Messages

1

Tech Talk / Re: Different spring for Fox Twinclicker

« on: June 23, 2015, 11:55:33 pm »

An update after my long silence.

I was fortunate to come across a suspension magician: Phil Douglas who got me all sorted. What a difference a softer spring and the talent of a real suspension pro make...

It is all here: http://www.xr500only.com/xr500-c-j-hpf/fox-twinclicker

2

Bike Talk / Re: C&J XR500 vs HL500

« on: June 23, 2015, 11:35:53 pm »

I own a few C&J Honda, never tried a HL500.

I rode one of the C&J in the Baja a few years back, you can read about it here: https://www.xr500only.com/candj-mugen-al-baker-baja-commander

And follow other projects here: https://www.facebook.com/groups/207461083953032/

I say, ... go Honda ;(. XR500 only mate!

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Honda / Re: C & J on it's way

« on: June 02, 2013, 11:38:50 am »

Went riding today with these two.

4

Tech Talk / Re: Aftermarket spokes? Has any one used these?

« on: April 23, 2013, 11:44:34 pm »

The Caswell kit comes with almost all you need.
Watch this http://www.youtube.com/watch?v=AzaxO6iODaQ
I am told that finishing with chromating (even transparent) will greatly increase resistance to oxidation over time.

5

Tech Talk / Re: Aftermarket spokes? Has any one used these?

« on: April 23, 2013, 01:18:14 pm »

I have done two sets of spokes with the zincplating kit.it goes really well. Preparation is key.

6

Tech Talk / Different spring for Fox Twinclicker

« on: April 16, 2013, 05:07:00 am »

Hello all,

I have refurbished the  80's Fox Twinclicker fitted to the XR500 HPF.
It seems to me that the static and rider sags are too small, the spring is too stiff. Would love some views

Here is some data.

With zero preload:
Static sag: 3cm
Rider sag: 8,5cm
So I figure a spring 30% softer would bring me in the right range with some room to augment preload if needed. Is that right?

Current spring:
ID: 58mm
Length: 26cm
Rate: 11kg/mm
Wire diam: 14mm

I believe that I need a spring with the same ID, same or shorter length, and a rate of about 7.5 kg/mm (around 30% less than current).
What you folks say?

Cheers, E

7

Tech Talk / Re: Aftermarket spokes? Has any one used these?

« on: April 16, 2013, 05:03:07 am »

I buy spokes from Buchanan's http://www.buchananspokes.net/
Make sure you have all the measurements ready when you call. The lady on the phone will give you the root canal...

8

Honda / Re: They come out of the woodwork.....

« on: March 27, 2013, 03:18:25 pm »

set of Fox Forx on Mark's this morning - but $3K though.

Hey, you can have one of mine for that money

9

Honda / Re: Honda XR500 C&J Fox monoshock HPF

« on: March 27, 2013, 03:07:44 pm »

Slowly, the restoration is getting there.
The spring at the rear feels way to hard, the front fork is too soft, engine is back firing, valves need adjustment, gears sometimes don't go in easily, but it is good to go for a ride.

http://youtu.be/KL5FlokWnj4

http://youtu.be/4uwzYnUiBDs

10

Tech Talk / Re: XL500 R engine question

« on: January 29, 2013, 04:19:33 pm »

I find that Helicoils go well on these motors. Never had problems. This looks like an easy job Assuming you have the cylinder on the bench.
Never used Timeserts, cant comment.

Alternatives:
- tap the holes for 7mm bolts (there is not much metal on the timing chain well side...)
- get another s/hand cylinder jug (lots of them everywhere on eBay)
- I wonder if any body has ever tried to use JBWeld on these sorts of situations, ... and dared to report

Note that, contrary to what the two pictures together could suggest, these two bolts do not go down to the crankcase, they only hold rocker cover + cylinderhead + cylinder.

