Down under, an idiot and a 400F

[redwillissuperman]

Can you please take some photos of the CNC part that mounts in front of the rear set. What is its purpose?

 

[andycafe]

8)

 

[neevo]

looking real good, what colour anodising are you going to do?

I'm currently thinking just silver. If there is one with a hint of gold in it (more silver than the forks), I might plum for that. But at the moment probably just silver.

 

[neevo]

Can you please take some photos of the CNC part that mounts in front of the rear set. What is its purpose?

It's the outer plate for the rear brake arm. It has an internal part that the brake rod attaches too and then the brake pedal rotates this.

They are from TTR400.

 

[redwillissuperman]

Thanks. Would it be possible to take dimensions from the motor mount hole to the brake pivot (x,y) and the depth of the boss for the motor mount bolt (spacing from frame)?

I'm building some mid-mounts for a CB dirt bike project and this is almost exactly what I had planned.

 

[neevo]

So I have been costing up the motor parts from David Silver in the US as I thought it might be cheaper than the UK in the end by the time it all got delivered. Turns out my approach to replacing all the bearings and seals with genuine is not the cheapest option by a long run. Here is the current list of parts:

Description Colour QTY
Crank 1 Left (bottom 0.038mm, top 0.038mm) Green (C) 2
Crank 2 (bottom 0.05mm, top 0.038mm) Green (C) 2
Crank 3 (bottom 0.05mm, top 0.038mm) Green (C) 2
Crank 4 (bottom 0.076mm, top 0.05mm) Brown (B) 2
Crank 5 Right (bottom 0.05mm, top 0.076mm) Brown (B) 2
Big End 1 Left (D 0.038mm clearance) Yellow (D) 2
Big End 2 (D 0.038mm clearance) Yellow (D) 2
Big End 3 (D 0.038mm clearance) Yellow (D) 2
Big End 4 Right (C 0.038mm clearance) Green (C) 2
Valve Stem Oil Seal 8
Cam Chain Blade 1
Cam Chain Tensioner Blade 1
Primary Chain 1
Tachometer Seal 1
Breather Cover Gasket 1
Clutch Cover Gasket 1
Crankshaft Oil Seal (Left) 1
Crankshaft Oil Seal (Right) 1
Cylinder Barrel Oil Control Valve Gasket 2
Base Gasket 1
Cylinder Head Cover Gasket 1
Final Drive Sprocket Seal 1
Gear Change Seal 1
Generator Cover Gasket 1
Afterarket Carb Boots 1
Carb Boot Inlet Manifold Oring 4
Kickstart Seal 1
Oil Pan Gasket 1

Gaskets, bearings, new cam chain parts and primary chain, plus some aftermarket carb boots: $970

That's a bit more coin than I have at the moment so I'm going to have to wait to push the button until I have the cash together, so a few more weeks to wait until I can put the motor back together. Provides me some time to triple check the big end/crank bearings again and make sure I'm ordering the correct ones.

 

[neevo]

Also finished up the SS rear upper engine bolt. I trimmed the excess length off the rod on the drop saw them set to threading it on the lathe. What a massive pain that was. Must be that the drop saw work hardened the shit out of the rod and threading it was a major pain in the arse!

In the end I didn't get much thread on the end, certainly not enough for the amount I needed, plus it was not 100% straight so I thought I would flip it and extend the thread on the other end instead which worked out fine.

The slight angle on the bolt from the dodgy thread can be fixed when I weld the nut on anyway so it's all turned out fine.

Obligatory picture:

 

[DohcBikes]

What's your current trail measurement? Looks to be a very small number.

The rear brake setup looks over complicated. Maybe i'm missing something.

 

[neevo]

What's your current trail measurement? Looks to be a very small number.

Couldn't tell you to be honest. If you can give some pointers on how to measure it all I can have a go at it and post the numbers up. I still have to fix the rear end height a little as the shock shaft length is still too tall as I'm only planning around 10 degrees of swingarm droop vs what's there at the moment. I can dial off the spring preload to get that where it needs to be though to get a rough estimate of trail.

edit: also don't I need all the motor together to ensure I have the final bike weight on the suspension too?

The rear brake setup looks over complicated. Maybe i'm missing something.

Yeah, maybe. I just bought them off the shelf and they seem to have been run through their paces as TTR400 runs them on his race bike I believe.

 

[crazypj]

Quickest easiest way to measure trail is with a plum-bob, straight edge and rule. (drop string from center of axle to get contact point and use straight edge down fork center line side through axle -just like in the pictures you find online)
Measurer fork angle (rake) with plum-bob and protractor.
Should be more than accurate enough if you have the wheels and tyres your going to use fitted.
You don't need engine weight if you set frame to the 'running' height' your intending to use

 

[neevo]

OK, with a view to trying to work out my rake/trail I set out tonight with some string, a shock spring spanner, some tape, a homemade plumb bob, ruler and an iPhone app.

