Bigger jets that came w/the jet kit..use them (seriously, pls read) - Sportbike Forum: Sportbike Motorcycle Forums
 
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post #1 of 5 (permalink) Old 08-01-2000, 10:22 AM Thread Starter
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Location: San Antonio TX
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I have a 97 Kat 750. Full Yosh system (headers, 4-1) and three degree ignition advancer. When I got the jet kit, the instructions stated that if you are running a "street pipe" like the Zyclone that I have, DON'T change the jets (don't install the bigger ones that came with the kit, stick w/the stock ones) Per the instructions, I changed the needles, float level and reset mixture screws. The instructions say only change the jets if you are running a race pipe. But....I'm curious. The bike has great top-end now, but throttle response could be a bit snappier. The short answer, I know already "just change the jets and find out". Well, if you've never worked on a Katana before, you already know that to get at the carbs, you have to remove EVERYTHING FIRST. Windscreen, mirrors, signals, both fairings AND the tank, just to get at the carbs. If anyone has had any experience with this, I'd appreciate it. BTW, the new jets are one size bigger than stock. Thanks.

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Cosmo
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post #2 of 5 (permalink) Old 08-01-2000, 02:11 PM
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Greeting fellow Texan! This is just my opinion on the matter, but it should be helpful...I don't recall you mentioning a K&N air filter (or equivalent), but if you do install a free flowing filter, and you're "total" exhaust is substancially more free flowing, then a main jet size one up should not cause any negative effect. I thind the instructions are assuming a slip-on can that is not a great deal more free flowing than stock (they're out there). So, if you're bike is breathing more air, more efficiently, it should be able to handle more fuel. It would have to to gain any real power gains...then again, the more airflow that passes through the carbs venturi, the lower the pressure, which means more fuel should pass through the same jets anyway...Ok, getting too indepth (my tech side talking). If it were my bike, I'd put the bigger jets. Leave all the goodies off that you can and test it before reinstalling all the panels and such. Maybe even get a small bottle to hold a little gas if need be and loose the tank. I'm not familiar with Kats, so I may be exagerating some. Only one true way to tell...DO IT! All it could do is run rich...or like a bat outta hell!
Be safe and have fun!

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Thomas

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post #3 of 5 (permalink) Old 08-01-2000, 08:13 PM Thread Starter
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Hi Tom,
Thanks for the reply. I can tell you that the aftermarket exhaust flows a lot more air than the stock. For one, the header pipes are literally twice the size, as is the main downpipe that all four header tubes merge into. The end can is a helluva lot louder than the stock cans and almost if not as loud as some "race" cans that I've heard. I guess all I need is about 12 hours with nothing to do and I'll experiment. Gee, wish I had a dyno lying around! Thanks again.

Mike

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post #4 of 5 (permalink) Old 09-13-2000, 06:27 AM
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I have a 95 Katana 750 with the same exhaust and ignition advancer as you. From what I can tell the jets are more air filter dependant than the type of exhaust.

I have pulled apart the carbs several times and yes it is a pain in the ass because to really know if one has the right jet and needle settings one has to ride the bike.

To make a long story short, if you are not running a K&N filter (either stock replacement or twin direct bolt on kind) then I'd stay with stock jets.

With the twin K&N filters (one filter per two carbs directly clamps on) I had to use the largest jet. With the stock replacement K&N with no center hole restrictor I had to use the second smallest jets (kit was a DynoJet that came with 4 jet options). With the stock replacement K&N with the restrictor in place I used the stock jets.

However, any of the larger dyno jets cause a 4K rpm hesitation which was annoying, but after 4K the bike really pulled well upto redline.

Bottom line, I'm back to the stock jets using K&N stock replacement filter with the restrictor hole in place. This is not the best performance option, but is more streetable.

Rob.

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Cheers, Rob.
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post #5 of 5 (permalink) Old 09-15-2000, 03:36 AM Thread Starter
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Hey Rob,

Yeah, I agree w/you on this one. After much research and a lot of begging free advice from the mechanics at the local dealerships, I've given up on trying to turn my Katana into a Gixxer! I'm close, but this is about as close as I'm gonna get it! Streetability being the key thing here. I know a guy who has 750 Kat (96 I think) he's got it bored and stoked to almost 900cc's. Stage three jets, open exhaust the whole 9 yards. The thing screams after you hit about 9k, but below that it backfires, belches and generally barely runs. That's not what I want. My bike is a big pussycat once it's warmed up. Since I installed the needles and adjusted the floats, it takes a looooooong time to warm up. Even in 90 degree weather. Won't idle w/o the choke on for the first 5 minutes or so. That's ok though becasuse it gives me plenty of time to wipe down the bike and make it all sparkly clean prior to a ride. Also check the tire pressure and stuff like that. Important stuff, you know.

I read about your problems w/the bike cuttin out under heavy braking. All very good responses that you were given. personally, I'm at a loss, but I'm leaning towards a fuel problem. Being that you've checked your battery and all electrical connections already. You did double check the connections that you had to repair some time ago due to a mechanics negligence, right? There's a chance that the electrical tape or whatever could've come loose or worn away. Good luck w/that.

One more thing...it's funny how you and I are thinking along the same lines. We both have 750 Kats (great ride as far as I'm concerned) and we both are going to sell our souls to Mephisto when the 1000 Gixxer hits the street! I can't wait! I do want to see a full review done by a major bike mag first though. Even though those mags are not the "be all end all" of last word in motorcycling, they are darn close. Plus, they get to take a new bike (at no cost to them) and TRY TO BREAK IT. This is good for us as consumers. At least we know that the bike has been put through the paces and will hold up to whatever we can throw at it. Cheers.!

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Cosmo
"Do you know how fast you were going, son?" "Gee officer, if I guess right, can I go home?"
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