Need help with custom intake!

[AJ]

I do have an S&S Harley manifold to try but just by looking at it the angle will be way too wide. It will end up being really short (carb will stay close to the motor) which is good but the bends are going to be really sharp and hurt flow. I'm planning to use 3/16" plate for the flanges that bolt to the head and some 1.25" exhaust tube to make the intake runners. I'll probably end up rolling some sheet metal to match the OD of the carbs head side and then using a hose to attach the carb to the manifold. Since that hose will be flexible I plan to have a bracket come down from the frame help support the carbs.

Hmmm, wonder what the spacer was like on the Triumph 650 Tiger. The bends in that manifold are truly horrible.
http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=146741

How about getting a good exhaust shop to make you two nice S-offset pipes in stainless. Slice off the sides after the bend in both pipes, weld the open cuts together, re-form it into a circle, maybe re-weld it since you'll probably damage the welds. You don't have a lot of length to play with here.

 

[Wyldesoul]

Sums it up for me.

Kind of a DIY crackpot idea to put a way too powerful engine in there.

Don't anybody have any respect for all the testing and work hours the factory engineers put into a bike?

Take it for granted they already been there, and it didn't work.

Well I must say that is a horridly pessimistic way to look at modifications.

I mean, especially such wild, radical and downright awesomely idiotic things!
Where is your hot rod spirit? Weren't the original "hot rods" just small, entry level cars with way to big and way to powerful motors shoehorned in with no regard to safety or structural stability?

If it weren't for those crackpot DIY guys, the car industry would never have recognized such a demand, and would never have sent their teams of engineers to figure out how they can make something like that to sell, and we'd never have muscle cars.

Even the motorcycle industry has taken tips from crackpot DIY guys. If enough people do it, they see that it's liked, and they find a way to make it themselves. But if everyone just trusted the engineers knew what they were doing, and leave things alone, the motor industry would be much, much blander than it is now.


My input to the project that is the subject of this thread?
Go for it! You are without a doubt being some shade of idiot for trying this, and if you kill yourself it is your own **** fault.
But if you succeed?

Sweeeeeet. That will be one killer ride.

 

[boontonmike]

I'm all about modifying stuff out the ass, but that frame is just about the last style frame I would want to use for a big 4 cyl. If anything I'd be trying to stick a super light dr650 / 400 or some thumper thats built up and weighs next to nothing and would fit the frame alot better. To be fair though it is your project and if you really are into it go for it, I'm not gunna stop ya.

 

[AJ]

I'm all about modifying stuff out the ass, but that frame is just about the last style frame I would want to use for a big 4 cyl. If anything I'd be trying to stick a super light dr650 / 400 or some thumper thats built up and weighs next to nothing and would fit the frame alot better. To be fair though it is your project and if you really are into it go for it, I'm not gunna stop ya.

That actually makes some sense.

You could also hotrod the heck out of the original motor.

But there is that "impossible dream" thing to be considered.

 

[Steve]

For a visual, see the parts fiche picture for an '84 GS550. A "siamese carb" has two throats and one slide.

Thank you for your indulgence,

BassCliff

For a little more "fun", here is a visualization from the only other bike that I know of with siamesed carbs, the KZ1300 from '79 to '82.

You think it's bad with two of those suckers? Try it with THREE of them.
.

 

[Racing Geek]

Hmmm, wonder what the spacer was like on the Triumph 650 Tiger. The bends in that manifold are truly horrible.
http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=146741

How about getting a good exhaust shop to make you two nice S-offset pipes in stainless. Slice off the sides after the bend in both pipes, weld the open cuts together, re-form it into a circle, maybe re-weld it since you'll probably damage the welds. You don't have a lot of length to play with here.

That link isn't working for me.
I don't remember the exact measurement but I think it was 5" to 6" of room to make the manifolds. I've actually been considering making the intake out of foam and casting them from aluminum like the manifolds for the CB750.

Well I must say that is a horridly pessimistic way to look at modifications.

I mean, especially such wild, radical and downright awesomely idiotic things!
Where is your hot rod spirit? Weren't the original "hot rods" just small, entry level cars with way to big and way to powerful motors shoehorned in with no regard to safety or structural stability?

If it weren't for those crackpot DIY guys, the car industry would never have recognized such a demand, and would never have sent their teams of engineers to figure out how they can make something like that to sell, and we'd never have muscle cars.

