need to take the head off the engine and take it down to a shop. You're probably looking at maybe $50 worth of work + the new cam cap. I can guarantee a new head will cost way more than $50.
 
wilit said:
Whoops, didn't notice you had a KLR. Yes, you will need to take the head off the engine and take it down to a shop. You're probably looking at maybe $50 worth of work + the new cam cap. I can guarantee a new head will cost way more than $50.
Click to expand...

I can see how the machining process would make the cam caps consistent, but can they ensure proper clearance from the camshaft?
 
electric!sheep said:
I can see how the machining process would make the cam caps consistent, but can they ensure proper clearance from the camshaft?
Click to expand...

As long as you tell them what year and engine the head is from, they can look up the clearances and make sure they're right. After all, that's the entire point of getting it line bored.

Line boring achieves only 2 goals. Making sure the journal is round, and the right diameter. That's it.

FYI, I just checked Ron Ayers, and the complete cylinder head lists for $613.
 
wilit said:
As long as you tell them what year and engine the head is from, they can look up the clearances and make sure they're right. After all, that's the entire point of getting it line bored.

Line boring achieves only 2 goals. Making sure the journal is round, and the right diameter. That's it.
Click to expand...

Right, but I'm going to guess that the clearance spec is not enough to get a good match. I mean, if the clearance spec were exact, then wouldn't they just make replacement parts to spec and call it a day? The fact that the cylinder head is all machined together and you have to buy things that way suggests that there are non-trivial variations from spec in each cylinder head/part. Thus, even if I have the journals to spec, the cam might not be. Does that make sense? I'm not trying to give you a hard time, I just want to make sure I do the right thing. I really appreciate the advice. :)


FYI, I just checked Ron Ayers, and the complete cylinder head lists for $613.
Click to expand...

THANKS! That's actually not TOO bad in the long run, considering I got the bike for $2200 and would have peace of mind about the top end. I need to go back and check the instructions in my manual to see how hard the install would be. Not that I want to spend 600 bucks to fix a stupid crack...I'm just trying to justify the possibility to myself. :D
 
electric!sheep said:
Right, but I'm going to guess that the clearance spec is not enough to get a good match. I mean, if the clearance spec were exact, then wouldn't they just make replacement parts to spec and call it a day? The fact that the cylinder head is all machined together and you have to buy things that way suggests that there are non-trivial variations from spec in each cylinder head/part. Thus, even if I have the journals to spec, the cam might not be. Does that make sense? I'm not trying to give you a hard time, I just want to make sure I do the right thing. I really appreciate the advice. :)
Click to expand...

Dude, you're WAY over thinking this. The head is cast as one part. the cam caps are cast as seperate parts. They need to be bolted together and machined so they fit together fo create a perfect circle at the correct diameter at the factory. There is ABSOLUTELY no way you can cast any part and get the kind of repeatability at those close tolerances required for mass production. It's impossible. The only way you can create a part that's an EXACT copy with those close tolerances to to machine it from billet stock. That is extremely expensive.

This is something machine shops do daily. It's not rocket science.

As for your difference in kits and prices, I don't know. You'd have to call. It probably has something to do with the manufacturing date. I don't know that much about Kawi's. My buddy bought an EX250 and the cam caps cracked and his bike spent 2 months in the dealership waiting for a new head and cams. I've never been a fan of Kawi's since. :D (true story BTW).
 
You must log in or register to reply here.
Back
Top