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Front forks (again)

bobk100

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Hi All

Sorry if this is repitition but I haven't the time to trawl any more posts.

My bike has 100mm of travel before it bottoms out and 40mm sag when I take it of the stand.

To get 25mm sag I have to load the tube with so many spacers it's hard to get the screw tops again it's a challenge to get'm done up again and it restricts the total travel as I presume the springs are jammed up.

Sound about right?

Anyone ever machined the bottom of the forks to accept brake bleeders? Is there enough 'meat' to do the mod.
 
I'm sure that it's me not understanding your posted numbers so I'll elaborate. The NC700X has 137 mm of fork travel so a target sag of 25 mm is a lot less than most tuning guides call for. 25 to 33% of travel gives an acceptable target sag range of 34 to 45 mm, this is sag under weight of bike, rider(s), and normal cargo. I agree that it would be difficult to install the fork caps with enough preload to get 25 mm of sag but it's not difficult to install fork caps with enough preload to get 40 mm of sag.
 
Does the OP have an NC7x0X, an NC7x0S, Integra, or some other variant of NC product?
 
Thanks for your replies.

It is a NC700X 2012.

The 25mm figure came from an article that suggested 30mm for road riding and 25mm for track and I used the 25mm as an illustration of how difficult that would be to achieve. I suppose that 25-33mm would be right for a travel of 100mm.

This is a recently aquired bike without history hence me trying to 'sort it out'. However, your figure of 137mm of travel is revealing. Something is amiss as I have 100mm. which suggests non standard springs or perhaps hydraulic lock?

Mmm - it's 0320am - I need some sleep. I'll ponder this later today!
 
So - the plot thickens!

I took the springs out and the total travel is 125mm. Springs in = 100mm

dduelin quotes 137mm

https://www.motorcyclespecs.co.za/model/Honda/honda_nc700X_12.html quotes 153mm

So I'm not sure what I've got going on.

I'm guessing my next step is to take the lot apart again, undo the damper rod and see what's on the end of that and post a picture to see if resembles the OE.

Getting a bit tired of burning the midnight oil on this. Can't help thinking I'm missing something completely obvious but for the life of me I can't think what.
 
Are the springs stock Honda progressive springs, or are they an aftermarket spring?

I would put no faith in an independent on-line specifications source. Even Honda is well known for making specification mistakes on their own web site.
 
They look like progressive originals. Mmmm here's a thought - there's a metal tube on top of the spring about 6 inches long - is that OE?

Thinking about it - they must be OE as they are the length 397.
 
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I think there is likely a burgeoning communication or language issue. The OEM spring collar on top of the spring is 150 mm.

Don't go by specifications you find on random web sites. My advice is to purchase a genuine Honda Service Manual if you are going to be messing around with critical items.
 
Hi

Thanks for your replies.

Well - the bottom line, after a lot of work (those fork caps have been in and out more times than I've had hot dinners!) is that if I take the caps off, remove the 6" or 150mm spacer and 397mm spring, the total distance between the upper and lower movement of the fork leg when they hit the stops is 125mm, the forks cannot travel any further.

All assembled, the caps are easy to screw back with just a little resistance, the max movement is then 100mm, with a sag of 40mm.

So I reckon that the spring is fully compressed at 100mm and not allowing full movement, to gain that missing 25mm?

Any ideas what's wrong? What am I missing?

If you're getting frustrated with this issue, imagine mine. How did Honda get it so wrong?

Thanks again.
 
I wouldn't count Honda out just yet.

After I did the fork emulators on the first NC I took a couple of zip ties and placed them tightly around the left fork leg above the seal wipers. I jacked up the front of the bike so the wheel was off the ground and the forks were fully extended. I measured 137 mm from the top of the seal wiper and made a small mark on the fork leg with a felt tip Sharpie pen. I slid the upper zip tie up to the mark so the lower edge of the zip tie was 137 mm up. The other zip tie was left just above the top edge of the seal wiper. I got the bike off the jack and center stand and gently on it's wheels (with me on it), had my wife push the lower zip tie against the wiper and then measured the distance between the zip ties. This figure subtracted from 137 was the amount of rider sag. I don't remember what it was.... 45 or 47 mm seems to stick in my mind.

I then went out and did several full out emergency stops from 30 mph on a section of bumpy pavement to measure if the forks bottomed out under duress. Back in the garage I examined the zip ties and found the lower zip tie was at the 137 mm mark and had displaced the upper one by 2mm (139mm). The zip ties are 2mm wide, so the bike had bottomed the forks and traveled at least 137mm. I was shooting for at least 10mm of travel in reserve so I raised the fork oil level by 10 mm and did this all over again. I ended up raising the initial oil level by 20 mm in order to save at least 10mm of travel in normal riding, albeit aggressive riding.

The exercise showed me three things. Real world fork travel, rider sag, and how oil level makes the feel of the fork springs more progressive without changing the spring at all.

Try it and see what happens on your bike.
 
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