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Old 09-12-2012, 05:49 AM   #1
sailah OP
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Noob 4 cyl carb tuning help

So I have built 2 frankenbikes at this point, first one is a 2004 Yamaha FZ1. Running stock motor with Ivans Performance pod filters and the jetting kit for these pods. It has the stock headers with EXUP valve intact and then a Sailah Customz midpipe to a Arrow exhaust can.



The second bike is a 1997 CBR. I kept the stock airbox, stock filter. I built the headers out of slightly smaller OD tubing, same length pretty much, into a midpipe and then out a carbon Arrow exhaust.



The FZ1 I have been riding for 2 years now. I always felt it had a flat spot off idle but honestly it had so much power that I never really bothered to change anything. A buddy who also had an FZ1 mentioned he thought the bike was down on power so it got me thinking. I set up Ivans kit exactly how he described it, settings and all.

The CBR went on her maiden voyage last night and I couldn't believe how much snappier it was than the FZ1. Yes it is a lot lighter but the motor was much more peppy and just seemed much more willing to pull harder at all throttle settings. More eager if you will. Maybe that's a function of the motor vs jetting but regardless I am interested to learn more about carb tuning.

I can take carbs apart, I can clean them, I know where the various components are located and what their names are. But I still have a very fuzzy understanding of how they interact, and also how to interpret their behavior. Like that bog on the FZ1. I know that's not a main jet problem, but how do I know if I need to go up or down or change the mixture, slow speed jet?? See what I mean? Noob here.

Since I have two bikes and can weld, I thought it might be interesting to use a wideband o2 sensor like the innovate LC-1 setup. That way I can use one gauge to tune both bikes.

Maybe I'm just looking for the easy way out but any reason not to go this way? Or do you have any other suggestions? Bear in mind both bikes are not factory and rather involved in removing components, especially the carbs. I have precious shop time and would prefer to spend it smart than just randomly throwing parts at the bikes.

Here's the setup I am considering with a gauge so I can mount it on the bikes
http://www.innovatemotorsports.com/products/lc1.php

Thoughts and constructive criticism other than to stop build wacky bikes and buy a stocker? Ha, I did that this winter and bought a new Husky 449. Bike still doesn't work and no warranty and that has fuel injection
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sailah screwed with this post 09-12-2012 at 05:58 AM
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Old 09-12-2012, 10:53 AM   #2
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Start here

mikuni.com.
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Old 09-12-2012, 01:57 PM   #3
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Quote:
Originally Posted by sailah View Post
But I still have a very fuzzy understanding of how they interact, and also how to interpret their behavior. Like that bog on the FZ1. I know that's not a main jet problem, but how do I know if I need to go up or down or change the mixture, slow speed jet?? See what I mean? Noob here.
I use my neighbor's carb book from Sudco.

On some carbs you can put the choke on a little and try to recreate the symptom and if it's better, then you need to richen the pilot jet/cutaway/jet needle/needle jet/main jet depending on the throttle opening of the problem. (If a problem is RPM related it is probably resonance mismatch in the airbox or exhaust, but if a problem appears at a certain throttle position, it is probably carburetion.

BUt as I said, I refer to a book myself.

Quote:
Originally Posted by sailah View Post
Since I have two bikes and can weld, I thought it might be interesting to use a wideband o2 sensor like the innovate LC-1 setup. That way I can use one gauge to tune both bikes.
Is the LC-1 a controller for injection or a meter for carbs? The way I read the site you'd probably want the LM-1. But I really don't know anything about Innovate or their products. I, too, want a wideband sensor and meter because the fuel/air ratio can be wrong for a short time in some situations where it's hard to determine if the bog is lean or rich.

Quote:
Originally Posted by sailah View Post
Thoughts and constructive criticism other than to stop build wacky bikes and buy a stocker?
DO NOT STOP building wacky bikes. They entertain me. You can send me one if you'd like.
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Old 09-12-2012, 03:52 PM   #4
sailah OP
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DO NOT STOP building wacky bikes. They entertain me. You can send me one if you'd like.
thanks for the advice I'm just going to jump into it

Youre in luck too. I'm moving home to maine next year, bikes are coming with. Cmon over for a wacky bike night and you can ride em all. Portland area fyi
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Old 09-12-2012, 05:15 PM   #5
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Got some extra coin for a dyno session with a air/fuel ratio readout?
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Old 09-12-2012, 06:51 PM   #6
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yes I could certainly do that but I hate spending money and not learning something. I force myself to tackle projects with the sole purpose of learning a new skill.

I'm not the kind of guy who brings his car to the dealer. Maybe if there was a dyno guy who didn't mind someone asking 4000 questions, but I'm guessing that would be annoying.
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Old 09-13-2012, 05:37 PM   #7
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Maybe you could bring along the jets and do the tuning yourself?

I'm just used to tuning the Yamaha RDs, those have easy to access plugs and carbs, which make road tuning cake.

