What Mod's to do to make this yz400f a one kick starter?
Posted May 21, 2011 - 10:00 AM
I've got a 99 yz400fl1 and i have done a ton of work to this bike. I have adjusted the valves, checked the timing, checked the stater and coil and rectifier and kill switch. All of these are checking out good. I adjusted the valves to within specs and i just rejeted the carb. I ordered a jet kit from JD Jetting and went compleatly throught the carb. I ran wire through all the jets and passages and it is compleatly clean. Nothing any where. Still having problems getting this bike started.
I can pull start it and as soon as i pop the clutch it fires rite up. I have tried everything that has been suggested to me and with no luck.
Ive tried kicking through the compression stroke, using the decompression lever to get it about 1" past TDC. Ive tried every thing from no pumps from the throttle to 5 pumps. No matter what i have tried this bike just doesnt want to start by kicking it. It normaly takes about 15-20min of kicking this bike to get it started. This isnt going to work trail riding.
I have herd some say that they can get thiers started on the first kick.
For those indaviduals what mods have you made to your bike?
because every thing i have done to this bike so far has not changed how this bike starts at all.
Im getting realy frustrated. I have a ride planed for next thursday and if i cant figure out somthing i am going to miss out on another ride.
Verry aggrivated yz400f owner
Posted May 21, 2011 - 11:40 AM
Posted May 21, 2011 - 11:43 AM
The two best things you can do are to install an auto decompression cam, which won't fix the carb but it takes the starting drill down to two steps instead of three with no guesswork involved, and the big one; a late model FCR-MX carb from an '05 or later YZ450. It's basically a bolt-on, with a couple of minor details to work out, but it really is a major improvement. Be sure to buy one that includes as much of the hot start and cabling as possible.
One other thing is the strength of the ignition. A coil-over-plug conversion will help, and iridium plug will help, and making sure that the stator is in good shape will help.
Posted May 21, 2011 - 12:26 PM
Thanks guys. I just put a new plug in it. a NGK CR8E. The stater is testing good. Every thing on this bike is testing within specs. I will try to get the decompression cam and try that but it will have to be a winter project. I have about blown through my budget on this bike allready.
I will try to pick up one of those plugs and see if that helps. Im going to run up to Iron Poney tomorrow to look for a few things? I will see if they have any.
The carb seems to be in great working order. every thing is good and tight. Not much slop. The jet kit has helped the mid range and idoling issues i was having but it just the starting now...
Thanks for the tips guys. Im ready to hit the trail with this bike but where we ride if i get out and it wont restart its a 30+ mile hike back to the trail head... You can see why im hesitant.
Posted May 21, 2011 - 08:42 PM
I kick it to TDC, then an inch past, crack the throttle once with the choke open, and kick it usually 6-8 times to get it to start cold, but it doesn't always idle until I get it warm.
When its warm though I never really have a problem starting it with the "TDC, inch past, kick" technique, but I find that when I can lean against a tree and kick while standing on the pegs its a lot easier, but I can kick it while standing.
Posted May 21, 2011 - 09:39 PM
i am planning on putting a kick stand on it for when im on the trail.
i just dont have any confidence in this bike rite now. when it runs OMG is it a power house. i love the power it has just not the problems im having starting it.
will the decompression cam hurt its performance any?
Posted May 22, 2011 - 01:13 PM
Posted May 23, 2011 - 03:38 AM
hope this just isnt a fluke thing but it worked last night. thats the easiest it has started yet. oh and i didnt have the choke on or the hot start on either. it fired rite up. now im waiting on a new o ring and spring for my pilot needle then ill know what ive got a little better.
Posted May 23, 2011 - 04:20 AM
as long as it's jetted right and the valves are in spec it should start with one kick
mine had a 426 cylinder with 2mm overbore making it 444cc at 13:1 I ran it on pump 93 octane gas, the piston was special order, not sure if they are available anymore
Posted May 23, 2011 - 06:22 AM
Octane has not one single little thing to do with how well the engine starts. It may well be that with two fuels of different octane ratings, one might start better than the other, or get better mileage, make more power, or any of a host of other things, but the octane rating will not give you any indication of this. Octane number is a measure of a fuel's resistance to detonation under heat and pressure; to ignition by sources other than spark or flame, and tells you no more than that.
