Front Springs - again

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Mark W
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Front Springs - again

Post by Mark W »

I wondered where some of you guys went when I no longer saw any of your wisdom being shared anymore - now I know why and where you all went.

Anyway. I have a 2002 KDX220 and have owned it for one year (I bought this bike after the recommendation of many of you - thanks). It is my first motorcycle of any type. My son and I ride MX tracks (me slowly, him much better) and do trail riding as well. I weigh 200 - 205 lbs without gear. As mentioned above, I don't ride hard but intend to get better.

I see the need for better springs in the front. I have the manuals and have found other useful information on how to change the springs and fork oil - it doesn't look beyond my capabilities - yet. My questions is the following:

1. I am fairly certain that I want the XR400 springs as they seem to make sense (longer, hot wound, etc...). Where do I order these from and what exactly do I ask for?

2. It seems that I am in a middle of two spring rates weight - any suggestions on which one to go for?

3. I see quite a bit written on spacers and see the need for them as the XR400 springs are longer. I also see to cut them out of 1" pvc pipe (schedule 40 I believe). My questions is where do these spacers go? Top or bottom? Any best recommendation on spacer length? I know it is a personal choice and all, I just don't think that at this stage of my cycle riding I'll notice too much of a difference.

4. Mobil 1 ATF fluid for the fork oil?

I think this is about all for the front fork questions. Next task is to grease all the swingarm bearings. I'm sure there will be questions here as well.

Nice to find you guys again.

Mark W
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Indawoods
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Post by Indawoods »

Hi Mark and welcome to the forum.

I have a new set of .42 XR springs for sale in the parts for sale section which is right for your weight. These are the Factory Honda springs that are desireable. Spacer length depends on how the springs fit in your forks. How much space is left and they go at the top. Between 3 and 6mm preload is what you are looking for. You can use ATF if you wish but the wt isn't consistant. Use 7 wt fork oil if available... but it's really a preference thing on wt.

If you didn't know, I put a KX front end on my bike so I don't need the springs.
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Post by KDXGarage »

If you are 200 - 205 and ride on a MX track, (disclaimer warning) FROM WHAT I HAVE READ (disclaimer over), you may want a little stiffer spring than the .38 or .40 Honda OEM XR400 springs.

1. If you go with them, servicehonda.com was the cheapest place I saw for them.

2. Stock springs are for a trail bike, and they are .35. If you are riding the same bike at your weight on a MX track, I can't imagine the .38's being quite stiff enough for your application.

3. The spacers go on top. Since you have a manual, just look for the picture showing the stock metal spacers. You replace these metal ones with the PVC ones.

4. A few years ago, a few suspension shops were running part ATF and part "their own secret blend". I have read the secret blend was, in part, to to keep the fluid from braking down so much. I posted an oil weight chart I found on the Internet. You might want to search back for it. I think it was in November. It shows a good comparison of various oils and their equivalent weights.

Like most areas of tuning, there are many opinions. Most of the time, no one answer is the 100% best answer for your application. Good luck on finding a good starting point, then tuning from their to suit your individual needs.
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I should clarify...

Post by Mark W »

My MX riding consists of following my son around making sure other riders see him. I ocasionally do small jumps (they seem big to me until I see other riders going 5X farther and higher).

I am too old to be breaking bones and one bad enough accident on the track has allowed me to realize my limits..

I was searching through the previous threads and found the article mentioned on oil weights and whatnot. I'll have a looksie.

Thanks for the info everyone.

Mark W
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Post by KDXGarage »

Well, it sounds like you are almost as slow on a MX track as me. :lol:

I thought you meant big jumps and such.

I think the manual recommends 5 weight oil. I think most any high quality fork oil should work fine.

If you have not changed the fork oil, then it will be super nasty black when you take the old oil out. :grin:

I have read that the stock springs have a lot of preload. 10mm is a common recommendation, though it varies by taste. I have read that stock is around 30mm or so, maybe it was 38mm. The http://www.buykawasaki.com site may say how long the stock spacer is. You can cut the spacer to some length shorter than the stock length for your chosen amount of preload.
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Post by Indawoods »

That's the beauty of PVC! Cheap, easy to cut and try different preloads! :wink:
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Preload verses spacer and springs for sale

Post by Mark W »

Preload and spacer length aren't the same? I thought they were. Could someone explain the difference to a rookie?

I bet I am way slower on an MX track than anyone here. Funny story. I took my son and myself to dirt bike school at a nearby track. We were the only rookies my oh let's say 2-3 years of experience. I was in my usual position following my son most of the day when one of the instructors told me he would follow behind him and observe. He told me to take off and have some fun.

My new freedom didn't last too long. I made it around 3/4 of the track really enjoying myself and then came to a small triple then a double combination. Unfortunately I thought it was a double and then a triple. I hit the front side of the last bump of the triple and went right over the bars catching my leg somewhere. My shifter was bent in two as well as my leg. I was done for the day and a month afterwards. Ever see someone carried away at dirt bike school? My son did.

I sure am enjoying the KDX. I seem to be missing a little on the top end and will look into that after the new front springs and regreased rear suspension.

Wouldn't .42 springs be a bit stiff? From what I have read, that may be more than I need. I thought I was looking more at .40 or .41? I'll buy them if this is what I need. I just don't want to get pounded on.

Thanks again -

Mark W
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Post by Indawoods »

The spacer is what takes up the remaining space your springs don't. Preload is the amount of PVC that you cut above and beond the existing space. If you cut your spacer flush with the top of the tube, then your preload amount will be how far you cap compresses (preloads) the spring. This is how you determine preload amount.
Clear as mud?
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Post by bradf »

Remember that there is a race sag for the front as well as the rear. Once the correct fork spring rate is chosen, the pre-load will be adjusted for the correct race sag.
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Post by KDXGarage »

Preload is the distance that the fork springs are already compressed before a bump causes them to compress. When assembled, the springs are already compressed a small amount. This is called preload. If the springs were 470mm long, for example, and some length of spacer tubing caused that to be reduced to 460mm on assembly, then that would be 10mm of preload. The length of tubing is cut to whatever length it needs to be. The length of tubing varies on different bikes.

If a 100mm tube produces 38mm of preload and you want 10mm of preload, then you would have to cut the 100mm tubes to 72mm. Since the tube is 28mm shorter, the fork springs would be compressed 28mm less, resulting in 10mm of preload.

It took me a while to figure it out, so just keep reading. It will come to you.

Oh,m and as far as doubles, the only double I do is at Wendy's!
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Post by Mark W »

Indawoods,

How do I get ahold of you to maybe buy your springs you have for sale? I do have a couple of questions beforehand if you don;t mind.

Mark W
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Post by Indawoods »

Just PM me Mark and we can discuss the in's and outs.
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