I have an irregular wear pattern on my upper bridge. There is one area that is darker than the other areas and I figured I may as well replace the bridges while Im in there. Any idea on the cost here?

 

Is it obvious wear that you can tell needs replaced without measuring?
Bolt it back to gether without putting the cams in, torque to spec, and then measure internally with a bore gauge (little telescoping thingy that you measure with mic or caliper after removing from bore), all around at several locations, particularly where you see the wear mark. I can give you the specs later, I'm at work and don't have access to the shop manual right now. You got your manual yet? I'm just assuming this spec is in the manual, because my Honda manuals give these specs (350X has no ball bearings on the cam either).
Wonder what the wear is from - your motor doesn't have many hours on it. Maybe the previous owner ran briefly with no oil pressure or something, for some wierd reason??

 

Rockey,

You will see more wear on the top of the cam bores simply because that is where the cam spends all of its time spinning against. This is because the cam is always pushing down on the valves and overcoming the valve spring tension which in turn pushes up on the cam while it spinning. The cam bore is is slightly larger (.001-.002)then the cam diameter so the cam doesn't saddle into the bore perfectly, causing only the center of the upper bore to wear. This is normal and no cause for you to blow a couple a hundred for a new one. If you run a top quality oil, made for four stroke motorcycle engines and change it regularly, wear will never be a problem. On the other hand, Getting beat on the hill IS a problem so put that money to better use... [img]i/expressions/face-icon-small-wink.gif[/img]

 

Rocky -
I know you're doing port work, but why do you have your cams out? Are you just doing a valve adjustment, or are you gonna do more performance modding than just the portwork this time around? I ask because of what you said earlier about the cam sprockets, and the sprockets wouldn't be coming off unless you were changing cams! What's up your sleeve?[img]i/expressions/face-icon-small-wink.gif[/img]

 

<< Rocky -
I know you're doing port work, but why do you have your cams out? Are you just doing a valve adjustment, or are you gonna do more performance modding than just the portwork this time around? I ask because of what you said earlier about the cam sprockets, and the sprockets wouldn't be coming off unless you were changing cams! What's up your sleeve?[img]i/expressions/face-icon-small-wink.gif[/img] >>



I actually took the sprockets off before I realized that they didn't need to be removed, but it did make it easier to get the cams/timing chain out. Everything on the head has to be removed so when the port work is done the head can be cleaned really well. With all the tiny bits of metal flying around, its hard to tell where they try to end up. I was really surprised by the odd wear pattern on the cam bearings considering I only have about 25 hours on the quad and it has been maintenaced well and never overheated. I am going to have an engine builder look at the bearings and see what he thinks about them.

Good points JSDS! I think I will put the money towards more go fast parts if it is still in spec.

 

With all the secrecy that goes on with internal mods these days, you never can tell what a guy is doing!

 

<< With all the secrecy that goes on with internal mods these days, you never can tell what a guy is doing! >>



Dude, you are not kidding!! I couldn't believe it at first. You would think that this is the NHRA where there are high dollars at stake. Im used to a Mustang website Corral website where everyone shares everything they can just to help each other out. Even the NMRA racers that I ran with would share just about everything. The only real secret to winning is hard work.