A new twist on the single carb swap

[PKR Customs]

Here is a little video of a custom single carb swap on my venture. I own my own shop, PKR Customs out of Findlay, OH, and am willing to answer any question anyone may have.

 

[Freebird]

Interesting. I've seen this tried a few times but have not heard of one that truly works well. I don't remember all the why's or why nots but it will be interesting to see the final results of your setup. I know that there have been one or two others here who have tried other variations of this. Please keep us updated on how it works out.

Edited September 27, 2016 by Freebird

[CaseyJ955]

I just love projects. It does sound responsive, the v4 is just a musical beast!

 

What sort of MPG are you getting with it? I have imagined my Vmax with a Dellorto DRLA or progressive Weber after seeing the supercharger kits with a small Holley. Pretty cool stuff there!

 

X2 keep us posted.

[PKR Customs]

I am currently unaware of the MPGs I am getting because the this setup has only been in the bike for about a week and I have not had to refuel the bike yet. As soon as I get the numbers I will post them for eveyone. I have on the other hand had a chance to test out the power of the bike and it is amazing, I have a buddy with an 02 cobra and the bike will pull away from him with ease. I cannot wait to do a few more upgrade to the bike such as coils, exhaust and brakes to unlock the bikes full potential.

[Condor]

I cannot wait to do a few more upgrade to the bike such as coils, exhaust and brakes to unlock the bikes full potential.

 

That's really interesting. I wonder what it would be like with V-Max heads and cams?? OR that set up on a V-Max instead of the boost. Just not having to fiddle with 4 carbs is a plus in my book....

[PKR Customs]

I have been wondering the same thing but at the moment the budgetvfot this build does not allow such upgrades to the motor. I have been in contact with the owner of UFO to try and figure out a few more options for our bikes as far as exhaust systems and performance upgrades.

[mmaleney]

Very nice.

 

Did you have to swap out jets or can you adjust jets / needles to get the ratio where you need to be.

[PKR Customs]

I did not change anything on the carb, it was bolt on and go. Now the jets are easily accessible from the top of the carb should you want to change them. Knowing that I would be doing a custom free flowing exhaust I left them alone, if you wanted to use the stock exhaust I would jet the carb down but I like my bikes loud.

[mountainmanVR]

I did not change anything on the carb, it was bolt on and go. Now the jets are easily accessible from the top of the carb should you want to change them. Knowing that I would be doing a custom free flowing exhaust I left them alone, if you wanted to use the stock exhaust I would jet the carb down but I like my bikes loud.

 

Howdy....

 

After reading your post.. and fighting carb issues (leaking)... this sounds like a viable alternative to the original 4 carb setup..

How does one do this with positive results?

[PKR Customs]

Howdy....

 

After reading your post.. and fighting carb issues (leaking)... this sounds like a viable alternative to the original 4 carb setup..

How does one do this with positive results?

 

Well I have attached some pictures crime the build process to help show exactly what I did to buod this set up. As of last night I did discover the fist downfall to this set up that will be addressed as soon as I get a couple other projects done, the builders projects are always at the bottom of the list when running your own business lol.

 

The issue I discover last night - As I was leaving a friends house at about 11:30pm (51 degrees out) I noticed that the bike had a stumble at lower rpm and after crusing for a short time at 3-3500 but was fine after cracking the throttle and at higher rpm. When I got back to my shop I inspected the set up and found that front had formed on the bottom of the intake collector, I removed the carb and found gelled fuel in the in the intake.

 

The fix for this issue - I will be adding a coolant heating chamber - heated by the coolant of the bike - to keep the manifold warm enough to eliminate the gelling fuel issue.

 

If you a have decent welding skills and patience, this is a very easy modification to perform.

 

Carb - holley 5740 bought new off eBay

Intake runners - 1 5/8" 180 mandrel bends bought from hellsgatehotrods.com

Throttle connection - uinlink kit bought off eBay new

Air filter - gl1100 stock filter bought off ebay

Carb mount - short cut 1/4" plate steel bought from a local steel supplier

Machining - holes in the plate were done by a local machine shop for accuracy and cleanliness

Carb to runners - 2 3/4" exhaust connector from any auto parts store ovaled to meet my needs

Various vacuum caps and brass fitting all bought from local auto parts store

 

All in all this swap has run a total of $200 at the most although the biggest variance will be the carb because there are so many different prices for them on eBay.

