'73 CB250 - Doing it right this time round.

[doc_rot]

Frame mounted fairings don't turn with the forks. So, the headlight trajectory is behind the turn.

considering the forks turn in the opposite direction at speed wouldn't the light be pointing even farther away?

There is an interview out there with Rob muzzy where he says the first thing he did on the KZ1000 for Eddie Lawson was remove the fork mounted fairing as it made the bike unstable at speed.

 

[hooligan998]

considering the forks turn in the opposite direction at speed wouldn't the light be pointing even farther away?

True. Countersteer at speed (around 18 mph or so when countersteer becomes effective) will put the light a slight bit more behind on a fork mounted light versus a frame mounted light.

 

[irk miller]

considering the forks turn in the opposite direction at speed wouldn't the light be pointing even farther away?

There is an interview out there with Rob muzzy where he says the first thing he did on the KZ1000 for Eddie Lawson was remove the fork mounted fairing as it made the bike unstable at speed.

At what speed? Why use a scenario "at speed" (which I assume is a speed above 60) and compare interviews or data from a race bike? I'm not arguing with you or Rob Muzzy, but there is a little bit of difference between Eddie Lawson's 1981 KZ1000 race bike and this 1973 CB250. Eddie Lawson was hitting 170 mph. I'm not sure this bike will go that fast. I'm also more inclined to consider the the major use of this bike. What's the top speed and will it make a difference at that speed? Will it do most of its riding on big highways at 70mph+ or are we riding small city streets with blind corners and 35mph speed limits?

 

[Green199]

At what speed? Why use a scenario "at speed" (which I assume is a speed above 60) and compare interviews or data from a race bike? I'm not arguing with you or Rob Muzzy, but there is a little bit of difference between Eddie Lawson's 1981 KZ1000 race bike and this 1973 CB250. Eddie Lawson was hitting 170 mph. I'm not sure this bike will go that fast. I'm also more inclined to consider the the major use of this bike. What's the top speed and will it make a difference at that speed? Will it do most of its riding on big highways at 70mph+ or are we riding small city streets with blind corners and 35mph speed limits?

50/50. Suitable for both is what I am looking for as it will be pretty equally split. I think the best course of action is frame mounted, but I am not welding anything on to this frame. I'm struggling to find a suitable place to mount some bolt on brackets, and how they will work as well. It will be easier when its in my hands to play with the mounting.

Worst comes to the worst, it will be fork mounted for the time being until I can design something suitable.

One of the first builds I really enjoyed was FlyingJ's CB550, who has a similar fairing. Again it is fork mounted, maybe not an ideal scenario but definitely a possibility. And if its 'ok' in the larger capacity bike I am sure it will be suitable for the 250.

 

[Erskine]

Exhaust 'U' clamps around the headstock can make a no-weld solution.
Will you be doing 170mph?

 

[Green199]

Exhaust 'U' clamps around the headstock can make a no-weld solution.
Will you be doing 170mph?

Depends how big a hill I can find! ;D

 

[Maritime]

Fork mount will be just fine, I have a windscreen on my GL shaped similar to the fairing for arodinamic reference and I can corner it on the freeway at 125 mph without any I'll effects. That little cb250 will not have any issue either way.

 

[Maritime]

Oh and good choice I think it will look great.

 

[Green199]

I'm now planning on running the stock rev counter alongside a small 2.5" speedometer.

The stock Tacho I have isn't in 'the worst' shape, but the faceplate is a bit scratched and the PO has painted on the 'red zone'. So until I can get some replacement decals I am just gonna have to run it.

I'm modifying the backing plate to retrofit a mini LED voltmeter into the gauge.

I cut the gauge face using a Dremel and then filed it to size. Then mounted it and secured with some epoxy putty. Should be solid enough for a mount. I'll also replace the backlight bulb with an LED alternative.

I also had a go at shortening my throttle cable today. I ended up drilling out a wooden mould and casting a Silver solder nipple on the end. It worked very well and seems strong enough for a throttle cable. I may just have to redo it tomorrow now I know the method works as I could so with shortening it another 10mm.

