350x Front Suspension

[JoeNasty]

Today I was out riding on my trike for a little bit and really noticed how weak the suspension in the forks are. They easily press all the way down and I'm new to working with these so I'd like to know how I'd be able to fix this.

[barnett468]

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it would help to know what your weight is and exactly what conditions they bottom under.

can you easily bottom them simply by pushing on them?

do you plan to hit bumps fast?

[barnett468]

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this problem could be caused by low oil level, oil too thin for your weight, wrong springs, worn out springs, springs too weak for your weight and/or insufficient preload . . there’s a few different things you can check to help determine the causes of the problem . . the following are just a few suggestions.

Get the front wheel off the ground then measure the distance from the bottom of the lower fork clamp to the top of the lower fork leg.

next, get in front of the bike, then grab the front axle with both hands and try to pull the wheel forward . . this will tell you if the fork tubes are loose in the lower legs and if the steering bearings are loose . . repair as necessary.

Put the bike on the ground then sit on it as if you were riding then have someone push down on the forks a few times without them pulling back up on them then have them measure the same two points and post the results . . if they compress around 1/2 way or more, the springs are likely too soft . . if this is the case you can remove the fork caps and put around a 1” ling spacer inside to preload them . . this will raise them up 1” which will not be enough if they are compressed 1/2 way or more . . you can also carefully put some air in them thru air valve in the top of the fork tubes . . this can be done whether you add spacers or not . . they require an extremely short blast of air . . if your air source has a regulator, turn it down to 12 - 15 lbs . . too much air might damage the seals.

after installing the air, use a gauge whose highest pressure reading is around 15 to 20 lbs . . after installing the air, use the gauge and set the pressure to around 10 lbs . . you must remove the gauge quickly when you are ready to remove it because it will loose a lot of air if done too slowly . . if you remove it quickly, it will likely only loose around 1 lb at the most . . if the fork seals are bad, the air will leak out.

You could ride it a little after this and see how it is.

Even if it is acceptable, I would do the following simply so you know what you have.

Put both wheels in the air . . its best if the front is lower than the rear but it’s not “necessary”.

Loosen the fork tube pinch bolts on the top clamp.

Remove the fork nut while keeping light pressure on it because it might have a little pressure on it from the fork spring which might fling it into your face.

Remove the top spring . . it’s only a few inches long.

Pull the lower springs up around 10” . . shove something like a paint stick between the coils so they will stay there . . leave them there for 5 minutes . . this allows the oil to drain off so the following measurement is accurate plus it’s less messy when you remove them.

After removing the springs, take a tie down and hook it onto the axle and the other end onto the bars then use it to compress the forks all the way.

After the forks are compressed, take a regular metal tape measure and extend it around 12 inches and lock it then stick it in the tube to measure the oil level with . . this is the level from the oil to the top of the fork tube . . the factory spec is 8.5” . . you can start by sticking it in 7 inches, then 8, then 9 until the end gets wet, then do an accurate measurement . . If this level is low too low, it can cause problems . . if it rode acceptably with the additional preload on the springs and/or the air, and the level is only around 1” low, you can just top it up with non synthetic auto trans fluid like type f or type fa or dexron/mercon type I, II, or III or just about any fork oil you have, although since you are already at this point, you might as well change the oil.

If the forks were still too soft with the additional preload and/or air, I would definitely change the oil and put at least 15 weight in them . . after this, replace your additional spring spacers and/or the 10 lbs of air and see how it is . . if it is still too soft, I would buy stiffer front fork springs.

You can get springs from a few places . . the one below also has a spring rate calculator that will estimate the rate you need for your weight.

http://racetech.com/ProductSearch/3/Honda/ATC350X/1985-86

[barnett468]

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oops, i forgot, here's a free online owners manual . . the fork section starts on page 11-12.

http://www.oscarmayer.net/atc/manuals/honda/85-86_ATC350X_Service_Manual.pdf

[barnett468]

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oops, here's free factory online microfiches for bikes and atv's . . they also sell nos parts . . just click on the bike imake you want..

http://www.cmsnl.com/honda_model8286/

[oscarmayer]

Talk to onformula1. He is a major suspension guy. He can hook ya up!


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