 

One thing I did forget to mention in the video was that i eliminated the yics chamber and caped off the ports on the motor. I also connected the vacuum advance for the tci to the sync port on the left from carb boot.

 

Edited September 28, 2016 by PKR Customs
typographic errors

[Flyinfool]

I wonder how that manifold would work with a small TBI system instead of a carb??

Yes the carb will be a LOT easier to set up initially.

You will need to add throttle position sensor, O2 sensor(s), higher pressure fuel pump and lines, vacuum sensor mass airflow, etc.

But I hate carbs..........

[mmaleney]

Sounds like you may have old gas in the tank, Ethanol can have that effect on gas after about a month or so.

[PKR Customs]

I wonder how that manifold would work with a small TBI system instead of a carb??

Yes the carb will be a LOT easier to set up initially.

You will need to add throttle position sensor, O2 sensor(s), higher pressure fuel pump and lines, vacuum sensor mass airflow, etc.

But I hate carbs..........

 

I'm the complete opposite, I'd rather not clutter my bike with electronics. If it were a different style bike that a carb wouldn't look right on then ok but I love the look and the ease of tuning.

 

Sounds like you may have old gas in the tank, Ethanol can have that effect on gas after about a month or so.

 

I doubt it, I emptied the tank and resealed it as well as all new line and filters

[GaryZ]

That's really interesting. I wonder what it would be like with V-Max heads and cams?? OR that set up on a V-Max instead of the boost. Just not having to fiddle with 4 carbs is a plus in my book....

 

My '85 VR has Vmax cams and springs stuffed in an '87 version 1300 engine/trans. The carbs gave me so much trouble that the bike has been gathering dust for about 2 years. I have been brooding over how to put a Q-jet on it to take advantage of the vacuum secondaries. A friend gave me a fresh carb from an '85 Camaro v6. It is basically half of a Q-jet. The problems with using this carb are numerous; It is made for a 3.8L engine with smog controls. This thread showed me another carb with vacuum secondaries and jetted for a 1.6L. I think this is very close to what I need for my maxVR! I found a new carb on ebay for $55 and ordered it . . .

[PKR Customs]

My '85 VR has Vmax cams and springs stuffed in an '87 version 1300 engine/trans. The carbs gave me so much trouble that the bike has been gathering dust for about 2 years. I have been brooding over how to put a Q-jet on it to take advantage of the vacuum secondaries. A friend gave me a fresh carb from an '85 Camaro v6. It is basically half of a Q-jet. The problems with using this carb are numerous; It is made for a 3.8L engine with smog controls. This thread showed me another carb with vacuum secondaries and jetted for a 1.6L. I think this is very close to what I need for my maxVR! I found a new carb on ebay for $55 and ordered it . . .

 

You do not want vacuum secondaries on our bikes, they do not create enough to use the full potentiAl of a carb like that. The carb I am using in my swap is a progressive 2 barrel not a vacuum carb, the secondaries are opened manually depending on how agressive you are on the throttle.

[VanRiver]

Hey @PKR Customs Great project and thanks for sharing the details! I'm building a 86 Venture MAX project, 1300 Venture bottom end with V-max heads and Cams and would love to add this carb setup to the project! Would you be interested in building me one of these? I can supply the carb, but would like to buy one of your intakes if you make more!

 

 

All in all this swap has run a total of $200 at the most although the biggest variance will be the carb because there are so many different prices for them on eBay.

[PKR Customs]

Hey @PKR Customs Great project and thanks for sharing the details! I'm building a 86 Venture MAX project, 1300 Venture bottom end with V-max heads and Cams and would love to add this carb setup to the project! Would you be interested in building me one of these? I can supply the carb, but would like to buy one of your intakes if you make more!

 

Pm me and I will give you my contact information. I am currently not a supporting member but plan on becoming one here soon and do not want to violate any of the policies of the site. My mention of $200 is what it has cost me to build the setup on the bike, not what it would cost for me to build this setup for someone. I will have to figure out final cost that is fair for anyone that is interested in having one built and if it becomes a large enough demand, after I become a supporting member, I would consider setting up a group buy with permissions from the admins.

[GaryZ]

You do not want vacuum secondaries on our bikes, they do not create enough to use the full potentiAl of a carb like that. The carb I am using in my swap is a progressive 2 barrel not a vacuum carb, the secondaries are opened manually depending on how agressive you are on the throttle.

