So the original shock on my FJ gave up the ghost last year, bought an f4i shock and finally got around to putting it on the other day. First question is adjustment, the stock valving settings weren't working for me at 1 1/2 turns out each, set them to 1/2 turn, that's fine but how do you know where the spring is set? I looked at it forever and for the life of me can't find a mark or stamping anywhere. I'm 230lbs 6'3", where "should" the spring be set? Looks like I have to pull the shock out completely to adjust preload.
The other is chain tension, I set the chain on the center stand like I do everything, and when it came off the stand the chain was tighter than a piano wire. Living alone I can't have someone sit on it while I adjust the chain so I put blocks under the side stand to the bike was almost upright, set the chain again, sat on it and reached down to find the chain rigid. Seems like raising the rear end up throws the geometry so far out that the chain is impossible to get right, on the center stand it has over 3" of play but has none with me sitting on it off the stand. Not sure what to do here, I can't afford the aftermarket options for a shock assembly, this seemed like my only choice.
It would help a lot if you mentioned what year FJ you have. The rear suspension is one area that changed a number of times through the various models.
If you've got a late model FJ with dogbone links, you can make longer links to reduce that ride height.
If you need more than 3" of slack in the chain when on the centerstand, and the chain is still tight in ride mode, you're going to have to fab up some kind of chain tensioner.
When I first did the F4i shock mod, I purposely did not provide a step by step set of instructions and setup.
If you're making these kind of major changes to your bike, you need to know how to adjust it for best ride.
At 230 lbs you're likely close to the limit of what the stock F4i spring and damping will properly control. You may want to replace the spring and have the valving modified.
If you need a plug and play shock option take a look at the RPM shock.
I can add some information.
Your signature line indicates you own a 1985 1100 so I assume that is the bike you are working on.
The swingarm now is at a different angle and you possably have more travel. I used an F4i shock and had the same problem.. You will need to run the chain loose. 3 inch's is a bit excessive though, I ran mine around 1 1/4" from memory. BUT mine was a 1990 with dog bones so I could adjust the height.
I weigh in the same range. The stock spring was to soft. Don't think you can get the correct SAG or at least in a good range without a new spring.
I took a shock preload adjusting wrench and modified it a bit so I could adjust the preload adjuster. It was a 15.00 Cycle Gear wrench that I cut one end off and tweaked it a little.
How to and where to adjust the shock and fork preloads involve understanding SAG numbers. A good review and "how to's" are on You Tube. You should have a good understanding of the balance of the bike. Getting the proper or useable SAG settings are important. I am no expert here, there are some members here that have this down solid. Through evolution, reading the files section, reviewing You Tube posts, and reading a lot of books I got things sorted for my bike. Balancing the front and the rear end suspension is the road to control.
If you have a "plug and play" shock then you are probably close to the correct settings. When you modify or adapt you are pretty much on your own and need an understanding of where you want to go and expect you will run into challenges (those aw shit moments).
Please don't get me wrong, my bike suspension is modified front and rear and I enjoy playing with it but that's me. As a note I later pulled the F4i shock and now I am using another adapted rear shock.
There are some members here that have installed the F4i shock in early FJ's they will hopefully be able to add more information for you.
George
My F4 shock came with a remote cylinder which has the rebound setting on it the compression setting is on the bottom of the unit. I had to take both muffler's off to adjust the compression screw and to crank up the spring. I used a large channel lock on the spring adjuster and I set it to the max which is 6 or 7.
The rebound and compression settings I also set close to max I am going to ride on a particular corner that has produced missbehavior in the past and see if these settings helped.
Chiz
Yeah sorry guys its an 85, spaced that part. The RPM shock is awesome I'm sure but this bike is only worth about $1200, thanks to a low speed slide last year. Kinda hard to put that kind of money into it. I've got the compression and rebound screws both 1/2 turn out, I just can't figure out where the spring is set, so I don't know if its maxed out, or set at 3 like stock would be, or even wound down to 1, no clue.
The spring collar is stepped. The one that puts the collar highest is 7 which is were your going to probably want it with your weight. But it will also put the back a little higher. Compression and rebound will need to be higher too. The spring is replaceable.
You can get an eibach spring off flea bay for about $90. But you need a collar that you have to get from one of the shock rebuilders. It's been a while I can't remember who I got mine from(Race Tech? I think)You will also need a spring compression tool .flea bay.
900lb eibach spring. Is about the limit for the stock valving on the shock. It's still a little soft for my 280lbs.
But a thousand times better than the stock shock. I have about $160 total into my f4i including buying the spring tool.
Took a muffler off and turned the collar until it wouldn't turn anymore (counterclockwise looking down at it), so I'm assuming its on 7 now, still can't identify a mark anywhere indicating where its set. Also cranked the screws in all the way. Its still pretty soft, lots of movement. And for the life of me I can't get the chain adjusted right still, I got it to where I had 30mm of play with the bikes own weight but its still rigid-tight when I sit on it, not to mention free play with it on the center stand is obscene. Not liking the chain fight having the bike sit higher.
Is there an affordable new OE replacement shock/spring assembly out there? I don't ride the bike hard, just cruise around (can't really ride it hard with 2nd jumping anyway, hah).