1/4 mile racing advice

[beetz]

Planning to race my blown valk this weekend here on Kauai. I'll have new tires (shinko se890 journey) with a 200/55/16 on the rear, stock size on front.
- recommended tire pressures?
-recommended launch RPM?
Any oil in particular to use for final drive?

How about ideal water/oil temperature to race at? I have water temp and oil temp gauge with dual spal fans. One fan comes on all the time and the 2nd one is supposed to kick on when hot. I see water temp of 195 and oil temp a little less when in traffic. 2nd fan has not come on yet.

Is there a warm up or cool down procedure for the blower?

I've heard traction may be an issue, so any advice on race tactics would be appreciated. I've drag raced for a few years but usually sport bikes. Thanks in advance

[Tazman11]

I have no experience racing motorcycles but for cars I do decrease the tire pressure a bit. I hold the tach to 5000 and drop the clutch when the light changes to green. Obviously you will need to adjust so you don’t pop a wheelie. If it were me I would start slowly and develop a technique that works . I would start like I would for a fast start at a street light. Build your results over time. Unless I had money or pink slips  on the results learning over time would be most prudent. You will probably break 12 seconds and 110 mph without to hard. Try to be faster each run. I’m sure there are some YouTube videos that would help you.

[Jess from VA]

Yaz's advice is sound, working up in a scientific (and skill level) method will produce a more harmonious result.  (Though I have no idea what the charge is each time you go down the track.)

I personally would try to do a few launches away from the track, lest my first experience at the track be a source of great amusement to the spectators (and unhappiness for me).  Although no doubt illegal.  

I'd also be running a car tire.  It's not hard to spin a 180 bike tire.  Esp with a hot track.  Straight down a drag strip, there is no downside to a car tire at all, and a heck of a better contact patch (and stability).  

One of my two interstates (with trunk removed) used to have a dual bottle nitrous wet shot rigged to it and was run at the track.  The owner told me he did it twice and then never again (scared him).  He was an older gentleman.  The nitrous was removed before I bought it, as illegal in my state.

I can get in all kinds of trouble without nitrous.  

[da prez]

 It has been at least 50 years since I drag raced a bike on a track.  Practice runs are a must. Wheel spin and hook up are a practiced knowledge. If tire hooks up to soon , you do not have the take off. To much wheel spin and you are all show and no go. Practice makes perfect. I predict the 9 second with 120 mph.
 Best of luck and report to the board.

                                                     da prez

[mello dude]

Do a video went you run it?

[steveB (VRCC UK)]

2 clutch diaphragm springs ?

[Bagger John - #3785]

It's not hard to spin a 180 bike tire.  Esp with a hot track.

I tuned my first I/S (heavier rear end than a Standard or Tourer) and even though normally aspirated it would gladly light the tire up under certain conditions.

A 200 series motorcycle or car tire is definitely called for here, though a Valkyrie isn't my first choice for a drag bike.

[Jess from VA]

a Valkyrie isn't my first choice for a drag bike.

It beats a 150 Dream.  

[RDAbull]

Having done quite a bit of drag and dirt track racing in my youth, my best advice is:  Don't!!!

It gets very expensive and is damed hard on equipment.

[dago mooserider]

I’ve raced my valk in 1/8th mile a few times. Even on a sticky track, traction is an issue with my 200 metz rear tire. I bought another rear wheel and mounted a 205/55 toyo proxes r888 and  when running that tire it hooks much better and will lift the front on take off. Getting the right amount of throttle and clutch is difficult. With traction, You should be able to bust an 11-something possibly even a high 10. I think my attic rat prepped engine would get me around a 12 flat (7.65 1/8th). You will definitely have to drop some air in the rear probably down around 25 or so and make sure you let her cool down between runs. When I hot lapped mine each subsequent run was a tenth slower. Have fun and good luck

[Bagger John - #3785]

Having done quite a bit of drag and dirt track racing in my youth, my best advice is:  Don't!!!

It gets very expensive and is damed hard on equipment.

If Valkyrie driveline parts dry up, no one's going to be racing these bikes much. Or they will until something breaks. At which time, the machine is relegated to the scrappers.

Belt or shaft final drives really aren't where it's at in regards to drag-strip campaigning. Chain only, for a number of reasons. Likewise, the proper camshaft drive mechanisms factor into a campaignable/sustainable motor vs. a potential hand grenade.

[beetz]

Thank you all so much for the replies.

I got the new tires put on today, new fork seals, front brake pads + new fluid, rear brake fluid and clutch fluid.  The master cylinders were all gummed up badly.  Disgusting.  Previous owner rode the bike 3k miles in 10 years. Never touched the brake/clutch fluid.  He mentioned it slipped in 3rd gear under heavy load.

I rode it about 50 miles today (pretty far on this island) and its slipping in 4th and 5th gear under load.  It is perfectly fine under normal riding.  Even flat out in 3rd gear its fine.  This is a blown valk, and the previous owner thought the extra power was causing the clutch to slip.  Can the stock clutch handle the blower? He included a set of barnett friction plates, steel plates, and diaphragm spring.  Can't drag race it until I take care of this slipping issue.

[h13man]

I would use and engine oil additive to clean the clutch plates and a 20% mixture of tranny fluid would be my go to for this and run it 100mi. then change.

[Chrisj CMA]

Thank you all so much for the replies.

I got the new tires put on today, new fork seals, front brake pads + new fluid, rear brake fluid and clutch fluid.  The master cylinders were all gummed up badly.  Disgusting.  Previous owner rode the bike 3k miles in 10 years. Never touched the brake/clutch fluid.  He mentioned it slipped in 3rd gear under heavy load.

I rode it about 50 miles today (pretty far on this island) and its slipping in 4th and 5th gear under load.  It is perfectly fine under normal riding.  Even flat out in 3rd gear its fine.  This is a blown valk, and the previous owner thought the extra power was causing the clutch to slip.  Can the stock clutch handle the blower? He included a set of barnett friction plates, steel plates, and diaphragm spring.  Can't drag race it until I take care of this slipping issue.

Most slipping clutch issues I have seen were due to improper engine oil. If it says “energy conserving” in the specs ring  that will be the problem