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Are all years of forks compatible with all models , length , diameter and fittings?
 

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Not sure, the big outside bits probably yes. Inside bits no. The way to check is to visit parts site like fowlers or partzilla where you can punch up exploded parts diagrams of any bike any year and simply compare part numbers thru the years.
 

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You can swap pairs of forks between carb and Fi but there are differences.

Fi forks are 6mm shorter than Carb forks.
The Fi handlebars are 6mm shorter in the clamp area so the Fi forks can be mounted 6mm lower and put the axle in the same place.
The stanchions are different lengths between carb and Fi forks.
The fork lowers are different to account for the wider slide bushes.
Fi slide bushes are wider than carb ones.
Fi damper rods are aluminium - Carb damper rods are steel.
 

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To agree with deano:

You can swap a pair of forks for a pair of forks. Be mindful that carb forks are longer, and to locate the axle in the same place, they need to stick out further at the top. You should use the axle and spacers that correspond to your wheel, not the axle and spacers that might come with another set of forks unless they are physically identical.

The fender and brake calipers will mount in exactly the same way.
 

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Not to spam the forum with a new thread - but when people talk about 142mm air gap for EFI Birds, I presume this is calculated with forks assembled, springs in?
 

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I presume this is calculated with forks assembled, springs in?
If you follow the Honda WS manual then it is springs out ..... but of course so many of us have changed the springs (a lot use longer springs) so the air gap only applies to OE springs.
Different springs will displace a different amount of oil and so the assembled air gap will be different from the Honda intended one. The 142mm is a good guide but once you have changed something personal choice (and feeling) is more important.
Note the air gap only comes into play at the end of the piston stroke.
 
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I can't find any info on length of my current springs (10N/mm Hyperpro linears) compared to OEM ones.

Since the service will be done at the shop - what should I tell them to do then? Go by the book, 142mm?
 

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Looks like you are sorted -Tom- (y)
 

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Does 120mm gap sound like it might turn the fork overly stiff? Coming from 142 to 120, seems like a proper decrease. Plus the springs are stiff as is already.

I bought Motul's Fork Oil Expert 5W for this, around 18 cSt.
 

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Does 120mm gap sound like it might turn the fork overly stiff? Coming from 142 to 120, seems like a proper decrease. Plus the springs are stiff as is already.

I bought Motul's Fork Oil Expert 5W for this, around 18 cSt.
I run 110mm with my cartridges so 120 might or might not work for you.
As I said the air gap only comes into play at full compression so has no effect for 'normal' riding. The oil change will make the biggest difference and as you note the cst is the number you should be aware of.
You can see if the oil works with your springs and the standard damping by bouncing the front end in the workshop. The fork should rise relatively quickly and settle. If the oil is too thin the fork will bounce (spring too strong and the oil is passing through the damper too quickly).
 
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Hello all,
Since there is a discussion about forks, how much travel is there in the front forks before they bottom out?
Kind regards
Sam
 

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Full fork travel is 120mm. Of course there won't be that much travel available when you are riding because the bike weight and your weight will have already compressed them (sag).
 

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Thank you Leigh
I’m trying to figure out what to do with my front forks. A good while back my Honda dealer did a service on the bike and noticed a sweep in the front fork. So the did a service on both and changed the oil to wt15, as my weight was 95kg and I had mentioned the front end had jarred occasionally on trips. They had said the front end was soft and suited for a 77kg person. The oil change helped but still a lot of travelled was used up (zip tie on fork) and the rare impact. 12 months ago it decided to get some racetech 1.0mm linear springs to assist the oil with the weight which worked well. But I have now since lost some weight down to 82kg, and I am finding the front to be a little hard, as our NSW country roads are rubbish. Was thinking of changing the oil back to a 10wt. Zip tie seems to compress about 100mm.
Any suggestions?
Sam
 

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A diet of big macs will get that weight back on and solve the issue!. But probably not the approach you were planning. I'll let the fork gurus provide the right answer.
 

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No guru here, diet or otherwise. You still have a few ways to fine tune the forks....for very little money.

1. Measure front sag. Needs to be roughly 1/3 of travel or 40mm. Unfortunately, the blackbird forks are not adjustable so the preload can only be adjusted by changing the length of the spring extender sleeve.
2. Change the oil level or air gap in the forks. Less oil = more air gap = less effective spring action due to less air compression. In your case go with less oil.
3. Change oil viscosity. Need actual guru help for this one.


On a different bike with same forks, I used 1" diameter heavy wall PVC pipe as a spring spacer. 3+ years, no issues. Cheap and easy to cut.
 
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