Posted May 23, 2011 - 07:33 AM
I have a 2002 426 and it is box stock, except for the exhaust. If the plug has less than 25 hours on it, it is a one kick affair.
Posted May 23, 2011 - 08:44 AM
Good point, and often overlooked.
That little o-ring around the pilot screw makes a big BIG impact. I cannot count how many FCR carbs I have worked on that have either a mangled or simply AWOL o-ring.
Posted May 23, 2011 - 11:39 AM
Things I did were; adjust valves, rebuilt carb, and replaced all seals where there could be any air leaks. I had many cracks in the seals from the airbox to the carb to the engine. I replaced all those and it made a difference. Also make sure your air filter is not over oiled and use the highest octane gas you can buy in your area. I think manual recommends 95 octane but the best in my area is 93. Recheck your valves as well. I adjusted mine but they were so bad when I bought it that I checked them again after two rides and had to adjust them a second time. A year later though and they are fine now. Hope this helps
Posted May 23, 2011 - 11:49 AM
The manual calls for gasoline with a Research Octane Number of at least 95. The roughly equates to ~86-87 Motor Octane, or, using the U.S. Anti-Knock index posted on gas pumps in the US and Canada, about 90-91. Any fuel sold in the US at 91 or more has a high enough octane rating.
...use the highest octane gas you can buy in your area. I think manual recommends 95 octane but the best in my area is 93.
Posted May 23, 2011 - 05:10 PM
I just got my new pilot needle, spring, washer and o ring tonight and put it in.
I drained the gas and put some fresh 93 with ethanol which where i buy my gas makes it 97 octain. Now it runs like a dream. It idols and is very responsive when i crack the throttle.
I bought a new plug yesterday. Its a IRIDIUM CR8EIX and put it in tonight since i had it tore most of the way apart. It has seemed to help over the NGK CR8E.
The starting is sill alot different on this bike than what every one has told me to try.
Ive got to twist the throttle 4 times kick 3 with out the decompression lever!!!! twist it 3 more times and normaly on the second kick it fires rite up. (HELL YEA!!!) i can deal with that. This is a major relief for me rite now. I am going riding with 5 of my buddies thrusday at Wayne National Forest Thursday and i was worried i was going to miss out on another ride.
I have done a tone of work to this bike in the last week and now it is running and idoling great. Thanks everyone for all your help and ideas.
Ive finaly got it down and i couldnt be more happy about it.....
Its all about figuring what works best for your bike on these bikes. As long as it stays like this i wont have to mess with the cams. One thing i did do that has helped me kick it harder is bought a new pair of Thor boots with the reinforcment in the soles. Now i can kick it through the compression stroke and it doesnt kill my foot and ankle. I have ruined 2 pairs of boots in the past week trying to kick start this bike.
Posted May 24, 2011 - 12:49 AM
Once the carb was set up it started first or second kick and yes when stalled hot it was a 'b' to start sometimes.
The decomp cam just makes the kicking much easier, it just requires a smooth steady stroke of the kickstart without having to go through the motions of finding TDC etc.
Regardless, the key to starting is usually the carb set up.
Posted May 24, 2011 - 04:26 AM
Im just glad it doesnt have the titanium valves in it. At $100 a pop its a large investment in a bike that is 12 years old.
Does the decomp cam help with the hot start when you stall it?
I know its a bear when mine was hot. I havent really rode it enough with all the weather to start playing with the hot start.
Posted May 24, 2011 - 11:40 AM
However.....I don't do that now, now that I know her well. She always starts within three kicks.
One comment I would have is that the auto decomp is not necessarily going to improve your starting. It makes it slightly less complicated, quicker and 'easier', which is great for racing, but, personally, I wouldn't waste the money on it unless you can't be bothered pulling the little lever....
If you've got money to throw at it, I'd get the carb set up properly then take your mates to the pub.
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