1992 KX500 Snow bike engine for Brent

[Sandblaster]

Here is a view from the exhaust port... Before..

KX GURU RACING 1992 KX500 SNOW BIKE ENGINE BUILD FOR BRENT 135.JPG (53.21 KiB) Viewed 33196 times

And after the rough cutting is done..

KX GURU RACING 1992 KX500 SNOW BIKE ENGINE BUILD FOR BRENT 136.JPG (56.6 KiB) Viewed 33196 times

Now I need to finish the other side to match.
Then, I need to install the exhaust valves and mark them so that I can get the ports to match the open and shut position of the valves for maximum flow.. Breathe baby breathe!

[Hartmanbw]

Man I'm so excited! It's gonna be torture breaking that bad boy in!

[Sandblaster]

Ok... I wasn't gonna say who's engine it is but now everyone knows lol..
Yes, we have a whole series of directions for breakin which include re-torquing the cylinder base nuts and the head nuts.
KX500's are notorious for chucking head gaskets during the first hour or two of operation if you don't re-torque them.
If you follow the directions you won't have any issues.
I'll email you the list.
It's nothing special or difficult but it is something that needs to be done.

I know your going to run a Smart carb.
What pipe and reed valve are you gonna be running?

[Sandblaster]

Ok... I have both sub ports roughed in.

KX GURU RACING 1992 KX500 SNOW BIKE ENGINE BUILD FOR BRENT 137.JPG (115.03 KiB) Viewed 33192 times

The cool thing about this porting is that if Brent decides at some point that he needs more power, we don't need to do a lot of work to boost it.
Add a base gasket spacer and take a bit off the deck and your going again..

[Hartmanbw]

We had talked about doing the 10mm reed spacer acne the v force 2.said you guys know a guy that does a billet combo of the 2? And my pipe is an fmf gnarly af pipe as o have an aluminum frame. I want to upgrade the pipe, but haven't been successful in finding another set up that's not a custom cone pipe...

[Sandblaster]

That's right...
I have talked with so many people about K5 stuff since then that I spaced it..
A custom cone pipe would be crazy... but not cheap..

[Hartmanbw]

Yeah, not really in the budget right now, and don't know anywhere to do it that's close enough to bring the bike in to have it fit. Not to mention it's snowing in the hills! Haha

[Sandblaster]

Yeah... At this point we are waiting for gears to come in..
I'll call our vendor and see if there is any kind of update..

[Sandblaster]

Last week before I sent the crank out I took some pics and forgot to post them.
A lot of guys don't know that when you send a crank off to have it rebuilt, the company that rebuilds them does not clean them unless they come packed in mud or something... Even then they will probably knock just enough of the mud off so they can press it together
I have had cranks rebuilt by many different companies so it's a common practice.
So, some time ago, Jason and I decided that we would clean them up before sending them out and the results were immediately noticeable.
Here is a comparison of a crank half that we cleaned up, vs one that is not cleaned up.
I did not polish the whole crank, but I did the OD as well as where the rod bushings go.

KX GURU RACING 1992 KX500 SNOW BIKE ENGINE BUILD FOR BRENT 138.JPG (151.77 KiB) Viewed 33180 times

KX GURU RACING 1992 KX500 SNOW BIKE ENGINE BUILD FOR BRENT 139.JPG (119.25 KiB) Viewed 33180 times

[Sandblaster]

Making sure that you get all the foreign material off isn't exactly easy but the results are worth it.

KX GURU RACING 1992 KX500 SNOW BIKE ENGINE BUILD FOR BRENT 140.JPG (133.42 KiB) Viewed 33179 times

One other point... Remember how bad the bearing journal looked on the left crank half?
Well, it was undersized by a couple of thousands.

KX GURU RACING 1992 KX500 SNOW BIKE ENGINE BUILD FOR BRENT 107.JPG (129.42 KiB) Viewed 33179 times

Some guys will still use them by applying some loctite on the journal.
But this does not address the issue that cause the problem in the first place.
Sure, it will work for a while but that is not the kind of engine we want to build.
I took the crank half to a company that does industrial hard plating.
They grind the bad journal undersize just enough to get it to clean up.
Then, they plate it just slightly oversize, and finally they grind it to the correct tolerance.
It isn't cheap to get done but it is a lot less expensive then buying a new crankshaft.