Even the motorcycle industry has taken tips from crackpot DIY guys. If enough people do it, they see that it's liked, and they find a way to make it themselves. But if everyone just trusted the engineers knew what they were doing, and leave things alone, the motor industry would be much, much blander than it is now.


My input to the project that is the subject of this thread?
Go for it! You are without a doubt being some shade of idiot for trying this, and if you kill yourself it is your own **** fault.
But if you succeed?

Sweeeeeet. That will be one killer ride.

Not sure what to make of everyones talk of "idiot." If it makes you all sleep better at night, I do have a background in mechanical engineering and this isn't my first project.

I'm all about modifying stuff out the ass, but that frame is just about the last style frame I would want to use for a big 4 cyl. If anything I'd be trying to stick a super light dr650 / 400 or some thumper thats built up and weighs next to nothing and would fit the frame alot better. To be fair though it is your project and if you really are into it go for it, I'm not gunna stop ya.

If I wanted a supermoto I would simply ride my KTM instead of doing this. I'm curious why everyone thinks this frame is such a bad choice. Is it because it is physically small compared to the frame the engine came out of? Is it because I cut away so much of the back bone? Please share.

I'm not trying to be smart ass. I just figured if people have an issue with what I'm doing it would be good to discuss it (in a civilized manner) since someone may have something to say that has slipped my mind.

That actually makes some sense.

You could also hotrod the heck out of the original motor.

But there is that "impossible dream" thing to be considered.

That is pretty much why I'm doing this. How many people would ever consider this? Now how many of those people would actually follow through with the idea? I'm hoping this will be a true one of a kind bike when I'm done. For those of you in the midwest part of the United States, I'm hoping to have the bike in the show at Rockerbox in Milwaukee and do the Fall Slimey Crud Run on it this year. I'll probably end up doing the Spring Crud Run on the KTM or Triumph. If any of you will be doing it let me know and maybe we can ride together for part of it.

For a little more "fun", here is a visualization from the only other bike that I know of with siamesed carbs, the KZ1300 from '79 to '82.

You think it's bad with two of those suckers? Try it with THREE of them.
.

I know a guy with a KZ1300. Those things are tanks and the 6-1 exhaust makes the thing sound like an exotic car. Sex for the ears.

I would imagine it's probably just as bad as cleaning and synching all 6 CBX carbs. This bike I'm building is sort of my way of getting the CBX back (motor went boom and it was sold). It will have similar looks, a better power to weight ratio, and probably just as much of a "wow" factor all for under a grand.


I'm going to a swap meet Sunday so hopefully I'll find some carbs there. If not I know of a pair of VM34's for a nice price. I've decided I don't want to use CV's on the bike if I can get away with it.

 

[Steve]

I would imagine it's probably just as bad as cleaning and synching all 6 CBX carbs.

Actually, it was rather easy to sync them. :-k

Only three carbs, TWO adjustments, you're done.
Of course, I did have to spend a few more bucks and get the SIX-tube set of mercury sticks.

Still have them, still use them.

.

 

[koolaid_kid]

And it really does not matter whether you agree or not. I personally would not stuff a 1000 hp motor in a standard car frame, but some do.
We are here to assist, not to judge.
At least, that is my take on it.

 

[boontonmike]

I think the outcry over the frame is because the frame is only a single tube downtube and toptube. Atleast thats why I don't like it. The engine has alot of torque and without the support of a dual downtube and alot more supports like most bigger japanese 4 cyl frames (which alot of people even complain about and brace up) its's going to want to flex alot. It will without a doubt work physically.

I think the sheer massiveness of the engine and how wide it is on such a small chassis design just doesn't flow. I think the original engine and exhaust configuration looked perfect. Now again this is all just one opinion, take it with a grain of salt, and do whatever you please as everyone should.



What kind of KTM do you have? I wanted a 525 and ended up getting a DRZ400E with a street title. Still dream about the KTMs though.

 

[Wyldesoul]

Not sure what to make of everyones talk of "idiot." If it makes you all sleep better at night, I do have a background in mechanical engineering and this isn't my first project.

There is the fact of a very large motor in a very small frame is just inherintly dangerous, but in a seriously awesome way.

Just like motorcycling itself. We all have to be some shade of idiot to get out on what is functionally an engine with wheels, blasting down the highway at seventy miles per hour with nothing between us and the world to keep us safe.

But the joy of the experience is well worth the risk, and so it's okay that we're all a bit of an idiot for being in this hobby.

