416 and XR cam

[RR900_Pilot]

By looking at the past posts, I can tell that this discussion has taken place many many times, but I would like to get input yet again.

I am going to go to a 416 on my 2000 EX soon and was considering other options since I will have the top end open any way.

Here is what I have today...
White Bros. e-series with 6 discs
White Bros. rev box
UNI foam filter with lid removed
Jek kit with 150 main
other non related accessories

I have read posts about the XR400 cam--
It is just a drop in. Correct?
What other valve components will need to be replaced as a result of the new cam installation?
I am going to go ahead and do Viton seals.
What can I expect to be bad, or good about the install? What other changes need to be made (jetting etc)

Piston:
Probably going with 11.?:1 and continue running pump gas.
JE or Wiseco and WHY?

XR400 gasket to up the compression a little more???

Will I need to do anything to the crank and bottom end because of these mods? If so, I probably need to back off a little (wife thinks this is a cheap hobby).

Thinking about letting Marcums do the machining. Any complaints? How long does it take and approximately how much will shipping cost?

Thanks

[VegasEx'r]

The xr cam is a drop-in, and you don't have to change anything except for the valve seals. There's nothing bad about the installation, just make sure to break it in properly. Once the old cam is out, make sure to not let the cam chain fall into the crankcase (that would be real bad).
As far a jetting goes, I would always prefer to foul a plug instead of burning up my piston (or something else equally bad), so I like to start rich & work down. I don't know what elevation you ride at, but I would probably start w/ a 165 main. Once that is dialed in, you could maybe try a 40 pilot (or if you decide to remove the choke, go to a 42).
My understanding of advertised CR's is that they were done using the xr head gasket, so using it will put you very close to 11:1. Remember that 11:1 is the line that usually requires race fuel when you cross it, so I don't know if you will be able to run it with pump gas. With the 10.8 piston, Sparks advance key & xr gasket that I use, I was pinging at the top of third gear. I am still. playing with fuel mixtures to see how little race fuel I can use, but so far, I have found a 50/50 mix to work best. My point is, w/ 11:1 CR, you may have to yse race fuel, & it usually isn't cheap. You don't have to do anything to your bottom end. I don't know about Marcum's machining, but his prices are good.

[mopar 400]

I am in the same boat as Vegas EXR and just ordered the 416 kit, Whited brothers valve seals, and a xr400 cam from Marcums. I am letting my engiune builder throw it all together in a few weeks, and then on the Dyno it goes. I was wondering what type of breakin process any of you with the kit installed went through, and how much performance I can expect from this kit?

Also have any of you done any mods to the stock carb, or went and bpught a new one??? If you ran the stock, what type of jetting changes did you make?

[RAPTORAZ]

If a strong midrange pull is what you want, then an XR cam will deliver. However you need to open up your exhaust. 6 discs is much to few. You need more like 18 discs. Look in my signature for my recommendations on tuning.

[shook]

Before I ran the xr 400 cam again I d call xrs only and get a hrc copy cam little more cam and believe youd be much happier with it.