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Switching to Bike Carbs. Heres a write up!

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#1 ·
Switching to Bike Carbs. Heres a write up!... IT IS COMPLETE!

Hello everyone!
This is going to be my first write up. Please feel free to ask questions and make suggestions! http://****************.com/smile/emthup.gif By the end of this build i hope to have step by step instructions so that all you good folks out there can set up some bike carbs too!

I recently traded my 77 rabbit for an 82 Caddy with a 2.0 swap. The CIS fuel system was never fully installed, and is currenty hooked up just so that it gets me from A to B. I have been researching on what route i want to go with the fuel system and have decided to go with some bike carbs! My reason for this choice is my extreamly limited budget (Currently going to tech school, typical poor student
), the ease of the install, and the effeciancy of bike carbs over Weber carbs.
My plan is to gather and fabricate all of the needed parts and then spend my Winter break installing and tuning the carbs. I will be trying to contact "Bogg Brothers" to figure out what jet sizes i need and order a few smalll parts.
Parts List Needed (please contribute if im missing parts):
Bike Carbs
Correct Jets
Fuel Pressure Regulator
Manifold
Fuel Hose
Tonight is day one of my gathering. I purchased a set of Yamaha YZFR1 Carbs off ebay. I cant wait for them to arrive so i can get them all cleaned up! Ill begin posting pics ASAP.
Here is an artical and a couple vids to get you PUMPED!
http://www.totalvauxhall.co.uk...7.pdf
http://www.youtube.com/watch?v=Tb7ILh6ZxxA
http://www.youtube.com/watch?v...lated


Modified by Miami Blue at 10:35 PM 1-3-2010
 
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#2,108 ·
^ I can comment on that. You're correct that bike carbs are essentially a side-draft design. However, if you look at how they are installed on the motorcycle, the sport bike carbs are almost always installed steeper than a 45 degree angle, and often even more extreme at about 60-70 degrees.

Using the float bowl gasket line as a reference point for level goes out the window with a lot of these installations. Here's a couple of motorcycle installs that show the extreme angles:



 
#2,122 ·
Glad you mentioned that. Carbs are simple in principle, but with their multiple circuits and lots of fine passageways inside, it's easy for minor contaminants to cause trouble. Doing a carb refresh isn't necessarily hard (I enjoy it) but a rack of four can add up to a couple hundred bucks in parts.

One important note: The small engine world has found that modern gas with the higher ethanol content seems to really cause problems in carbs. I'm not positive, but from what I read the ethanol draws in moisture, and that in-turn creates deposits in the bowls and even can corrode some of the fittings. As clumps move around, they can easily clog those tight passageways.

Some people seek out ethanol-free gas, but supposedly keeping the tank full (minimal air space) and running them regularly with high quality gas helps a lot.
 
#2,109 · (Edited)
As Jettaboy said, in most cases the carbs in the bikes are installed at about 60-70 degrees, mine are installed at 65 degrees, if reduce this angle the fuel will over filling the bowl, if increase the angle the fuel level will be not enough to feed the jets at high rpms.

As Jettaboy said, the float bowl gasket line is a good reference and must match with the ground level, but depending on the carbs you are using, this angle could be different.

I,ve seen a few configurations with bad angles, causing a lot of issues with the fuel.
 
#2,111 ·
Seeing them now not right up against the firewall has changed my opinion on install in 8v JH motors. I may have to try and assemble a parts list!

If a throttle cable linkage design that works with a sweeping motion, and FPR and Return lines ironed out seems like it could be a pretty easy swap without standalone needs on early 80s motors.
 
#2,126 · (Edited)
My Keihin CVK's (36mm) came with 148 mains, and I replaced them with 162's from Jets R Us which helped a lot. But I never spent much time dialing those in as I traded the car shortly after installing them. This was on a low compression '85 Golf 1.8L.

Using a wideband O2 I was able to get the idle circuit running fine on whatever jets it had, with about 3.5 to 4 turns out. I remember that at about 5 turns out the screws got a little questionable.
 
#2,155 ·
I wanted to revive this thread with a quick thank you in case any of the original contributors are still around and viewing this forum. Based on all the info in this thread I just pulled the trigger on a set of Honda CBR900RR flatslides that will be going on a mild ABA build that I'm prepping for eventual swap into my '86 cabby. The amount of information in this thread was immense, and answered just about every question I had about putting this engine management package together.

