Advise to anyone fitting an R6 rear shock

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mike YPVS
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Advise to anyone fitting an R6 rear shock

#1 Post by mike YPVS » Thu May 29, 2014 11:30 am

I guess everyone who has an R6 rear shock fitted will know this (or hopefully will), however I have just recently fitted one to my bike. (well over the winter, but not done many miles on it so far this year)

My MOT test was due the other day, so I went through the bike and adjusted the drive chain tension. As a lot of people know by fitting an R6 shock you lift the rear end of the bike slightly. This also means that when the bike is sat on it's center stand the rear tire will still be on the floor. So without thinking I placed a piece of wood on the floor and got the bike onto it's main center stand stood on the piece of wood, so as to lift the rear tire off the floor so I could adjust the chain tension. I did a lovely job then wheeled it off the piece of wood and put the bike away until the next day when I rode it to the test center.

The tester was checking through the bike and stopped when he got to the chain, his comments were " it's as tight as a banjo string " I looked and sure enough it was, "How did I manage to do that" I was thinking. Anyway, the bike passed the test but I had an advisory note to adjust the chain.

I rode home and once again placed the bike on the center stand on the piece of wood with the rear wheel clear of the ground. The chain seemed to be at the correct tension, so I wheeled if off the center stand and checked the tension while it was on the side stand. Yes, it was very tight.

I set the correct tension while the bike was under it's own weight, then got my wife to sit on it while I checked it again. I tightened up the rear wheel bolt then placed the bike on the center stand and piece of wood to see what the tension was like, Jeez! it was so loose that it looked like it would jump the spockets, I have about 5cm of loose chain movement. But as you never ride it on it's stand, it's more important to get it right with weight on.

The moral of this story is, if you fit the R6 shock (which lifts the ride height) you cannot adjust the chain on the main stand anymore. The tension must be checked with weight on the bike or at least stood with full weight on the rear wheel or you will end up with a "banjo string" which is very damaging to your bike, chain and other things.

I must point out that in all the things I have read about fitting the R6 shock to an RD/RZ 350 I don't recall reading anything about the chain been looser due to the longer length of the shock. I should have double checked I know, but not all riders are mechanically minded enough to understand exactly what differences a longer shock will make.

All in all a very good and cheap conversion, just that now it makes the front forks feel CRAP lol. Need to do somthing to them asap. Stronger springs ? thicker oil ? progressive springs ? Idea's please lol.

pearljam724
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Re: Advise to anyone fitting an R6 rear shock

#2 Post by pearljam724 » Thu May 29, 2014 12:59 pm

I don't know how you European guys resist killing someone going through this nonsense. Did he also point out that your handle grips were too hard ? I feel my suspension is perfect for fairly aggressive, high speed, twisty riding. I weigh 185 pds. Have the R6 shock adjusted to proper sag according to my weight and stock forks. Factory recommendation is to not exceed 17 pds of air in the front forks due to precautions of blowing out a seal. I set mine at 20 pds and lowered the forks through the triple trees close to a half inch and I feel my bike handles fantastic. The nose of the bike hardly dives. If I were to jam on my brakes at a high speed for example. Which is what I like.

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Re: Advise to anyone fitting an R6 rear shock

#3 Post by silverstrom » Thu May 29, 2014 1:14 pm

mike YPVS wrote: The moral of this story is, if you fit the R6 shock (which lifts the ride height) you cannot adjust the chain on the main stand anymore. The tension must be checked with weight on the bike or at least stood with full weight on the rear wheel or you will end up with a "banjo string" which is very damaging to your bike, chain and other things.
Regardless of which shock you have you always need to check chain slack with the bike on its wheels. You can raise the bike to make the adjustment, but you should always be measuring with the bike on its wheels.

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Re: Advise to anyone fitting an R6 rear shock

#4 Post by pearljam724 » Thu May 29, 2014 1:30 pm

silverstrom wrote:
mike YPVS wrote: The moral of this story is, if you fit the R6 shock (which lifts the ride height) you cannot adjust the chain on the main stand anymore. The tension must be checked with weight on the bike or at least stood with full weight on the rear wheel or you will end up with a "banjo string" which is very damaging to your bike, chain and other things.
Regardless of which shock you have you always need to check chain slack with the bike on its wheels. You can raise the bike to make the adjustment, but you should always be measuring with the bike on its wheels.
Correct. Proper chain slack is actually a result of sitting on the bike. Manufacturers usually suggest 1 1/2 of slack when adjusting. But, if the suspension sag is not correct given the proper shock adjustments for that riders particular weight. The proper chain slack gets thrown out the window and won't mean a thing. Regardless, of adjusting it at the factory slack suggestion. The suspension sag has to be correct for a person's particular weight. Which is usually around 1 1/2 of sag at the rear of the bike. Front sag, usually tends to be around 3 to 3.5 inches. Some bike models slightly differ. Handle slightly better at slightly different sag rates. But, those numbers are usually the norm for high speed riding. On most models.

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Re: Advise to anyone fitting an R6 rear shock

#5 Post by JonW » Thu May 29, 2014 7:28 pm

Thanks OP for the heads up, I always do my final 'fingering' of my chain slack on the wheels, same as doing up any suspension bolts as the weight and swing of the parts means things move. It is worth pointing this stuff out as it seems not everyone does that stuff the same way, probably depends on which bikes you grew up with, I was always riding dirt bikes and chain adjustments were done with both wheels on the ground, usually in the rain or snow with minimal tools and frozen fingers, so speed was needed LOL
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Re: Advise to anyone fitting an R6 rear shock

#6 Post by hondaror » Fri May 30, 2014 3:22 am

The key is swing arm movement. As the rear wheel moves with the "crush" of the suspension, the chain is tightest when the swingarm is in line with the sprockets. The whole idea of the slack is to not have the chain under undo stress when the sprockets are at the farthest from each other in the arch of the suspension. When you add a longer shock, the distance of the sprockets actually moves closer to one another as the fulcrum of the swingarm pivots more moving the wheel farther down from the seat, and closer to the front of the bike. The chain becomes slacker, so the general 1-1 1/2" free play, no longer applies. This is why, suspension slack is so important. If it is set up correctly, the bike behaves as it was designed, relatively stable...or as stable as can be.
I have recently aquired an R6 shock, but am going to look into a modified shock mount, which will keep the bike within specs for ride height. (A higher upper mount).
Ideally, the chain should be adjusted when the bike is squatted so the sprockets and swingarm are all lined up, about 1/2" of play.

Steve, (Off Road) has a thread about this. The problems encountered with the longer shock install. It's lengthy, but a very good read.
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mike YPVS
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Re: Advise to anyone fitting an R6 rear shock

#7 Post by mike YPVS » Fri May 30, 2014 6:30 am

Yes, it's ok to have a longer shock. The R6 shocks work really well for no money. The MOT tester remembered my bike from last year, and commented that the rear end felt much nicer now.

Just remember not to set the chain tension while the bike is on it's stand. In my case the bike was actually on the bike bench to lift it up to my level ( I don't get down on the floor anymore lol) With the rear wheel lifted of the ground the R6 shock will make the chain look VERY slack.

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Re: Advise to anyone fitting an R6 rear shock

#8 Post by RuZty » Sat May 31, 2014 7:01 am

pearljam724 wrote:I don't know how you European guys resist killing someone going through this nonsense.
Nonsense is all relative, they never had catalytic converters on their bikes. :smt003

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