Topic: 74 CB750 USD and Mono build

[SOHC4 Cafe Racer Fan]

haha yes I noticed that after, I had it on the floor at first so it got in the way

Just a bummer that you need to take them out again.  Remember you will need to swap the tubes left to right -- you cannot simply turn them to the rear as they will not match up correctly.

[chowpay]

Ah thats no big deal at all I just put them on to snap a photo. Even when the whole bike is put together I have to pull it all apart again to get the frame painted. Wont know what final tab positions should be, right ride height etc etc till I toss it all together.

[Jerilee]

The pore mans dynomat http://www.lowes.com/pd_154017-81326-PS625_?fromStore=true
I had been 'restoring' (un FUBAR-ing) an 82 El Camino and the folks in those circles have been using this stuff and swear by it. I went with this brand because, at the time, it was rumored to be *the* one.

I had put it on the roof, cab-rear and door panels and inner skins and it *did* help a with some vibration issues and heat... A true heat-shield? I can't say, but it sure was better than bare metal in the summer with a black roof while I had no headliner!

It sometimes has a little trouble with vertical surfaces or moist areas. But, it stuck inverted to my roof like a champ through last year's 100+ degree days -in the sun- last year and a winter, spring and another summer in 'storage'. As well as to the doors and cab-rear after some initial fuss. My 'truck' leaks like sieve in heavy rain so water would get under the adhesive goop, I highly doubt you'd have that problem here.

Hope that helps!
Fun build to watch, good luck!
- Jeri

[SOHC4 Cafe Racer Fan]

Ah thats no big deal at all I just put them on to snap a photo. Even when the whole bike is put together I have to pull it all apart again to get the frame painted. Wont know what final tab positions should be, right ride height etc etc till I toss it all together.

I really like how the seat is taking shape.  Nice job! I'm also impressed by your creativilty in using the PVC pipe to mock up the shock. 

[FrankenFrankenstuff]

I like the loom of your oil tank better than the Benji seat. Tack some cooling fins down the back and call it a day. IMHO.

[Retro Rocket]

what is the offset? I imagine it's not much, so with the stock triples, you're gonna have a big stability problem.

Its actually the opposite Terry, less offset means more trail which adds stability but makes steering slower making the bike feel like its falling into corners...  I used to think it meant less trail therefore less stability but if you look at the way trail is measured, smaller offset clamps bring the forks closer to the steering head so the measurement down through the axle in the vertical plane is the only measurement that changes. The line through the center of the frame neck to the ground sits forward of the axle so if the vertical line that determines trail length is moving backwards towards the front of the bike due to the smaller offset , trail increases, making the front end less responsive to rider input..



Forget what it says at the bottom about "typical values" thats wrong, it is more complicated than simply saying something is typical, rake and wheel size also come into the equation...

[chowpay]

@retro Cool info,  More stuff for me to factor in when going with the wheel size.

@frank thanks!, At the moment I got this beji stuff .. might as well use it. IF there is a next build I want to build a cool icecream truck chaser, My last one (XR50 w/118 stroked) got stolen by some bastards. Nothing like a bunch of kids running to get icecream and a chinese guy BRAaaap'n right past past them.

I actually have a lot of material left from making this tank. I was thinking.. everyone seems to want an oil tank that goes in the triangle like this:

 

If there's enough interest I'll make a small run of them out of aluminum. (I need something to justify the break press i want to buy haha)

@Jer, that is exactly the stuff I was thinking about. I'll wait to see how much of an issue the heat is going to be. Since there is a gap between the seat and the tank.. plus the tank is aluminum the circulating air might be enough so I don't get baboon ass.

@CB750 Thanks dude, if I have time I was working out a mock-up motor. This stupid thing weighs like 200lbs. Every time I watch my gf heave it into the frame I feel bad, so I think all that can be done with a 5 lb foam block as long as all the points I care about match up.

[Terry in Australia]

what is the offset? I imagine it's not much, so with the stock triples, you're gonna have a big stability problem.

Its actually the opposite Terry, less offset means more trail which adds stability but makes steering slower making the bike feel like its falling into corners...  I used to think it meant less trail therefore less stability but if you look at the way trail is measured, smaller offset clamps bring the forks closer to the steering head so the measurement down through the axle in the vertical plane is the only measurement that changes. The line through the center of the frame neck to the ground sits forward of the axle so if the vertical line that determines trail length is moving backwards towards the front of the bike due to the smaller offset , trail increases, making the front end less responsive to rider input..



Forget what it says at the bottom about "typical values" thats wrong, it is more complicated than simply saying something is typical, rake and wheel size also come into the equation...

Thanks Mick, I wasn't actually talking about trail, I was saying reducing your offset by using the Gixxer triples, you will pull the front wheel closer to the engine, thus reducing the wheelbase (and reducing stability) and under brakes (coming into a tight corner for instance) the front wheel will "tuck in" under the bike, further destabilising it.

That was Ken's experience when he first built my K2, and it almost spat him down the road on his first ride. It's also the experience of most guys who try to marry a modern front end with not much offset and (usually) a smaller front wheel to an older bike. By increasing the offset to something similar to OEM, Ken was able to increase the wheelbase, thus increasing the stability of the bike, especially in corners. Cheers, Terry.

