The XR400 Thread

Discussion in 'Thumpers' started by Hayduke, Jan 16, 2008.

  1. IronSpadeCycles

    IronSpadeCycles Button Pusher

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    I almost forgot, keep a 6mm 1/4" drive socket with a short extension and ratchet in your tool bag with a 17mm wrench and a short Phillips and straight blade screw drivers. If you need to change just the main jet on the trail it can be done in about 10 minutes, if you need to pull the bowl to change the pilot it will take about another 5 minutes. Trust me I know I did this several times over a few weeks and 5200 miles logged from Durango CO to Portland OR and back to my home town of Port Lavaca TX. You don't need to remove the carb or even turn it, just drop the lower bowl drain screw with the 17mm wrench. When you get the main out take care not to loose the small white plastic skirt that shrouds the jet. I often used a dab of grease to hold it in place each time I changed a jet.

    Hope this helps.

    Later Travis
  2. Davidjohnson

    Davidjohnson Been here awhile

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    Travis, thanks for posting this. I will need time to digest all of it but it is very helpful. I do not have any kind of monitor that reads temp but will look in to that.

    David
  3. IronSpadeCycles

    IronSpadeCycles Button Pusher

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    David, the TrailTech runs about $120 and honestly it was an eye opener to be able to see exactly how fast I was going and mileage I was getting with different gas from different areas of the country. In CO and UT I made better than 60 miles per gallon but in Nevada and AZ it dropped to just above 45mpg. I'd call that a significant difference based on how much ethanol was blended into the fuel. You might just be trail riding in the CO mountains but if you've only got a stock 2.5Gal tank, if set up properly, at best you'll get 120 miles before you go on reserve. At worse you'll run out of gas before getting back to the station and pushing a 240lbs bike up any hill in CO just plain sucks ass.

    Just my .10 cents. Later Travis
  4. Luke

    Luke GPoET&P

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    No wonder you were having trouble with jetting. Mikuni and Keihin jets sizes have nothing to do with each other. According to the manual, if your correct main jet at sea level was 162, you should run a 152 at 7000 feet. Not 122.

    Here's the chart:
    http://john.rushworth.com/Pics/XR400/XR4FAQ/main_cor.htm
  5. Luke

    Luke GPoET&P

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    ...
  6. Luke

    Luke GPoET&P

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    Thanks guys! Licking a finger and grabbing a wire is another way to check for 100v, but I was never brave enough for that. I've done it enough times by accident. :D
  7. Brewster

    Brewster Adventurer

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    +1


    Cheers
  8. HopheadRed

    HopheadRed Adventurer

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    So, I just hung up with John and mentioned what you said regarding the drill. He clarified a few things for me -- The spark is strong, when it sparks. He said using the drill with the plug grounded out on the head it will spark 4-5x and than not spark again at all. Consistently inconsistent? Lol.

    He said while using a car powered roller on the back wheel it will fire and run for a few seconds and die. Won't fire again for seconds and than same thing.

    I'm all :ear .....If he can't get this thing to run before I get back to town, how the hell do I go about squaring up with this guy since he's put quite a few hours into this thing but no results?!? I won't be happy paying out a bunch of cash for a bike in pretty much the same shape I dropped it off in...

    He insists its electrical still - what are the chances the "working" CDI from and my existing CDI have the same issue? Would an issue with the wiring harness cause these type of symptoms? I think that's the only part of the ignition system yet to be replaced. baaaahhhhhhh!!!!!
  9. IronSpadeCycles

    IronSpadeCycles Button Pusher

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    No Luke I wasn't running a 122, I was just making a point based on Mikuni as I have a MIkuni 34mm on my XR600. And I realize that I made a mistake in my advice just today. Another reason not to take everyone's advice blindly without doing your own homework.

    I have the stock Keihin in my XR4 and I think I had a 168 at sea level but I still wasn't sure it was right. I didn't have the Trailtech hooked up till I got to CO so I really didn't have a baseline to go off of. When I got to CO the shop in Durango suggested a 142 and I even thought that was wrong but I went ahead and got it with a 148, 152, 158, 162 and a 166 cause they had them. I was wrong all the way around. I ended up putting in the 166 in Moab for the whole rest of the trip till Reno and it ran better but not perfect. I also pulled the top end in Reno and discovered the 10:1 piston and about 1.5mm of carbon build up on top of the piston. Those two factors raised the compression to around 11.5:1 and once I got it cleaned off the temps came way down and I jetted back to I think 152 above 4000 and 162 at sea level to 4K. The only damage I noticed from the high heat problems was a noisy cam bearing that cost me $12 at the Reno Honda dealer.

    Owell she held up and my compression is still very good. I'll probably put a 440cc kit in it when it needs freshening and rejet all over again.

    Thanks for the link about the Kehin. Later Travis
  10. booger1

    booger1 Long timer

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    Just had this problem, weak to almost no spark witht the e-botton. I had also done mine with a kick starter and it would start with that very well. however when the motor got hot it was very hard to start. I tested the excitor coil leads and was only getting max of 30v, your suppose to get 100v min. I installed a 200 watt stator and it works great now. I had also replaced the cdi before the stator with no results. Try there next.

    Sorry, I jsut went back and read the post, you already changed the stator, but the wires may be reversed in the plug and you'll have to sort that out. But get a voltage reading from the excitor coil.
  11. huckleberry

    huckleberry BACK ROAD BOMBER

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    ok so now i belong ---- new owner of a 97 xr4! where's the best place for stock parts?:lol3
  12. Brewster

    Brewster Adventurer

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    I use Bike Bandit for all my OEM needs.

    Cheers,
  13. Ace100

    Ace100 Monkeywrencher

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    +1 on BB. Not as consistant on aftermarket goodies but really good on stock.
  14. Whistling Weasel

    Whistling Weasel Adventurer

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    I'm trying to find some info on using the mikuni TM 34mm carb on my 2004 xr400. I know some people have used it but can't find any info on their experience and or problems. Any help would be greatly appreciated. Thanks
  15. Tspoon

    Tspoon CRANKIT

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    Lots of carb info here

    http://www.thumpertalk.com/forum/showthread.php?t=822033
  16. Whistling Weasel

    Whistling Weasel Adventurer

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  17. booger1

    booger1 Long timer

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    I think your thinking about a TM36. that's is what I have and can't believe the differance it made in starting and power delevery.
    Well worth the money.
  18. huckleberry

    huckleberry BACK ROAD BOMBER

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    was hopeing some one could tell me if the pivit works brgs are as good as stock stuff. I need some wheel brgs and shock brgs and the pivit works stuff is less expensive.
  19. Switchblade315

    Switchblade315 Long timer

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    I've used them with no problems. would defently use them again.
  20. booger1

    booger1 Long timer

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    I've got the pivot works and all balls bearings throughout the bike. Can't tell a differance, only time well do that. they've been on the bike for about 1 1/2 years so far. Pivot bearings in the linkage for about 3 years now.