Purchased Hot Cams-What Next/Else?

[Kawabuggy]

I purchased the HOT CAMS Stage 1 cam for my '93 XR600R last night. I am waiting on it's arrival. I plan on pulling the head to replace the valve guide seals, do a valve job (if needed) and replace piston, rings, wrist pin, and w/p retainers all in one shot.

I was wondering if the cam replacement will require re-jetting the carb? Now that I have the cam coming, should I buy one of the high-flow side covers-the type with the screen inserts? The bike already has a K & N air filter on it that was installed by the previous owner. The bike is being shipped to me so I don't know if the snorkel bypass mod has already been done. Heck I don't even know if this bike came with a snorkel on the air cleaner. Regardless, if it has a snorkel, I will bypass it, or remove it.

What about an after-market exhaust? Should this be my next step? I have heard that the exhaust should have been my first step, but the bike is burning oil pretty badly so I knew I was going to be doing top end work 1st, so I decided to just go ahead and do everything on the top end all at once.

I would like to get a stainless after market exhaust as the stock one on the bike is missing the heat shield, and is rusty. How much should I expect to pay for the header? What about a "slip-on" muffler? How much should I expect to pay for a different (preferably smaller) muffler? Are some better than others? Which is a good one at a reasonable price (under $200 is reasonable to me).

Any other updates that I should consider at this point to make the bike more reliable, and have more power?

I must admit when I had my old Yamaha TT600 I tried to find performance parts for it but there really was not that much available. I like that you can find a plethora of performance parts for the XR's..

[Beyond The Pale]

If the ability to run 87 octane is not a requirement, then get a high compression piston. You can also go big bore and get a 100mm piston. That will boosts you to 628cc from the stock 591. There are 10.25 or 10.5 to one pistons available that will run on premium. The Honda HRC kit piston is available, but it is 11 to one and may present issues with premium gas. There is a guy on ebay selling those HRC pistons for something like $18 plus shipping.

Aftermarket exhaust will help, but I don't think there is much available for $200. I have the stock pipe, but I got a replacement baffle. The stock baffle has such a tiny hole that it really does lcork up the exhaust. The aftermarket baffle was only $80 or so. It flows much better, but it is still very quiet compared to some of the aftermarket exhausts.

The bike did come with a snorkle. I have mine, but it was already removed from the bike when I got it. I have never seen a XR600 with the snorkle installed. As far as the drilled cover goes, it is not as needed on a XR600 as it is on a XR650R. The air inlet at the top of the airbox is pretty big.

When you pull the cylinder off, take a good look at the transmission gears. Third is the gear most likely to have issues. Second and fourth can also have problems.

I pulled my top end last year because it was blowing oil out the breather. When I took mine apart I found that both second and thired gears were pretty bad. I split the cases and replaced them. Not cheap, but it was less expensive than if a gear blew up. I ended up just doing rings since the piston and the bore measured well within specs. That was OK since I had to spend my piston and bore money on tranny gears.

A few years ago I had a bad valve. It turned into a nightmare. First I took it to a local shop and they tried to fix it. They didn't. I had it apart again a few months later. I sent the head to XR's Only and they fixed it right with 2 new valve seats. Then I put it together with the old cam chain and tensioner. The tensioner failed a few months later and I had to take it apart yet again to put in a new tensioner. I did a new cam chain too.

[Billahjack]

General tips. I don't own a XR600, but I have tinkered with the XR650R's.

An engine is an airpump that burns fuel. Pumping more air allows you to burn more fuel and make more power. Keeping this in mind, a cam allows more air to go into the engine. This will require a larger jet. I would suggest getting the next 6 consecutive larger main jets. Go up one at a time until you get rid of the bog associated with opening the throttle. When the bog is gone, you are close. I would do a ride, get home and check your spark plug. If it is light brown and flaky on the tip, then go one size larger on the main jet. If you get a surge while transitioning from full throttle to closing the throttle, your main jet is too large.

If you open up the intake, you probably need to open up the exhaust to keep the air flowing through the motor. If you choke off flow somewhere (intake, exhaust, cam/valves), then that is your limiting factor.

Listen to your bike run before installing the HotCam so you know what your valve noise sounds like. I found it hard to adjust the hotCam valve lash and am still working on it. THe bike starts ticking at the end of the ride right now. I'm going to adjust them 0.001-0.002" less than stock reccomendation next time.