the low slung 74

[slug]

new to the forum, decided to document my new 74 project.

Overview:
74 motor...supposed to run. Have an 80 motor that is ready for a 750 kit...
80 frame, cleaned up and stripped down. Keeping it raw.
19 mag front, 18 mag rear (xs400) or 19 spoked f & r using 2 front wheels...
78 650 forks, hammerhead rears, rebuilt discs f & r
early yamaha mx tank or possibly an xs400 tank...
2 seater...shaved down a stocker to get an idea
gonna mill me some triples outta chromoly and bend up some bars to weld to em
either make or buy some rearsets once I figure out the stance
an exhaust of some sort.

Would like to run internal throttle and cable to hydro front but everything I have seen is way expensive. If anybody has any suggestions on this feel free to post up.

That's as far as I have gotten. Doing this build as cheap as possible. Only have a few hundred into it thus far.

 

[jamesgs4]

that's a cool tank, looks like a good start. I like the way the dual 19's look.

 

[jedi_]

looks like a fun project. Keep us updated

 

[Tayno]

This sounds cool. Are you going to remove the centre stand tabs? Would make that line around the bottom of the frame real nice.

 

[jchrisk1]

Always wondered what an xs would look like with a dt tank on it. Now I know. I think I like it.

 

[slug]

Always wondered what an xs would look like with a dt tank on it. Now I know. I think I like it.

Yeah I was surprised how well it fit... sits really low which adds to the whole low slung approach. It's pretty narrow compared to the 400 or 650 tanks, but works well with the motor.

 

[Ghetto]

Wheels are nice.

 

[slug]

Not much progress but i did get my seat pan cut and shaped, along with the basic shape of the seat. The neoprene is actually really nice. Might just keep it low profile. Gonna stick with the 19/18 mag combo and the old mx tank.

My new 7/8 die showed up the other day. Other than that, just waiting for parts.

 

[jchrisk1]

Any progress? Curious to see how this will turn out. I'm really digging the tank.

 

[nafets]

Always wondered what an xs would look like with a dt tank on it. Now I know. I think I like it.

dt tank? What kind of tank is that? looks really great.

 

[jchrisk1]

They were on 70's Yamaha enduro's.

 

[nafets]

oh cool thanks! look forward to seeing how it comes along.

 

[jchrisk1]

Me too. But he hasn't been on here in almost 7 months.

 

[slug]

Back from the dead after nearly 3 years!

Life happened, which caused me to put the bike building on hold for the last couple years. I have been slowly collecting parts since and I am finally ready to resurrect this build.

Plans have changed and then changed again. Decided it would be best to do two seperate builds since I can't seem to pick a single build direction.

The Plan:

Bike #1 - Vintage race style. Fairing, monoshock / radian swingarm, R6 front end with clip-ons, modified XS400 tank, 18" wire wheels with cush drive rear, modern brembo brakes, maybe a 750 kit for my basket case 80 motor, who knows if I'll ever get this far...still collecting parts and will start a build thread at some point.

Bike #2 - Cheapo Tracker spare parts thing. 80 special frame, early 70's mx tank, R6 front end with moto bar risers, stock trussed swingarm with some NOS hammerheads I had laying around (junk), stock front 19" mag, XS400 18" rear cush drive mag, Brembo/SV650/XS650/YZ450 brakes, stock 74 motor with VM34's and some sort of exhaust.

Forks and brakes will be nearly identical on both bikes so I will be make duplicates of certain parts to make things easier on myself...for once.

What's done:
-Frame completely stripped and de tabbed, raw brushed finish so far.
-MX Tank fitted to frame with bungs welded.
-Made up a basic seat pan and shaped seat foam...thinking about chopping the rear frame / upper shock mounts for something different.
-Modified the stock pegs to fit some bates style pegs I had.
-Motor has been cleaned up an painted.
-Got the R6 front end fit on the 80 frame.
-Turned a pair of stepped spacers and center spacer to get the wheel to fit.
-Modified the top R6 clamp to fit moto bar risers.

Immediate To Do list:

-Machine a couple of rotor spacers to offset the 320mm rotor for the front.
-Make a hanger the brembo caliper to fit the R6 forks.
-Make a sprocket spacer for the rear XS400 hub to get the chain line right.
-Build a truss for the stock 650 swingarm.
-Figure out the rear brake setup...brembo?

 

[slug]

My progress from the last week:

-Made up a sprocket spacer for the 320mm brembo. Plenty of clearance for the caliper now.
-Made some bars over the weekend.
-Also took a shot of the stepped spacers for the front wheel.

 

[slug]

Little update:

Decided to tackle the front caliper hanger today. Used some delrin stock to make the mockup. Took me a few hours but I pretty much nailed it the first go around. I will use this to build the hanger in CAD and have them cut on the CNC at work. I plan to use this identical combo for my other 650 build to make things easier.

Also started looking into the rear brake setup. My choices are: little gold brembo (only have one and planned on using it on the racer replica build), stock XS caliper and hanger (massive paperweight), funky upside-down SV650 caliper, or the little YZ450 caliper which is integrated with the hanger and would be a pain in the ass to make work. I think I'm gonna break down and buy another gold brembo so I only have to design the hanger once which I will use on both bikes.

 

[slug]

Made a little progress over the last week.

I got the sprocket carrier finished up...at least until my new sprocket shows up.

Made a mockup of the rear caliper hanger and will be finalizing the CAD model today.

Sent my buddy CAD files for the front caliper bracket and rotor spacer so hopefully I will have some fresh cut parts by the end of the week.

Started playing around with the rear master placement, hopefully have that figured out this week.

Also pulled the bike out for a couple quick shots. Happy this thing is actually a roller now...no zip ties or duct tape holding it together. Pushed it down the street a few times and the suspension feels really solid. Don't think I'll ever run sub 43mm forks on any bike again.