hey there fellas.

Bottom line i have a good head besides the fact that it eats camshafts. I want to explore ideas to get things back in order. I suspect the camshaft journals are worn out as this is the second cam this has happened to. Its sitting in there tilted so each lobe gets the clutch side of it worn down.

So what do you think? San i have a good cam welded and then cut down, hone out the journals and get a tighter fit?

Are there any types of sleeves that would work for this to put over the camshaft or in the head journal?


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I know i could get a used head but i want to avoid gambling on a head that could give me the same results as i currently have. I wouldn't be able to inspect it (ebay). On top of that who knows what the condition of the valves and seats are of a used head.

Thanks for any ideas/input

 

If you changed the exhaust rocker arm along with the cam,then probably is the head. You can take it to a machine shop,but your cheapest best is to find a later model used one. This rarely happens except on older, abused machines. Several later model heads on ebay,plus have the journals measured on your old head to the book specs to make sure this is the problem. http://www.ebay.com/itm/2008-Polaris-Sportsman-500-H-O-Cylinder-Head-with-Valves-/361054198281?pt=Motors_ATV_Parts_Accessories&hash=item541081da09&vxp=mtr

 

I held off on the head until I checked out mine right now and here's where I'm at...

Well we tore into it this weekend and my dad got some of his mics out. The clearance from the cam to the bore was .002 vertical and a little more horizontal with the telescoping bore pin, but still within specs and the limit. The rocker shaft has some wear on it and the rockers can tilt side to side while on the shaft, however, they to are within spec. With a depth mic, we measured how much slop the cam had, and couldn't get it to move more than .002".

So the original cam got chewed up, all three lobes were scarred, diameters were all well below specs and the exhaust lobe was practically gone. I found an aftermarket replacement and put it in. Great, problem solved right?!

Nope
After a year or two I went back to adjust valves and check on the cam.
The replacement CRU aftermarket camshaft and (all 3 new) rockers were scarred up.
Crap. That's not what I wanted to see.

This set has a lifetime warranty so I had it replaced 500 miles ago when I rebuilt the motor.
And now the replacement CRU camshaft and again new rockers are yet again getting chewed up.

Where do I go from here?

1999 Sportsman 509. wiseco 93mm forged piston. Moose gaskets. CRU aftermarket HO camshaft. new diaphragm and block. Summit water temp gauge. EPI clutch rebuild. custom spacers on both clutch springs. runnin Mobil 1 0W-40

 

If all your measurements are within specs and you've gone through two of these particular aftermarket cams,then I'd try another brand or bite the bullet and get the oem cam. This is one company that has had a good reputation in the past.http://www.hotcamsinc.com/ProductInfo.aspx?item_id=6616

 

A hot cam or one of the popular sets on ebay was gona be my next choice. One from superstore has 61 sets sold

One of my other bikes is at the shop for a rebuild right now, doing the cylinder and a full valve job.
He took a look at the cam and rocker on this one and thinks it could be an oiling issue?....
If things are within spec then it would have to be either oil or material quality, correct? Said to run 15W-40 during the summer. Everything I have read says this is what to do if you want to ruin your cam...

I get 5-9 psi or so on startup and by the time it's done warming up and I ride it's down to 2 psi or something, hard to read it that low.
I have a wiseco right now and I like to let the bike warm up before I ride it. How much should I let her warm up?
Were there any changes in the head/cylinder to allow more oil flow to the cam in later years?
I'm waiting to get the 04's head back from the shop to compare. I checked it's oil pressure before I tore it down and got the same readings as my 99.
Only part I could hung of is the hole from the head bolt to the cam journal that would allow more flow.

1999 Sportsman 509. wiseco 93mm forged piston. Moose gaskets. CRU aftermarket HO camshaft. new diaphragm and block. Summit water temp gauge. EPI clutch rebuild. custom spacers on both clutch springs. runnin Mobil 1 0W-40

 

Don't use 15w40,too thick for start up.. Oil pressure should be around 20 psi at 5500 rpms on average. 12 psi minimum.Not accurate if you test pressure at an idle. If you can't get at least the 12psi listed,then the oil pump may be the cause of the problems.

 

Thats what I thought too.

The oil pump was replaced at the rebuild. Brand new pump. And I do get 20 psi at the specified rpm.

 

Could not enough oil getting to the cam cause this uneven wear?

1999 Sportsman 509. wiseco 93mm forged piston. Moose gaskets. CRU aftermarket HO camshaft. new diaphragm and block. Summit water temp gauge. EPI clutch rebuild. custom spacers on both clutch springs. runnin Mobil 1 0W-40

 

Possible if oil passage is blocked,but a quick way to tell is to have the cam cover off and check oiling on top end as it's running. Kinda messy.You can also pull the bolt,spring and valve on the one way check valve to see if this area is stopped up,but it's mainly there to stop oil from draining into the crank case from the oil tank when the engine is off.

 

Thanks again OPT.
how does this sound?

When i get home this weekend i will throw the cam back in and pull the spark plug, crank it over and see if i get oil flow. Just as a quick check so i don't have to put the gas tank and healdlight pod back together. If that doesn't work I'll hook the tank up and run it. My block and oil tank heaters will come in handy so i can test oilflow with cold, and hot oil.
If i am getting oil I think we would assume that its probably the cam at this point, and I would be looking at this one. Has a 1 year warranty which is enough for me to rack up some miles and check out the cam again. http://www.ebay.com/itm/321177391332?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
And if that cam doesn't work out ill be looking for a new(er) head.