KX Riders
Maintenance & Technical => KX450F / KX250F => Topic started by: Scott Marks on January 31, 2007, 11:48:12 PM
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Just bought an 06' 450F, because the guy was having trouble kick starting. Push it and it takes right off, but won't kick start. He has has the head rebuilt with new valves & checked nearly all the electrical. He thinks there is a problem with the wiring harness. I am taking a simpler road, starting with the carb and checking all the basics and mainly cleaning to ensure there is no trash in the carb. I took the Pro Circuit T-4 pipe off (which is for SALE at a resonable price) and put the stock pipe back on. Starting with all stock jetting, settings, and installing all new hot start components. Just wondered if anyone has any tricks or things to look for.
Thanks,
Scott
P.S. Make me an offer on the Pro-Circuit T-4 header & silencer
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If it's hard to kick start the valves could be out of tolerance. I know that my fo-fiddy is a pain in the butt to start when the valves are super tight. The right intake will be tighter than the left intake due to it getting the blast of intake charge. I can start my bike without the hotstart unless it washes out in a turn. Make sure the air filter is clean also these thumpers like clean filters and clean oil. I'd make you an offer on the pipe but I don't like pro-circus or it's parts. I'm also trying to sell my thumper to pay some bills off if you know any one interested. But while the carb is apart remove all the jets in the bowl, main area and there is a jet in the intake tube from the air box. Blow out all the passages in the carb. Check the spark plug for a light tan color, if it's black then the valves need to be checked and or shimmed.
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Thanks for the feedback, I put the carb back on and began kicking. Nothing happened until I twisted the throttle a few times and then the big backfire. Did this a couple more times so I decided to check the timing and valves. Exhaust are a nice .008 and I can't even get a .002 thru the intake. Should be a .005.
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Do you have the factory service manual to do the valve work? If not I can send it to you in a PDF file. But the exhaust should be in the area of .17-.22 and the intakes at .10-.15 on TDC with the timing mark aligned with the notches and the cam lobes facing to the outside of the head away from each other.
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Yes, I purchased a service manual. I am at TDC with the cam lobes facing out. This is where I took the measurement I mentioned below. FYI, when I took the buckets off the shim on the left side was marked 220 and the shim on the right side had a marking of 230. This would indicate the RT valve is tighter than the LT. Correct? Do you have any suggestions what shims I should get?
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I would think they both should have been either 220 or 230. I will have to look at the stockers I took out. I got a hot cams shim kit off e-bay and use it. I have only had to shim it once so far. But I have since parked it after spec'ing everything out while I await it's sale. I will look at the shims I took out and see if they are different.
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That would be great! I have a few smaller size shims on their way from the Kawi dealership. Any idea why the intakes are tight and the exhaust are fine? Is it common for the intakes to tighten up more than the exhaust after you re-work the valves? This is what happens when you buy 2nd hand, you often have to start from scratch.
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I just checked the stockers and they both start and end with 5 the middle number is worn off. I shimmed them both the same and haven't had to reshim them yet. The right intake runs cooler than the rest because the intake charge is blasted on that valve as it exit's the carb. If they get any worse then a valve seat cut is in order.
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I've had different shims from the factory, no worries, your only talking thousanths, and no manuf. process is that close. as far as your clearances, I think one of you is talking thousands and one mm.
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You are correct, we have mentioned both mm's & thousanths. The service manual lists both clearances as well. I was able to gain the past history on the bike and that helps a bunch. Chad Watts (Watts perfections) rebuilt the entire motor about 10 months ago. They broke a radiator and cooked it. He had all the info on his computer and provided me with the shim #'s for all (4) valves upon the competion of the engine rebuild. The guy I bought it from tore it down, put in a new piston, rings and had the head re-worked again. Now I am able to compare the shims from job #1 to job #2. (2) are .002, (1) is .004, & (1) is .006 different. Easily changed by doing a valve job. Sorry for being so long winded, I am trying to trust the work that has been done. I know I should go ahead and pull the head off and see for myself. I feel like the valves seated in and tighted up after job #2 and that is why they are tight now. I am going to get the clearances correct and see if I can kick start it. Ride it a few hours and check them again. If they change again, then I will pull the head off. This bike also has the wrong spark plug in it. The correct plug has the electrode and ground protruding past the treads. If the spark is being delivered up in the treads, I can't think this will help in kick starting.
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You can order the plugs off www.sparkplugs.com if your local shop don't carry the correct plugs. The wrong plug could cause damage to any motor.
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Just thought I would give you an update. Set the valves and put in the correct spark plug, still the same. I took the bike to the Kawi dealer and they have been working on it most of the week. All electical components check out o.k. they even took the CDI off of another bike and nothing. Only backfires. Kawi tech support says it's electrial and to check the timing with a timing light. They can't get the timing light to work because they feel the spark output is to low. Makes no sense to anyone especially given the stator, coil, CDI, and other components check o.k. Our next step is to take all the electrical components off a running bike and see if that makes any differnce.
I let you know!
