426 kit install

[ATC350X 85]

I will be helping my friend install a J&E 426 kit in his 05 400ex. I am mechanically qualified for this but I would like to know if there are any tips, tricks, things to watch out for etc when doing this job. Anything to be careful of upon disassembly or assembly? I believe he is also going to get bigger valves, porting and a stage 1 cam. Anything to watch out for when putting in the cam? Does anyone have a thorough write-up on this kit? Thanks in advance.

[Franky G]

I would recomend if you put a 426 bore upgrade to heavy duty studs from GT Thunder its worth the money!

[Chino886]

Originally posted by ATC350X 85
I will be helping my friend install a J&E 426 kit in his 05 400ex. I am mechanically qualified for this but I would like to know if there are any tips, tricks, things to watch out for etc when doing this job. Anything to be careful of upon disassembly or assembly? I believe he is also going to get bigger valves, porting and a stage 1 cam. Anything to watch out for when putting in the cam? Does anyone have a thorough write-up on this kit? Thanks in advance.

1. make sure you don't over torque any bolts..

2. make sure the timing chain does not drop or come off the gear, big headache if it does.

3. make sure you take out the decompression mechanism and spring

4. make sure the gaskets are good.

5. go buy a complete gasket set from the local honda dealership

contact me if you need anything else

[exracer416]

what chino said if you are putting in a hot cam you dont need the decompression spring setup but keep those little things around its like 10 bucks foir that pin other than that dont over tighten the rocker cover bolts and have fun

[ATC350X 85]

Chino, I briefly looked thru my xr 400 service manual, similiar engine. Does the 400ex need to be spun counterclockwise to be lined up at TDC? Also is there a way to zip tie the cam gear to the chain or is the gear too big to slide thru the head/cylinder when removing/installing it?

With the hot cam i remove the decompressor assy? Im unclear on the procedure for that.

[Chino886]

Originally posted by ATC350X 85
Chino, I briefly looked thru my xr 400 service manual, similiar engine. Does the 400ex need to be spun counterclockwise to be lined up at TDC? Also is there a way to zip tie the cam gear to the chain or is the gear too big to slide thru the head/cylinder when removing/installing it?

With the hot cam i remove the decompressor assy? Im unclear on the procedure for that.

Hey ATC,

remember one thing, I am no expert, but I have done this before....yes you need to spin it counterclockwise to line it up at TDC...if I were you I would just take the cam gear off since you are taking the cam out, just zip tie the cam chain to the frame...the decompressor mechanism and spring need to be removed if you are going with a hot cam....if I remember correctly, it is on the left side of the head (facing front) in a little hole...

Let me know if you need any more help...

[ATC350X 85]

Cool, hopefully we will be tearing it down this weekend to have it bored and whatever else he plans on doing to it. I'll let you know how it turns out.

[dariusld]

Replace the two screws for the cam gear with new ones. This might help. (http://www.lspsonline.com/howto/400ex%20hotcam/) Be careful with the valve cover bolts, the bolts and the threads strip easily,don't over torque.:mad:

[ATC350X 85]

Thats a good detailed write up. Do you know of any for a 426 kit?

[ATC350X 85]

The 426 kit was very easy to do and it came out well, he went with a stage 2 cam. We are in the process of breaking it in. Now we need to jet it a little better. Thanks for all the help guys.