Sneezing & Coughing & Blueing??

[Sterlin]

I recently purchased an '04 VMAX with 1,000 miles on it. It has two minor (I hope) issues; 1) sneezing at idle and low speed, and, 2) the right front exhause pipe is blued for about a foot from the engine. I removed the brass plugs and found the following settings:
Cyl 2 Originally set @ 3 turns, I set @ 2 1/2 turns

Cyl 4 Originally set @ 1 1/2 turns, I set @ 2 1/2 turns

Cyl 1 Originally set @ 2 1/2 turns, I set @ 2 1/2 turns

Cyl 3 Originally set @ 3 turns, I set @ 2 1/2 turns

Due to the weather, I haven't been able to checkout the new settings. But would the Cyl 4 setting at 1 1/2 turns contribute to the blueing of the exhaust pipe? Any other suggestions/comments would be appreciated.

 

[KJShover]

have you synced the carbs yet?

 

[Sterlin]

I have not sync'd yet. Need to get equipment...

 

[naughtyG]

When you say you removed the brass plugs, do you mean the A/F screws, or do you mean that the plugs were still in place from the factory in front of the A/F screws?

1 1/2 turns sure sounds a little on the lean side, but from bike to bike you never know..

Also, the sneezing usually indicates clogged up carbs, and an '04 with only 1000 miles has most obviously done a lot of sitting around - not good.

I would start with the peashooter and the shotgun cleaning methods with Seafoam, but to be honest nothing is as effective as a carb tear-down, proper clean and inspection/replacement of any perished rubber parts. You'll be amazed how much gunk old gas can create!

Anyway, easiest thing for starters is to put a couple of ounces of Seafoam in your gas tank (don't overdo it it's not a car-sized tank!), run it like that and see how much it helps. That stuff eats gunk for breaky. Then shotgun and peashooter (all info found in the carb section) and if still not happy then take yer carbs off and clean them thoroughly.

Oh and of course the carb sync - that is due once a month according to Yamaha's service manual!!

 

[Sterlin]

I drilled and removed the factory brass plugs covering the fuel mixture screws. Exactly what these screws are called (pilot, fuel/idle mixture, etc.) is a little confusing.

 

[KJShover]

Air/Fuel mixture screws.

 

[Thevmaxrider]

It sounds a lot like a "lean sneeze" that can be common in bikes that haven't had their A/F mixtures adjusted properly. I also agree that if the bike has that low of mileage for its age a good go through might be just the trick for the carbs. The peashooter and shotgun both can help, check your float levels, and re-synch the carbs. This should get you going and any other issues that might pop up can be dealt with on an as needed basis.

 

[naughtyG]

Cyl 1 Originally set @ 2 1/2 turns, I set @ 2 1/2 turns

Cyl 2 Originally set @ 3 turns, I set @ 2 1/2 turns

Cyl 3 Originally set @ 3 turns, I set @ 2 1/2 turns

Cyl 4 Originally set @ 1 1/2 turns, I set @ 2 1/2 turns

I find it quite interesting that the A/F screws were set like this at the factory. I've often wondered how they would have been set as mine had already been tempered with when I got my bike.
There must be a reason, and surely they have ways to tell/test what the optimum settings are when assembling the bikes? Even more so considering that this setting is supposed to be 'for good' since it's then sealed by the brass plugs and in theory, should/would never be disturbed?:ummm::ummm:

 

[Thevmaxrider]

The factory sets them on the lean side for emissions testing to ensure that they meet the standards. Yamaha inserts plugs to show that they have done what they can to ensure that the settings are not "modifiable" and yet make them fairly easy for us to change to optimize the carbs.

 

[maxout1200]

That much discoloration with only a 1000 miles makes me suspicious that the factory may have screwed up the settings causing a lean condition. They do make mistakes occasionally.


That may not be the reason for the bike not running well at this point though. Dirty carbs a good bet. What did the spark plug look like from the blued cylinder compared to the others?

 

[m-cman]

There is no way a stock header pipe should be that badly blued in that short a time. I would not drive much till you find what is causing the lean condition in that cylinder. It is running way too hot. Something is wrong inside that particular carb.

 

[Sterlin]

I pulled the spark plugs. They are all the same; gray with no carbon build-up.

 

[dannymax]

I removed the brass plugs over the A/F screws @ 10,700 miles and recorded the factory settings:
#1...............1 1/8 turns out
#2...............2 turns out
#3...............1 1/4 turns out
#4...............1 3/4 turns out

I have aftermarket Marving slip-ons on, each A/F screw is now @ 2 3/4 turns out, carbs sync'd and it runs very well.

 

[m-cman]

I believe Yamaha sets them using the exhaust sniffers to the lean EPA settings to pass regs. Probably done at the factory but the dealers have the sniffers also and could do them when in for maintenance.

 

[naughtyG]

I wish there was an easy and reliable way to set each screw to its optimum setting!? :ummm::confused2::ummm:

So far everything I've seen / heard has been more or less guess work and/or hit and miss..

The closest to a reliable method I can think of was Lankee's laser temperature gun on the headers method, but even that has its flaws.. (exact distance, variation in metal thickness, heatsink effect of adjacent parts etc)

 

[Sterlin]

Could there simply be a problem with the exhaust pipe? Anyone ever had experience with a stock exhaust bluing? I've had straight pipes on other bikes bluing...

 

[m-cman]

The exhaust sniffers that Yamaha dealers use would be the best way. Just set to optimum performance settings instead of EPA settings.

Tha head pipe should not blue if it is a stock double wall pipe. That is why I was so concerned in an earlier post. If one of the stock pipes is badly blued, that carb has to have a problem or there is an air leak leaning the mixture or ?. Something is causing too much heat in that pipe...

 

[Sterlin]

Re: Sneezing & Coughing & Bluing??

I ordered a Carbtune and will sync the carbs.

I also like the 1) Lankee's laser temperature gun on the headers to detect any overheating and 2) the using the exhaust sniffers that Yamaha dealers have and set to optimum performance settings instead of EPA settings.

Many thanks for your comments and advice. And I welcome any new thoughts. This site and the experience it contains and is offered is super!!

It will be a while before I can get through all the check-outs; winter in the NY Catskills kinda slows things down a bit......

 

[dannymax]

The exhaust gas analyzer the Yamaha dealer has is prolly the best way to tune. Northern Tool, and I think JC Whitney sold a small EGA unit for around $200 that would work also but I heard they aren't very user friendly.

 

[jfeagins]

The exhaust gas analyzer the Yamaha dealer has is prolly the best way to tune. Northern Tool, and I think JC Whitney sold a small EGA unit for around $200 that would work also but I heard they aren't very user friendly.

I bought one of those Whitney sniffers years ago and have successfully used it to tune my Max. The trick is to build a small brass manifold with in's (from the carbs) and a common out (to the sniffer) with a shutoff on all four. Start out connecting all cylinders to the manifold and as you sync, you dial in each cylinder, one at a time and only have to turn the small brass shutoffs between tuning each cylinder. Otherwise, you have to stop and take off the sniffer from one carb and re-attach to the next carb etc. one at a time as the sniffer has only enough attachments to do one carb at a time.

The sniffer readings DO bounce around a bit, but once you get the hang of it, it's a piece of cake.