38 / 18 sprockets

bigbore2 · April 21, 2013, 02:42:13 AM

My 84 came with 17/42, but went to the 18/38 as per recommendation here and I was getting ready for a 3500 mi. trip. 18/38 is a must on the highway for any distance and is still no problem starting out from a stop at lights etc. in town with the 18/38 gearing. However, around town i like the 17/42 for the extra surge one gets with lower gearing. It is easier for me to tune the bike also with a more responsive engine in the lower gearing [17/42]. I just thro on the 18/38 for any long distance riding and keep the 17/42 on for around town.

Alf · April 21, 2013, 04:53:08 AM

I tested the 18/38 combo and I didn´t like it at all... so if anyone is interested about to buy a cheap 18/38 combo (Renthal front and JT rear), I sell it
Less than 500 kms on both sprockets
Rear fit only GSXR rear rim conversion

ribbert · April 21, 2013, 05:41:56 AM

Quote from: bigbore2 on April 21, 2013, 02:42:13 AM
My 84 came with 17/42, but went to the 18/38 as per recommendation here and I was getting ready for a 3500 mi. trip. 18/38 is a must on the highway for any distance and is still no problem starting out from a stop at lights etc. in town with the 18/38 gearing. However, around town i like the 17/42 for the extra surge one gets with lower gearing. It is easier for me to tune the bike also with a more responsive engine in the lower gearing [17/42]. I just thro on the 18/38 for any long distance riding and keep the 17/42 on for around town.

Just how hard do you need to ride around town?

I'm curious, what do you consider a long enough ride to change the sprockets and how many times a year do you do this?

Noel (18/41)

oldktmdude · April 21, 2013, 06:20:15 AM

Quote from: ribbert on April 21, 2013, 05:41:56 AM

Just how hard do you need to ride around town?

I'm curious, what do you consider a long enough ride to change the sprockets and how many times a year do you do this?

Noel (18/41)

I think you've just started a new trend in the way to sign off.
Pete (18/42)

ELIMINATOR · April 21, 2013, 03:01:00 PM

4,750 = about 90mph.

bigbore2 · April 21, 2013, 11:29:14 PM

Here in Albuquerque we have 2 interstate freeways intersecting [east-west and north-south] in the center of town. Population around 400,000. Not a podunk village with a little main street. I grew up in one of those. Freeway ramps are a good place to hammer the throttle while keeping things relatively safe for all concerned. Speed limit on the freeways are 65 mph. Don't know the kph conversion. ~ 105kph? For a speed run, just go 6-8 miles to the edge of town and hammer it.
I am turning 59 in May. Maybe I should drop "hammer it" from my vocabulary.
I plan on another trip to Wisconsin in a few months, 3500 mi. round trip, I will put on the 18/38 gearing for that. If I was going 200-300 mi in a day, or more, I would put the 18/38 gearing on.

barry [17/42, 18/38]

markmartin · April 27, 2013, 10:34:59 PM

Just fitted the 18t front sprocket to go with the existing 38t rear. I like it a lot, it suits my riding. I'm not looking for 6th gear so much either.

Mark M

ELIMINATOR · May 02, 2013, 06:47:57 AM

With the 18/38 gearing, the acceleration drops off above 130 :good2:Still left the Audi TT driver in my wake though, before I backed off at 145. Next day I took my Guzzi California to work, thought I needed to calm down

movenon · May 02, 2013, 09:40:09 AM

Quote from: markmartin on April 27, 2013, 10:34:59 PM
Just fitted the 18t front sprocket to go with the existing 38t rear. I like it a lot, it suits my riding. I'm not looking for 6th gear so much either.

Mark M

+1 I took mine out the other day for the first time since all the mod's and I also enjoyed the 18/38 combo especally in stop and go traffic. Found myself not shifting gears as much.

Eliminator: 145 wow ! I think the fastest I have ever been on a motorcycle is 115, maybe 120 on a burst of speed. Don't know exactly because my eyes were out in front

I did go about 100-110 for about 80 miles straight one time in Nevada (lots of straight roads in Nevada, I think it was 318). After a while all the "what if's" started to creep into my mind so I decided it was time to slow down. FJ's are runners that for sure. Wonder what the top speed would be with 18/38 gears..... Let me know if you find out

Cheers George

andyb · May 02, 2013, 05:28:27 PM

Quote from: movenon on May 02, 2013, 09:40:09 AMWonder what the top speed would be with 18/38 gears..... Let me know if you find out

You can use the calculators to figure that sort of thing out. In theory, assuming a 170/60-17 tire that neither grows nor slips at those kind of speeds (we'll pretend it does both and they cancel out), and assuming you've got the horsepower... 18/38 gearing at 9500rpm works out to 176mph. Unlikely that it'd pull that far without some rather serious motor work, though. Peak power is around 8500 with a reasonably stock motor, and that'd give 157mph.

Fast enough to get into an awful lot of trouble in a very short period of time, anyhow.

movenon · May 02, 2013, 07:54:13 PM

That's a little faster than I well ever go on 2 wheels.. But it's nice to know

. Think I will just go to the Salt Flats and watch.. The 18/38 combo for me seems to work just fine for me.
George

CatTomb · May 06, 2013, 09:59:35 AM

OK, so I am running 17/41 on stock wheels and tires. I am looking to reduce vibration and RPM's at highway speeds.

If I am understanding correctly, if I go 18/38 I will be kookaloo. If I change one sprocket or the other I will be half kookaloo as 17 to 18 would be the same as going from 41 to 38.

I just received the invoice for the work the previous owner had performed before he let the bike sit for a couple of years. It totaled $1342.52 (got to love dealers $$$) and included new sprockets and chain. The chain listed is RK506120 530XSO-120. The other work included oil/filter change, carb overhaul, rotor replacement and three sets of brake pads.

So, my questions are... if I was going to just change the front or back sprockets which would be better and if I change them both would I have to shorten the chain?

Thanks,

Jeff (17/41)

ELIMINATOR · May 06, 2013, 04:00:42 PM

hmm, I'm no expert, but, I'm sure I read that if the front sprocket is increased in teeth number, then as well as dropping the revs for any given speed, the chain leads an easier life.

Anyone correct me on that if I've made an error.

I assume

that as the sprocket is larger the chain links do no rotate as much as on a smaller sprocket.

The 18/38 combination does not leave a lot of room for chain adjustment, but, I'll have to see how it goes.

I got 48mpg, (remember this is a bigger gallon than yours in the States) this includes the very short 145mph burst, and some 80 to 90mph runs.

markmartin · May 06, 2013, 05:28:26 PM

Quote from: CatTomb on May 06, 2013, 09:59:35 AM

So, my questions are... if I was going to just change the front or back sprockets which would be better and if I change them both would I have to shorten the chain?

Thanks,

Jeff (17/41)

Maybe not. I had the 17/41, now have the 18/38 and didn't have to change the chain length, though the wheel is further back. That's not a definite answer but I hope it helps.

Mark M

movenon · May 06, 2013, 06:22:11 PM

Quote from: markmartin on May 06, 2013, 05:28:26 PM
Quote from: CatTomb on May 06, 2013, 09:59:35 AM

So, my questions are... if I was going to just change the front or back sprockets which would be better and if I change them both would I have to shorten the chain?

Thanks,

Jeff (17/41)

Maybe not. I had the 17/41, now have the 18/38 and didn't have to change the chain length, though the wheel is further back. That's not a definite answer but I hope it helps.

Mark M

+1 Same as Mark said. Wheel sits a bit more to the rear... 18/38 on mine. 110 link chain
George

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38 / 18 sprockets