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View Full Version : 400EX, no fire after rebuild



02CR500Rex
09-15-2007, 09:06 PM
Hey guys, I've been having a really rough time with this bike. I tore down my bike a couple weeks ago to diagnose a problem in the tranny. Found that the right mainshaft and left countershaft bearings were siezing once the engine heated up to operating temp. Alright, I find this whole problem came from the left carrier bearing being completely gone, putting strain on the front sprocket. Well anyway, I got new bearings, and figured I'd cure the smoke puffs, so I ordered a Wiseco 11:1 std. bore piston, rings, and wrist pin. Figured I might as well replace the clutches while I had it down, as I had both adjusters all the way out. Pul all this stuff in, along with new valve seals. Well, I've just been running into problem after problem. The swingarm pivot bearings were junk, so I ordered new ones and stuck them in. Steering stem bearing was gone, replaced it. Sprockets and chain were shot, so I ordered a new set, 14/38 and a new chain. Ordered new carrier bearings and seals, turns out my carrier was messed up, so I ordered a twin row carrier off eBay. New brakes all around, new shifter, new grips. Painted the frame and a arms, cleaned everything else with a grinder/wire wheel, wire brush, steel wool, scuff pads, etc...got the bike looking pretty good.

Well, I put the frame together, put the engine back on, ran ll the wires, cooling system, cables, etc. Ran into some electrical issues...no power to the starter, buzzing solenoid, etc. Turned out I needed to sand down the spots the rear frame meets the front frame so that the engine would get a good ground. Makes sense now that I think about it. I also sanded the places where the voltage regulator and coil mount. Well, now the engine spins like a dream, but there's no fire. I can't get the old plug out, because I don't have the right plug wrench (yet) and...well anyway, I put a new plug in the plug cap and set it against the jug...no spark. Took the plug cap off to test the resistance, and there's no contact...like I even put a piece of 8 gauge power wire down inside the plug boot on the end the plug wire goes in, and tried testing the resistance...still nothing. Says in the service manual that the coil and rev box can't be tested without special tools, but I don't see how anything could be bad...it ran great when I pulled it apart, now it doesn't.

Sorry for such a long post, just figured I'd share my pain...I've been holding this in and I'm getting so frustrated. It's like, I've been talking to a shrink for the past 10 minutes...and the readers of this post are the shrink. So thanks for listening haha

Anyway, I traded a 1994 Eagle Talon that I paid $300 for...and I put $400 worth of stereo system in it...for this quad. I've put 594.40 into it so far, and I'm pretty well broke now...not really, but I can't put any more money into it. I just need to hear it run...to know I haven't wasted the past 2 weeks...the most aggrevating 2 weeks of my life on a lost cause. If anybody has a suggestion, I would love to hear it.

Thanks ahead of time.

Paul

HondaEXrider22
09-15-2007, 09:13 PM
First, think all the stupid stuff before we panic. You say all ground are OK. What about the battery ground and cable? I was having problems where i would start it and it would click until i played with the ground wire.

Next, I would try popping the clutch to start it and let it warm, then shut it off and see if it starts after that.

02CR500Rex
09-15-2007, 09:16 PM
Oh it's getting excellent ground now. I forgot to meantion I cleaned off the area behind where the ground wire mounts to the frame.

Hit the starter and the engine turns over like a dream...just no fire going to the spark plug?

EX LONERIDER
09-15-2007, 10:22 PM
Originally posted by 02CR500Rex
Oh it's getting excellent ground now. I forgot to meantion I cleaned off the area behind where the ground wire mounts to the frame.

Hit the starter and the engine turns over like a dream...just no fire going to the spark plug?

id look at the coil where youve been messing with grounds and make sure everything is ok near that area. if it was running fine before, check the places youve had your hand in.... by no means saying you screwed up, just that those are the places where something has changed.... thus making it my first guess as to where to look. not to be a jackass but your kill switch is set to "on" right? i know ive gone to start my bike and dont realize it till ive flooded it.:p

like mentioned before...... check the simple "duh" stuff.

