18/30 chain length

miller0613 · Full Member Joined: Jun 27, 2007 Posts: 111

I am getting ready to order my new chain and sprockets but don't know what length chain to order how many links for the new set up? Also I have a 79 special I don't know if this is one of the "new electronic " ones john speaks of to retard the timing. I have looked at the timing and the PO has moved it from away from the F mark but do not know if I will have to dril and cut and so forth to adjust it. Any info will be appreciated. Rode 190 miles yesterday and I my butt is still numb so something had to be done.

xsjohn · Posted: August 3, 2009, 12:15 pm Post subject: Re: 18/30 chain length

104 I think is stock links........then shorten the chain as necessary......can grind the pins and punch it out if you don't have a chain breaker.....as for the timing set it where it doesn't get cranky with the taller gears at say 2000 rpm so you can go around slower corners without it getting cranky........that equates to about 1/8" on the right of the F mark at 1200......with the ATU models I guess you will just have to play and set it where it does the above mentioned...if there is even a problem with the ATU ones...considering spring tensions and greased properly and all..... ?

xsjohn

pumps · Posted: August 3, 2009, 12:18 pm Post subject: Re: 18/30 chain length

If your bike has points, it is NOT one of the electronic ignition ones. Look under the left side cam cover. I think 79 was the last year for points but I suppose a late one might have electronic.

nj1639 · Posted: August 3, 2009, 8:00 pm Post subject: Re: 18/30 chain length

My chain with the 18/30 has 102 links. Had to take a couple off, no problem!

jerseykat1 · Full Member Joined: May 03, 2009 Posts: 79

I just ordered 18/30 sets myself. How is it to ride around town with. My stock set up I kinda find myself cruising around a lot in 4th or 5th gear, and 50-55 mph is about all I feel comfortable with on the highway, any faster I start to feel like a piston may come flying through the heah and pop me in the chin. Lol. Hoping to bring that comfort zone up to atleast 65.

xsjohn · Posted: August 5, 2009, 4:57 pm Post subject: Re: 18/30 chain length

(TCI) Retard the timing about 1/8" or even a bit more from the F mark at 1200 with the 18/30 ..............xsjohn

miller0613 · Full Member Joined: Jun 27, 2007 Posts: 111

So then do I set the idle at 1200 mark where the F mark is shut it down and then move it or how does one go about adjusting that. I have been shocked by a distributor before adjusting the timing and would like to avoid the "lesson" I learned by grounding myself to the fender.

xsjohn · Posted: August 8, 2009, 9:06 pm Post subject: Re: 18/30 chain length

There is no high voltage here like there is on a auto distributor........the tci probably could only be measured in milivolts and the points can would be about 12 volts............

And on the ATU bikes ....if mine I would just ride it and if it gets cranky down low then try retarding it a bit.......experimentation.........maybe someone with tall gears on the ATU bikes can chime in..............

xsjohn

baclay9 · Full Member Joined: Jul 30, 2009 Posts: 88

I don't want to post jack but didn't want to start a new post for this either.

I weight about 300 lbs and am building a 79' bobber. I was wondering if the 18/30 sprockets would still be a good idea for me. I am just building this thing to cruize around on but would like to at least be able to do 65 for short runs on the highway. Thanks for your help.

acbanks · Posted: August 9, 2009, 9:28 am Post subject: Re: 18/30 chain length

I weigh 150lbs and just switched to 17/30 sprocket...The acceleration lost in 1st gear is very apparent, and the clutch is really tricky. I'm going to try retarding the timing as John suggested and then really spend some time setting up my carbs. Hopefully I can get enough power to stop it from bogging.

On a 1979 and with your weight, you would probably be better off buying an overdrive gear instead of changing sprockets. I don't think they make one for my old thing, but that's really what the bike needs.

Joseph · Full Member Joined: May 22, 2007 Posts: 767 Location: NY

I weigh 200 and didn't' really notice much different except for better cruising with 17,30 on an 80. Id try the 17. 30 1st. If it works well try the 18. These bikes are geared so low a few extra revs to get going is worth the cruise, again it didn't noticeably affect negatively me though.

baclay9 · Full Member Joined: Jul 30, 2009 Posts: 88

What is the overdrive gear all about?

If I just run the stock gearing is that just going to equate to higher rpms on the highway. Seems like they built the motors to run at the higher rpms or they would have geared them differently. I would love to have lower rpms on the highway but I need something that will pull my big butt around down low as well. Most of my riding on this bike will be in the 45-55 mph range with maybe some short 65 mph highway runs just to go to town for bikenight or something.

acbanks · Posted: August 9, 2009, 10:19 am Post subject: Re: 18/30 chain length

You can buy it here, $60, 1978 and later bikes only. You'll have to bust the case open though.
www.mikesxs.net/products-22.html

They say these things can handle the high rpms, but I'm wary. I also don't want to lug it since I've heard you can dent the crank bearings.

If you don't want to do the overdrive gear, I'd recommend doing the 18T front sprocket first. It's easier(besides a little bit of grinding) and will be a smaller change than going to the 30T rear like I did.

Here's a nice spreadsheet made by Pamcopete that lets you play with different gear ratios.

dejaviews.org/f/xs650revs.xls

nj1639 · Posted: August 9, 2009, 6:55 pm Post subject: Re: 18/30 chain length

baclay9 wrote:

What is the overdrive gear all about?

If I just run the stock gearing is that just going to equate to higher rpms on the highway. Seems like they built the motors to run at the higher rpms or they would have geared them differently. I would love to have lower rpms on the highway but I need something that will pull my big butt around down low as well. Most of my riding on this bike will be in the 45-55 mph range with maybe some short 65 mph highway runs just to go to town for bikenight or something.

With 18/30 gears, 8-1 compression and your 300 lbs, 45 to 55 mph range would be in 4th gear, around 3 to 3500 rpm mos' likely- edit to add- and still have 5th to go 65 @ around 3500 rpm.
Did a 2 up last weekend, 300 lbs+, and that's about where it was at.
Low gears were allright but had to have them in their high r's when dropping in otherwise they dog.

baclay9 · Full Member Joined: Jul 30, 2009 Posts: 88

I think I will just start off stock for now. If I don't like it I will do the 18 tooth front. After that I might try a 32 tooth rear. I would rather have some grunt down low for the kind of riding I will be doing.

I need to just get this thing together and then worry about upgrading I guess. Thanks guys!

nj1639 · Posted: August 9, 2009, 9:44 pm Post subject: Re: 18/30 chain length

You'll be ba-ack! Ha!
Just a note on the 18 front, I didn't grind the shift rod down, just keep your chain spec and you should be alright. No problems yet.

miller0613 · Full Member Joined: Jun 27, 2007 Posts: 111

So I finally got my new chain and sprocket on and it is all its cracked up to be rides nice. Couldnt believe how close it is between the clutch push rod and shift lever and chain wow gotta keep it tight. Anyways I have a 79 with points can someone walk me through step by step how to adjust the timing since i am new to points thanks

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