The routing is not the best as it has to go round the stock master cylinder. It should be ok running like this as the action is smooth and returns nicely. Just looks a bit bent.

 

[Green199]

We're getting aerodynamic! (kind of...)

Fairing arrived today. Quality wise it is ok, can't really fault it for what it is. It's a bit wide, so the top mount will 'pull it in' a bit so it is less round, but I am digging the shape! Think I will run a bottom mount to the lower yoke bolts, and a top mount will interconnect with my gauge mounts. The headlight will be mounted directly to the fairing with some aluminium brackets bolted to the fairing.

It said the hole was for a 6 inch headlight, but this is obviously to fit entirely through the hole. My 7 inch headlight sits perfectly on the ridge and keeps it central, just like it was designed for it! ;D

My order from David silver came in, so I replaced the gas tank seal as it had perished completely!

I also cut and mounted my smoked plexiglass splashguard. I have around 1 1/2" clearance to the rear tyre. If I need more I will simply heat and bend the middle for a more rounded profile!

Mounted some LED turn signals on the rear too. The seat kind of overlaps them a bit too much so I will either create a spacer to push them further outboard, or I will mount them to the seat itself.

 

[Green199]

Splash guard is all mounted up. Clearance 'should' be OK, but will know for certain when its up and running.

I finished up modifying and reassembling the rev counter with the inbuilt voltmeter. Not the prettiest but it will do for the time being. Just trying to sort out the brackets and placement for it and the speedometer. Made a couple of brackets out of scrap for me to finalise the position, and I will redo them once I get in it in the best position.

 

[Green199]

Oh, and there's this

 

[Nj732port]

love the gauge with the volts in it and that front fairing is kick ass really looks great!

 

[Green199]

Thanks Nj.

I started fabbing up a few brackets to hold the headlight directly to the fairing. Just need to drill the fairing and bolt the headlight in. Then I can start working on the mounts for the fairing itself.

 

[Erskine]

Nice.

 

[hooligan998]

Nice. Use a nice stainless button head allen bolt for going through the fairing. It will look sweet!

 

[DohcBikes]

Pretty sure that splash guard will have clearance issues. I see that you are hopeful but i'm doubting it. Good news is that you can easily gain another inch or so if you need it.

The fairing looks fantastic.

Are you surpassing your own expectations yet?

 

[Green199]

Thanks Maritime and hooligan! All bolts on the fairing will be black Allen heads to blend in!

Pretty sure that splash guard will have clearance issues. I see that you are hopeful but i'm doubting it. Good news is that you can easily gain another inch or so if you need it.

The fairing looks fantastic.

Are you surpassing your own expectations yet?

Yep, It definitely looks closer in the pictures than in real life, but I am still not sold on it. I will leave it for the time being until it is up and running, but will easily gain more clearance if necessary.

Not sure about surpassing my expectations. I'm still looking at a load of the imperfections and wishing they were sorted!

 

[neevo]

Thanks Maritime and hooligan! All bolts on the fairing will be black Allen heads to blend in!

Don't bother unless you can get some anodised Alu bolts. The black steel ones rust in an afternoon. Useless for a bike build and I've since replaced all mine for stainless.

 

[jpmobius]

Don't bother unless you can get some anodised Alu bolts. The black steel ones rust in an afternoon. Useless for a bike build and I've since replaced all mine for stainless.

Nylon bolts are good for the windscreen - they will not crack the paint or gelcoat. For the actual mounts, a rubber grommet with a steel or aluminum sleeve will protect the fairing and last indefinitely. I've mounted quite a few race fairings on street bikes, and it is a good idea to not crunch down on the glass with fasteners. Not too important on a race bike, but for a daily driver you need to plan farther ahead if the appearance is important to you.

That's a great looking fairing, but it looks like it aims "up" a bit. Is the headlight aim independent of the fairing orientation?