pilot screw 5 turns out

[Mike R]

I've been having problems with backfire thru the carbs so I did alot of reading and most say pilot screw is lean so I went 4 turn and then 5 a little better. My question is why do I have to be out so far on my pilot setting? I should mention it has a k&n air filter and the box top has been opened up quite a bit and the stock mufflers have been opened up also

Thanks

Mike

Edited April 1, 2015 by Mike R

[BlueSky]

The first thing I would try is to put some cleaner in the gas. The forum recommends seafoam. I might would try some Gumout with regane on the label available at Walmart.

 

How long has it been since the valves were adjusted?

[rbig1]

um I think it wont run right till you close the air box back up. there touchy about that.

[Flyinfool]

All of the things that you have done will each make it leaner. You will most likely need to change the main jets to get it to run right with all of those mods.

 

Depending on just how much you have opened things up you might be able to get close by playing with the needle shims and/or the pilot. If not then either close some of the breathing back up or start playing with the main jets. These bikes do not like the airflow to be messed with. Most of the people that have messed with the airbox are now running around with patches on the air box to get back to stock airflow.

[Condor]

Gotta ask... Are you back firing up through the carbs when starting, or the mufflers when decelerating?? There's a lot of things that could cause backfiring up thru the carbs. Timing being one of them. The idle jets are when you are backfiring upon deceleration or so I've seen written.??... Personally I think exhaust come mostly from an exhaust or intake manifold leak somewhere... OR you're running on 3 cylinders....??

[dingy]

I thought the enrichment diaphragms also helped with the backfiring on deaccel. Maybe a bad one?

 

Not positive though.

 

Gary

[Mike R]

Thanks guys , the guy I bought it from in December said the valves were done recently. ..yes I am back firing thru the carbs ......I've ran 3 cans of sea foam thru the bike in the last two in a half weeks ...The air box is easy repairable ......any more ideas would be great. ....

[Brenner]

I had the same concern on one of my carbs so I pulled the slider cap and removed the spring and o ring and use a can of air intake cleaner with a straw and blew into the pilot orfice and turned the screw all the way out and repeat and once I felt it was clear I put it back together and my pilot required only 1.5 - 2 turns as per spec. YMMV

[KIC]

um I think it wont run right till you close the air box back up. there touchy about that.

 

:sign yeah that::sign yeah that:

[rbig1]

lol you got me. I think there are a couple members not to far away. how far off is the syn of carbs. condor is right about 3 cylinders firing. see if the pipes are hot when you first start it. had that problem when I first got mine. the first gens arnt short on power when setup correct. also add what bike you have and year that will help get the right info. welcome aboard you might as well join a wealth of info here.

[Mike R]

I'll check the cylinders I'm also thinking stage 1 jet kit for a vmax. ..what's your guys thoughts on this?

[skydoc_17]

Hey Mike,

Welcome to the forum. It would really help if we knew what year your bike is. Here's some general info about what is going on with your bike currently. Yamaha when to a fair amount of trouble to "tune" these bikes to be a trouble free touring bike. By opening up the airbox, changing the air filter, and removing the back pressure from the exhaust system, you have basically turned your Venture into a "DRAGSTER"! The only way this bike is going to run, is WIDE OPEN. Now, far be it for me to knock anyone that wants to make their bike go faster, Lord knows I enjoy the "pucker factor" as well as the next man. The question you need to ask yourself Mike is, "what kind of bike do I want?" If you are looking for a quiet, dependable, touring bike that will carry two adults, plus luggage, at highway speeds, then you may need to back up here and return the airbox and exhaust to stock. If you are looking for a "tire burning" stoplight monster that gets 25 miles to the gallon, well then by all means, rejet the Carbs. But lets be honest here, at 800 pounds, you are NEVER going to be able to run with a Yamaha R1, or a CBR1000, or a VMAX for that matter. I can honestly say that above 125 MPH to 145 MPH the fairing on a First Gen. makes the front end so light that the "pucker factor" turns into the "terror factor"! Lets say for the sake of conversation, that all of your Carb. parts are functioning properly, (big IF here) a restriction in the exhaust would allow you to get closer to normal adjustments as far as Pilot Jet Screws, Carb. Sync. and Idle goes. Remember, NOTHING on your bike is going to adjust normally because of the opening up of the airbox, and the gutting of the exhausts. The way the PROS would attack this project would be to run the bike bone stock on a DYNO, open up the airbox and DYNO it again, gut the mufflers, and DYNO it again. Rejet, and DYNO it again. Since you got the bike in it's current condition, you will have to answer the question I asked earlier, "what kind of bike do YOU want".

Earl

[jasonm.]

I see you really have altered both intake and exhaust . BUT if you are getting backfiring thru the carbs...that's a sign of "no combustion". Can be tight valves or too lean condition. Lean can also be the intake o-ring(s) are worn out. I can tell you 1st hand these are possible....as both happened to me. All my carbs came in on the EGA/ dyno machine 2.0 to 3 turns ccw for best idle. You really need to find someone with one of these set ups. YOU MUST EGA THE BIKE with these alterations. Otherwise you are chasing the "wild goose". Each head pipe has a 10mm headed bolt. Need to thread a 6mm pipe designed for Yamahas into these spots and then the bike is EGA'd...exhaust gas analyzed. You may need to make the device to thread into these spots yourself. I recommend Stainless allen screws with 6mm x 1 pitch x 10 mm L. thread. And 1/8" or 1/16" hole drilled down their centers. How do I know this ?... I made mine . But have lost them. I am sure I could find them if I look hard enough. The smooth head allen heads allow the sniffer hose to go onto them. Carbs must be sync'd too. Good luck.

[scuff]

I say easy way to find out if its the airbox is do what I did on my v-max get the duct tape out and start covering the hole your po made, put a piece of tape on it and ride it around, put some more on it and ride it around do that few time gradually covering the hole up until you have back to approx. stock size and see what that does should give you some more info to go on. oh and if your thinking about the DJ stage one kit, let me know i'll sell you the one out of my Max I don't like it, and not sure how it would work in a Venture, but everyone on the V-Max forum advises against the stage 1

Edited April 5, 2015 by scuff
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