Kawasaki KLR 650 Forum - Reply to Topic
1987 to 2007 Wrenching & Mods For maintaining, repair or modifications of Generation 1 KLR's. 2007 and earlier.

Thread: Broken Cam Cap question Reply to Thread
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  Topic Review (Newest First)
05-05-2018 08:00 PM
Tom Schmitz Ben,

It is very common for cam caps, connecting rod caps and main bearings to be line-bored while they are assembled. This is necessary to ensure that the parts fit correctly to their mating shaft(s). At one time, machining technology was such that parts so made were definitely not interchangeable.

Modern machining technology has advanced greatly from those days, but such parts are still not considered interchangeable. Now, in truth, they often can be because the tolerances that are held prior to the line-boring (which in this case would be the positioning of the dowel pin holes) are so precise that the line boring operation is highly repeatable. I have no insight as to how Kawasaki does the machining, but I'd bet that the line boring is done on the same CNC machining center and in the same set-up as the rest of the machining on the head, with the cam caps installed mid-operation. In days gone by it would have been done on a different machine and in a separate fixture.

To Paul's point, the only thing that is important is that there be the proper clearance around the camshaft for oil flow.

There have been many engines that were cobbled together under a shade tree, using parts available the mechanic that might have come from a number of engines, that weren't 'right' but worked fine. Given an assortment of cam caps you can find one the fits the dowel pins, you can turn that cap backward, you can omit one dowel, you can lap the bottom of the cap, you can shim the cap, you can use an intake cap instead of an exhaust, etc. All you need is some Plasti-Gage to determine when the clearance is right. You would not be plowing new ground; you'd be following in the footsteps of a pre-teen who is now in his 90s. The sad thing is that there are no caps available because they get tossed with grenaded heads and often it is only the right exhaust cap that is truly bad.

I don't understand how what is essentially just a reinforcing rib got broken off without something flying around in the head, but that's a different matter. When you get a picture of it I'll be happy to help post the picture if needs be.
05-05-2018 07:24 PM
edaggett
Quote:
Originally Posted by pdwestman View Post
I understood exactly what was broken. Therefore others could understand also.


You are correct, I am not implying that you misunderstood me. Just that some people might. You requested a photo, and since my engine is not currently opened up, this was the best I could do. Plus, I see no logical connection between the statement "Therefore others could understand also" and "everyone does understand". When I called Engine Dynamics, I gave them the same description I did on here and they were convinced a different part of the cap was broken. I know it's a major crime, punishable by public ridicule and harassment, for someone to ask a question without reading through existing threads. I want to make sure that those who do read this thread in the future are clear on what is being discussed here. That's all. I meant no offense.

I am not riding the bike and I am sending the cap to Eagle Mike for repair. I will detail the outcome for everyone once I get the part back. He estimated a 2-3 week turnaround time.


Also, just wanted to point out some conflicting info I received from Engine Dynamics. They told me that if any part of the cap is broken, it cannot be fixed. They also said that contrary to the prevailing orthodoxy that states you cannot take a cap off of another bike as a replacement, you certainly can and it will work fine 99% of the time. Take that as you will.

Cheers,

Ben
05-04-2018 09:39 PM
pdwestman
Quote:
Originally Posted by pdwestman View Post
I wouldn't advise riding it. The cam sprocket needs to be kept in-line with the chain & the lobes need to stay centered over the tappets.

A loud knocking noise & loss of power seems to be more than just a broken guide flange on a left hand cam bearing cap.

I'm pretty certain that Eagle Mike has welded a few broken or cracked bearing flanges on KLR's. Give him a call, Eagle Mfg & Engineering
Also, Engine Dynamics has repaired many cylinder heads of all kinds, ENGINE DYNAMICS

We can't see your parts.
I understood exactly what was broken. Therefore others could understand also.
05-04-2018 05:42 PM
edaggett Hello again,

After contacting Engine Dynamics (trying to get as much information as possible), it became clear that people may be misunderstand exactly what is broken. Here is photo (not my photo) to help. I will take a photo of the broken cam cap once I get the bike taken apart.

