The XR400 Thread

[IronSpadeCycles]

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

[Luke]

Originally Posted by IronSpadeCycles

I hope this helps. I've purposely not just given you an ideal jet size cause every bike is a little different and your idea of "uncorked" may be very different than my interpretation. So if you know your bike is spot on at sea level and your intended riding area is on average 7000 feet, you would reduce the jet size by 4 sizes (7000ft/1750= 4) (Mikuni jets are in steps of 10 equals 1 full step and 05 is a half step) So if 162 was stock dialed in sea level jetting a reduction to 122 main is what they suggest, but again this is only a suggestion.


http://www.4strokes.com/tech/howtojet.asp

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...Q/main_cor.htm

[Luke]

Originally Posted by HopheadRed

yeaaaahhhh... What would cause a sheared flywheel key?

I have absolutely no idea. But it would cause the timing to be off. On the list of possibilities to investigate, I'd put this way down on the bottom. Unless you verify some other way that the timing is actually off.

I just don't understand the fact that it was running previously with the DS kit - kinda makes me lean towards wiring?

The DS kit wiring and the ignition wiring should be mostly independent. The exception is the black/white kill wire. Unplug that and they should be totally separate, and the ignition should work. If you have spark, then the DS wiring isn't the issue.

Yes, the valve was not bent - He initially thought it was, but that was prior to removing the head to find the screw. He said the valve was surprisingly not damaged and seals fine.

Ok, as long as the seal was checked. These bikes are very hard to start with tight valve clearance, I figure a slightly bent valve would make it impossible.

Maybe do a leakdown test anyway?


Choke assembly and carb are in good order and clean. Spring is tight, etc.

Ok, good.

This def crossed my mind - after what I've read between here and TT, I was thinking along the lines of this knowing you have to kick this machine like you mean it. But I would think between the drill and the car-powered roller to try and bump start it it would fire.

When I first tried the e-start, I thought it was turning over the motor well but there was just no spark. I changed the CDI and got spark. I'd suggest checking for spark when using whatever powered starting gizmo you're using. If you have spark then it's good, if not you're wasting your time.

...

[Luke]

Originally Posted by HopheadRed

+1 on the custom adapter btw! Sweet!

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.

[Brewster]

Originally Posted by Luke

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...Q/main_cor.htm

+1


Cheers

[HopheadRed]

Originally Posted by Luke

A few random thoughts:

So it has a strong spark, but the mechanic is 100% sure the problem is electrical. Uhhhh.. ok. The spark could be at the wrong time, but the most likely cause of that is a sheared flywheel key.

Speaking of.... the drill test may not mean anything. The e-starter doesn't turn the motor over fast enough to get the CDI to fire, converted bikes usually use the TRX CDI which will fire at low speeds. The drill may not be turning the motor fast enough to get spark.

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 .....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!!!!!

[IronSpadeCycles]

Originally Posted by Luke

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...Q/main_cor.htm

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

[booger1]

Originally Posted by HopheadRed

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 .....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!!!!!

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.

[huckleberry]

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

[Brewster]

Originally Posted by huckleberry

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

I use Bike Bandit for all my OEM needs.

Cheers,

[Ace100]

Originally Posted by Brewster

I use Bike Bandit for all my OEM needs.

Cheers,

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

[Whistling Weasel]

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

[Tspoon]

Originally Posted by Whistling Weasel

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

Lots of carb info here

http://www.thumpertalk.com/forum/sho...d.php?t=822033

[Whistling Weasel]

Originally Posted by Tspoon

Lots of carb info here

http://www.thumpertalk.com/forum/sho...d.php?t=822033

thanks for that I'll give it a good read.

[booger1]

Originally Posted by Whistling Weasel

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

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.