YZF600 carb swap

[match417]

Pics will be in the next post, i took them this morning but i'm at work on lunch break and can't post them yet. so be patient, this evening Hawaii time they'll be up

ok guys, I know some of you have been waiting on me to actually start the carb swap that I have been talking about for months. You'll be pleased to know I started it today because we start work late on fridays, so i had time this morning..woohoo! I did some measurements of the carbs and they are considerably larger. The measurements of the outside diameter of the bottom of the carbs is about 1 6/10 inches(41mm ish) (my mic goes in tenths of an inch and I'll put the exact measurement up later when I get back to my house today). The inside diameter of the little intake manifolds is about 1 4.5/10 inches(37mm ish). Also, the outside diameter of the intake manifolds is about 1 7/10. The new carbs will flow more air than the FZR ones did, add 2/10's of an inch to your diameter. That's a LOT more air flow!!! And there are larger jets too.. I tried to loosen the rubber up with brake fluid so maybe the rubber would stretch but the carbs still wouldn't fit, but I have another idea...

So what i'm planning on doing instead of cramming the carbs into the manifolds is buying some radiator hose that is a similar diameter and putting some clamps on it then fitting it around the carbs and slipping it AROUND the manifolds instead of the carbs going inside of them. This way I don't rip my manifolds that already have small cracks. The carbs will sit a little bit higher than normal, then if you add in the height of the velocity stacks they just barely fit under my R6 tank, it's a really tight fit. I have to figure out how to get filters on top and I already have an idea in the works that involves buying individual K&N filters and putting them around the velocity stacks. But I don't know how much more height that will add to the setup. You guys with the yzf600 tanks shouldn't really have an issue with the carbs being taller because that tank has more room in the carb area. And I think the stock FZR tank cover has plenty of room as well. I'm also going to mount them to something to make sure they stay sturdy, i'm not trusting the radiator hose to support them.

Cables have to be routed to the left side, around the forks, and under the tank cover (or gas tank if you did a swap). On the YZF600 they are routed around the right fork, under the triple tree, above the radiator, under the frame and into the carbs. I tried to route them this way...the cables kink and the throttle sticks. Also, there might be an issue with the grip end of the cables on a stock FZR handlebar, the piece where the cables go in that attaches to the grip has a notch where it fits into the YZF600 handlebar to hold it in place, this isn't an issue for me because I have a YZF600 handlebar that came with my box-o-YZF600 parts, had some trouble making it fit in the FZR clamp due to the FZR bar being notched so it can fit in the clamp, the notch is in a different place on the YZF600 bar. I just ground the metal stub down in the clamp so the YZF bar would fit in the clamp. Problem solved

Anyway, that's it for now, i'll put pics up tonight with more exact measurements, i took pics of the micrometer beside the carb bottoms with the size of the manifolds mic'd, so you guys can see the difference in size vs reading "2/10's of an inch larger..blah blah blah." Anyway, subscribe to this thread! Happy modding guys!

[slayermd]

Sweet. Maybe your write can give me a reason to spend even more money upgrading my FZR, .

[match417]

k, pictures!!

measurements:
(..I don't have the exact measurements of the bottom of the FZR carbs, i sold them before I thought about measuring them)
little FZR manifolds inside diameter = 1.434 inches (36.424mm or 1-7/16)
YZF600 carb bottom, outside diameter = 1.643 inches (41.732mm or 1-21/32)
i don't remember the measurements of the outside of the FZR manifolds, i'll mic that tomorrow, or whenever the next time is that i have time to fiddle with the bike.
the sweet thing is adding 0.209 inches to each cylinder!! that's almost 1/4 inch!

other stuff to know:
you cannot use the stock fzr cables on the yzf600 carbs, it just doesn't work. and as far as i know you can't modify the stock switch setup to accept the yzf cables, just change it all out. the switch rewire is easy, i'll post that up later. And if you want to get yzf600 left switches, then you can use the handlebar choke that is on the left side switch assy for the yzf600. this switch rewire is also easy and i'll post that up later when i get to that part.


measurement of the inside diameter of FZR manifolds


measurement of the inside diameter of the manifolds when looked at beside the carbs


mic'n the carb bottoms


both the stock cables and the new YZF ones (that have to be used) are in this pic, stock ones are hanging in the middle of the pic, the YZF ones are under the flap on top of the engine, this is how they are normally run on the YZF600, i ran them this way to see if they would work, they didn't, so don't run them this way. They bind and the throttle sticks.



