17 tooth gearbox sprocket zr550

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17 tooth gearbox sprocket zr550

Postby TREVOR9 » 18 Nov 2018, 22:55

Has anyone tried a taller gear on the 550?
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Re: 17 tooth gearbox sprocket zr550

Postby Larry02ACR » 19 Nov 2018, 05:28

I have a 17 tooth on the front.

Chain barely clears the metal guard behind the cover, but I have yet to have any problems with it.
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1990 Zephyr 550, 1978 KZ400, 2004 KX250
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Re: 17 tooth gearbox sprocket zr550

Postby TREVOR9 » 21 Nov 2018, 15:49

What does it pull like? Because it is quite Torquey in std gearing pulling easily from 20mph in top up to the red line.
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Re: 17 tooth gearbox sprocket zr550

Postby Larry02ACR » 21 Nov 2018, 19:19

Well, I bought the bike as a non-running POS, and for whatever reason I thought I'd go up two teeth on the rear sprocket during the rebuild.

After getting it on the road and riding it a bit, I decided 1st was too short and basically useless, and it was way too buzzy in sixth at 75mph. So I went up one tooth on the front.

Net effect is almost the same gear ratio as stock, maybe a tad taller. I never rode it with stock gearing, so I can't help you there.
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1990 Zephyr 550, 1978 KZ400, 2004 KX250
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Re: 17 tooth gearbox sprocket zr550

Postby Corey » 22 Nov 2018, 15:56

Play with this site:
https://www.gearingcommander.com/

Back in 2003 when I acquired my first GPz550, I wanted to get the best gas mileage, so I kept the stock 38 rear and went with the largest front, 17. Over time I have messed with different rears(40 and 42), and other fronts(16 and 15). I do know that just by changing the front sprocket only, +1 or -1 from stock, will have you at about 500 rpm difference at freeway speeds. The 17 was too large, and I could feel it when riding in the city, with a lot of stop and go riding. Almost like starting off in 2nd gear. I am back to 16/38 stock gearing and about 6200 rpm at 80 mph.


Think of it like this:
Odometer reads off the front wheel, so speed is constant.
Changing the rear sprocket, front sprocket, rear wheel, or rear tire size, will only change the rpm difference at that same speed.
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1985 GPz550 Daily Commuter (loads of fun stuff)
2003 SV650s Racebike #44
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Re: 17 tooth gearbox sprocket zr550

Postby ZR468 » 24 Nov 2018, 00:27

I took the sage advice from this site and experimented with a 16T front sprocket. The stock sprocket for my ZR750C is 15T. It does reduce the RPM by about 400 to 500 rpm at hiway speed which makes a calmer ride. What I like about it is at city speed, I can keep the bike in 3rd gear and stay in the power band without feeling like I was racing it. This reduces the amount of shifting in the city. I can not detect any change in acceration or in gas mileage.
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Re: 17 tooth gearbox sprocket zr550

Postby hugojose » 24 Nov 2018, 11:42

Well....the Zeph 750 at 15/39 came geared to short from factory initially. Accelerated like an old KZ900, but reved like a 650.

The fact that the last encarnation of the KZ750-4, the ZR-7 sold in North America until 2005, had a 16/38 ratio, indicates that even Kawi called for some moderation. If I recalled correctly, the last Zeph 750 still sold in Japan in 2008 had a ratio more in line with the ZR-7
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Re: 17 tooth gearbox sprocket zr550

Postby ZR468 » 25 Nov 2018, 02:06

I am happy with my 16/39 combination. That is 6.25% less rpm at the same speed than the stock 15/39. The 16/38 combo will be about 9% less than stock. I don't plan to experiment with 16/38. Leaving well enough alone.
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Re: 17 tooth gearbox sprocket zr550

Postby David Richard » 26 Nov 2018, 20:44

hi sorry its off the thread a bit ,I have a 17 front on my 750 d1 its way less revs than the standard 15 teeth but I had to have a spacer made up to pack out for the sprocket its suits the engine just right ,david
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Re: 17 tooth gearbox sprocket zr550

Postby hugojose » 27 Nov 2018, 01:13

It is way off as this is about the 550, not the 750.

Trevor, why do you want to get taller gearing??. The Haynes manual suggest in the UK the ratio for 550 was 16/38, but in the US was 16/41......this is somewhat equivalent to go 17T on the front for the UK model..although the reason may be stringent US regulation made the 550 slower. any way, it is a trade off, you add a tooth, revs come down, but acceleration is a tad slower....top speed goes higher, but am sure you are not racing, or you wouldn't ask.

If you are a mild rider, you won't feel the difference if you prefer low revs. The bigger front sprocket also improves chain life.
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