New build, straight line speed attempt...

Started a new build, wanting to go faster with the modified motor I did a while ago. This is going to be a bit of an experiment in many ways. I'm really rusty at welding, but doing better after more than 40 years of none at all. I finally got the shop set up well enough to do this one, after a few months in the new place in northern New Mexico. We moved from Tucson to Raton in the last year. Here's the shop now, wood on one side & metal on the other. Nice to have room again for work.
Grinders.jpg Metal.jpg
OK, enough background, here's the build so far. I'm in a small town, so there's a lot of shipping of parts involved. The brake hub & disc arrived, but there was a slight mismatch on the hole sizes & locations. The hub is an American standard size, but the disc was made to metric specs. Used the drill press to correct a .05" offset & stretch the holes back into shape. It's going to be a 1" live axle build. All's well that ends well. HubDisc.jpg
Next is the front end. I just have some 7/8" DOM tube & 1/8" plate for the steering setup, so that's what I used. Have to make all parts with an angle grinder, drill press & other basic metal tools, but no real stuff like a mill. It takes longer, but in the end the parts are good enough to work. I spent most of my time as a wood worker, so the metal shaping is still a little strange for me. It's the same skill set, just a different material. Here's the front end so far. Waiting on parts to arrive, as usual.

Using a 10" steel rim & "S" rated Michelin tire from a scooter. Hopefully it will hold up to the higher speeds I'm going to be working with on the runs. Using about a 4" trail for the steering geometry (1 1/2" offset for the TTT). A damper is planned, but it's not here yet, so I'm holding off on assembly. Man, I'm really rusty at welding... TTT-2.jpg TTT-3.jpg
Last post for today, the tires are mounted & I'm ordering a new wider axle for the back end. I had figured on the 1" X 14" axle kit, but once the slick was in place, the rotor was set on the shaft & a few measurements were taken I ran out of room for the sprocket (Hmmm). Decided to go with the extra length of a 16" axle, so that's on the way now. With that tire profile it's going to need more HP to use the contact patch. Chasing my own tail on this one.

The current motor is a HF 212 hemi. That was an older build, but basically it's the stock block, Bullfrog 11:1 piston, Black Mamba cam, Mikuni VM22-133, header, mild porting, billet rod & flywheel. It wakes up on the top end & pulls really hard. I need to look at hooking it up a bit better, trying to figure on a torque converter or maybe a better clutch. Since I'm building for top end, gearing will be an issue sooner or later. For now it's on the back burner & simmering. Here's the setup so far. TiresMounted.jpg
Thanks for all the details.

I love the way those raised white letter Hoosier slicks look.

Takes me back to the 70's...deep dish mags, and wide raised white letter tires...!
Maybe I have my head up my backside, but it looks like you're building a drag bike.
Your thread title said "straight line speed attempt". That would be more on the order of a salt flats built, and that big slick on the back isn't really what you would need for what the title says.

Just my thoughts.....Roger


Active Member
Yea, I 'am real curious also, on what ''straight line speed attempt'' means,, with this project ……
Definitely the wrong rear tire for the Salt flats, or for paved ''long stretch'' running ………..
Edit for the post about the front tire, it's only an "L" rated tire. I was looking for a higher rating, but had to settle on the lower rating for the one I found. My bad for the brain-fart typo. 75 mph is the best rating I could find for a 10" rim.

As far as the "straight line speed" title, it's what I want to build, my "rules" (there aren't any), my ideas & my best effort for the bike. Bonneville isn't allowing mini bikes to run on the salt, due to all of tech inspection stuff. I guess it's possible, but tires are just one problem. I watched one of the tech inspectors tell a bike rider that he needs working brakes on the front end, but to always keep off of them on a run, "Never use the front brake" was what he said. The surface is just too slippery & a front brake on the salt is a big no-no on a bike. The Texas mile is similar with their tech stuff, so this is just a fun build for me. That being said, the salt really is sticky on a bike, PITA to clean up afterward...


Bonneville isn't allowing mini bikes to run on the salt, due to all of tech inspection stuff.
I too have heard that from people who crew annually in some of the other events. However in 2018, they ran mopeds, and Cushmans. Brake requirements vary by chassis class. Entries vary by engine displacement, construction, fuel, and chassis classes within them vary by several construction restraints as well.

When addressing Bonneville Land Speed Record competition, the AMA says, This AMA-sanctioned event, which also includes Fédération Internationale de Motocylisme recognition, offers competitors the opportunity to clinch AMA national and FIM world records aboard machines from 50cc mini-bikes to 3,000cc.

Here are last year's rules and results. Various promoters are going to have their rules, but I don't see where mini bikes are precluded as a whole.

We realize now that you were talking about a personal project of your own design, but I thought I'd chime in with the current status of mini bikes and LSR competition, since it was brought up in your build thread. Welcome back, after your move!
The image is of one of Japan's factory team riders. We were both in the pits looking at the bike (50 year celebration of the record run, Indian put on a good show of the movie in the bend camp ground). He didn't speak a lot of English, but asked me if it was OK to touch the bike. I asked one of the crew if it was OK & the reply was "Does he want to sit on the bike?" He lit up like a little kid when he understood the offer & then sat into a crouch on the seat. I got the picture, but missed the good shot. When he sat back up, he bowed to the bike, sorry to have missed that one. Bonneville is like that, lots of good people from all walks of life sharing a love of speed. 20170811_202828.jpg