6MM Spacer Under Rear Shock

After a number of trackdays and the chance to compare the Storm to a well setup R1 the main problem I had was getting the bike to turn quickly and hold a tight line. All of this is due to the conservative geometry. Because ground clearance was an issue I decided to raise the back of the bike by installing a 6mm thick space under the rear shock top mounting if any of you are thinking of making the modification here is a diagram for the spacer.

Result

Much quicker turn in and the bikes line can be tightened easily on fast sweeping corners.

Stan Stevens ported cylinder heads

Stan Stevens is well known in the UK for his two stroke tuning work but over recent years he has broadened his expertise to the Four stroke engine market. The official Honda UK VTR1000 race bike is tuned by Stan Stevens and they managed to get 145 BHP from the engine so he knows his stuff. The VTR1000 runs out of steam at the top of the rev range and my hope was to have more power at the top end without sacrificing the awesome midrange stomp which makes the bike so easy to ride. Another requirement was reliability I do about six to eight thousand miles per year and a number of those miles were in Germany. The heads were ported to the same standard as the race bike and then the standard cams dialed in to make best use of the extra port volume.

Dynojet Kit and K&N Filter

Obviously going to the expense of having the cylinder heads ported would all be wasted if the carburation wasn't setup to suit so Stan fitted a Dynojet kit and new K&N Filter.

Yoshimura Full Race Exhaust System

Getting all of the extra fuel back out of the engine is the next priority and I chose the Yosimura because I could get one at a really good price. It's definitely loud German Police don't like it but it does help make more power and saves around 7 Kilos in weight over the standard system.

Performance graphs

click for larger image

WP Proline spring installation and fork oil change

The front forks on the VTR1000 are lightly sprung for maximum comfort and overdamped to control wheel movement. In order to achieve the correct level of rebound damping on my Firestorm the front the adjustment needed to be set to minimum. Also the compression damping can go solid under hard braking as I found out to my cost while trying to avoid rear ending a CBR600.

Trevor Franklin Performance Bikes July 1997

With the brakes full on, the forks dived and locked solid. On the worn, rippled road surface the front tyre bounced along as the wheel momentarily locked-up every time it skipped off small rises.....

.....Ron Williams: 'VTR1000? We've just done one, last week. It's all to do with compression damping, it just goes violent. Push down on the forks stationary and it doesn't feel that bad. But on the brakes the cartridge compresses and the one-way valve inside completely shuts off to make the forks go absolutely solid'.

The fork internals are similar to those fitted to the CBR600 which runs 5wt oil as standard. As the rebound and compression damping are both too harsh I decided to experiment with oil weights and air gaps.

These are the changes I tried

• Change Oil for 5wt with standard air gap.
• Wind in preload to set static sag to 30 mm (the lowest I could achieve)
• Set front rebound so that as you bounce on the forks with the brake on they rebound once and then settle. (Easier to demonstrate than explain)
• The fork action under heavy braking was progressive without any sign of lockup but I could get the forks to bottom out quite easily.
• Reduce air gap in 10mm increments.
• Progressively reducing the air gap bought improvements to fork travel under braking but still the chance of bottoming the forks until the air gap was 120mm then the fork action was harsh at the end of its travel although the forks didn't bottom out.
• Change Oil for 7.5wt with standard air gap.
• The fork action under heavy braking was harsher and I could just get the forks to bottom out.
• Reduce air gap in 10 mm increments.
• Progressively reducing the air gap didn't improve feel under braking when the air gap was 120mm then the forks would again go solid under hard braking
• Install WP fork springs
• Change Oil for 5wt with standard air gap.
• Wind in preload and set static sag to an ideal 25mm.
• The fork action under heavy braking was much more progressive without any sign of lockup and I couldn't get the forks to bottom out my ziptie on the fork leg showed that I was pretty close though.
• reduce air gap in 10mm increments. Progressively reducing the air gap bought improvements to fork travel under braking I stopped adding oil at 130mm as I knew that any less gap caused a problem I was now using about 85% to 90% of travel.

Final Configuration

WP fork springs (these are progressively wound springs and their Length is 25mm longer than standard),Preload wound in 1 line, Rebound 1/2 turn harder than standard.

Result

This configuration has been excellent for most tracks but at Cadwell park I had to increase the rebound by another 1/2 turn because of chattering through two of the bends. Increasing compression damping would have been a better solution but that will have to wait for the Fireblade forks.

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