Exhaust Fumes

[Zeus36]

...One thing to think about. With Vboost closed (at part throttle) it makes the bike leaner, because you now getting the air from 2 carbs. Ive got an A/F meter on the bike and Ive seen this. So with Vboost closed, the fuel smell should get worse, but the underlying problem, is running too rich with the main jets. That will make you too rich everywhere...

My understanding is without Vboost active (closed), each single cylinder is fed by a single carb and the result with correct jetting is ideal A/F mixture. With Vboost ON (open) (above 6K), the butterfly valve opens to allow two carburetors to feed the firing cylinder. Yamaha refers to it as "supercharging" in their text. (I don't agree with that term) According to them it is effective at higher RPM and higher airflow.

If you have Vboost always ON, you are "supercharging" or double carbureting at all RPMs. This would seem to dump more fuel into the cylinders and create a richer mix, especially at lower RPMs and lower airflow.

The reason I don't like Yamaha's term is because superchargers are big air pumps that force more air into the engine, not fuel.

 

[Traumahawk]

My understanding is without Vboost active (closed), each single cylinder is fed by a single carb and the result with correct jetting is ideal A/F mixture. With Vboost ON (open) (above 6K), the butterfly valve opens to allow two carburetors to feed the firing cylinder. Yamaha refers to it as "supercharging" in their text. (I don't agree with that term) According to them it is effective at higher RPM and higher airflow.

If you have Vboost always ON, you are "supercharging" or double carbureting at all RPMs. This would seem to dump more fuel into the cylinders and create a richer mix, especially at lower RPMs and lower airflow.

The reason I don't like Yamaha's term is because superchargers are big air pumps that force more air into the engine, not fuel.

Well at part throttle, having Vboost open, it will make you leaner everywhere, at full throttle, having Vboost open makes you richer everywhere.

EDIT...I wanted to go a bit more into detail. So at part throttle with the Vboost open, say at 3000 RPM, your still running on the A/F mixture screws, (up to 1/4 throttle) which is a little bit of fuel, but getting the amount of air from 2 carbs....so your actually running lean. At 3000 rpm at full throttle at full throttle your getting into the needles/main jets so you still have twice as much air, but now twice as much fuel as well. I believe that it was Sean that dyno'd with T-boost, and basically lost either 10 lbs of tq of 10 hp thru the mid range.

 

[thor_eyerdhal]

Mine was smelling Gas at stoplight when i was using 175 DJ main jets ( main circuit way too rich), especially after a WOT run. No way to reduce this smell with idle tuning (from 1.5 to 3.5 turns).
Now (after WB tune) i am running 147.5 MK main jets, no more gas smell at stop...
My gas smell was an after WOT issue (like if the exhaust gas cloud was following me ), don't know exactly why...

 

[PMaxx]

I don't have the Morley kit, but if I put my hand down near the rear valve covers it smells like fuel. There's no popping so I don't think there's an exhaust leak. The bike seems quite rich though and the mileage kind of sucks.

 

[Traumahawk]

I don't have the Morley kit, but if I put my hand down near the rear valve covers it smells like fuel. There's no popping so I don't think there's an exhaust leak. The bike seems quite rich though and the mileage kind of sucks.

Even a stock Vmax can be too rich. Sometimes the PO had no idea what they were doing to these bikes.

 

[Traumahawk]

I don't have the Morley kit, but if I put my hand down near the rear valve covers it smells like fuel. There's no popping so I don't think there's an exhaust leak. The bike seems quite rich though and the mileage kind of sucks.

Oh, one good tidbit of information on checking plugs. If you have an aftermarket exhaust, and a jet kit, then you are looking for tan plugs. If the bike is stock (airbox, stock headpipes....etc) then your plugs will always be towards the whitish side. If they arent, you really are too rich.

EDIT*** here is a copy of my first dyno run. You can see on it that I was too rich. A/F screws were about 3 turns out, I had slip on's, and everything else was stock, well I had COPS. The ends of the slip-ons were a tad sooty, and the plugs were still white. Here is also a pic showing where people might be rich at, based on where the color is on the plug.

 

[blaxmax]

Too rich the plugs would be black. Not tan.

 

[PMaxx]

Thanks, I plan on changing the plugs next weekend so I'll post some pictures of what they look like. My bike came with a Mark's 4-1 full exhaust and a Dale Walker Stage 1 jet kit (not sure of what that includes exactly). The mixture screws have definitely been messed with because the brass plugs are missing. I'm thinking of doing a pea-shooter cleaning and counting the mixture screw settings to see where it's at.

Any idea how many turns the mixture screws should be at with my setup?

 

[blaxmax]

Thanks, I plan on changing the plugs next weekend so I'll post some pictures of what they look like. My bike came with a Mark's 4-1 full exhaust and a Dale Walker Stage 1 jet kit (not sure of what that includes exactly). The mixture screws have definitely been messed with because the brass plugs are missing. I'm thinking of doing a pea-shooter cleaning and counting the mixture screw settings to see where it's at.

Any idea how many turns the mixture screws should be at with my setup?

