You pressures are going to depend on the type of tyre you're running (brand/carcass compound and tread pattern), but I tend to run around 20psi for mixed conditions (off-road and paved sections between), and dropping to 15psi for more rough terrain... Actually I lie, for a long time now I've used [Desert spec] BIB mousses in my tyres (Michelin Deserts) on my XR - which are a nominal 18psi, although they go a bit softer with age and use. Best thing of course, no chance of a puncture. I wouldn't worry too much, just be wary that lower pressures while offering better traction in certain conditions, also make tubed tyres more susceptible to pinch flats and the tyre moving on the rim unless you're using rim-locks. Hope that helps... Jenny x
Very cool I have a similar story but have stayed in the dirt bike world the entire time since my last xr400 which was 18 years ago I have come full circle I suppose. My last dirt bike was a 2008 crf450x had a crf450r and many others before that I decided on buying a xr400 for the second time and don't regret it a bit. BTW I bought a set of those KKE wheels for mine the CNC set and have had them on some nasty shit and they are holding up great. 2 days ago I did a ride up Red elephant trial it's a advance 4x4 trail in Empire Colorado YouTube it it's steep narrow Rocky as hell and loose video doesn't do it justice it's so damn steep going back down I could not stop using both front and back brakes without sliding Almost the entire way down. The rims took some big hits with pressures at 10 psi going up and down and no damage so far and I was doing 20 plus through some knarly boulder gardens you know the saying "When in doubt throttle out" this was the saying of the day. A little disclaimer however... I added electric start to mine this time around. [emoji16]
Thanks, Jmo. You seem to be a pretty good source of information around here. I'm assuming +/- for front AND rear? I see BIB mousses in my future.
I'm definitely into the magic button mod! Where do I look for that ? My last dirt bike was a 04 CRFX 250. It actually was a pretty good bike once I opened it up and re-jetted it. I sold that in about '09 (I guess that means I sold my XR about 13 years ago!) and bought, of all things, a Harley. Had fun with that and rode around much of the country with a friend. Cell phones have ended my street riding days. Its just too sketchy now. The previous owner of this XR had it sorted out pretty good. Its pretty sano. Stoked about the bike and will have lots more questions!
Hi Lookatdirt - yes, pretty much front and rear, although generally speaking if you're going to change pressures, it's better to keep a little more air in the front (to help prevent pinch-flats from impacts on square-edged rocks etc.), and air down the rear for better traction. Mousses are certainly the way to go though - fit and forget... my currently ones have been in there for two years now (including having done the Baja Rally in 2016), the front is pretty soft now, but for trail conditions, they still work fine. Jenny x
I ride 15 - 20, maxxis front and rear - no problems of any kind around Phoenix on 7 springs, bloody basin end to end, etc but do get some bounce on baby heads and ledges at 20. I'm no rocket, and new to xr4, jmo is an experienced desert racer, so she's the knowledge source here. I don't have the budget for mousse. Great bike for AZ...
If you don't mind, please post those questions and answers here in the Thread, so everyone can be savvy. Here are a couple: https://advrider.com/f/threads/1998-xr400-build.650272/ https://advrider.com/f/threads/the-xr400-thread.302523/page-499#post-28664003 Also, click on the 'XR400 Thread Index' down there in my signature. Scads of useful XR4 info, free for the taking.
Thanks, mkn, that is a generous offer. Let's help out Stretch, too! Is there a section in this 676 pages of thread that details this? I'm guessing that the assembly is coming off of some Honda quad with a similar engine. I guess I'll start my questions with- 1. Are the parts readily available? 2. How big of a project is it? Lots of fabrication involved? 3. It must require a standard battery- where does it go? To start.
