Help - Need Advice (warning long)

Sounds like she's still rich, I'd check ALL the jets against what the manual says is supposed to be there, check the float height, and make sure there's no crud of ant kind causing it to hang open....check the float needle and seat for burrs that might keep the needle from seating too.

Sounds like the "new kid" might have really hosed things up in there :)....good luck,

Hi Guys, I have been away in Sydney all week on course and have just got back. My bike is still in pieces on the garage floor :) . I sent the better half into the shop in my absence to pick up some jets for me including a 42 pilot and 162 main jet. The plugs are still coming out heaps black, and after talking to other 426 riders in the area it seems that with the mods my bike has (ie minimal) it should run just fine and dandy on a 162 main jet and 42 pilot with needle clip in the 3rd position. By all accounts, the 175 main and then the 170 that the shop installed are way too rich for this area (confirmed by going through 5, very black and wet plugs.) I have checked the cam install and timing myself and that all looks good. The problem seems to be intermittent because the bike runs okay until the plug starts fouling and then the running gets gradually worse until the plug is so fouled that the bike won't run or start anymore. I am pretty sure it isn't electrical, but won't rule it out altogether at this stage. I will install the 162 main and 42 pilot tomorrow and let you guys know how I get on. If these settings don't work then I guess it is pretty safe to assume the problem is elsewhere. Will cross that bridge tomorrow. Thanks yet again for all of your great suggestions.


Sorry to hear about the problems u are having..I had the same thing happen to me with my 03 450. I feel it is definitly a jetting issue, and I found out the hard way, that the more changes you make with your jetting, the longer it will take you to sort it out. Ok...this is what needs to be done first, imho...Read the jetting q's sticky all the way will take you about an hour or so to do it. In that thread, is literally thousands of hours of research on the issue. You cannot make drastic changes in jetting. I would start with the stock settings on all jets and clip positions..then start by moving the clip..make notes...then move on to another section after you run out of clip positions(main jet) then start with the clip with the new change etc...Please read the jetting q though..u will be an expert in carbs after that!

Good luck! :D

P.S..make sure the air filter is clean ..this will give u fits also! :)

The problem seems to be intermittent because the bike runs okay until the plug starts fouling and then the running gets gradually worse until the plug is so fouled that the bike won't run or start anymore. I am pretty sure

This is why I recommended checking the needle/seat for damage or crud floating around...if the needle hangs open you'll have a sudden, intermittent rich condition...

Arghhhh!!! I am still going nuts here. I reset all of the jetting to stock (42 pilot, 165 main and 4th needle clip position) and they bike is still doing the same thing (running poorly, very black plug). I checked the needle, seat and floats for gunk and damage and they look fine. I gave the carb a general clean out and used compressed air to clean the air jets. I have checked the timing and cam install and that all looks good. Could it be a valve getting stuck open or something? How would I check for this? It is just weird that the plugs are coming out mega black even at the stock jetting settings.

As an aside, when I put the 42 pilot in, I discovered the shop had installed a 48 pilot :) (instead of the 45 that the told me). This means that the bike was running on a 175 main jet and 48 pilot. Seems way off the mark for a stock engine to me. Also, because I was away I sent my better half, Sally, into the shop to get the jets for me. They told her that they don't stock those jets because they aren't a Yamaha Dealer. This means they didn't even attempt to do what I requested when I took the bike back in. I asked them to install a 162 main, 42 pilot and needle clip in the 4th position. What they did was install a 170 main, 48 pilot and needle in the 1st position. Also, they said to Sally that it is probably the cam and that I have no idea what I am on about and were really rude to her. Sal then went to the Yamaha dealer and picked up the jets for me. Not happy Jan!

So, it looks like it is not just a jetting issue (come on, where are the "I told you so's" :D). I am gonna double check everything now (timing, valve clearances, clean the carby, check connections) but I have to say I am feeling somewhat discouraged right about now. I just wanna ride! :D

Hi yet again guys. I am currently in the process of double checking everything. Thankfully my tools have arrived so it is a bit easier to work on the bike now. I have ripped the carb out and sat it to one side. The air cleaner was pretty clean anyhow, but I have given it a good scrub. I have cracked the engine cover off and am now in the process of checking the timing again. The timing marks on the cams themselves line up as per the instructions from Thumpertalk, however I am also checking now using the TDC mark under the timing plug. According to the workshop manual I am looking for a line to line up with the little marks on the top and bottom of the timing plug, however when i crank the engine around and look in the timing plug all i can see is some arrows, a couple of holes and what looks like the word "HI". I thought the TDC line may have been the "I" in the "HI". Can you guys tell me exactly what I am looking for as there doesn't seem to be a line that looks like the one in the work shop manual. I want to do this double checking the right way. The shop obviously screwed something up and for the $700 they stung me if it turns out to be the timing I'm gonna be asking for a refund. Surely this is elementary stuff to a qualified mechanic.