The red arrow is pointing the "lip" I am describing. Note, this lip does not have any contact with the cam shaft. The part that prevents the left/right play is the flange/groove on the left side caps. The outer lip on the left front cam cap is what is broken. I believe this is why the mechanic believes it is okay to ride as it has no interaction with any other part of the engine. I believe these lips are only present for structural reinforcement. Again, I will take a picture once I get her apart.





EDIT: Not sure why I am still unable to post pictures. It seems that the process to post photos on a forum hasn't changed since 2003, and remember not being able to figure it out then either.

I guess for now I will just post a link to the imgur photo. Again, this is not a photo of my cam cap. It's just to point out the raised lip that broke off. Rode the bike home today with no issues.

https://imgur.com/Hq6lm2E

05-04-2018 12:33 PM
edaggett Okay, just talked to Eagle Mike himself. What a cool guy! For the help of future info seekers I will post what he said.

Regarding riding the bike with the broken flange. This flange prevents left/right play on the journal cap. If you don't get it fixed, you run the risk of the cam operating out of alignment which can cause more serious problems. He recommends one not ride the bike without the fix.

He also confirmed that the only way this part broke is that it was assembled out of alignment by the mechanic. I urge you to avoid "House of Motorrad" in Boulder, CO. His shop guys are good people, but the owner is a crook.

I am going to send the part into Eagle Mike. I will post a pic of the part once I remove it. Luckily it's sitting right there on top.
05-04-2018 12:11 PM
DPelletier Yes, you can weld aluminum. :-)

Dave
05-04-2018 12:05 PM
edaggett Dave!

Thank you for your response. I have done more reading and have abandoned the idea of buying a new cap (which it seems people are calling a "cam journal cap"). Mostly, I was just frustrated with this "throwaway" design. In looking at the valve cover, these grooves on the outer edge of the four journal caps do not fit into anything and as such do not appear to be a guide of any sort. The caps are attached via two bolts and those bolts keep the caps snug and aligned. This leads me to believe that these grooves are simply for reinforcement, which makes me a little more nervous that the journal cap will break eventually.

Regarding the loud "knocking noise": the mechanic assured me that the noise was the result of the engine going out of time as a result of the part failure. It is no longer making this noise as he re-timed everything. He inspected all of the gears and chains and assured me that there was no damage. The piece of metal is clearly very soft aluminum. Seems odd that a bearing surface of this importance would be made of aluminum. I rode the bike into work this morning and she seems fine. I'm guessing he is correct in his assessment that the pieces are down in the oil pan somewhere. My only worry is that they get into the clutch plates. Maybe that isn't even possible, but I'm now very paranoid about this bike. I suppose we'll see what happens.... After all, if she blows up or disintegrates, I'll just become a guy without a motorcycle, which is what I was three weeks ago. I have nothing to complain about.

On a more serious note, are there symptoms I should be looking for regarding the cam journal cap wearing out or breaking? I would like to avoid the cam seizing up on me.


pdwestman,

Just saw your response. I will call Eagle Mike today and see what they have to say. It would be awesome if they could weld the flange. Can you weld aluminum? I will take your advice and not ride for the meantime (except to get home from work today, of course).

Thank you all for your responses. It's awesome having a resource like this!
05-04-2018 11:12 AM
pdwestman I wouldn't advise riding it. The cam sprocket needs to be kept in-line with the chain & the lobes need to stay centered over the tappets.

A loud knocking noise & loss of power seems to be more than just a broken guide flange on a left hand cam bearing cap.

I'm pretty certain that Eagle Mike has welded a few broken or cracked bearing flanges on KLR's. Give him a call, Eagle Mfg & Engineering
Also, Engine Dynamics has repaired many cylinder heads of all kinds, ENGINE DYNAMICS

We can't see your parts.
05-04-2018 10:58 AM
DPelletier Paul's got more experience on this that I do, so listen to what he says.

- yes the cam caps are matched to the head.....a mismatched set can be re line bored but that'll cost a fair bit too. No easy fix here.

- I normally wouldn't worry about the damage to the lip, but I'd be concerned as to where the broken pce went and what damage was caused by the "loud knocking noise".


OTOH, you have little to lose by running it now as long as it all sounds normal. Eaglemike has talked about a fix for this in the past; I'd recommend giving him a call to get his opinion.

2 cents,

Dave
05-03-2018 10:56 PM
edaggett So, given the current damage to the raised lip, do you think I'll be okay to ride it?
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