1985 ATC 250r Suspension

[maddog1927]

I have a 1985 ATC 250r Bone stock with low hours (original grips hardly worn). I want to leave it mostly stock but would like to at least get springs for my weight (210#). Would just springing for my weight be the way to go, or is there a special "Sand Dune" Valvling recipe?

On other sites I have posted, progressive front spings seem to get the thumbs up. Also PEP suspension seems to be well regaurded for trike suspension.

What are your opinions.

[RIDE-RED 250r]

I dont really know how to answer your valving question. I go 210 as well, I just adjust my preload to my comfort level. I ride mainly seasonal roads, not hitting whoops and stuff...

HOLY CRAP! Nice trike bro!!!

[Mosh]

I run 190lbs, and run Progressives in the front no spacers, with 10 wt fork oil. My rear shock is stock, but re-valved big time. ( I have no idea who did it). So much so, that I have all the spring rate backed down and a plus 3 swinger and I cant sack it out off of 8-10 foot up jumps. It makes it twitchy in the rear on hi speed braking bumps and whoops, but I have learned to deal with it.
The fronts will sack out out anything over 6-8 ft in the air if I come down hard enough. I could probably bump up my oil weight ,to help the fronts.

So I would suggest at least the progressive springs in the front, and maybe a good re build on the rear shock with some new valving and thicker oil in the back as well, but definately go with 20 wt or higher fork oil in the fronts with the progressives.

I run MX tracks and trails on mine, I have no idea on how she would feel in the dunes.

Nice ride!

[Vealmonkey]

I'm curious as to what "sack it out" means? If it means bottoming out, then I'm really confused as springs are for compression and fork oil is for the rebound.

[Mosh]

I'm curious as to what "sack it out" means? If it means bottoming out, then I'm really confused as springs are for compression and fork oil is for the rebound.

I call it "sacking out" when you bottom out.
I do not know the exact specifics and science of suspension tuning internally, to qualify me as an expert by any means. So feel free to research and correct me if I am wrong.
All I know is what I have read and been told by others on forums, and the guys at the trike races, and what I have changed or altered on my stuff, and the outcomes from those changes.
Oil does indeed control your compression via dampening as wells as return rebound. As the oil passes through your valving, the thickness of your oil and amount of oil, in conjunction with the restrictions of orifices in the mechanical valving will help slow the spring compression rate as the piston or fork leg travels down. So if you need a little more compression, you can add oil in the forks if there is room, or actually thicken the oil up with weight changes. If that does not help, then more valving can be added to slow the exhausting of the oil through the valving to add more dampening.
That is why when your rear shock blows the oil out, it becomes a pogo stick, because there is no longer fluid to slow the compression of the spring and shock.
That is what has been explained to me.
I never thought either, that air pressure in your tires will make a difference on rebound or dampening as well. But it does.

Before spending hundreds of dollars on a rear shock for the trike, there is a lot of good builders that can make a stock 250R shock alot better which (was pretty decent in stock form,) just by doing some valving and spring rate adjustments at a fraction of the cost. Progressives and thicker oil in the front are a must though if you plan on jumping the trike anything over 5 feet up. IMHO.

[legacy51]

Having the rear shock revalved to your weight and riding style will help out a ton.

[Billy Golightly]

The best thing to do is to get a high quality fork oil that has as little stiction as possible (Stiction is the amount of pressure it takes before the suspension starts to move) and start with some progressively wound fork springs. There are definitely other options out there as far as specific valving. I'm running a set of RaceTech gold valve emulators in my hill climb 250R (with progressive fork springs, and a few other goodies) and I'm*very* happy with the performance. I have plans to sort of write up a suspension article on the main page here in the coming weeks.

PEP has a fantastic reputation and if you don't mind sending the parts out to get worked on I don't think you can possibly go wrong with them.

[maddog1927]

(with progressive fork springs, and a few other goodies) and I'm*very* happy with the performance. I have plans to sort of write up a suspension article on the main page here in the coming weeks.

PEP has a fantastic reputation and if you don't mind sending the parts out to get worked on I don't think you can possibly go wrong with them.

Did you get to that write up yet?

I have been doing some thinking and have decided that I would like to focus on being able to through the woops at the sand dunes on the main drags and at the bottom of the hill.

I am torn about sending to PEP. I am sure I would be happy with the results, but with shipping it aproaches 900$. I am considering just changing the oil and springing for my weight.

Also on race tech web site when I enter ATC 250R it gives me the choice between '81-'85 and '86. That seems odd to me. shouldn't '85 and '86 be the same suspension wise, and the '84 be very different than the '85?

Should I enter '86?

http://racetech.com/ChooseVehicle.aspx

is there a better spring calculator out there?

[maddog1927]

After much debate I have decided to change the oil, respring, and go from there.

For the front I am going with progressive. From there I will play with oil weight, and air pressure to dial it in.

http://www.bikebandit.com/progressiv...rings?b=279689

My E-mail to progressive: I am considering your fork springs for my 1985 honda ATC 250r. P/N 11-1127. I know these are progressive, but in general how do the spring rates compare to the OEM. I am 215# where as the stock spring is for a 165# rider. Is this the correct spring to make up for the +50#, or do you have a heavier spring rate that would work better for me?

Their Response: We only offer one rate of spring but being a progressive rate it does cover more apps than stock. It basically starts near stock and then gets stiffer, up to about a 20% increase. You can also add length to the spacer to fine tune it.

For the rear I will just change the oil and install a 6.2kg spring. (that is the race tech recomendation for an '86 TRX 250r)

[55stone`]

that is a amazing trike wow... good look with the suspension let us know how it goes.. love suspension so much..

[maddog1927]

I ended up having schmity racing suspension do a 3 stage valving, and 5.4 KG spring. Will be going to the dunes in a few weeks, I'll report then.

In the mean time.

Where do I measure when setting sag? He said to set it at 3".

Also on the front I changed the oil. How much air pressure do you guys run?

[maddog1927]

Many years ago I said I'd report... Well Schmity did me a fine job

[Flyingw]

Evan has done two shocks for me with no complaints. The Schrader valves on the forks are for letting air out not in. The reason is after a hard ride on a hot day, the air inside the forks expands and needs to be released. The forks are hydraulic forks, not pneumatic forks.

[cobradude]

Many years ago I said I'd report... Well Schmity did me a fine job

Way to follow through [emoji106] lol