11

Tech Talk / Re: What air pressure in Fox airshocks

« on: January 12, 2013, 11:51:22 am »

I did a little research on why nitrogen is better than air..
Unlike air, nitrogen does not retain moisture and thus is not susceptible to sudden changes in temperature which can cause a change in pressure.
Typically a shock pressurised at 140lbs with air can increase to as much as 160lbs at the end of a moto where as nitrogen would only increase around 5lbs. That is a fair increase in airshocks when air is the spring.

Numbers great! This is where the truth is to be found

I would love to see the math. Seriously.

The Specific Heat and Gas Constant values for Nitrogen (N2) and Oxygen (O2) are different (see here: http://www.engineeringtoolbox.com/spesific-heat-capacity-gases-d_159.html) but not that much.
With 1/4 of an air volume being O2 and the rest being Nitrogen N2 (with small amounts of water vapor, unless you live on the west coast of Ireland), the differences in SH and GC are then 3/4 smaller even.
My guess-timate is that Pressure and Temperature of either gases in a shock absorber at work are likely to be quite similar (and possibly hard to detect without measuring equipment). For where I stand, right now, Nitrogen or Air seems to be a personal choice, but that is just me.

But I would love to see the math, or actual measurements (like temperature of the shock at the end of a race, one with air, one with Nitrogen), seriously. But won't loose sleep over it

I also hear that Nitrogen is better for tires... oh rats, here is another conversation coming

Here is a good chat about this: http://www.thumpertalk.com/topic/936969-shock-pressure-nitro-vs-air/
I suggest you red those that show actual numbers...

12

Tech Talk / Re: What air pressure in Fox airshocks

« on: January 11, 2013, 05:21:26 pm »

"Oxygen behaves differently to air, compressed air, nitrogen and other inert gases. It is very reactive. Pure oxygen, at high pressure, such as from a cylinder, can react violently with common materials such as oil and grease."
www.hse.gov.uk/pubns/hse8.pdf

Oxygen under high pressure 500-3000 psi is a very different beast from air at low pressure (like our shocks), 300 psi max.

 But hey, enjoy Nitrogen if you wish

13

Tech Talk / Re: What air pressure in Fox airshocks

« on: January 11, 2013, 05:13:01 pm »

Actually, I believe so, mostly. More a marketing trick than a real improvement, in my view, at least from what I can see when I do the maths (PV=nRT yadhayadha) with what is left of my physics knowledge. In truth, when I do the maths, there is a difference, but so small that it is unlikely to actually make a significant difference. But hey, I am far from being an expert in anything....

Some put a wing on the trunk of their car and they swear it makes them go faster No offense meant.

I have a pair of Fox Airshox to rebuild, cant wait to get to that part.

As for oil and oxygen being an explosive mixture, hmm, there is some truth in that but it seems to me not really applicable to our use cases.
I seem to remember that this is derived from the physics of the diesel engine (but will not ignite without a source of intense heat...) or the absolute necessity to never apply grease to the threads of compressed oxygen cylinders (memory from veterinary school many years ago). Thankfully the pressure in our shocks or forks can never reach the levels of compressed cylinders, by a long shot...

But hey, again... I am far from being an expert in anything....

14

Tech Talk / Re: Powder coating engine cases

« on: January 11, 2013, 04:49:24 pm »

Hey I apologize in advance if I sort of highjack this topic.
Am very interested in this. Looking for a solution to the same question.
Would powder coating limit heat dissipation?
I was thinking of having cases and top engine (all aluminum) anodized.
Has anybody tried that?
Thanks,
E

15

Tech Talk / Re: What air pressure in Fox airshocks

« on: January 11, 2013, 04:26:26 pm »

Ah, the 100% Nitrogen vs 80% Nitrogen conversation is back
Are they Fox Airshox or Fox Nitroshox?
Is there really oil in the bladders? Snake oil?
Air (O2 + N2) does not behave differently from Nitrogen (N2) under pressure when it comes to the first principle of thermodynamics....
But yes, Nitrogen is much more cool