02CR500Rex
09-15-2007, 11:31 PM
Originally posted by EX LONERIDER
id look at the coil where youve been messing with grounds and make sure everything is ok near that area. if it was running fine before, check the places youve had your hand in.... by no means saying you screwed up, just that those are the places where something has changed.... thus making it my first guess as to where to look. not to be a jackass but your kill switch is set to "on" right? i know ive gone to start my bike and dont realize it till ive flooded it.:p

like mentioned before...... check the simple "duh" stuff.

Thanks for the reply LONERIDER. The problem is, I've had my hands in EVERYWHERE, and I very possibly did make a mistake or a few somewhere or anywhere. This was my first small engine tear down. I've been working on it for 2 weeks...the bike has been down for a month...I'm just getting aggrevated. Here's what I HAVE done so far, as far as troubleshooting.

Well, I have a multimeter with a...well a setting that will beep if the 2 leads make contact (sorry can't explain it much better, but I'm sure you've seen these before). This setting also measures ohms in the process. Well, if you touch the leads together, it pulls .01 ohms. I hooked one lead to the negative terminal on the battery and touched it to various ground spots and discovered that the ground wasn't making it from the battery to the frame. So, I bared the frame behind the ground wire...checked continuity; no ground to the front of the frame. I cured the no power problem today by taking a wire wheel and cleaning up the 4 spots where the rear section of frame meets with the front section. Now, there's ground to the front of the frame. I can put one lead on the negative terminal of the battery or the ground post...or the bolts holding the voltage regulator to the frame, and get a beep by touching any of the other bolts, the engine, a-arm bolts, axle, swingarm, handlebars, etc. But, I didn't clean off the frame behind where the coil mounts.

I pulled the plug wire earlier and checked for spark...none, so the light bulb comes on in my head...I need to pull the coil and bare the metal behind where it mounts. I did this, put the coil back on, still no spark from the new plug. I checked to make sure the coil was grounded...the multimeter beeps and it reads .03 ohms. .03 ohms anywhere on any bare metal, bolt, aluminum, etc. I opened the manual and went to the ignition section...it said to "unscrew" the plug cap from the plug wire and check the resistance. It said if the ohms were "infinite" or "indefinite" can't remember which one it said, that it needed replaced. Well, I unscrewed the plug cap off of the wire and tried to check the resistance...there was none. I had my multimeter set to audible ohms setting and it made no contact whatsoever. I put a piece of wire down inside the end that the plug wire goes into...put one lead of the multimeter up into where the spark plug goes, and the other lead to the end of the wire I stuck in the end of the cap...still not making a connection. I looked down inside the plug wire side of the cap and couldn't tell much...like what I was supposed to be touching to see if there was a connection.

Well, I figured I probably wasn't able to get something down in there to do the job, so I tried putting the plug cap back on the plug wire....put the new spark plug in it and checked for spark again...still nothing.

The manual says that the coil and rev box can only be checked by a honda dealership and that the other ignition component (exciter I think? maybe the exciter is the rev box, I don't have the manual in the house with me) has to be ruled out by process of elimination.

I dunno though, I'm "kinda" thinking the plug cap might be messed up, but I really don't know. Like I said, everything worked fine til I took it apart haha I've just been so many places. Is there anything inside the stator cover that I could have messed up causing it not to spark? What sends the reference to the coil to tell it when to fire? Is there anything I can check...resistance, voltage etc. to start eliminating things? I checked the wire going to the coil...black with a green stripe I believe...maybe black with a yellow stripe...anyway I unplugged it and checked the voltage with the key on, and there is .3, .03, or .003 volts going to the coil. I can't remember which one...I think it was probably .03.

And, the kill switch is on...i've cycled it many times from one side to the other to make sure it didn't corrode inside or something. Can I check any of the wires to make sure the key switch or the kill switch are allowing juice to run to the coil?

Grr...enough typing sorry for the book everybody. I'm just trying to explain everything I've done as far as how far apart I've had the bike, what all I've had my hands in, what all I've done to try to correct the problem etc.

Where to go next?

02CR500Rex
09-16-2007, 07:17 PM
Hey, just wanted to give an update in case anybody runs across this thread down the road. I got it to fire...turns out that I needed to sand down the mounting points on the coil...they had rusted and were not contacting well enough. I now have fire, but sadly she won't start :( That's for a different thread, though. Thanks for the replies everybody.