Orange with envy!

My brother picked up his brand new 2001 KTM 520SX today. It sits right along side my 00 YZ426. We immediatly dumped a splash of gas in the Big Orange Beast and decided to start it. I was particularly anxious to see how difficult this would be since starting my 426 is worse for me than a root canal. Well, dead cold 26 degrees outside, we turn on the gas pull out the choke and give it ONE easy kick and the thing lights right up. I was almost in tears. We shut it down and then it was my turn. Again one kick. Im completely serious when I tell you that big 520 starts easir than my sons Cobra. No Kidding! It seems to me that Yamaha needs to play catch up here. I am seriously considering keeping my CR 250 and selling my 426 simply because I can't start the thing. My next one will be Orange!

Later, med56

med56 I had the same problem with my 00 426 until I changed the jetting. I went richer on the pilot,main and 2 turns out on the air screw. Then I installed a 12 0z. flywheel weight. The one last thing was to install a kick stand from baja designs so I could get some leverage of the kick stater. After that it started first kick about 60 % of the time. One last thing on the 426. Be shure you are buying you gas from a station that sells lots of gas so that it is fresh. Then if you leave that gas in your bike for more than 2 weeks , drain it out and put in fresh. One trick I would try if I was feeling lazy would be to take a 5mm allen and turn the drain screw on the bottom of the float bowl to let the old gas out of the bowl and let it refill from the tank. Small amounts of gas like the amount in a float bowl go bad in about a week. You can smell the difference. I hope this works for you as well as it did for me. I cant tell you how much easier it made the bike start both hot and cold. Also , if you make these changes, dont use the choke to much when it is cold. It wont need it.

Onward thru the fog.

I’ve ridden a 520 SX and they are MUCH easier to start (I started it on accident trying to find TDC) than my 426, but that’s the price we pay for riding a 5 valve VERY high compression hot rod. I can’t remember exactly but I think the 520 is a very XR-like 9.5:1 (vs. 12.5:1 for the YZ).

Having said that I have an oversize (97 mm Wiseco) high compression piston (13.5:1) in my 426 (444, whatever) and it doesn’t seem any harder to start…

But it sure does haul, I’d love to drag race a 520 now (but it’d have to be a short race since the SX is missing a gear :) ). If jealousy gets the better of you I recommend the bigger piston.

For over two months there was a 520 SX sitting at my local (bonehead) dealer (and looking very lonely. I had to stop going in there, it was too sad). If those silly Austrians made it a five speed there’d be one sittin’ in MY garage too.

I was having major carburation/fouling problems with my 01 426 and I seriously considered a KTM. The YZ was a MAJOR hassle before its carb swap and resulted in a DNF in one race (no throw-aways so I am toast for our HS 5-race series now). What about the KTM 520 MXC? Six speed CR, electric start, 3.7 gallon tank, 248 lbs. Talk about the perfect HS dead-engine-stradle-the-front-wheel-start bike. I guess they aren't released yet, but they sound great. Not cheap though. I was reluctant to put a deposit because I was worried that the tank might be too bulky and that parts might be expensive and hard to get. Has anyone heard anything about this bike?

hey JK what size pilot, main , and needle positions did you use on your 426! My 01' 426 sucks to start when it is cold outside but when it is starts first kick every time! Thanks,



I get my kicks on a 2001' YZ426!

Friendswood, TX

Malcolm Smith's in Riverside tried to sell me a 400MXC last weekend, which is identical to the 520MXC except for displacement. They said they've sold one 520MXC and still have 10 deposits to fill (they're not taking any more deposits on that model). You're looking at well over 8000.00 out the door and they aren't making any "deals" because of the supply/demand situation.

The tank is not that bulky for it's size, because the shrouds are part of the tank and hold some fuel.

I don't know why I was looking at the MXC, because I rarely get out of second gear on my 426. All that money for Euro handling, phallic fender and suspension that needs to be reworked? I don't think so.

Holeshot: Thanks for the info. I was afraid of the KTM availability thing, and that it might also be true with parts. A friend of mine who has contacts at a KTM dealer in the midwest says they have both SXs and both EXCs on the floor. Probably not the same demand there. I haven't checked with him about MXCs since they have been released. Are you riding tight trails so that you don't get out of 2nd? Our hare scrambles course has alot of 4th. Some guys (not me) get 5th. Maybe that WR250F would be good for your terrain. Looks like a cool bike. I found my 99 YZF too much a handful in the woods (well here its more like rocks), stalling it even with a 10 oz flywheel. I didn't want to gear it down because I loved it stock on our MX track (no time to do regear everytime you ride). In defense of the KTM for HS, it has 6 speeds, a large tank stock, its lighter and still has both electric and kickstart, it has a hydraulic clutch, and reworking the suspension is something alot of people do on the YZ as well. But I agree, that fender and the orange are really ugly.

i don't get it, i have started my 01 426 in gear, on a hill hot or cold, the only time it is difficult is when it tips upside down, i have stock jetting, clip on 1 richer, pilot screw 2 turns out, bike runs flawless, although i did foul 2 plugs (9's), so i switched to a cr8ek plug dual electrode plug, will keep you guys posted

TMX AND MY DOGS BITE!!!!!!!!!!!!!!!!1


Iceman, I don't know what to say. You are either really lucky or really good. I can't start my bike in the garage while it is on a stand! I'm not kidding!! I've only had it about a month and the temps have been below freezing here in upstate NY for most of that time. I sure home the cold temps have something to do with it. Perhaps it will light up easier when the mercury rises? My 426 is a 00 model that is stone stock. I haven't even ridden it yet. Our season is basically late March through November. I ride MX only. My 00 CR250 had me smileing all summer long. I sure hope I didn't make a mistake. Any suggestions?

