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Discussion in 'Thumpers' started by leonphelps, May 16, 2007.
front is 17mm if its stock
I need you guys' help! I bought a cheap 1993 DR350s with a rattle sound. Checked the timing chain tensioner and it was all the way out! So i thought it was just the chain and bought one. Upon removing the head cover I found this... (Please excue the previous owner's overuse of sealant).
Metal shavings around cam
SEVERELY gouged rockers
Gouged Cam journals
I do not know what to do next. I have a head cover/rocker assembly from an old DR but the rocker arms have different numbers on them, 7s on the old one and 1 and a 5 on the "new" one.
Notice in the pic below, the journal on the right is missing metal and the rocker is chewed up.
Below shows the metal shavings.
More metal shavings and the cam does not look too good either.
Damaged head cover on the left (rockers stamped 7 & 7). A "new" cover on the right with rockers stamped 1 & 5.
Damn, that's not good. You might simply replace the rockers and camshaft (and clean the metal shavings up). It would fix most of the problem and only cost 25% as much money or so. That cam scoring isn't too bad at all and only has much scoring in the center part - DR's still seem to run okay like this, but are a bit noisy. Replacing the head cover might work, but the two parts have the camshaft hole drilled at the same time, so it might not line up? Something to check/think about. Good luck!
I actually have a spare camshaft with manual-decompression like yours, good condition. Message me if interested.
Oh, some guys use old camshafts so they can make "upgraded" ones, so don't toss it in the trash.
Check my build thread for a similar problem. The previous owner of my Blue Bike had run it like that until it bound up and sheared the cam. First thing you need to do is remove the camshaft and look at the journals underneath. Likely they are munched so your best bet is a new cylinder head. They are pretty coveted because failures like this happen more often than you'd think. It's generally attributed to oil starvation.
Send me a PM if you end up trying to do a head swap for an E start head on your kick start bike. I did that on my blue bike and have been riding it ever since.
********For reference here's my build thread: http://advrider.com/index.php?threads/dr350-fun-build.1166102/ ********
"I crashed while looking at the marks. Can I have 10$?"
I crashed while reading about him looking at the marks. How bout tree fiddy?
Common problem from owners running them dry on oil, because they burn a little oil and the owners never check the oil. Mine was worse than that when I got it. I ended up replacing the head and cam. While I was in there I found heat damage to the cylinder wall and gouges on the top of the piston from someone putting the wrong spark plug in. I would suggest you tear down the head the rest of the way. You're already in there, won't take much more work to get it off. Better to check.
I suggest you replace the head, cam, and cover. They should be matched obviously so try to buy them all from a single seller. It will take some time for you to keep watching for a head in good shape. Beware ebay sellers who sandblast/mediablast the head. It disguises any wear in the cam journals, but will wear at a very-accelerated rate if you try to run it. I've seen a few heads like that. Just make sure the cam journals are shiny, and not a matte finish.
You could also take this time to put a big bore kit in it if you want, but that's gonna be more $. Good that you got it cheap though.
Have you or a loved one suffered from injury or death while taking advice from people on the internet? Call the law offices of Woody & Johnson.
Regarding the head and head cover required matching I found that it's not true. Here at http://www.motorcycleproject.com/text/lies_mother.html
if you go down to the "Item: The "Line bored" swirl " Mike Nixon says "Align bored or not, the cam cap on an early Honda DOHC four or CBX, a Honda V4, any number of Honda, Kawasaki, Suzuki and other overhead cam engines, can indeed be put on another cylinder head of the same model, without problems."
If Mike Nixon says it, it's probably right.
Never heard of him.
You might get away with it, but using matched parts that are bored together has got to result in a better out come. I would not use mismatched parts.
Brand new heads and cams? Sure, switch them around if you want. The problem is that in used heads, when the cam rotates in the journals, they create small peaks and valleys. The cam is worn into these peaks and valleys and is contoured with them. When you put a different cam in, it will put more pressure on the peaks, and rapidly wear them down. This will create freeplay between the cam and journals and accelerate wear more and more.
The point he makes on the website is that they are not usually bored at the same time, but on separate machines. No clue on the validity of that, but he seems to have a personal bias against people on forums. God forbid someone else just as experienced as you has a different opinion.
That simply doesn't make sense. Boring a half hole would deflect the boring tool and be really inefficient. I've never heard of any process that would bore a bearing surface one half at a time. Crank shaft bores are not done that way and align re-boring is not done like that.
Its becoming clear, at least to me, why no one has heard of this Mike Nixon guy...
Perhaps he's not saying that each half is machined separately. It is theoretically possible that the bores are located so accurately with regard to dowel pin locations and mating surfaces that the parts can be interchanged. It seems to me that this would need to be verified on a case by case basis. Perhaps Mr. Nixon has verified this with enough of a sample size that he concludes they must be interchangeable 100% of the time.
OEM parts are sold as matched pieces.... http://www.ronayers.com/oemparts/a/suz/50d3ab7ff8700220d0b72260/cylinder-head .... If you are buying used parts, you have the choice to buy matched parts or not. Your choice.
To be fair it looks like he's more experienced in motorcycles than most of us. Curriculum developer for Motorcycle Mechanics Institute is pretty legit. http://www.justcarbs.com/about/about_v2.html
Haha, yeah, I'd say that's a pretty good claim.
Is it just me, or does anybody else think wkbogie would probably be okay with a new camshaft and rockers? That alone would probably improve his engine rattle by 2/3 at least IMO. (and cost a lot less) A bit of scoring on the center cam journal doesn't sound too bad to me, and the two ends look great... Thoughts?
I bet guys would buy your top end as-is for around 100$ plus, so don't throw stuff away if you decide to replace it all. Top end stuff is valuable, even with some damage