Many thanks, but what I meant was to post the info for others interested in e-start conversions. I've already built mine. Scroll down to 'Electric Start Conversions'. https://advrider.com/f/threads/xr400-thread-index.852074/ --- There seem to be two schools of Electric-Start Conversions for XR400's. One is that you put the TRX400EX crank, flywheel, stator, and starter assembly in XR400 cases so that the engine will drop right into the stock XR400 frame. The other school is converting the bike to fit a TRX400EX engine. This is what I did. --- Posted on a TRX400EX forum after I built my e-start XR4, when someone posted that the two engines are interchangeable... The cases of the two engines are not identical. They will not simply interchange between vehicles. I just got done putting a 2000 TRX400EX engine in my street-legal 2002 XR400R. The swingarm bolt hole in the rear of the engine cases seem to differ by a few millimeters. Since that's the engine mount that can't be changed, the other mounts (except for the bolt-on front mount) must be modified. With the TRX engine in the XR frame and the swingarm bolt in place, the front (bolt-in aluminum) mount will mate up to the engine like it's supposed to, but the lower (welded-in steel mount) is a couple millimeters low and to the rear. Also, the upper (bolt-in aluminum) mount at the cam cover is about a half-inch to the rear. No problem really, just mock up new ones out of cardboard, lay out the design on 1/4-inch aluminum, then drill the holes and cut the mounts out with a bandsaw. The welded-in steel mounts at the bottom of the frame must be removed (cut the welds with a cut-off wheel in a die grinder) and re-welded in their new place with the mounts bolted to the engine. The end result is the engine being tilted forward about a half-inch, due to the slight difference between the TRX case and the XR case. One must therefore also re-locate the welded steel front muffler mount on the XR's subframe, and modify the airbox boot to come forward that half-inch to hook up with the carb's new location. Engine internals are mostly identical, with the exception of the crank (TRX is longer to make room for the starter clutch & gear under the flywheel), cam profile (more low-end torque for the ATV), clutch (heavier duty for the ATV). First gear is almost the same, but then the TRX has progressively lower gears compared to the XR... XR400R 2.830, 2.620, 1.840, 1.400, 1.120, 0.930 TRX400EX 2.826, 2.916, 1.937, 1.473, 1.181, 1.000 The countershaft is a bit different, in that the non-sprocket end that you see under the clutch basket is a bit bigger than the XR's. That keeps one from installing the kickstarter idler gear from an XR4. I think I can get around that by machining a different bushing. Then simply install my XR right case cover and kick-starter. A 2005+ engine with reverse would be nice, but those engines are about 500 dollars more than a 1999-2004, and I've spent a ton of money on this project already. I used a TRX400EX wiring harness, CDI, Regulator / Rectifier, and ignition to eliminate mating troubles between the engine and bike. That wasn't a drop-in affair either... scads of cutting and splicing (solder, then heat-shrink tubing) to avoid thick wads of extra wire in some spots and too short of length in others. Battery and box is from a DRZ400, with welded-in mounts on the left side of the subframe (opposite side of the muffler). It starts and runs great, with 14.5 Volts DC at idle. At times like these, Honda's lack of modularity between seemingly similar engines can be quite maddening. It has been a lot of work over the past few weeks, but I love to tinker, and I now have one damned nice XR400. --- That was nearly six years ago, and I'm still running the same setup. It was well worth the effort.