 

The advantage of a carb like the Q-jet is it's ability to self-tune for elevation changes and different loads. It has a power valve for the mains and the vacuum controlled secondaries. Does your Holly have a power valve or something similar? Does the '83 Escort carb that I just ordered have a power valve?

 

[PKR Customs]

The advantage of a carb like the Q-jet is it's ability to self-tune for elevation changes and different loads. It has a power valve for the mains and the vacuum controlled secondaries. Does your Holly have a power valve or something similar? Does the '83 Escort carb that I just ordered have a power valve?

 

 

Yes the carb from the escort has power valve, it actually has 2, the main power valve for the primary and then a second one that is activated when you open the secondaries to account for the increased air flow. The second valve is controlled internally on the carb by the location of the throttle. My concern with the a jet is one the size of the carb compared to our engines and two the lack of vacuum to properly operate the secondaries.

[GaryZ]

Yes the carb from the escort has power valve, it actually has 2, the main power valve for the primary and then a second one that is activated when you open the secondaries to account for the increased air flow. The second valve is controlled internally on the carb by the location of the throttle. My concern with the a jet is one the size of the carb compared to our engines and two the lack of vacuum to properly operate the secondaries.

 

I am pretty sure we are on the same page here . . . Thanks for the valuable info!

[PKR Customs]

I finally got time to do an update video on the single carb set up on my bike. I have done a few power comparisons to a family members 97 vmax with stage 1 jets and a full ufo exhaust and continuous vboost, a friends stock 03 mustang cobra and a random c7 corvette, all with positive results.

 

My bike Vs the 97 vmax with upgrades - my bike was able to pull away from the vmax on a 20mph 2nd gear pull, I was able to accelerate smoother at lower speed without downshifting, a 3 gear pull from 40 to 70 on the highway was also faster on my bike than the vmax.

 

My bike Vs a friends stock 03 cobra - I was mildly suprised when my bike pulled away from the cobra, mainly due to power to weight ratio, but the bike was able to pull away from the cobra on a 20 - 100 pull. The bike didn't "blow the doors off" the cobra but it was a consistently growing gap between us. My friend was a little upset that an old jap cruiser was faster than his American muscle, but still impressed by the bike.

 

My bike Vs a random c7 corvette - I was crusieing the highway when this one happened and know nothing more about the car other than it was a blue c7, after complimenting him on his car at the gas station prior to getting on the highway and explaining what I had done to my bike. I was going 60 mph in 3rd gear when the c7 and I both opened them up and we were both impressed with the bike. I was able to keep up with the c7 up to 100 mph when I let out of it for my own safety.

 

All in all I am very impressed with the performance of the bike so far, and I'm not done yet lol.

 

[CaseyJ955]

Thank you for the update. It's still got me thinking. I have yet to break into my carbs but if they are a mess I may try a single like this. Very sweet and still watching with great interest.

[Condor]

That is just plain AWESOME!!!!

[flyday58]

PKR, my bestie lives in Englewood (Dayton), mother is in Findlay, good people. I'm intrigued by your swap, but I live 9000' above sea level and the lowest the bike gets is around 4000'. How do you think my '83 would run up here with your set-up?

[PKR Customs]

PKR, my bestie lives in Englewood (Dayton), mother is in Findlay, good people. I'm intrigued by your swap, but I live 9000' above sea level and the lowest the bike gets is around 4000'. How do you think my '83 would run up here with your set-up?

 

Well I will first start off by saying that cv carbs are going to be "better mannered" at higher elevations just because they are designed to "keep things within spec" during altitude changes.

 

That being said I have not had the pleasure of taking this bike on a ride at those elevations but i took my last bike, an 81 gl1100 with this carb setup and upgraded coils/exhaust, on a few trips through the Smokey Mountains and it performed well. I could tell that the bike was a hair less responsive at WOT and was a bit more cold blooded at those elevations but was fine during normal riding after it was warmed up. I would definetly try upgrade to the ignitch TCI and have it tuned properly before doing any extended rides at 9k elevation and I wouldn't ride the bike until it was warm to help reduce the possibility of the fuel gelling in the intake and fouling the plugs. I live in an area of 780ish' elevation and am getting beautiful results from this set up, but I do plan on upgrading the TCI and trying to find better could for the bike. If you are going to perform the swap please keep me informed on the results so if I ever run into this type of question or make a road trip to those elevations I will know what to expect.