Pics of my 79 XS400 Cafe Racer Build With Single Carb Setup

[weeza1989]

And XSChris, just saw your comment now about the year of the bike. It is a 1978. You are correct. Good eye! Apparently you know more about my bike then I do! Dont know why I have been thinking 79 this whole time!

 

[padre]

Thanks,very practical and ingenious .Way cool to!

 

[Scorpio1963]

Manifold is mandrel bent exhaust piping from a 1980 honda CX500 cut down and made into a Y pipe with the stem being slightly larger in diameter for carb to boot to. Made the mounting plates from just 3/16 steel. Jetting is custom. Pilot jet is ALMOST un touched. Needs very very little on pilot. Main jet is ported out quite a bit.

I made the mistake when I first hooked it up of drilling out the jets too big thinking it would need twice the fuel. Well the cylinders have very little overlap in their timing so for the most part its only one cylinder at a time pulling in which. I ended up WAY too rich and had to pull the jets from the other carb and just do it little by little. I prob pulled them out and filed a little more 10 times checking the plugs each time before I got it right where I wanted it. Just dont drill them out too big. If you do make it too rich, you can heat up the jet(out of the carb) with a torch and fill it with silver solder. Then just re-drill to size. Gonna be trial and error. No two ways about it.

If it isn't too much hassle maybe you could measure your jets and what carb you used to help others out that want to run this setup.

 

[Recreateme]

The way you describe it makes it seem like the jet sizes are stuff we can just pick up at Mikes... They sell Main jets that go way over stock, pilot seems like you could buy easily.

 

[weeza1989]

I wouldnt be surprised if factory pilot jet worked in most cases. How would one go about "measuring" a main jet? The number system jets use is proprietary for each brand. for example, the stock 142.5 is not an actual dimension as much as its just a random number.

 

[ratrodder69]

Pin gauges would be the proper way but you probably don't have them. If you have a set Of tiny drill bits you can use the shaft side like you would feeler gauges slide them in and the one that slides in snugly without binding or being forced is the size

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[weeza1989]

Next time I have the carb off I will do that. I'm sure its not gonna help much though. Jets are dependent on exhaust, elevation, air density, air filter, fuel used, exact manifold dimensions, runner length, needle height, etc. The best suggestion I could give if you go the single carb route is to do what I did and file, test, file, test, file, test. Be the only way you will get it perfect for your bike. You have two sets of jets to work with since you will no longer use one of the carbs.

 

[ratrodder69]

For the record this bike kicks ass I'm just mad that you posted a video of you doing wheelies! Now I really want to get mine running!!!! and here I thought I was rolling along pretty good with my 6 month build two and a half weeks really!!!!!! Now I feel like such a slacker o ya and your exhaust sounds bitchin I really just like this bike as a whole good work

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[weeza1989]

Thanks man! It was a fun build. I have learned that I get bored of stuff fast, so if I start a project, I need to hammer it out in one setting otherwise I lose the vision. Its more of a vice then a virtue. I am quite pleased with the exhaust too.

 

[Lou Ranger]

I am very impressed and would like to nominate you for the 2013 MacGyver-of-the-Year award.
Will anyone second the nomination so we can vote?

 

[weeza1989]

Thanks Lou. Main jet size. 0.08"

 

[xschris]

So that's like a 203 jet, wow!

 

[weeza1989]

I'm just curious, how do you make the connection? How would you know that a 0.08 jet would equal a #203? That would be helpful info....

 

[xschris]

.08 inch is 2.03 mm or 203 jet size stock is 135 or 1.35 mm or .053 inch

 

[weeza1989]

Oh... Hmm.... Ok. I was told that the jet # sizes were proprietary and had no relation to actual measurements... Makes sense though... Guess you cant trust all sources!!!

 

[xschris]

I use micro drills to make custom size jets it's cheaper and faster than buying new ones. Never had to go any bigger than a 145.

 

[weeza1989]

Yup. Thats what I used. I dont see the sense in buying two jets for $50 lol.

 

[xschris]

$50 I can buy jets for $6 each at my local yamaha dealer and even cheaper on ebay.

 

[weeza1989]

Well, I meant one of the "kits" they sell on eBay that supposedly have the perfect set matched for your current mods. A 99 cent torch tip file and fine drill bit did the same for me.

 

[xschris]

Those kits are a rip off anyway