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Discussion Starter · #1 ·
So I have decided to tear down my 03 and do a full rebuild. Got a bad tick on the last start so I figured I would check things out. Guy I bought it from said it was a 440 so I wanted to measure the piston and verify it had the stage 2 hotcam as well.

First thing I noticed was both jam nuts on the intake valve adjusters were completely missing. The adjustment screws were hitting the caps. Found the nuts under the valve cover by the timing chain. Bad news. What damage can that cause? Mashed valves?

I did find a Hotcam installed. Can't ID it though. I'll get some pics later today.

Bottom line is I'm planning on building this this this as much as possible. I ride with a few guys who are all on 450r so I want my 400 to stop their bragging. Looking at a whole top end rebuild kit. Wondering what to go with though. Looking at a BP Racing kit with 89mm cylinder, CP Piston, and Cometic gaskets. Looks like it runs 11.5:1
What gas will I need to run this? Or is there something better?

I currently have a full Yoshi exhaust, Keihin 39mm FCR, Big Gun CDI, Uni filter with no air box lid. Not really concerned with cost (to an extent) and I want this to be the baddest 440 on the block so to speak.

Also not sure if there is any reason to rebuild the bottom end?

Thanks for the help in advance guys. Looking forward to hearing what has worked for others here and I will keep updating this as I move along with the build.
 

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Discussion Starter · #3 ·
I can live with that. 92-93 octane with dominator octane boost gives me a solid 96 or so. If the previous owner told me the truth, and it's a 440 already, I think I've been pretty lucky. Never overheated, never ticked, never blew head gaskets. Hopefully this build will be as reliable.

Here's my list so far:
1. BP Racing TRX 400EX Black Diamond Valves Springs Guides Head Rebuild Kit https://www.amazon.com/dp/B00MYD1L8Q/ref=cm_sw_r_awd_QMIevb1WGEP5S
https://www.amazon.com/dp/B00MYD1L8Q/ref=cm_sw_r_awd_QMIevb1WGEP5S

2. TRX400EX 400EX 400X ARP Heavy Duty Studs Stud Kit https://www.amazon.com/dp/B00UY5JUD4/ref=cm_sw_r_awd_SNIevb01EDG6D
https://www.amazon.com/dp/B00UY5JUD4/ref=cm_sw_r_awd_SNIevb01EDG6D

3. TRX 400EX 400X XR400 89mm 440cc Big Bore Kit https://www.amazon.com/dp/B00POM1E9U/ref=cm_sw_r_awd_KOIevb07QE55B
https://www.amazon.com/dp/B00POM1E9U/ref=cm_sw_r_awd_KOIevb07QE55B

4. Port & polish

5. Re-jet and hopefully get the tune right.
Any other suggestions?
 

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