How to fix difficult starting on YZ426?


35 replies to this topic
  • wc426mx

Posted January 12, 2005 - 04:51 PM

#1

I'm new to the board, so I may be kicking a dead horse, but my '02 YZ426 motor is very hard to start, and I'm looking for ways to help this. I'm wondering if it would be better to get the Hotcams YZ426 Auto-Decomp. cam, or the YZ450 Auto-Decomp. cam? Why? Which would better suit a fairly stock motor (full exhaust & filter)? Also, what about the BK Mod? Is there anything else that will help starting?

  • Chills

Posted January 12, 2005 - 05:30 PM

#2

Hey WC,



As being a new member also, and still reading my way through post and learning a bunch, your not beating a dead horse, just not looking enough. Everything you have mentioned has been posted and is avail for viewing in the Thumper FAQ.

At the top, on the navigation bar for Thumper Talk, there is a search button that will allow you to enter in key words for searches for everything you have asked, it will also allow you to limit the search area just to the YZ400/426/450F forums.

As far as the Cam mod Question, I am...Let me correct myself, I was in your same shoes as of this afternoon. I order the 450 Cam for a couple of reasons.
1. Cheaper
2. Increased Performance
3. The amount of test applications and post about the 450 mod and its success.

With the Hot Cams, in order to get a performance increase, you must also get the Intake Cam. On top of that the price of each cam is about $150 (+/-) EACH.

With the 450 Cam mod, the performance increase is there with just the 450 cam, the cost is cheaper, I got mine for $95, and the success rate and rave about it unparallel.

About Starting, There are the Blue Wire mod (BW Mod), the TSP Mod, James Now Mod, and a few others.

Take a peek at the FAQ, and take you time searching through the forums. This website is packed with more info than you can believe...

  • wc426mx

Posted January 13, 2005 - 12:05 AM

#3

Thanks for the reply Chills. I was just a little cautious about the YZ450 cam, but I suppose it works just fine? I'll check out the FAQ section and do some more reading. If anyone else has any information that they'd like to give, please feel free.

  • blue_beast_wins

Posted January 13, 2005 - 12:39 AM

#4

Hey WC,



As being a new member also, and still reading my way through post and learning a bunch, your not beating a dead horse, just not looking enough. Everything you have mentioned has been posted and is avail for viewing in the Thumper FAQ.

At the top, on the navigation bar for Thumper Talk, there is a search button that will allow you to enter in key words for searches for everything you have asked, it will also allow you to limit the search area just to the YZ400/426/450F forums.

As far as the Cam mod Question, I am...Let me correct myself, I was in your same shoes as of this afternoon. I order the 450 Cam for a couple of reasons.
1. Cheaper
2. Increased Performance
3. The amount of test applications and post about the 450 mod and its success.

With the Hot Cams, in order to get a performance increase, you must also get the Intake Cam. On top of that the price of each cam is about $150 (+/-) EACH.

With the 450 Cam mod, the performance increase is there with just the 450 cam, the cost is cheaper, I got mine for $95, and the success rate and rave about it unparallel.

About Starting, There are the Blue Wire mod (BW Mod), the TSP Mod, James Now Mod, and a few others.

Take a peek at the FAQ, and take you time searching through the forums. This website is packed with more info than you can believe...

Chills, your on the money :cry:

  • Chills

Posted January 13, 2005 - 09:45 AM

#5

Also,

I do apoligize, I meant to refer you to www.thumperfaq.com sorry for the confusion. I know the website gears you around the 250F, but you can find a TON of useful Mods, help, Info, ect here.....

  • skthom2320

Posted January 13, 2005 - 12:27 PM

#6

There's no reason to put a new cam in your bike to have easy starting. I have an '01 426 that is a 1-2 kick bike every time. Even after it has sat for 4 weeks. And my bike is completely stock.

Basically to get easy starting you need to know how to kick it over properly and you get the pilot circuit jetting (fuel screw and pilot jet) dialed in.

(1) The starting drill (from cold) on the 426 is the following

a. NO twists of the throttle and NO twisting the throttle during kicking due to the accelerator pump. (note some people will find that their own bike likes one or two twists of the throttle on cold days - avoid that until you get your bike dialed)

b. choke out

c. kick it to the hard spot, then use the decomp lever to push it slightly past TDC

d. return it to the top and kick it like you mean it

e. If you twist the throttle while yuo are kicking it will be a bear to start

f. If it won't start, put in a fresh plug. This will usually result in a first kick start as long as you are using the drill above and yur jetting is ANYWHERE near where it needs to be.

(2) Jetting - A cold bike likes a rich mixture on the pilot circuit - fuel screw OUT to richen. No more than about 2.5 turns out otherwise you need a richer pilot jet. You have the jetting dialed if it starts easily from cold, there is slight popping on deceleration from medium revs, and there is no hesitation just off idle (with bike warmed up), i.e., it is "snappy" when you blip the throttle and when you roll-on the throttle.

(3) A hot bike likes a lean mixture on the pilot - this why you use the hot start which just lets in air through a hole.

So, the question to you is, when is your bike hard to start? The first start of the day? When it is hot? When you "flame out" in a corner? All the time? Is your jetting stock? What is your pilot jet?

The bottom line is that easy starting can be yours with a little "dialing in" and maybe $10 worth of pilot jets.

