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Suzuki GSX-R carbs on A-series???


Bomboyj

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Maybe on datsun1200.com. Seems to me I have seen it also but cannot remember where.  Also recall a video of a Hyabusa (sp?) motor in a 1200

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42284454192_72da03f567_z.jpg961 by mastersr6, on Flickr

 

There are things to consider in terms of what year GSXR determines what type carb it is. With a 1.2L engine you'd probably do fine with re-jetted stock CV carbs, but earlier GSXRs 1986 came with box slide Mikunis. By the early 90s they were CV. I would stick to 750cc bikes as the 1100 came with 38mm carbs. Way more than you'd need.

 

http://community.ratsun.net/topic/73889-l20b-compatible-carbs/?p=1568231

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I've run 39mm Keihin flat slides exactly like the ones pictured above. They are awesome, the only thing with bike carbs is you need very low fuel pressure (no more than 2psi).

 

I had been running an A15 in my car but the A12 in my car now. It's just a matter of jetting. Camshafts can have a unexpected jetting change. If the cam has a lot of overlap you'll end up going leaner on the pilot jet regardless of engine displacement.

 

If you do get bike carbs get the airbox as well. You will need to come up with a custom manifold, go to Datsun1200.com for that as there are several different set ups that people have done. I wa lucky in that the custom manifold came with the carbs.

 

A final word on the Keihin FCR flat slide carbs; if someone tells you that your going to have flat spots or they won't work well at low RPMs, they don't know what they are taking about. My Beta dual sport bike uses the same carb and both it and the 1200 work flawlessly.

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I've run 39mm Keihin flat slides exactly like the ones pictured above. They are awesome, the only thing with bike carbs is you need very low fuel pressure (no more than 2psi).

 

I had been running an A15 in my car but the A12 in my car now. It's just a matter of jetting. Camshafts can have a unexpected jetting change. If the cam has a lot of overlap you'll end up going leaner on the pilot jet regardless of engine displacement.

 

If you do get bike carbs get the airbox as well. You will need to come up with a custom manifold, go to Datsun1200.com for that as there are several different set ups that people have done. I wa lucky in that the custom manifold came with the carbs.

 

A final word on the Keihin FCR flat slide carbs; if someone tells you that your going to have flat spots or they won't work well at low RPMs, they don't know what they are taking about. My Beta dual sport bike uses the same carb and both it and the 1200 work flawlessly.

 

I've never messed with Keihin flat slides, but maybe they have the secret sauce to keep smaller engines from bogging. A set of those will set you back $1,900 though. A new set of Mikunis are $600. 

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This will break your heart, I got mine with the manifold for $250!

 

If you shop around carefully you can find them for the same price you'd pay for Mikunis. You have to look around on various bike sites. The smaller sizes, 39mm, can be found for a lot less, I've seen them as low as $500 but you're more likely to pay $750 to $1,200. Like anything you need to shop around. Nothing should make you shy away from a used set, they are simply but absolute works of art.

 

The FCR carbs flow more than DCOE style carbs mainly due to the lack of a throttle shaft (8-10mm restriction). Even if you spend $600 more they make enough power to justify buying them. My otherwise standard A12GX motor with the only change being the Keihin carbs made 73whp. That is 18hp more than the SSS (DCOE carbs) motor done in New Zealand and the twin carb standard GX motor. The D-Sports Racer guy I got the carbs from said the made an instant 12hp increase on there race A13.

 

Also a big plus for left hand drive cars is you don't have to move the brake master like you do if you wish to install a pair of DCOE style carbs.

 

They only knock I will give them is you need to run pod filters on the street or fab up a custom air box. The motor will make more power with a proper air box.

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Oh snap you guys gave me plenty to work with. I mean some people argue the Weber 32/36 is too big for the A14 but mine chugs along great with 32mpgs the only hang up is if you are really in tune with your car you can feel that slight delay if you pound it to the floor at low RPMs but I have learned to adjust by easing into it but only for like a second then give it the beans.

 

There are so many routes you can go I have always loved the option of mini carbs because if I change TOO much might as well just swap it but if I can make the little A14 scream for few $$$'s why not. It is all learning experience to me I love wrenching on my Datsun but she never lets me because she has been too reliable(only thing that shit out is the starter in 4 years).

 

I just wish there was more Datsun guys in NJ.

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Mikuni VM series carbs will mount on any DCOE type manifold with the rubber mounts used on a lot of engines, and the use of a 4-cylinder bike or snowmobile throttle cable will pull them all open (older bikes had these 1 into 4 cables).

And the VM series carbs are available in very small bore sizes.

 

The rubber mounts for the 36-40mm VM carbs have almost the exact same bolt spacing as the DCOE, with only a few passes with a round file to match up.

Carbs smaller than 36mm will have slightly smaller bolt pattern, but easily adapted.

 

If you haven't seen it in other posts, here is my L-series/VM Mikuni set up:

Original pre-planning -

DSC00553.jpg

 

Final assembly after I figured out how to fit everything around a 620 brake booster & distributor -

DSC08125.jpg

DSC08124.jpg

DSC08123.jpg

 

The distributor clearance issue was only because I wanted to use the Z-car air cleaner.

Was going to cut the throttle shaft bosses off the manifold originally, but it made for a nice mount for the fuel rail.

 

Note: The clear fuel line is NOT vinyl or urethane lawn mower crap, but actually Motion Pro Tygon, and will last just about forever.

The other stuff will harden & crack over time, which leads to engine fires, especially on cars with non-cross flow heads.

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My car actually uses fuel filler hose to mount the carbs to the manifold. On the surface it seems a bit cheesy but the set up came off a RunOffs winning sports racer so it's good enough for me. The filler house actually allows for a little bit of adjustment.

 

Now as for that video; why are they lugging motor??? A-series motors make a very distinct sound above 8000 rpm, sort of a high pitched screech..........this is how I know to shift. At 9,000 it sounds like the rods are going to fly out the block. The motor in the video sounds like it's in the low to mid 7s.

 

I suck at posting pictures but here's a link to my set up.

 

http://datsun1200.com/modules/myalbum/photo.php?lid=26124

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On my car the velocity stacks are close to the hood. When the A15 goes back in I will likely have the dry sump system done so the motor will be sitting close to 2" lower which may allow me to get a proper air box on it.

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