[speedrattle]

lol

i use silicone

 

[GrandPaulZ]

Alright alright! (as Matthew McConaughey might say) My ZRX is approved to run NexGen 3!

So, we'll have VF750F in NexGen 1, Ducati Fogg in NexGen 2, and ZRX in NegGen 3. The good thing about THIS is, ALL THREE can run in Formula Thunder, too! So, we can be on track together for TWO races each day.

This is going to be EXCELLENT!!!

 

[TBS]

nothing other people cant do. its a 1970 T120, with freash aerco 649cc barrels and a 1974? 9-1/2 bolt head.

crank is billet steel by RoDy Machining, pistons are JE 11.75 to 1, cut by ed valiket.

the head has oversize intakes and exhausts and was ported by rob hall. twin plugs.

kibblewhite pushrods and tappet blocks. stock rocker box assemblies, mushroom adjusters and aluminum nuts.

primary is a 40mm bob newby belt. no alternator. 36/68.

right now final drive is 21/39 but i have 38 and 37 too.

ignition is an old ARD, running split diode plug wires. all four plugs spark together every 360. fixed advance at 30btdc. plugs are NGKB9ES. cannot for the life of me remember the 10mm ones in the center.

completely stock gearbox. took off the kickstart fir clearance, so i use a remote hand held starter off the crank nose.

carbs are 35 mm FCRs.

cam timing is 106/109 lobe centers. open pipes are 1-5/ x 34 inches.

mostly what ive done is tried to come up with a motor that will live at 7250 rpm or better, and then just adjust everything so it all works together. nothing ive done requires secret knowledge. id never built s race motor before so ive just tried to use common sense and lots of testing.

testing is the key unless youre a natural like truckedup who does it by instinct and gets it right first time. which annoys me

i forgot- megacycle 510-X2 cams, 008 and 010 lash. plus everything in the motor has been meticulously cleaned inspected, and any issues corrected before assembly.

Thanks for that most interesting. I expect the main power comes from the porting in the head. Love the video great stuff.. my flywheel let go at 7k and now I'm left with a head, clutch and gearbox!!. Billet steel is the obvious way to go!!

 

[GrandPaulZ]

nothing other people cant do... nothing ive done requires secret knowledge. id never built s race motor before so ive just tried to use common sense and lots of testing... plus everything in the motor has been meticulously cleaned inspected, and any issues corrected before assembly.

Here, here.

Same with my bike, but in AHRMA Historic Production classes, the engines are supposed to be "stock" with only allowable upgrades being electronic ignition, and overbore to .020", both of which are the ONLY modifications done to my bike.

If you have ever thought about, or dreamed about, racing, THIS is the way to go. The only thing ADDED to a bone-stock bike is number plates and lockwiring (safety wiring). Possibly the lowest-cost way to go racing that can be done.

I have heard plenty of talk about people building "sleeper" engines, but that gets my goat. There is a class for that, it's called Sportsman.

In Historic Production, it SHOULD be all about beginner riders honing their basic racing skills. In my case, I've never stepped up because my bike isn't capable of much more than I've been able to do, not in my hands anyway. I'm not one of those "natural talents". Nevertheless, I've had more fun that you can imagine.

So, get out your classic Triumph 500/650/750, pull off the lights, lockwire all the oil connection fasteners and fuel lines, bowl screws, drain plug, etc, slap on some cheap number plates and GO RACE!

Think about it-

DAYTONA!!! (already passed)
Roebling Road Raceway, Bloomingdale, GA
Carolina Motorsports Park, Kershaw, SC
High Plains Raceway, Deer Trail, CO
Thunderhill Raceway, Willows, CA
Hearland, Topeka, KS
NJ Motorsports Park, Millville, NJ
WEATHERTECH / LAGUNA SECA!!!
Ridge Motorsports, Shelton, WA
Blackhawk Farms, So.Beloit, IL
Gingerman Raceway, South Haven, MI
Talladega Grand Prix, Munford, AL
BARBER'S VINTAGE FESTIVAL!!!

Since when do "nobodys" on old clunker bikes get to go to Daytona, Laguna Seca & Barber's? Since AHRMA! (ONE footnote - you must run TWO prior race weekends to qualify to run at Barber's).

Most of these tracks have a track day on the Thursday of the weekend, and almost all (except the big 3 and Heartland) have racing school on Fridays. Go to School on Friday, you're on the track on Saturday! Only one racing school is required, and you're good for as long as you keep your license active.

www.ahrma.org

 

[speedrattle]

Thanks for that most interesting. I expect the main power comes from the porting in the head. Love the video great stuff.. my flywheel let go at 7k and now I'm left with a head, clutch and gearbox!!. Billet steel is the obvious way to go!!

the crank is good to 8 and has seen 9 once. i threw a rod two years ago, ground the crank and im still running it.

even after you choose parts that you think will work together, you have to tune it. there is no substitute. tony tunes his stuff on a dyno, and i just go tune at a local airstrip and at the races. it matters. ive tested pipe lengths of 32, 34, 36, 38, and 40 inches. 34 is best-- i lose 4 mph at 32 and 36. theres no way to know unless you test. carburation, ignition, and cam timing are the same.

plus figuring out how to sit on the bike. above 100 mph 90 percent or so of your horsepower is fighting the wind. any weird way you can sit that makes you small is worth it.

 

[Hooli744]

Great time to revive this thread!

It looks like if things go according to plan, I'll be on the track at Heartland Topeka, KS on the weekend of May 27-29.

My Bonnie...
View attachment 774166

Stupid question time, what on earth is that under the frame? looks like it makes the bike landmine proof!

 

[GrandPaulZ]

Stupid question time, what on earth is that under the frame? looks like it makes the bike landmine proof!

Wal Mart / Betty Crocker $3.95 cake pan oil catch (oil containment required under the rules, flexible as to design, and this was easiest).

 

[GrandPaulZ]

Well, it's over before it started.

I sold my 4-acre place with shop/garage, and I'm buying 10 acres and building a new barndo. So, time and money for racing is GONE.

Another contributing factor is my son Kevin who is stationed in Kansas was going to race with me at Topeka, but he got injured snow skiing; so that's out.

Hope y'all that get into it, HAVE FUN!

 

[StuartMac]

Hi Paul,

son Kevin
injured snow skiing

Not serious I hope? 🙏

Regards,

 

[GrandPaulZ]

Not serious I hope?

No, but he spent his play money and can't risk aggravating the injury with non-military activities like motorcycle racing.