  • 426mankiller

Posted January 13, 2005 - 02:50 PM

#7

skthom is right, be patient, learn the drill--my engine is stock and 1-2 kick start once I learned the drill too.:cry:

  • Ga426owner

Posted January 13, 2005 - 02:54 PM

#8

I'm new to the board, so I may be kicking a dead horse, but my '02 YZ426 motor is very hard to start, and I'm looking for ways to help this. I'm wondering if it would be better to get the Hotcams YZ426 Auto-Decomp. cam, or the YZ450 Auto-Decomp. cam? Why? Which would better suit a fairly stock motor (full exhaust & filter)? Also, what about the BK Mod? Is there anything else that will help starting?


When is the last time the valves were adjusted? This causes hard starting as well as not getting TDC top dead center during the starting drill.

  • BigDesto

Posted January 13, 2005 - 03:02 PM

#9

Everything they said! The DRILL:D !!

  • dezert_dominator

Posted January 13, 2005 - 04:20 PM

#10

I know how you feel, I have the same bike the guy I bought it from told me his way to start it and was not working at all. I thought this thing sucked and started to look for a new bike then I watched this video and now it starts right up..Here you go...

http://www.yamaha-mo..._stroke_fr.html

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • wc426mx

Posted January 13, 2005 - 04:46 PM

#11

Thanks for all the replies. I will check on the jetting, and try the starting drill. What about the BK mod? Is this a worthwhile mod to do? Thanks.

  • 426mankiller

Posted January 13, 2005 - 05:52 PM

#12

Patience Grasshopper-- Get it going first, ride it and get used to it, then do any mods you might think are necessary--THE BIGGEST IS TRYING TO GET RID OF ONE OF THESE AFTER A DAY OF RIDING:D

  • skthom2320

Posted January 13, 2005 - 06:01 PM

#13

Thanks for all the replies. I will check on the jetting, and try the starting drill. What about the BK mod? Is this a worthwhile mod to do? Thanks.


You don't need the BK mod for your year. It was helpful for '00 bikes but the '01 and '02 had different (updated) ignition maps and jetting that reduced the off-idle "bog" to minimal amounts. I did the BK mod to my bike and tinkered with a quite a bit. All it did was get me a hole in my carb since my bike was already jetted pretty well (with stock needle, although in very hot and humid weather I always long for JD's needles). Get the jetting dialed first. Once the pilot and remaining jetting circuits are dialed (and you understand it) you'll be a happy camper. If you want to spend money on something that will be helpful, get the JD needles from the TT store.

  • wc426mx

Posted January 20, 2005 - 02:03 PM

#14

I'm just looking to get the jetting NEAR where it should be. Once I get it in the same ballpark, I can fine-tune it.

If I list my location, sea level height, and bike mods, can someone give me an approximate jetting guide? :cry: I just don't know where to start. Thanks!

  • skthom2320

Posted January 20, 2005 - 02:39 PM

#15

Yes - but there is a jetting section that might get you some additional suggestions. Post in there.

  • Fastest1

Posted January 20, 2005 - 03:36 PM

#16

Dont rule out the 450 exhaust cam, just dont do it til your starting ritual or problems are worked out. Regarding the dependability of the 450 cam, there hasnt been a failure or problem caused by using it yet (from anyone). It will give you easier kicking with no drill, ability to bump back to life if you stall it and are still rolling, It is an easy to do mod. SKTHOM is right on about the BK mod and jetting in general. Also everyone loves JD's Jetting kit.

  • FZ1426

Posted January 20, 2005 - 04:34 PM

#17

Just past TDC and don't touch the throttle. Keep your right hand in the right side cover opening.

  • Chills

Posted January 20, 2005 - 05:00 PM

#18

The Starting Drill Works Yes, But you take 4 serious laps of hard labor, the front tire washes and you dump, Get back up, and in the heat of starting and trying to go through the drill and the frustration of trying to get it re-lite, when your already breathless, I'll take the 450 Cam Mod anytime!!

Proof in point, Yesterday at the track. Track was nice, but corners were over watered and muddy, front end washes on lap 4, the bike and I go over, and tried my damnedess to reach the clutch, and didnt get it in time, bike dies.....Get it up, pull the Hot Start, and 4 kicks later its fired back up!! Even with the 450 cam, and autodecompression, it was still tiresome kickin that over, yet alone trying to go through the drill without the cam....

450 Cam in my book is a 100% +
Bike fires on the 1st or second kick everytime...

Since I've had the 450 cam in it, I have yet to even reach for the decompression lever!!

  • yz426'r

Posted January 26, 2005 - 08:51 PM

#19

I agree with the method used by skthom 2320. That is what I use and I get the same results, 1-2 kicks. Once you get used to it it's great. good luck.

  • ibigcity

Posted January 26, 2005 - 09:04 PM

#20

Here's what I've done to my '01 426F. I did a modified version of the BK Mod, only adjusted the screw about one turn and the Blue Wire mod. Those helped quite a bit for sure. Then, I just recently bought the 450 cam and had the valves adjusted at the same time. WOW, I wound up with a new bike it seemed once I tried to start it. I've ridden the bike on just two occasions since the work and I'm totally amazed at how different the bike seems. Take my word for it, get the 450 cam and "screw the drill".

I was skeptical like the next guy, but now I'm a believer. For example, my brother came over to spectate while I was doing a shock service. Upon completion I had to show him how easy it was to start the bike now. I was standing beside the bike, on the right side, and started it with one kick with my right leg. You'd never even try this with a stock cam! I'm 6' 1" tall and weigh 153 pounds, not exactly a lot of mass to help out here.

Plus, for trail riding with my 13 year old son who stops all the time, bump starting is unreal. Second gear, barely rolling, just dump the clutch. Voom, you're off.

Do the cam and report back!

Bob :cry:





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