You guys and gals are awesome.
 
#8 ·
Ah. I'm just very familiar with the sound of webers and bike carbs have a different sound which is interesting. Do you know if those manifolds have vacuum ports for the brake booster? If not how do you deal with that? I'm also curious about the dizzy vacuum advance and if you need it.
 
#9 ·
Re: Switching to Bike Carbs. Heres a write up! (Miami Blue)

Quote, originally posted by Miami Blue »

Parts List Needed (please contribute if im missing parts):
Bike Carbs
Correct Jets
Fuel Pressure Regulator
Manifold
Fuel Hose

I would look at the Holley FPR PN 12-804 ($30-ish everywhere I looked) and a FP gauge so you know what your pushing in to your carbs.
Jets, I bought 4 sets, 165, 167.5, 170 and 172.5 I think?! They are a few bucks each and IMO worth spending a few bucks on insted of drilling.
Wideband, your gonna need one. I bought the Inovate LC-1 with gauge. You can find them used on here from time to time.
Silicone couplers to connect the carbs to your mani.
TON of clamps! A lot of sizes!
I'll think of more Im sure!
Cater fuel pump, 4070. I tried 2 cheaper ones with no luck.



Modified by FROZEN337 at 5:36 PM 11-14-2009
 
#11 ·
Re: Switching to Bike Carbs. Heres a write up! (FROZEN337)

Hey thanks frozen!
Did you do this swap on a 9a engine? If so, what size injectors did you go with? I went in to the Yamaha shop to price how much it would be to get a whole bunch of different sizes, nice and cheap!
I read up on what alot of other people did for fuel delivery and was probably going to use the CIS pump and an FPR with a return line to the tank to help keep the pressure safe.
As far as a vacuum source for the brake booster, ill just T out of the manifold that me and my brother will be making. I would assume that you could a vacuum advance dizzy the same way too. For now im sticking to stock ignition though.
Down side to this swap is that i wont be able to have AC
. Here in Phoenix... its pretty nice to have. To make the carbs fit i will have to move the alternator to the AC compressor spot, an then chop off the old alternator mount.
Some other people have issues with their radiator being in the way due to where the hoses go in to the radiator. I have a duel pancake fan set up already installed though so it looks like this wont be an issue. Specially with the AC cooler gone, i can move the coolant rad forward more.

Modified by Miami Blue at 5:17 PM 11-14-2009


Modified by Miami Blue at 9:31 PM 11-14-2009
 
#13 ·
Re: Switching to Bike Carbs. Heres a write up! (Miami Blue)

Im running a OBDI ABA with the stock MKI ignition system. Prolly not the best set up, but it works for me.
I used wraping paper roll to get my angles right! They are the same size as the 1.75" Autozone exhuast pipe I used for my mani.
I would ditch the stock fuel pump and run a low pressure unit, FPR and gauge. I picked up a cheap FRAM filter for under the hood, because Im that cheap! Had a nice glass filter but the housing split when I put the fittings in . . .
I dont have issues with the rad/carbs all fitting, its REALLY close with my filters on, but not an issue. Right now I have some mesh from Lowes on there because I killed two filters thanks to back fire in the carbs! ALT is close to, but they dont touch.
All said and done, it is cheap, it is easy, BUT it will be a PITA getting it all TIG'd, fitted, running! Sound is awesome and it is so worth it!
 
#14 ·
Re: Switching to Bike Carbs. Heres a write up! (FROZEN337)

Good call on the wraping paper roll, ill have to find some. How about your flange? Did you just cut down a stock intake?
Another decision i have to make is do i want to go fancy and get AN fittings and hose or do i want to save money and go with rubber hose and cclamps. The saving money part sounds preferable to me!
Its nice getting help from some one who has done this. Props man.
 
#15 ·
Re: Switching to Bike Carbs. Heres a write up! (Miami Blue)

I used gasket outline to make the flange. Any decent metal shop can cut it out with water jet or plasma cutter, if you dont have you.
I ran C clamps and rubber fuel line!
 
#17 ·
Re: (Flyingsheep)

Quote, originally posted by Flyingsheep »
Isn't an FPR unnecessary if you go with the carter 4070?

Absolute myth. If you look up the specs of the carter, it's WAY more than most sidedraft style carbs need. If it's running without an FPR, then there is also something wrong with the setup that is limiting the fueling, like too-small needle valves, or restrictions in the lines.
 
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