After I have checked the timing I will check the valve clearances again. Last time I checked them they were close to max, but within tolerances. I will double check them while the engine is open.

.....and another quick question. How exactly will I know if the carby slide has been installed upside down? What exactly am I looking for? The pictures in the workshop manual aren't overly clear.....well to a novice like myself anyways :). Cheers


Forgive me if this has been covered, I haven't read everything above to carefully, but have you checked your accelerator pump timing and/or duration? :)

Hi Lipskid, I haven't ckecked the accelerator pump timing or durations accurately yet, but I will be very soon as I will be doing the BK mod as soon as I get my bike up and running. I am checking the timing and valve clearances right as I type this, but I am still somewhat confused as to what I am looking for to find TDC using the timing plug. As I posted above, there doesn't seem to be a line like in the picture in the workshop manual. The timing marks on the cam line up as per the pdf file from this site, however they don't seem to line up with anything in the timing plug. So I am suspecting that the cams may not be timed to the piston correctly, but i want to be sure about what I am looking for through the timing plug.

I am pretty confident it isn't an accelerator pump issue. I know the squirt isn't hitting the slide, because when I pulled the carby out for the first time ever I got a good squirt of fuel in the eye! I bet you only to that once ever! :)


When I did the YZ timing awhile ago there was not a long hash mark on the flywheel as the manual shows. Your HI mark is what I found for TDC. My guess is that both of your cams are a tooth off.

TC, if this is the case and the "HI" mark is TDC, then on the compression stroke at TDC the cam timing marks are at the bottom (about 180 degrees out)and as you say they look to be one tooth out. I'm guessing this is bad :D The valve clearances also seem to be out at TDC ie no clearance on the intake valves and heaps of clearance on the exhaust.....what a mess!

So in summary, the shop installed the cam, as per the pic in the pdf file from this site, but it appears that they didn't use the timing plug to time the cams to the piston. They then tried to fix the intermittent problem with the jetting and screwed that too by going way too rich on both the pilot and main jet. And I paid them $700 to do this. Next question is....should I take a course of action against the dealer? :)

Well, back to the garage to fix the cams up and recheck clearances.

Absolutely take action. Dont ever let them work on your bike ever again. Find somebody who knows something or do it yourself with the help of your TT members. That is really sloppy work that you overpaid for! :):D

Well, I have reset the cams and timed them to the piston and I have swapped some of the valve shims around to try and fix the valve clearances (no bike stores are open in Canberra on a sunday :)). The clearances are still a bit out, but not too bad. Anyway, I fired the bike up and it started second kick. I took it for a 30 min ride and everything seemed okay - no more spluttering and loss of power. The jetting needs to be fine tuned a little, but at least the plug wasn't black this time. I am doing the BK mod next so I will need to mess with the jetting anyhow. I am off to Sydney now, so i just got bike back together in time. I will fix the valve clearances and take the bike for a big ride next weekend. If that is all good then I will do the BK mod. I have a feeling the problem has been solved, but I won't assume until the bike has been taken for a big ride. I will also get onto the dealer during the week to let them know where they screwed up. Thanks guys for all your help, I don't know where I would have been without you all. Two big thumbs up :D :D This has been a great learning experience for me. Have a great week! Cheers! :D :D :D :D

when I pulled the carby out for the first time ever I got a good squirt of fuel in the eye! I bet you only to that once ever! :D

:lol:i dont know what youre talking about :)

:thumbsup:for not getting pissed off and working thru the problem, now go :cheers:for all the hard work.


Glad to see you are on the right track. I think the only problem you have is trying to prove to the shop that they were wrong! If you can, I think they need to reimburse you at least part of the money. Ans the fact that a trainee was working on your bike the first time should get you something. Were they charging you an hourly rate with the trainee working on it?. I would be LIVID!!!

Good luck and let us know what happens!


I would bring it up with Yamaha Corp. directly. Let them know what you have gone through and tell them about the untruthfulness regarding the jetting you instructed and paid them to do. Dont stand for any rudeness, you are paying top dollar for their work, the customer is always #1.

Hey Holeshot. The problem is that the work wasn't done by a Yamaha dealer, as the local Yamaha dealer point blank refused to do the mod. As such the local Honda/Kawasaki dealer did the work (they have an ex-Yamaha mechanic working for them). Which probably explains the whole cock-up :). I thought I was doing the smart thing by getting "competent" people to work on my bike. I shoulda done the work myself. I am still gonna hit the bike up for at least a partial refund.

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