Start with 2 1/2 out

 

[Traumahawk]

thanks, i plan on changing the plugs next weekend so i'll post some pictures of what they look like. My bike came with a mark's 4-1 full exhaust and a dale walker stage 1 jet kit (not sure of what that includes exactly). The mixture screws have definitely been messed with because the brass plugs are missing. I'm thinking of doing a pea-shooter cleaning and counting the mixture screw settings to see where it's at.

Any idea how many turns the mixture screws should be at with my setup?

2 1/2-3.

 

[blaxmax]

Oh, one good tidbit of information on checking plugs. If you have an aftermarket exhaust, and a jet kit, then you are looking for tan plugs. If the bike is stock (airbox, stock headpipes....etc) then your plugs will always be towards the whitish side. If they arent, you really are too rich.

EDIT*** here is a copy of my first dyno run. You can see on it that I was too rich. A/F screws were about 3 turns out, I had slip on's, and everything else was stock, well I had COPS. The ends of the slip-ons were a tad sooty, and the plugs were still white. Here is also a pic showing where people might be rich at, based on where the color is on the plug.

Tan plugs----3rd line down from NGK-----

https://www.ngksparkplugs.com/about-ngk/faqs/spark-plug-faqs/how-do-i-read-a-spark-plug

 

[Traumahawk]

Tan plugs----3rd line down from NGK-----

https://www.ngksparkplugs.com/about-ngk/faqs/spark-plug-faqs/how-do-i-read-a-spark-plug

First of all, the only normal plug is the 1st one....every other one is abnormal due to wear, oil usage...etc. Unfortunately it wasnt Vmax specific.

My main goal is to get accurate info out there. As fair as dyno tuning....or dealing with the ignitech, I can prove all of that with the dyno runs that Ive done. Ive got probably 90 runs on the 07, and I was thinking about it earlier, thats probably 1000-1500 (just on dyno fees) that I spent to get a good running bike, and to be able to spread that information out there. I posted my successes, and my failures. There was a dyno run (3 hrs worth at 85 bucks an hr), and I walked away at 112 hp, which is worse that what i did with the stock airbox. I posted it all, because it was good info on what not to do.

So....I'm not being a dick, dyno your bike and post the A/F numbers and HP, take it down the strip, and post the info....etc. Copying someone is the sincerest form of flattery. If you can prove that your methods and ideas work, I will be your biggest fan.

Ive mentioned before that I would like to have a Vmax dyno day here in Lawton. If I can ever get it off the ground, your invited, please show me what you have, you have mentioned about coming thru to help me set the valves, so please bring the bike.

Your running a different set up than just about eveyone here, please post proof that it works.

This forum is not about being right, its about making certain that accurate info gets out there, and yes, Ive posted wrong links before, and answered incorrectly. Usually thats when I'm multitasking......but still no excuse, but all that I try to do is post the most accurate info out there about carbs.

Here is how I know what my A/F numbers are http://www.ebay.com/itm/270979863067?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

I bought it because it has a recording feature. People will look at you odd thought when you have it suctioned cupped to the tank, so that way you can get real world numbers. Yes, i have an O2 bung welded into the exhaust.

So, back to your regularly scheduled programming.

 

[blaxmax]

"Your running a different set up than just about eveyone here, please post proof that it works."

I have.

 

[Traumahawk]

I cant remember where.....can you repost the dynosheet or timeslip?

 

[blaxmax]

I cant remember where.....can you repost the dynosheet or timeslip?

No , this thread is about exhaust fumes, bye eric.

 

[Traumahawk]

No , this thread is about exhaust fumes, bye eric.

Bye J....

 

[sdt354]

This may sound simple, but is the crank case breather/vapor hose on the nipple at the rear of the air box? If your running big mains and rich everywhere else, and the hose is off? Just saying, vapors won't be getting sucked back into the intake. I run mine
not connected, but have it vented to the atmosphere. I sometimes smell fumes because of it. but then again I always liked those kind of smells.

 

[gentsvmax]

Proof is in the postings, Traumahawk, you've helped me more than I can post with your concise and well reasoned explanations based on your great working knowledge and experience with our bikes.

Recent jetting info you posted that I cant copy in right now really helped me out, I thought I had a sent a PM your way to say thanks.
Please continue your valued contributions.

 

[Zeus36]

This may sound simple, but is the crank case breather/vapor hose on the nipple at the rear of the air box? If your running big mains and rich everywhere else, and the hose is off? Just saying, vapors won't be getting sucked back into the intake. I run mine
not connected, but have it vented to the atmosphere. I sometimes smell fumes because of it. but then again I always liked those kind of smells.

Same thing happened to me after reinstalling the airbox. Didn't have the hose connected and I could smell engine fumes. Quick fix with a pair of large hemostats. Maybe the prior owner reconfigured the breather hose setup.

 

[sdt354]

Same thing happened to me after reinstalling the airbox. Didn't have the hose connected and I could smell engine fumes. Quick fix with a pair of large hemostats. Maybe the prior owner reconfigured the breather hose setup.

That hose is a major source of aggravation for many new guys. I had better luck with a hose clamp, then reaching in with a 1/4 drive long extention and a socket. I ended up putting a tee under the carb bracket to tie in my oil fill cap(with 3/8 nipple installed, to the crankcase venting. This worked out well because I could pull up on the tee and get the hose up secure on the nipple easy. Stage 7 filters solve that delema quick.