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Henry Martin spends his nights writing fiction and poetry, which predominately deals with the often-overlooked aspects of humanity. He is the author of three novels: Escaping Barcelona, Finding Eivissa, and Eluding Reality; a short story collection, Coffee, Cigarettes, and Murderous Thoughts; and a poetry collection, The Silence Before Dawn. His most recent published project is a collection of Photostories in five volumes under the KSHM Project umbrella, for which he collaborated with Australian photographer Karl Strand, combining one of a kind images with short stories and vignettes. He is currently working on his next novel narrated in two opposing points of view. He lives with his family in the Northeast.

Tuesday, March 8, 2011

KLR 250 Project: Here we go again!

Having semi-successfully completed the KLR 250, and I say semi-successfully for a reason, I went for a ride this past weekend. A few miles into it, (and this brings me to the semi-successful part in this saga), a strange top-end noise made me turn around, go home, and investigate. At first I thought it was caused by the valves, even though I set them myself. When I arrived home, I took the valve cover off, checked clearances, and found them to be just as I set them 20 miles earlier. But lo, upon closer inspection, I discovered the exhaust cam to be, how to say this mildly...busted! 

Needless to say, I was pissed off! I spent all evening researching cams, their prices, and any aftermarket options. Having discovered that the cost of new cams, rockers, and cam chain exceeded $500, I was about to give up, cut my losses, and sell the bike for parts.
Fortunately, I frequent ADV Rider, and fellow ADVers whipped me a new one for trying to take the easy way out. I don't know if it was the pep talk about inspiring others, or the attempts to make me feel guilty, but in the end I decided to give this another try.

So, after an hour and a half in the garage tonight, I managed to pull the engine out (again) to investigate further.

Turns out the rockers look okay, as does the head.

Thus, the overall repair will be slightly less expensive and may consist of only a new cam (or two), new cam chain, and a new cam chain tensioner. By the way, the tensioner is the probable culprit at this time.

Which brings me back to the semi-successfully part again. I've checked almost everything on this bike. One of the things I did not check was the cam chain tensioner. Why would I? When doing the valves, the chain tension seemed okay, the engine rotated freely, and started and ran fine. Well, it turns out that the previous idiot of an owner broke the automatic cam chain tensioner and to remedy this, he inserted a long bolt in place of the cap screw. The bolt then applied pressure on to the chain and acted as a tensioner. One problem though: the bolt did not allow the chain to retract as it rotated around, which the stock automatic tensioner would have. So, and this is only my own theory, the chain was too tight and pulled the cam harder against the rockers, causing the cam to wear out. Surprisingly, the much softer cam bearing surface (the engine head) did not suffer great damage.

Tomorrow I'll be pricing parts, as well as looking for a complete used engine. Whichever way will be less expensive is the route I plan to take.

5 comments:

Keith said...

OMG, that's got to be so frustrating after all that work. Kinda makes you wonder what else the previous owner bodged up, doesn't it?

What does the availability and price of a cam look? Would a used one work? Seems like there'd be some low mileage ones out there.

I'm glad you're going this route. You've put too much time and money to walk away at this stage. At least get that thing in the woods for an afternoon and then you can cut bait.

Henry Martin said...

Frustrating? Nah, frustrating does not describe it. What pisses me off is that I could have prevented this had I known.

Used cams are non-existent on Ebay and all the other places. I could get my cores hard welded and ground, but than you are looking at performance angles and the potential to having to upgrade rockers, springs, etc.

I'm currently negotiating on a used KLR 1989 (same as mine) with 11k miles on it to salvage the motor and do an engine swap. Easier than buying new cams and putting them in an old motor. This time, however, I'll check everything :)

Keith said...

That makes the most sense, then you've got some parts to sell off to finance the whole thing.

Jack T Bear said...

Greetings All
Well this is a fairly common concern of the KLR250 engine design.
I,ve just finished doing a post mortum on my D9 and have the same problem.
So as not to give your previous owner too much of a pasting, the cam chain tensioner mod is not the root cause of the failure, Low surface hardness and non synthetic oil is the cause of these failures.

Anonymous said...

The "Manual" cam chain tensioner is actually quite a common mod for dirtbikes (KLR, DR, etc). Unless it's ridiculously lose or overtightened it would not be the cause. Now - KLR250 seems to have a habit of chewing cam lobes. Not sure why perhaps the oiling mechanism is not perfect. I always top up the oil religiously and it still worn out.