I can start my 426 no problem also. It takes 2-3 kicks when cold and that is it once it is cranked it is cranked. I live in CO at 4000 ft and started on the 2 kick when it was 9 degrees outside and the bike had not been ran for a week. No plug problems either. I wonder why peoples bikes are so diffrent? I got about 20 hours on it now and have no compaints what so ever. Hate to say it but riding the yz426 is more fun than riding street.

motoman 393

My 00 426 came from the factory way to lean. I put in a 48 pilot anbd a l65 main,fuel screw 2 turns out. Nothing was done to the needle. You can tell if your bike is running lean if when you shut the throtle and coast it will make a sort of backfire popping sound. I got these specs from Stroker Speed.Probably the best or at least thing in addition to the jetting was the 12 0z.flywheel weight.You cant hardly tell it is there but what a huge help it is in starting the beast. Hope this helps.

Onward thru the fog.

Hey guys, Check out the Jan issue of DB. It has a pretty good article on lighting 4-strokes. The 426 section of the article is by Randy Hawkins. I have a stone stock 00 and like Med56 have not even ridden it yet cause I got the bike just as winter started here. Have been starting it with little problem in garage though! I just can't see spending another two to three thousand $$ more on a bike with a penis for a front fender! Manners and performance aside. I think the YZ compares quite well to the big orange bike for the cost.


like a kid again, 00426

Hey dirtdad,

Do you ever ride in NJ? Im about 10 minutes south of the Pa/NJ turnpike bridge. There is an amazing place to ride in south jersey, a place with about 10 pits, some a mile wide!!!, jumps everywhere, and miles of woods trails. Let me know if your ever interested. We ride all year, cold or not!


Hey Mike, Thanks for the info. I'm in Warminster. Is that anywhere near (within an hour or two) the place you described. I'm interested in anyplace I can ride and not travel half a day or pay through the you know what! My 12 year old son has a TTR-125l. Is this place suitable for him also?


like a kid again, 00426

Guy's what's going on here? I have a 01' 426 and most of my friends have 00' 426, 250f's and 400's, and no one, and I repeat no one has had the starting problems that you guy's have had. My bike starts on the first kick everytime. Are you guy's following the correct procedures? I can't tell you how many guy's I see at the track trying to start their bikes and doing a completly different method then the manual says and bitching about how hard it is. If you foul your plug thats one thing. The bikes come from the factory to lean, have a reputable shop adjust the gas mixture screw thats what my guy did and it rips right of the throttle. Good luck guys and follow protocol.

Yamadude1, I am following the drill to the letter. I have spoken to countless people in the know to double check myself and I have sought out every piece of literature and internet thread I can find on the subject. I can recite the starting proceedure in my sleep! I don't know what else to do. Jetting changes don't seem reasonable to me in order to get a new bike to start. Besides things look pretty complex on that carb. It sure as hell aint like Kehin on my 00CR250.

Well, I'll keep tryin! med56


I went back and read of your woes. Have you tried to richen the pilot screw on the bottom of the carb? Backing it out is a simple way to richen the idle and low speed jetting. You may need to back it out alot. Up to 3 turns with a stock pilot jet #42. Many YZ owners go bigger on the pilot jet to a #45 or #48 and don't turn the pilot screw out as far.



From my experience your bike came from the factory jetted lean especially in the low speed jetting. When you start your bike, you rely on the low speed jetting circuit. Combine this with the fact that it is quite cold (lots of available oxygen) and you have a recipe for a fuel mixture that is no where near ideal for starting a thumper. I can't guarantee that this will solve all of your starting problems, but I'm fairly sure that it will move you in the right direction. James Dean's suggestions are pretty close to where you want to be.

Good Luck,


My '01 426 is suffering from the same plug fouling problems that some others have seen (still have to go through some hoops before a carb swap will happen) but I've never had any problems starting. Nuts, I was even able to start without the choke on a 45 deg. F day! When you start, the choke dumps way more gas into the circuit than the pilot/idle circuit so it's not the pilot jet/#turns. Just give the throttle a couple of twists, pull the choke, find TDC, ease past and give it a good firm kick! 1-2 times max. Then enjoy that throaty roar!

Yeah, that 520 is tempting but 4 speeds? 2 oil filters? Change the oil every ride? Ugly orange color? Hideous front fender? Parts availability? Still, I'd love to have the 426 lose a few pounds...

Thanks Guys,

I'm gonna try backing the pilot screw out a turn or two to richen the low speed circuit.

I'll let you know how I make out.

Wish me luck! med56

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