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Discussion Starter #1
While my bike was down awaiting parts and repairs - I Rode my son's VN750 (he was at school during the week) The first thing that I noticed was that His fork would dive with even moderate front brake pressure can I adjust it to take out some of the dive and bounce?
 

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Change the fork oil. And swap in new Progressive springs for the very soft stock ones that may be dead (depending on how old this bike is).

Because of the little holding clip ring it's best done as a two-man job, unless you want to risk the clip ring flying away like a Jesus pin.
 

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Discussion Starter #4
so the fork is not adjustable ie. air it up between fork oil changes?

I wasn't sure if it worked like a bicycle fork or not
 

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so the fork is not adjustable ie. air it up between fork oil changes?

I wasn't sure if it worked like a bicycle fork or not
Think I read a post by lance that the first model year or two had air adjustable front forks. But I've been wrong before! :confused:
 

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Think I read a post by lance that the first model year or two had air adjustable front forks. But I've been wrong before! :confused:
You are right, for the first year or two there was an airvalve in the front fork tubes.

Edit: 1985 to 88 models had an air valve.
 

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Just my 2cents.

If your bike has air valves in the forks and you want to add air pressure to them, use a bicycle pump. Anything stronger can quickly blow the seals.

Using thicker oil in the forks is a horrible idea in IMO. What that will do is increase the resistance to diving and also increase the resistance to going back to the normal riding position. So imagine riding over a series of bumps on rough pavement. As you hit the bumps you would force more (thicker) oil through the tiny oil passages in your forks, but the normal pressure for the oil to move back inside the forks to the normal riding position would have a hard time doing it with thicker oil. As you hit a series of bumps the forks would compress and compress and compress. The lower they get the worse the ride over those bumps would be until the forks had a chance to eventually spring back to the normal ride height.

My suggestion would be to invest in some new Progressive Suspension fork springs and drain and replace the fork oil with the proper weight of fork oil as per the factory specs.

-Sloppy
 

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I agree with sloppy...you need new springs not just heavier oil.

I would first drain the forks as it is possible you do not have any oil in them and that is the problem...

But stiffer springs, or at least adding some more preload would be better than just using thicker oil.

KM
 

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Thanks - We will give it a shot - how do you know if the old springs need replacing?
When the " fork would dive with even moderate front brake pressure " ...or the forks seem a bit to easy to compress just holding the brake and pushing down.

Fork springs, and shocks tend to get mushy over time. The stock springs were pretty soft to begin with, so just a bit of wear and they pretty much are toast. The rear shocks however are a bit too harsh, and don't have enough rebound or compression dampening. Most riders that are over 185 lbs don't seem to be as offended by them, and because they also take air one can live with them a bit easier.

But the front forks, even the ones with the air fitting, (which does not really do that much) are kinda weak for any rider. And really seem soft if you add a large windscreen or fairing.

The progressive springs are one of the better bang for the buck improvements you can make , I strongly suggest them to all Vulcan riders.

KM
 

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You are right, for the first year or two there was an airvalve IN the front fork tubes.
OldHose....

Mine is an '86, I guess that means it has the Air Valve....
Where is it? and what does it look like? IN the front fork?
I've ordered the 11" rear shocks, but the front lowering springs were on back order...now I cant decide if I should just try to fix my soft and spongy front or reorder the new springs...any suggestions? From reading here, it sounds like I will need to get the new lowering springs to keep my steering quick for gravel and twisties. I know I'll compromise my cornering clearance some, but I dont "hotrod" the curves.....I just want an improvement over my VTX1300, it is real low and drags floorboards a LOT....

Thanks, Grits
 

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I have never worked on mc forks, but from the diagram in the Clymer manual, I surmise that the air valves on the bikes that have them, are just under the top caps. I suppose it looks much like a tire air valve.

You have had a couple of low cost ideas given for ways to improve the action of the forks even without the lowering or progressive springs, ie. drain and change the fork oil, and put in a longer spacer at the top for more preload on the springs. To make it ride a little lower on the front, loosen your pinch bolts on the fork clamps, and let the clamps slide down an inch on the tubes, then torque it back to spec.

If it still doesn`t ride to your liking, then you can decide on the lowering or progressive springs.
 
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