First up was to try and get the rear squat that would be similar to when the bike was exhibiting a decent static sag. To get this I had to dial the shock spring right off to get the bike sitting nicely:



This is much closer to the planned look with the swingarm angle closer to the stock 10-15 degrees, however I reckon I could dial it back a bit more.

Next I downloaded an app to try and get the headstock angle. It was bloody tough getting a pic and keeping the angle of the camera straight, but it seemed like this one was pretty close (22.32 degrees):



String + tape + makeshift plumb bob and we got a rough number:



135mm. No idea what that means. Hopefully it's a safe number:



Seems like I did something wrong as that's a fairly big number. Maybe I need to subtract the triple clamp offset for the actual real trail (32mm I believe for the '03 GSXR 750).

 

[doc_rot]

First of all let me say great build so far, great details and fabrication. i can't believe this has 168 pages and i haven't seen it yet.

You do need to subtract the fork offset from that value. Dont forget that because the rake is hitting the floor at an angle the amount you subtract will be slightly bigger than the actual offset. Personally i think measuring trail in that fashion is a bit tedious when there are excellent trail calculators out there, not to say that you wont get good results with that. An added benefit of the calculator is you can change the values around to see what different mods will do to the trail. I use this calculator. http://rbracing-rsr.com/rakeandtrail.html

22 degrees on the headstock seems too steep. most superbikes are in the 23-25 degree range. btw I have on app called "Angle pro" on my phone that works great, you can just slap your phone against the fork and get a perfect measurement, no need to photograph.

another note on geometry; because you have increased your swingarm angle and have less fork offset your wheelbase has gotten smaller. Just something to consider when settling on final figures.

If you can, I would recommend adding some bracing to the headstock to deal with the increased forces it will be absorbing with the stiff forks and more extreme rake. it doesn't look like there are a ton of opportunities to add bracing with this type of frame but the pressed steel backbone needs all the help it can get in this department imho. heres a photo of my kz1000 head-stock i braced for the same reasons.

 

[DohcBikes]

Beautiful work doc

 

[MotorbikeBruno]

First of all let me say great build so far, great details and fabrication. i can't believe this has 168 pages and i haven't seen it yet.

You do need to subtract the fork offset from that value. Dont forget that because the rake is hitting the floor at an angle the amount you subtract will be slightly bigger than the actual offset. Personally i think measuring trail in that fashion is a bit tedious when there are excellent trail calculators out there, not to say that you wont get good results with that. An added benefit of the calculator is you can change the values around to see what different mods will do to the trail. I use this calculator. http://rbracing-rsr.com/rakeandtrail.html

22 degrees on the headstock seems too steep. most superbikes are in the 23-25 degree range. btw I have on app called "Angle pro" on my phone that works great, you can just slap your phone against the fork and get a perfect measurement, no need to photograph.

another note on geometry; because you have increased your swingarm angle and have less fork offset your wheelbase has gotten smaller. Just something to consider when settling on final figures.

If you can, I would recommend adding some bracing to the headstock to deal with the increased forces it will be absorbing with the stiff forks and more extreme rake. it doesn't look like there are a ton of opportunities to add bracing with this type of frame but the pressed steel backbone needs all the help it can get in this department imho. heres a photo of my kz1000 head-stock i braced for the same reasons.

Great info, and the bracing looks amazing.

 

[jpmobius]

Right. You will have to subtract the fork offset. Trail is the distance the tire contact patch "trails" the center of steering rotation where it meets the road - pretty inconvenient to measure directly. You'll need to pick up the front of the chassis a good bit to get numbers that will drive properly.

 

[crazypj]

I think yokes are about 20mm offset from steering head so 115mm trail will be about normal.
Head angle is a little steep but not outrageous.

 

[75hondacb400]

Hi, I got almost the same set up on my cb400f, my front angle is 23.5, would it not be easier for him to drop the back end down to get a better front angle?

Sent from my D6603 using Tapatalk

 

[neevo]

Let me recheck all the info when I get back in front of the bike. Will use that website (thanks roc_doc I had that page saved already to understand the measurements) for all the inputs and see what it spits out for the trail to compare to my homemade version. Will also grab that other app to get a proper head stem angle and see if I can get the rear end squat closer to ideal.

Anyone have some ideas on bracing options? I know the frame and tank clearance is pretty limited on the 400F. I've seen a great website with stress images for the 400F (denoonsp) but it involves some hardcore bracing that removes the ability to keep the stock tank:

 

[neevo]

This looks ideal but you remove the ability to run the stock tank which I cannot do unfortunately.

http://www.denoonsp.com/frame-study.htm

 

[DohcBikes]

Great community input on the rake and the way to get it right. Like having a baby then not having to take care of it because you know the state will do it for ya ??? ;D :-X.