   

[Retro Rocket]

Yes. decreasing the wheel base will have its effects as well but reducing the wheelbase doesn't necessarily make it more unstable , its all those factors combined,  Just for an example, the 2005 GSXR1000 has a 55mm less wheelbase than the old Honda {1405mm compared to 1460mm}. I agree with the tuck in feeling, thats what i meant by saying it makes them feel like they are falling into corners, all of a sudden they just go ..
Having a bigger front wheel will also slow steering response {combined with the gixer clamps}.... .. The problem lies in the fact that the bikes are designed as a whole, when you start changing dimensions at one end there should be changes made at the other to compensate and even rake changes, although some changes can just screw up handling as we've discussed here...  Was just trying to explain the tuck in sensation and the fact that most people think less offset means less trail ...   The F models had less offset than the K model 750's but they also had slightly different rake as well and were noted for being more stable at speed.  I often see guys bolting front ends on these bikes and saying that they handle well, I think some of them have probably never ridden a good handling bike...{runs away and hides }

[chowpay]

Small update. The bung arrived last night so I quickly welded it on. Its pretty good quality. especially for the price.

[SOHC4 Cafe Racer Fan]

Small update. The bung arrived last night so I quickly welded it on. Its pretty good quality. especially for the price.

Looks outstanding. 

[FrankenFrankenstuff]

..,.shame to cover it up is all I am saying.....

[SOHC4 Cafe Racer Fan]

@retro Cool info,  More stuff for me to factor in when going with the wheel size.

@frank thanks!, At the moment I got this beji stuff .. might as well use it. IF there is a next build I want to build a cool icecream truck chaser, My last one (XR50 w/118 stroked) got stolen by some bastards. Nothing like a bunch of kids running to get icecream and a chinese guy BRAaaap'n right past past them.

I actually have a lot of material left from making this tank. I was thinking.. everyone seems to want an oil tank that goes in the triangle like this:

 

If there's enough interest I'll make a small run of them out of aluminum. (I need something to justify the break press i want to buy haha)

@Jer, that is exactly the stuff I was thinking about. I'll wait to see how much of an issue the heat is going to be. Since there is a gap between the seat and the tank.. plus the tank is aluminum the circulating air might be enough so I don't get baboon ass.

@CB750 Thanks dude, if I have time I was working out a mock-up motor. This stupid thing weighs like 200lbs. Every time I watch my gf heave it into the frame I feel bad, so I think all that can be done with a 5 lb foam block as long as all the points I care about match up.

Have you thought about an oil tank that doubles as a fender on the rear side of the triangle?

[chowpay]

I did, but it got in the way of the mono shock i'm working on.

I do have one of those tanks if you're interested.
http://www.benjiescaferacer.com/oil-tank.php  I got this tank years ago.

Since im not using it I'm willing to sell it off its already been castwell coated. PM me if you're interested.

[SOHC4 Cafe Racer Fan]

I like it but I'm not sure it will work with the seat I want to use.

[Terry in Australia]

That Benjii's oil tank looks poxy mate, yours looks much more professional! I'd order one of yours but I love my Frankenfarter finned sidies that Joe made at my request all those years ago. Keep making those alloy parts though, you've obviously got a flair for fabrication! Cheers, Terry.

[squirley]

That oil tank is looking great!

Keep up the great fab work!

[chowpay]

Whew.. finally finished.







I know! but like everyone says it would burn butt if I left it out

..,.shame to cover it up is all I am saying.....

@squirley & terry  thanks! took longer than I thought... but its the first thing I made out of alum that wasn't a shelf or a some kinda rack haha. hopefully the next one won't take as long..

now on to the million other things I gotta finish.

[SOHC4 Cafe Racer Fan]

Looks great. When you get a chance, post a mock up photo of it mounted.

[jojo]

Hi Guys

I'm extending a stem off a GSXR 1000 2005 to do the fork swap on my 74 CB750

To do this I made a plug out of 6061 alloy :


V-grooved both the plug and the stem pieces, tig'd it up filling the V and rough lathed off the excess




This was all kosher according to an engineer i've been bouncing Ideas off of.

But one thing I didn't consider.. What is the allow type of the stock steering stem? does anyone know?

Thanks for your input

How long was the stem on the gsxr tree before you welded the plug?

[Terry in Australia]

Whew.. finally finished.







I know! but like everyone says it would burn butt if I left it out

..,.shame to cover it up is all I am saying.....

@squirley & terry  thanks! took longer than I thought... but its the first thing I made out of alum that wasn't a shelf or a some kinda rack haha. hopefully the next one won't take as long..

now on to the million other things I gotta finish.

Looks beautiful mate, well done! is it vented for the breather? Also, (dumb question probably, so please don't take offence) did you leak test it after you ground the welds? I only mention this because I seperated and rewelded a fuel tank a couple of years ago, (to knock a dent out) leak tested it, it was fine, so I "smoothed" the welds and didn't think to leak test it again, and guess what happened? 

[spazz1984]

Hi Guys

I'm extending a stem off a GSXR 1000 2005 to do the fork swap on my 74 CB750

To do this I made a plug out of 6061 alloy :


V-grooved both the plug and the stem pieces, tig'd it up filling the V and rough lathed off the excess




This was all kosher according to an engineer i've been bouncing Ideas off of.

But one thing I didn't consider.. What is the allow type of the stock steering stem? does anyone know?

Thanks for your input

How long was the stem on the gsxr tree before you welded the plug?

If I remember on mine I had to add 10mm to it
Sent from my SPH-L710 using Tapatalk 2

[chowpay]

@jojo & Spaz Not sure the exact size. I have another I can measure for you tonight but it was just about 1inch off (shorter) than stock

@terry I left it with water on my counter over night. Seems ok. I did find an issue the first time though. I over screwed the bolts that tighten into the threaded hole which tore the aluminum. But its all water tight.

[chowpay]

Looks great. When you get a chance, post a mock up photo of it mounted.

Here ya go buddy:

[SOHC4 Cafe Racer Fan]

Looks great. When you get a chance, post a mock up photo of it mounted.

Here ya go buddy:

Looks great - like it will tuck right under the cowl. Nice craftsmanship.