x400r Posted October 1, 2005 are the xr400's with the 440 big bore kit very reliable? how many miles would you expect to get? do they run alot hotter? dwight? you out there? Share this post Link to post Share on other sites
Trailryder42 Posted October 1, 2005 I guess I'm about to find out, as I just had a 440 kit installed in my '00 XR4. It does run hotter, which is why Thumper Racing recommends running a cooler plug (NGK DPR9). It's best to run a good quality full synth oil too. My temp dipstick normally stays between 220*-250*. Share this post Link to post Share on other sites
Mike_Rides_Red Posted October 2, 2005 A XR 416/426/440 are very reliable if your bike is 1999 or newer. Older XR 400's have weaker tranny, crank pin, and starter spindle that might break if you have high horsepower. Share this post Link to post Share on other sites
hxr400 Posted October 2, 2005 I installed the 440 kit, 12 months ago, never had a problem. They are just as reliable as standard. I dont think of ever heard of anyone writing in a post about having a problem with a big bore kit! Share this post Link to post Share on other sites
Rockjockey Posted October 2, 2005 I got mine done 2 years ago,nothing but big grins since. You might find you need a heavier clutch set-up to handle the new found horses. The Hinson 8 plate set-up sold by XR's Only did the trick for me, and it really tames the heat created by the clutch. Share this post Link to post Share on other sites
01XR400Mike Posted October 2, 2005 What other, if any, mods are needed if one was to do the big bore kit? Is a larger size carb needed? I know that an after market one is better then stock but what about the size, or can jetting take care of the added engine size? I've been told many things by different dealers and since 1) they are dealers and 2) none of them have said the same thing, I don't trust any of them. What is the general opinion of the best kits out there? Mine is stock motor wise and am just thinking about the idea of the 440, keep in mind that I am over a mile above sea level. Thanks for any suggestions. Share this post Link to post Share on other sites
dale My Rides (2) Posted October 2, 2005 A XR 416/426/440 are very reliable if your bike is 1999 or newer. Older XR 400's have weaker tranny, crank pin, and starter spindle that might break if you have high horsepower. I have 2 96's, one with a 416 kit and have not had a failure of any type. I also have a 99 with 426cc and no problems. The big bores do run hotter. I have the XR's only temp dip stick and the 2 big bore bikes run 210-220, the stocker runs well under 200. Share this post Link to post Share on other sites
dominic888 My Ride Posted October 2, 2005 I had mine done more than a year ago and it now has over 2,000 miles of hard riding. It had the Wiseco big bore kit, racing cam, carb jettings and big gun headers. No problem so far, didn't change the clutch, just use regular motor oil 20W-50. Honda XR440 Share this post Link to post Share on other sites
Rockjockey Posted October 3, 2005 What other, if any, mods are needed if one was to do the big bore kit? Is a larger size carb needed? I know that an after market one is better then stock but what about the size, or can jetting take care of the added engine size? I've been told many things by different dealers and since 1) they are dealers and 2) none of them have said the same thing, I don't trust any of them. What is the general opinion of the best kits out there? Mine is stock motor wise and am just thinking about the idea of the 440, keep in mind that I am over a mile above sea level. Thanks for any suggestions. Yes, the stock carburetor will do the trick if jetted properly. I changed mine because of the re-starting drill after a fall and flood, and the off idle hesitation. In my opinion Thumper Racing does the best work on the 440 kits,cams,valve train work,etc. as the dont B.S. you they just tell you what has worked best for them and let you decide how fast you want to spend. Share this post Link to post Share on other sites
01XR400Mike Posted October 3, 2005 What kind of cost am I looking all together for the thumper racing set up? Share this post Link to post Share on other sites
Trailryder42 Posted October 3, 2005 It depends on what the engine needs/what you have done besides the big bore kit. Their website can give you their prices. They will look the engine over and let you know what they find and recommend a course of action. Besides the 440 kit, I had the cam chain replaced and had a valve job done with Kibblewhite parts. Also replaced a valve subrocker arm that showed excessive wear that they had found. Share this post Link to post Share on other sites
oldturtle Posted October 3, 2005 ...They are just as reliable as standard.... No way, no how is a big bore XR400 "just as reliable" as a stocker. Anytime you are making more power, wearing out tires faster, wearing out chains/sprockets faster, running hotter oil, you are also wearing out the motor faster. There is no free lunch. Period. You may never wear out your pumped motor but that does not mean that they are just as reliable as stock. The Baja racers quickly found the limits of more power on the XR600R. The quad/dune racers have also found the limits many times on reliability of the TRX400EX. Share this post Link to post Share on other sites
hxr400 Posted October 4, 2005 mmm, yes I spose you have a point there. Share this post Link to post Share on other sites
Rockjockey Posted October 4, 2005 Just keep a hat on and maybe nobody will notice. J/K Every one has an opinion. Share this post Link to post Share on other sites
