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Hi Everyone,

I'm new to the forum but love the content and my Honda CRF450X! This is a great site! So, I have bum news there is a good chance that I seized my engine, my trail tech with temp sensor docking station failed and went out for a ride with ear buds in so, I could not hear the engine, felt hot when riding and when I took the earbuds out and listened I could hear a ping or rattling. I tried to limp it home and boom it died. I could get it into neutral, stator & electric start seemed to work but would not turn it over. I then by hand tried to see if the kick start would move and it's locked in place... bad news I'm sure. I typically do all the work on bike but when it comes to cracking the engine open I'm not confident in my DIY skills there and have sent it into the shop. My question to you is if a complete rebuild is needed and since the engine is opened up should or could I have them do any alterations to increase the power? I've done everything you can to the bike for performance mods except anything to the engine itself and figured if it's open and they need to replace it or components why not optimize the parts. I ride 75% single track/enduro in the Washington Mountains, like to jump but do not track race if that plays in Thank you in advance for any feedback!

Welcome to the site !!

I have a 06 , which is basically the same platform , I also ride tight single track .... and desert and like to run it on the track some times when my other bike is down for any reason ....

... The best "mod" I have done to mine is a HotCams Stage 1 ... it takes a little off the top end , but bottom it will lug in the slowest tightest stuff you can find and still pull pretty hard mid range , it just tops out quicker than stock , but I can still hit 75 mph with it with 13/52 gearing (gearing from a 13/51 to a 13/52 helps a bunch as well) the cam almost acts like a Flywheel weight , it almost completely eliminated stalling ..... , also do the Pink Wire Mod , which consists of opening the airbox door , looking at the square plug with 4 connectors but only 3 wires , remove the pink wire from the connector and either just leave it out and cover it up with shrink tubing or move it to the blank spot in the plug , or run it thru a rocker switch ( a KTM Map Switch works great for this and that way you can turn it on or off on the fly) and have it right next to your kill switch so you can turn it on/off at will , what it does is up the rev limiter to about 500 more RPM , and give a bit more punch off the bottom , my bike is on the stock/original piston and clutch with around 250 hours on it .... and it runs so much better with just the cam and the few other things I mention below

Also cut the top off the airbox , so it is more like a R , it will help it to breath better especially with the cam , if you have the stock muffler , remove the baffle , but keep the spark arrestor screen .... jet it correctly for your elevation

Jetting Guide for Main Jet:(pilot 45) CRF450R/X

Sea level....165
2000 ft.......162
4000 ft.......160
6000 ft.......158
8000 ft.......155


Temperature/Elevation:
One main jet size (up/down) for every 2,000 feet or 25 degrees in temp.






I do however have something on it that you should put on yours to prevent this from happening again ... A Radiator Fan

That alone will keep you from seizing a engine , it will run off a thermostat , and will turn on anytime the temp gets above what it should be .... and shut back off when the temp is within a acceptable range ... I did my own setup with a Spal fan off EBay , and a Temp Sensor from AutoZone and ran the wiring to the battery (thru a inline fuse) so it runs even after you shut the bike off (it won't run down your battery ... but I use a Shorai) ... but the TrailTech Fan kit is a really good unit and it is really affordable and is self contained , you just hook it to the battery and you are done ..it even has a digital temp gauge...

My setup:







Trail Tech kit:

https://www.crfsonly.com/catalog/produc ... ts_id/5360

I run the stock 05 450R muffler with a Pro Moto Billet Endcap for the spark arrestor , and sometimes if I am going to a place where noise is a issue I either put in the Quiet Insert , or , I run my stock muffler with the baffle removed

I ride from about 2000 to about 8000 without any issues ... I also use a Flex Jet Fuel Screw , that way if you are changing altitudes drastically while riding , you can just reach down while riding and adjust your fuel screw to compensate for the elevation change if needed , I also run a QuickShot Accelerator Pump Cover and a O-Ring on the AP linkage (under the black cover where the throttle cables go and around the linkage and the screw on the throttle cam) and a NCVS Needle on the 3rd clip position .... Also swap out the Leak Jet with a #65 (leak jet is the small jet in the bottom of the float bowl that goes to the AP)



R&D Flex Jet:
https://www.crfsonly.com/catalog/produc ... ts_id/2792

Hi JimDirt,

I can't thank you enough for the awesome feedback! What's cool is I've done about8 out of 10 of the items you mentioned but the few I have not I way overlooked. IE) my radiators are in rough shape and probably accelerated or attributed to this problem. I was looking on the site and RockyMnt Tusk replacement radiators the prices seem higher than what I was expecting at about 400-500 USD, I'm assuming stay away from the ebay china ones that are a fraction of the cost? In addition, I've already ordered the Trail Tech Fan "thank you" BTW, your bike looks sweet man! How did you change the color of the forks and is that an aftermarket triple crown or did you polish it too? The strap on the back seat is an awesome idea, such a simple add yet I never thought of it. Another question when you have time is did you swap your stator out, I'm running a Trail Tech Voyager Pro, Tusk Street legal kit, HID headlight, and at night sometimes Thumper Jockey 3000 High Output lights and probably need to go with a larger stator now.