I haven't put the switches on yet, i'll do that later

[match417]

Sweet. Maybe your write can give me a reason to spend even more money upgrading my FZR, .

yes, and that's my goal! make other people spend more money!

[match417]

i can't find radiator hose large enough to fit around the fzr intake manifolds. i thought it would work, but it isn't. and when I try to force the carbs into the manifolds, the rubber starts to rip a little like i was expecting it to. I've heard that they can be forced into the manifolds, BUT if the rubber is too old then it just rips. Tomorrow i'm going to try to call the guy that I got the parts from and see if he will sell me the manifolds for the YZF600. Someone was telling me that using the YZF ones will not work because they are oval shaped, the bottom of the carbs isn't oval shaped, but the bottom of the manifolds (engine side) looks like it may be oval shaped. I was also told that the bolt holes match up, and the only issue is the oval shape. At this point i'm just going to get the manifolds and do what I can to make them fit. If the stock fzr manifolds are ovalshaped too and the oval is offset differently (like i think i was told) then i'll just make a gasket.

Oh, and who was it that told me about the oval shape originally? I've dug through posts trying to find where we were talking about that, but I can't find it. So if you can post the details on the oval again that would be GREAT! I remember you saying something about the bolt holes for the YZF manifolds lining up with the FZR, but there is an issue with the oval being slightly rotated more than on the FZR. I think. I don't remember exactly. If you're still out there and reading can you fill me in on the details?

[reelrazor]

You can shave the manifolds with a dremel tool and a pretty rough bit. (take em off first!). Much better than a rip in them. Soak em in hot coolant to loosen them up too.

[match417]

thanks, but i've thought about that. The walls for the manifolds would be too thin to support the carbs. I wouldn't want to brake hard and make the carbs shift forward, ripping the back side of the manifolds. Nice thought tho, thanks for the input.

[sweekster]

So i guess you haven't broken out the petroleum jelly yet? It's worked for me several times.

[reelrazor]

thanks, but i've thought about that. The walls for the manifolds would be too thin to support the carbs. I wouldn't want to brake hard and make the carbs shift forward, ripping the back side of the manifolds. Nice thought tho, thanks for the input.

I've done it a bunch on engines that have side draft carbs...where the carb is suspended horizontally by the manifold. (big carb RZ engines, and big carb XS 650 engines) w/o problems. You don't have to take material out to the point that the carbs fall into the manifolds..just expand the hole a little.

You're running the airbox, right? It has a stay and will help support the carbs from moving.

[thatkid]

So i guess you haven't broken out the petroleum jelly yet? It's worked for me several times.

Duane, we're talking about carbs here, not what you do in your spare time...

[match417]

airbox? no, the R6 tank doesn't allow much room for an airbox. I have to do individuals. I do want to modify a stock airbox by plastic welding it and making it fit. And the manifolds already have small cracks near the base and in the middle of the manifolds, but they don't go all the way through. The rubber is obviously cracking from age under normal circumstances, so I see the rubber cracking even more if i try something with it. So i'm just going to save the time (that i don't really have) and go straight to replacing them with yzf600 ones and doing whatever modification I have to for them to fit.

As far as petroleum jelly..no, haha..i haven't tried that, but I used a little coat of brake fluid on it because it softens up rubber that is hardening, that didn't work, so a couple days later I tried oil, and that almost worked but that's when the rubber started cracking more. So i'm not going to deal with it. The guy parting out the yzf600 lives 40 minutes away, i'll just call him up tomorrow and tell him what I need. He also has two crashed R6's that he's parting out. I'm hoping he hasn't thrown away his fairings, I want to try to convince him to give me the crashed fairings, then i'll repair them because all i need is sides to finish my conversion.