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Just bought an 06' 450F, because the guy was having trouble kick starting. Push it and it takes right off, but won't kick start. He has has the head rebuilt with new valves & checked nearly all the electrical. He thinks there is a problem with the wiring harness. I am taking a simpler road, starting with the carb and checking all the basics and mainly cleaning to ensure there is no trash in the carb. I took the Pro Circuit T-4 pipe off (which is for SALE at a resonable price) and put the stock pipe back on. Starting with all stock jetting, settings, and installing all new hot start components. Just wondered if anyone has any tricks or things to look for.
Thanks,
Scott
P.S. Make me an offer on the Pro-Circuit T-4 header & silencer
Sounds odd to me that it will push start and run but won't kick start and run, hard to believe that's is an ignition problem. Hope they figure it for you.
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This is so off the wall but it happened to me. Check the pipe and see that it is not blocked up. I had a '76 YZ25 that I did some work on and the guy brought me a pipe and said he wanted it put on after the rebuild. Long story short, put it on and the bike would not kick start. If you pushed it it would try to run. I found a mouse nest in it. Burned that out and it worked fine.
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It runs great when you push start it. Does the same with the Pro-Circuit exhaust & the factory exhaust. Sometimes it will kick start, but more times it won't. I am taking my buddies 450 to the dealership in the morning and they are swapping the electrical components. Tonight I am thinking the gear position sensor really needs to be looked at closely, given this is the only component that changes the ignition timing.
I will keep you posted.
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They swapped all the electrical components and no fix. So it has to be in the valve train. We need to check the flywheel keyway, pull the head and inspect the valves, & hears something to think about! Cams, the gear is pressed on the cam, could be the gear has moved.
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They swapped all the electrical components and no fix. So it has to be in the valve train. We need to check the flywheel keyway, pull the head and inspect the valves, & hears something to think about! Cams, the gear is pressed on the cam, could be the gear has moved.
Push starts and runs fine, but won't kick start doesn't sound like anything to do with the valve train, are you cracking open the throttle when you try to kick start the bike?? I not sure but I think these bikes have accelerator pumps on them.
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It's all in the head! All 4 valves are leaking, 2 really bad. Looks like a new head & valves.
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The Kawi dealer put in a new piston, rings, cylinder, head, & valves. Still won't start. Kawi tech support is going to talk with the engineers to see what they think. Kawi service guys think there is something wrong in the bottom end. Bearing, or crankshaft.
Will let you know.
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Are you paying for the new top end or the dealer or is Kaw.?? This is crazy what's going on with your bike.
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I have learned one very valuable lesson with this one. Don't ever by a bike cheap, knowing it has a problem. I am paying the bill, however, the Kawi dealer is working with me on this and helping me all they can. I'm into it about $1,200 so far. They don't like the way the bike kicks over and feels like something is binding or dragging in the bottom end. The kicker shaft is about to break, which tells them something is wrong in the bottom end. The only thing left is to go through the bottom end, which they are going to do tomorrow. The dealer did not have a flywheel puller when they swapped all the electical parts, so we did not swap the flywheel off the running bike. A good flywheel should stick to the side of a tool box, shouldn't it? This one doesn't. They are ordering a new flywheel as well.
I asked if Kawi will stand behind their product and the service manager told me, only if I was the original owner. Unfortunatly I am not. Yes, this sucks. But if this will help a fellow rider in the future it will be worth it.
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It seems to me that if they just threw a new piston and valve train at it and that was the problem then they should pay for those parts. You should not pay for their learning curve. When you push start this thing it runs great right? If that is correct I can't figure out what's in the bottem end that would cause it not to kick start but pull or push start.
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The deal is, they were going to split the cases and if they found nothing wrong, I won't have to pay the $200 shop bill. They didn't find anything other than a bunch of junk in the oil screens, which was a good catch. What was found was a bent kicker shaft. We are putting in a new kicker shaft and putting it back together. I suppose if there was enough bind from the bent kicker shaft that the moter wouldn't kick start, but run push starting. Do you still think they may be a problem with the flywheel?
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The bent shaft could have not allowed the engine to make complete power strokes when you kick it over?? Keep us inform when they get it back together. Unsure about your flywheel. I would suspect if the flywheel was bad then it bad all the time regardless if you are kick starting or push starting it.
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Let's keep our fingers crossed that the new kicker shaft will fix the problem. I really don't want to spend more money on a flywheel. By the way, your 5 hund is most awesome! My 13 yr. old is now riding a 250 and always asks what is it like to ride a 500? His only question, is it really double a 250 and I have to say, you can't even imagine! Someday he will have a chance.
Talk to you soon!
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O.K. Put the bottom end back together, so we have a complete new motor from the bottom to the top. Kicked and kicked and nothing! Put on a new flywheel and she cracked right off. Ran a hare scramble on Sunday and ran great, started every time. No one can figure out what went wrong with the flywheel, but some guys say it can happen. By the way the new flywheel does not have enough magnetic force to hold it to a tool box either, so don't go by that. Weird deal, but I sure want to share with everyone as it might help another poor soul out there fighting the same problem.
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That's cool that you bike is back up and running but man that's a strange issue for a flywheel. You would think if the mangets were weak then they should be weak all the time regardless if you are kick starting or push starting. If the center manget which has the pick up marks moved then the timing would be off all the time. Strange man very strange. Glade your bike is up and running.