TTR 230 spring mod

I'm working on a friend's 230, and the front forks are pretty soft. So, along the line of what I've done to TTR 125's, I...

Took 3 inches of coil off of the tightly stacked side of the spring. The spring was 24.25 inches long to start, and I added back a PVC spacer so that the length was 24 and a half now. I cut the spring by holding it to the side of a bench grinder. It's pretty wiggly trying to hack saw it.

The oil level was 8.5 inches from the top with the fork compressed and the spring out. The spec is 161 mm, or divided by 25.4, 6.33 inches. Yes, it was 2 inches low on oil. That doesn't help an already spongy fork. I refilled with 15 weight rather than the stock 10 weight.

Reassembly took about 2 minutes. This is the easiest fork ever to change oil on.

A huge piece of PVC was $1.30, plus a bottle of fork oil. Entire project time maybe 45 minutes, because the Derby was on.

The result was a noticeably stiffer fork, in a good way. Less bottoming over little stuff, more controlled. Still soft-ish, and always will be, but not downright bouncy.

Thanks for the post. You got me thinking. I need to redo the fork seals on my bike and would like to help out the forks all I can. I am about 175lbs on a good day and the forks need help for the trail riding I do. Would changing the fork oil to 15wt be enough without the cutting of the length of the spring? I am doing little to no jumping. Can washers we used to preload the fork instead of cutting and adding PVC? Let me know.

Yes to all of your questions. I've added a little PVC spacer without cutting the coils, but the fork will have a firmer overall spring stiffness if you cut the coil and replace with a non-moving surface like PVC.

The heavier weight is a subtle change, and this will never be a supercross bike. What I noticed during my brief test ride is that the fork is firmer in the second half of the stroke, more bottoming resistance.

Any ideas on how long the PVC pipe should be to compress the spring? 1", 2", 3"??? Also, any idea on the diamter of pipe you used? I have not taken my forks off yet.

The outside diameter is about 1.1 inches. If you're preloading the spring additionally without cutting the coils, I wouldn't preload more than about 1/2 to 3/4 inch.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now