Changing XR 400 Cam

I have to remove auto decompress. I was thinking of installing new cam while I'm in there. Does anyone have a suggestion of what cam? I trail ride only and I'm keeping original piston. (Can I change cam without removing engine from bike?) Any infoe will help.


Why are you having to remove the auto decomp?

You're probably looking at something like a hotcams stage 1.

Yes, you can replace the cam without removing the engine.

If you don't have a shop manual, download it. You'll need it.

go stage 3 mate, if u dont like it ill swap my stage 2

all the hotcams for the XR are incredibly mild anyway, i got the stage 2 and was told "FOR DESERT AND MOTOCROSS ONLY", put it on, besides a little more top end there was nothing too exciting going on.

and its very easy to change the cam without removing the engine. VERY :thumbsup:

Thanks for the info... The reason I need to remove it is it keeps sticking. When it does, obviously tough to start with a compression stroke...LOL Getting worried it may happen when I'm deep in. Would hate to push out. Too old for that stuff anymore...

if you do cam it, change the carb, and dont just get a 36mm pumper, its gotta be a bigger bore 1, changed mine to a bst40 yesterday, been fiddling with jetting, got it perfect, the standard 36 could never feed the stage 2 cam, i am simply amazed with how fun to ride my bike is now

Makes sense. May have to wait on carb change. I have 36 pumper now. I should also change cam chain also, right? Should I just get stock chain, or is there a better aftermarket one you would suggest.

I have a Stage 1 HotCam with a Mikuni Pumper and I have no complaints. You will need to use the manual decomp lever with the HotCam though (or at least I do). You don't have to replace the cam chain unless it is stretched or if you have enough hours / miles where you would want to do it for preventive maintenance. I have heard they use CRF450 cam chains but I am not sure if there are certain years or if they are all the same.

OK,..I'm going in, shop manual in hand. Can anyone give me an idea of any special tools or anything I may need before I open her up? Appreciate the help

If you're just replacing the cam, no special tools are needed.

Special, tool, a zip-tie, make sure you support that cam chain, cause if you drop it......

I see in the manual that you need to make a stopper plate to reinstall the cam chain tensioner. Do you even need to remove it? Other than that I'm all set. Thanks everybody !

Don't need to make the special tool. You can retract the tensioner plunger with a regular screwdriver. The special tool is just made in such a way as to hold it retracted.

Removing the tensioner gives you the chain slack you need to pull the cam away from the head to get it out.

I see in the manual that you need to make a stopper plate to reinstall the cam chain tensioner. Do you even need to remove it? Other than that I'm all set. Thanks everybody !

I just watched a short video on the cam chain tensioner from someone on TT. A big help... Thanks to everyone ....I appreciate it

last question....Someone told me that replacing the cam without a higher compression piston would make no difference...? Will I feel any more snap with the stage one and stock piston? I have a Mikuni 36 pumper, snorkel removed, 49 tooth rear sprocket, Big Gun Rev Limiter. When I changed the cam on my Harley, there was a noticeable difference. I hope someone says it's worth doing.

you will need a magnet on the end of a drill bit :thumbsup:

what's that for?

you'll feel a difference, but go for a bigger carb PLEASE!!!!

whoa, guess i should refresh before i post, the magnet on the end of a long drill bit is for retrieving the cam chain when it falls :thumbsup:

The cam and gaskets are in. I'm doing it next Saturday. Should I change cam, then ride it for 20 min or so, then change oil and filter? Or change oil and filter before starting and breaking in cam?

If you were going to change it anyway, do it now.

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