I took a picture of pretty much everything minus the crankshaft to get you started buying the stuff needed this is the bulk of what you need but minus the crankshaft. Additionally you will need a 400ex shifter the 400ex stator and a bolt Honda calls a special stud it's on the left side engine cover it's the bolt that has the 10mm nut on it. The xr4 bolt is not long enough to make it through the wider left engine case to screw on the 10mm bolt so you need to get longer special stud for the 400ex. As far as the starter you don't need to tap anything to mount it up you can simply use the existing threaded hole used to route the carb vet hoses and longer screw and use just one of the 2 mounting holes on the starter it will hold the starter just fine just thread lock the bolt. I did tap and add another screw but didn't need to. One thing I should point out go with a 2003 or older 400ex wire harness the wire loom is smaller because there is no reverse. I did a 07 and should have done a older one. I also used a 400ex balance shaft which you don't have to if you don't want to side by side they are different so keep that in mind. The 400ex balance shaft felt heavier as well. While your in there go ahead and through on a crf450x timing chain 112 links it's cheaper and the chain is beefier than the stock XR chain and it meshes perfectly with the gears. I took a picture of the battery box without welding. All I used were some clamps, bolts and nuts and sanded off the back of the drz box so it fit flush against the frame once you buy the box and look at the back you will see what I mean. With the clamps however the box is slightly tweeked inward so you need to make sure you have clearance at full bottom of the rear wheel. I did end up welding brackets later just showing you don't need a welder to mount up the battery box and can make it work. I also welded up some support brackets for the rear subframe I have no idea if they will be effective or not so far so good. I didn't go as cheap as I could go I ended up at just under 700 bucks to convert it you can do it for cheaper for sure going the plug in play is the easiest but most expensive. Standard cost to convert pretty much any current mx bike to e start is around 650 bucks for parts minus the labor BTW so the xr400 isn't far off the mark. Imo if you can't do the work yourself this mod may not worth doing unless you got the bike for 500.00 or less. Still a awesome mod shame on you Honda for not giving us e-start on the xr400. One last thing get yourself a OEM manual it's better than the cheaper manual. The Mikuni pumper tm 36 fits fine with the starter. View attachment 1927531
I used an eBay 440 bore kit that included piston, rings & cylinder. This in 2008 at that time was $349 Bought gasket kit separate eBay purchase. Still running same bore kit probably 15k Miles on it. I forget brand name - something that starts with N. But I’m sure it was from China. Did my estart conversation at same time. I went route of installing TRX crank in XR4 cases. So I have XR top end cam etc. (no hole relocation and I retained kick start capability) - although I haven’t kick started my xr4 since converting. Estart worth every cent and hour spent doing conversion! I used TRX cdi, regulator/rectifier. Starter solenoid and TRX wiring harness from (2002 I think) bought on eBay. (I purchased a TRX bottom end from eBay that way I got all the left side stator stuff along with the crank). I think if you buy all this 1 item at a time it will nickel/dime you. I recommend buying a whole bottom end from TRX. And try to find the entire wiring harness (main with regulator and handle bar controls section) together. That way you get all the connectors for a nice stock Honda parts conversion. Regarding battery: I tried the “in the air box mount” at first - don’t do that! Waste of time and Royal PITA to remove battery just to clean filter! So I welded up a battery mount under left side number plate. I used 3/4” round stock & 16g steel sheetmetal (I have a tubing bender and sheet metal brake) Works great and solid as a rock. In the end all the estart stuff (battery, starter, starter gears, etc) probably adds around 20lbs - again worth every ounce! No more kicking on an off camber hill, at 60 years old I hate kicking! The plated xr4 is still my go to bike for single track or most DS rides.
** Apologies if this request is in the wrong place - let me know and I will move. ** I picked up two XR400s last summer - a 99 that was in pretty decent shape, and a 2003 that was in slightly less good shape. My son and I rode all last summer with no problems, and most of this summer. But now the 03 has a pronounced ticking sound that seems to come from the top end. I am a noob when it comes to thumpers, and not really mechanically inclined, so could use some help. A couple of weeks ago, my son and I rode perhaps 600 or 700 miles (riding to Ouray, then a couple sections of the COBDR to Buena Vista) around 200 of which was on pavement. The bike was working hard to stay at 60mph-ish (bike in question has a 48 rear sprocket so rpms were high). I just checked the valves (following a youtube vid, and other than not being sure that I was at TDC on the right stroke, the process was easy) and the clearances were within spec. There is no decomp lever/cable, but the guide and mechanism is in place on the outside of the engine case. I didn't remove it and didn't know to ask about such. The shop I bought from (local KTM shop, the bike was owner's brother's) said the bike had been sitting for 10 years and that they had replaced the piston. I didn't ask for nor was offered details on that work. It started up and ran fine. Again, we rode all last summer and up til now, no issues other than a bit hard to start. This is my first kick start bike, and I don't know if it applies here, but sometimes I would get two or three kicks and then on the next kick the kickstart lever wouldn't move at all - like something was bound/stuck. Slowly pushing the lever down would get it past the strong resistance and then I could kick normally. I took an audio recording of both bikes on a cold start and uploaded it to youtube. The 99 sounds SO much quieter... Anyone care to take a quick listen and give me some hints as to what to look at next? Thanks!
