Topic: Manufacturers cup

[Bill/BentON Racing]

Scottly, you'd be correct young man! Actually 575-590 max.

[scottly]

Who are you calling young man? Nobody here that matches that description.
Didn't you mention somewhere that you only shifted into 5th at the finish line? If so, consider a lower gear ratio, so you can use all of the gears to keep the motor in the fat part of the power band.

[dragracer]

Hey Wilbur, have you been making any progress with changes to your bike?? Do you have everything you need?? Not sure I can help but let me know- I do have a few  laying around. I think Bill is good to go on both his bikes. I'm trying to make time to work on my carbs. They've been sitting on the work bench for 3 weeks now and I haven't touched them. Hoping I can mess with it on Monday while I'm off .

[Bill/BentON Racing]

Good to go on CG except wiring up shift minder,  Purple Rain needs 18 inch front wheel and carbs mounted and airshifter and shift minder. Working on it this evening. Yeh Wilbur,  you need anything? , Bill

[madmtnmotors]

Hey Wilbur, have you been making any progress with changes to your bike?? Do you have everything you need??

Yeh Wilbur,  you need anything? , Bill

I'm spouting Bill's mantra... "I need more time!" 

Did manage to button up the fuel system and the rear cargo bay floor of the tow vehicle:










Still don't know what was leaking. The electrical fitting that passes through the sending unit top plate would leak if I turned the tank upside down. Put a new o-ring at that location, a new o-ring under the sending unit top plate, and now when the tank is turned upside down there is no leaks or weeps whatsoever. Just have to keep an eye on it I guess. 

Started ripping the front end apart yesterday to add lowering bushings, drag bars, rev limiter, 1/4 turn throttle, and maybe a shift light. If necessary chores would quit rearing their ugly head I might try to get the longer swingarm in place as well.   

Two short weeks to go! 

[dragracer]

Great start Wilbur. The lower front end and drag bars will help immensely.

[scottly]

How do the "lowering bushings" work? Do they slip over the damper rods?

[madmtnmotors]

How do the "lowering bushings" work? Do they slip over the damper rods?

Yep. Lowriders by Summers offers 2" lowering spacers for $10 pair (scroll down to the bottom):

http://www.lowridersbysummers.com/parts/index.htm

Picture from his page:



I opted for bronze bushings 1-1/2" in length. These prevent the fork lower from extending fully by an amount equal to the length of the bushing. 1" O.D. and 3/4" I.D. works perfectly. By ignoring Tommy's advice to "cut the springs" I was able to add 1-1/2" of preload to the springs too. Had to get a little creative to install the fork caps with an inch and a half of spring extended beyond the top of the tube, but I "got er done" this evening and the front forks are now effectively an inch and a half shorter with an inch and a half of preload. The hairiest part was when I got the first cap started and realized I had not added fork oil back into the tube! Dammit! Had to remove the first cap to add oil, and managed to do so without putting an eye out!   

I'll need to tag the fork caps somehow to indicate the preloaded condition of the spring inside. 

Actually, the method I finally settled on for installing the fork caps provided a great deal of control and I was able to get the caps started by hand before even putting a wrench to them. Now on to the rest of the list! 

[scottly]

By ignoring Tommy's advice to "cut the springs" I was able to add 1-1/2" of preload to the springs too.

I'm not sure if that much preload is a good thing?

[Retro Rocket]

By ignoring Tommy's advice to "cut the springs" I was able to add 1-1/2" of preload to the springs too.

I'm not sure if that much preload is a good thing?

Should be fine on the drag strip....

[scottly]

It might be OK at the tree, but at 100+ mph at the end of the strip, a locked-up front suspension might not be a good thing, especially if the track is less smooth than a pool table, IMHO.

[754]

If a bike cant hit a hundred in saftey. With a short stiff fork.. The rails would be in huge trouble at 200-300 mph...

[Retro Rocket]

The cerriani's in the old drag bike I had were stiff as a board...

[scottly]

If a bike cant hit a hundred in saftey. With a short stiff fork.. The rails would be in huge trouble at 200-300 mph...

The flexy frame of a rail IS the suspension.  

[754]

If you dont set it up stiff, your reaction time suffers..
 Stiff suspension , very common ..

[dragracer]

The stiffer the better but not to the point of being rigid. It helps keep the forks from extending on launch also to assist with proper weight transfer to the rear shock. You want to plant the tire without shocking up but don't want to yank the front end up either. That's where good adjustable shocks come in to play for rebound and dampening. Dual shocks don't allow a lot of tunability unless you buy high dollar ones. That's one reason I'm trying to build a mono shock bike. The choice of shock is way better, even stock shocks outperform aftermarket dual shocks, IMHO. Wilbur is going to feel an immediate difference in  the feel of his launch that will enhance his starting line performance greatly. One less thing to cause distractions.

[madmtnmotors]

What I've done is no different than strapping down the front end...

without the straps.

This setup would not be my first choice for a bike that spends much time on the street.

[bwaller]

The spacers just limit travel, you could always get shorter springs if it's crazy stiff.

[madmtnmotors]

The spacers just limit travel, you could always get shorter springs if it's crazy stiff.

Or cut off one coil at a time until it was where you wanted it. To cut the springs to match the spacer would lead to a tendency to bottom out since the spring would be returned to near stock compression rate but travel has been reduced by the length of the spacer.

[scottly]

To cut the springs to match the spacer would lead to a tendency to bottom out since the spring would be returned to near stock compression rate but travel has been reduced by the length of the spacer.

When you shorten a spring by cutting off coils, it increases the spring rate.

[754]

Strapping down is worse. But it makes a huge difference.
What you are trying to do is move the bike forward, not up..
My R100RT was a fun bike to race, but terrible reaction times. The crowd lved the front end coming up ff the line, into second, and third.... But without good reaction times, hard to win a race..

[bwaller]

To cut the springs to match the spacer would lead to a tendency to bottom out since the spring would be returned to near stock compression rate but travel has been reduced by the length of the spacer.

When you shorten a spring by cutting off coils, it increases the spring rate.

Right on above, you'd need shorter springs. I have a set of RaceTech springs that are shorter to allow preload spacers. Something like that is what you need.

[madmtnmotors]

To cut the springs to match the spacer would lead to a tendency to bottom out since the spring would be returned to near stock compression rate but travel has been reduced by the length of the spacer.

When you shorten a spring by cutting off coils, it increases the spring rate.

Sorry I brought it up. I have no intention of cutting coils so the point for me is moot. If I were setting up a road racer then that would be a different story...

Strapping down is worse. But it makes a huge difference.

The strap itself seems to me to be the weakest link, besides looking hawky. I can't imagine how snapping strap(s) would affect handling...

Not to mention a recent bad experience with a strap:

[dragracer]

Wilbur, what's your status regarding the hurricane. Anyone hear from Larry?

[madmtnmotors]

Wilbur, what's your status regarding the hurricane. Anyone hear from Larry?

Just a bunch of rain. The yard has exceeded saturation:





Good excuse to work from the house today!