I dunno how the access is on that FZ1 that I almost bought.
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Old 09-14-2012, 09:05 PM   #8
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the innovate lc-1 has 2 outputs-you use 1 for the gauge and the other for an input to your efi system if you need it.I use to have a 1977 datsun 280z with laptop tunable efi and I used both outputs on the lc-1.I have had an fz1 for years.No bog problems but I still have the stock airbox-which has velocity stacks built into it.I know for your application the stock airbox had to go.You will find your find your problem quicker with the wide band o2 setup.Watch gauge-make changes-watch gauge again.Motorcyclists are cheap but if you consider the time + expense of jets getting it done faster and correctly makes the wide band worth the money.Wide band o2 sensors are also used in late model cars as an input to the ecm for a/f mixture correction.
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Old 09-15-2012, 06:24 AM   #9
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Thanks thats very helpful. I'm not trying to magically make the problem go away but as you put it, find the problem faster.

My fz1 has small velocity stacks that came with the filter kit. It's not enough if a problem to bother me right now and the cbr runs well enough that this might be a month or two before I get to it.
Thanks
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Old 10-22-2012, 03:34 PM   #10
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well I changed some stuff of the CBR and it ran terrible. Decided that I could waste more time and keep guessing or buy a wideband o2 and start guessing edumacatedly

Since I have 2 bikes that can benefit, I bought a Innovate Motorsports LM2 wideband AFR meter that also data logs. I spoke to Innovate and this was exactly the kit they recommend, especially since I have multiple bikes. The guy explained it like this. Weld in the bungs, screw in the O2 sensor. Hook up the analog wires to TPS sensor if I want (which I think could be really useful), tach output (splice in) put the SD memory card in the handheld meter, plug the power into 12v cig, toss the meter in a backpack or ziptie to handlebars and go ride. It will datalog all the relevant information during the ride, I can come back, download to my laptop and see where the fuel ratio is at all rpms and throttle positions. As I have never done this before, I imagine that there will be some learning curve, as well as some jetting purchases to correct the problems that I find. I could easily see spending hours and weeks trial and erroring this bike, or I can go for a short ride, come home and look at the data and make a more informed decision. I'm pumped for this tool, I think it will be really cool to try.



Hopefully I can keep a running log of what I do and post the info and folks with knowledge can chime in on proposed fixes.

If it works well, I plan to do that same thing to the FZ1. That bike already runs really well, so it might be more fun to try it on that bike first.

The CBR only runs at idle and full throttle. Which is exciting
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Old 10-22-2012, 05:43 PM   #11
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The BIGGEST problem is changing air filter/box and reducing the restriction, DRAMATICALLY affects jetting.
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Old 10-22-2012, 05:54 PM   #12
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This won't be easy, due to four carburetors, but it's simple.
You have two routes-slide cutaway or needle-jet height.
Notice carefully the decelleration characteristic. Is it lean-bogs- on acceleration, but doggy-rich-off throttle, I would cut a half-mm. off the top of the needle jet. Yeah, there's four and they have to be the same.
If the decel is crisp, I'd cut a half-mm. off the bottom of the slides, lowers cutaway in a roundabout manner. Replacement parts are available, but you're accustomed to machine work, from what I've seen.
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Old 10-26-2012, 03:04 PM   #13
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Dude that's the coolest FZ1 I've ever seen, and the CBR is awesome too! Got any more pics of the front of it?
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Old 10-26-2012, 03:23 PM   #14
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Dude that's the coolest FZ1 I've ever seen, and the CBR is awesome too! Got any more pics of the front of it?
Check out my build logs in my sig line. Lots of photos

So I got the meter and got everything ready for a ride. Welded in the bung, hooked up TPS and RPMs.

I also got the Dynojet jet kit so I'll have some needles to play with if I need them. I'm excited to see what this little device can do to help me understand the tuning process.

I think I was close to start, then went the wrong way with some drastic settings to see if I was headed in the right direction. I wasn't.

I'll get a helmet cam video shot if anyone wants to see what the meter looks like and the kind of numbers I get when pulling hard.
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Old 11-10-2012, 03:17 PM   #15
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So I finally got some work done on the jetting. I installed the Dynojet Kit to their specs. I also finished the Innovate Motorsports tuner install. Took it out today and just ran around town, hard to get any full throttle pulls in a city but I did my best.

I recorded a couple sessions which I think are useful for some insight into what is going on. First off, bike runs 100x better than last time. No weird bogs, pulls hard from idle to redline. I would probably leave it as is but that's not the spirit.

Bear in mind I'm a complete beginner here with Air/fuel ratios etc. Here's a screen shot of some varied throttle. The pink line is the AF ratio the red is the throttle position. There is one spike where I pinned it.



It APPEARS TO ME that the bike is lean at idle, where the AFR is above 20. When it is full throttle, it looks like I am getting down into the 9's which would be a little rich.

So any advice? I might be inclined to go down one step on the mains and possibly turn the fuel screws out 1/4 turn? It was still popping on decel.
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