It sounds like the auto decomp mechanism ( inside the valve cover, attached to the camshaft) is going bad, which is not rare on these bikes. I say that since you mention the symptom of occasionally seeing a lot of compression/ bound kicker at times. Another symptom is the bike will occasionally stall/hiccup for no reason- that's the auto decomp activating when it shouldn't. I don't know if parts are available to repair it. I believe it's just a spring that gets weak causing the malfunction. When my acted up I just eliminated and rely on the manual decomp now. I find it much easier to start the bike since I could never seem to find TDC with the auto decomp installed. Hard to tell by sound alone. A failing auto decomp pretty much sounds just like a severely loose rocker, since the auto decomp operates by activating and exhaust rocker. If you are confident that your valve lash is correct, I would investigate the auto decomp or check out your cam chain tensioner, just to be sure.
Right exhaust valve is loose. Prob .020" and makes a lot of noise. You we likely 180* out when you did that one. Could be the decompressor, but my bet is a loose valve. .004 & .006" cold.
Ok. I change my own tires, adjust my valves, etc., but that's way beyond my comfort zone. You are a Zen Master.
Wow this thread is insane, 677 pages! I bought a 2000 XR400 this spring. I took it to a buddy of a buddy who is a full time mechanic out of his garage to go through the entire bike and get it ready for the season. He rebuilt the carb and it would start in 3 kicks every time cold. When hot its always first kick, even if I drop it it fires up in a couple kicks without the decomp. The more I rode it the harder and harder it got to cold start. I'll admit I did run ethanol gas in it. Since I have drained the gas tank and ran enthanol free only from here on out. I was assuming that was the cause. I took the carb apart last night and it looked pretty good in there. The numbers off the jets were 142 & 526 if that makes sense. It ran perfect before so the jets seem correct. I live in Boise so I ride elevations from 2500 to 10000. I got it to fire but it will not idle. I have messed with the idle adjustment screw so much I'm not sure where it needs to be, anyway to find that out? Seems like the screw isn't doing much, all the way out or in and she acts pretty much the same. Before I disassembled the carb I checked the lean/rich screw on the bottom of the carb and it was about 1-3/4 turns out. I set it for that which should be correct from the research I've done. Some people say you can go out to 2-1/2 but that should be max, anymore and a guy needs to rejet. I also noticed I do not have the "cone" or "skirt" that is the carb, its the yellow thing you should see right away when accessing the bowl. Any recommendations? Should I keep playing with the idle screw and the lean/rich adjustment? Maybe I should order that skirt thing? I'm not sure what it does but it ran fine without all summer. Thanks for your help!! Edit, Maybe I should buy the Pumper Carb from XRonly.com and be done? Its spendy but I have heard amazing things about it. If its a game changer it might be worth the $400 or whatever. Although I have read they are way more complicated, might be over my head.
Hey, I suggest that you should take off the carb completely, or at least take out the jets and clean them out. Even if you don't see any residue/junk from the ethanol it could be there. Blow out the air passages on the jets (plus the thing the main jet threads into - I don't know how it's called in english), or put it in a ultrasoniv cleaner if you have one. The jets: well, I have to admit that I chuckled a bit when I read the 146/526 part the 146 is you main jet, the other is the slow/idle jet it should be between 50-60. Jetting is a tricky thing, I'm no expert in it so be cautious with my advice. If you have a completely stock bike IMO those jets should be fine. But if the Gordon mods have been done to the bike (no airbox snorkel, the welds in the header have been grinded, a less restrictive air filter and so on) jetting must be corrected. Some guys here run 162/62, 160/60, me (and I think shinyribs too - not sure on that one though) 158/55. You have to find out what suits your riding style and elevation the best. Check the spark plug, it should tell you if the jetting is way off or roughly good. The idle screw should be between 1,5-2,5 in general, but this depends on your jetting and elevation and everything! Set it to a position where the bike feels happy. Also, there is an index thread, where you can find lots of useful information about these bikes. Good luck with it and have fun