I didn't mean it insultingly, more in the way that they call some truly radical hot rods "Daft" or "looney" or "crazy" and so forth.

 

[850 Combat]

Well, not really (305 vs. 350). The 350 was a marvel of its day. The 360 ushered in some improvements and manufacturing simplifications, but never achieved the overall reliability until evolving into the 400 series.

Not that it matters, it really wasn't much evolution from the 350/360 to the 400/450. Buzzy 180 degree crank uncounterbalanced no power two valve to 360 degree crank 3 valve counterbalanced twin which was as quick as the two strokes. The 400 shares the spelling of the manufacturer's name with the earlier motor pretty much.

I've read that the 360 was less successful than the 350. Can't remember why. The only real difference I can think of is the 6 speed it needed because Yamaha and Suzuki had one.

I say go for it as far as the build goes. There are plenty of those old bikes around anyhow. A log style manifold might work and be relatively easy to build.

A guy I know put a Turbo Honda 550 in a TX500 frame. It had nitrous bottles hidden in fake mufflers on each side. The Exhaust went over the head. It made no sense, but he wanted to do it, and he did it.

 

[razor02097]

There is the fact of a very large motor in a very small frame is just inherintly dangerous, but in a seriously awesome way.

Just like motorcycling itself. We all have to be some shade of idiot to get out on what is functionally an engine with wheels, blasting down the highway at seventy miles per hour with nothing between us and the world to keep us safe.

But the joy of the experience is well worth the risk, and so it's okay that we're all a bit of an idiot for being in this hobby.

I didn't mean it insultingly, more in the way that they call some truly radical hot rods "Daft" or "looney" or "crazy" and so forth.

I apologize in advance and I don't usually do this...but I have to completely disagree.


A rider doesn't have to have a shred of idiocy to ride a motorcycle. The idiocy of a rider is described as a motorcyclist decides Not to use any protective gear, perform risky maneuvers, showing off, speeding and/or general reckless behavior.

When I ride I dawn padded gear, boots, gloves and a full face DOT and Snell approved helmet. I may not have a metal cage around me but I have metal, carbon fiber, lexen and synthetic materials. I may not have air bags but I do have massive amounts of padding to help prevent injury. Yes a car might be safer in most situations but no matter what you are in short of a tank you are suitable to injury during a serious accident.


It is because I enjoy riding a motorcycle and enjoy the benefits like fuel economy, motorcycle parking and the great communities that the motorcycle brings...not because of idiocy.

 

[AJ]

Don't know why the link to the Triumph manifold didn't work, but here's a photo. It's something like a "log manifold" like 850 Combat suggested.

 

[AJ]

Not sure what to make of everyones talk of "idiot." If it makes you all sleep better at night, I do have a background in mechanical engineering and this isn't my first project.

If I wanted a supermoto I would simply ride my KTM instead of doing this. I'm curious why everyone thinks this frame is such a bad choice. Is it because it is physically small compared to the frame the engine came out of? Is it because I cut away so much of the back bone? Please share.

I'm not trying to be smart ass. I just figured if people have an issue with what I'm doing it would be good to discuss it (in a civilized manner) since someone may have something to say that has slipped my mind.

That is pretty much why I'm doing this. How many people would ever consider this? Now how many of those people would actually follow through with the idea? I'm hoping this will be a true one of a kind bike when I'm done.

It's fun how this thread is evolving... going from "What the f**? This is crazy!" to actually trying to think creatively about how to pull this beasty off. RG, I think you've handled the criticism pretty well.

Back to the technical, I had not noticed how you had cut the back bone of the frame to shoehorn in the engine, but now see you've really gone to town with it. How much clearance do you have to brace that, especially because the tank tunnel is already tight? Are you planning to form a tube around it somehow? You'll need to close the bottom of the box for stiffness.

Also, will you be able to get your cam cover off for valve adjustments? And where the h@ll are the coils going to go? (ok, those are small fry questions, but inquiring minds want to know! )

 

[AJ]

Not that it matters, it really wasn't much evolution from the 350/360 to the 400/450. Buzzy 180 degree crank uncounterbalanced no power two valve to 360 degree crank 3 valve counterbalanced twin which was as quick as the two strokes. The 400 shares the spelling of the manufacturer's name with the earlier motor pretty much.

I've read that the 360 was less successful than the 350. Can't remember why. The only real difference I can think of is the 6 speed it needed because Yamaha and Suzuki had one.

To my eye, the biggest changes were the cam and the transmission to 6 speed. The 350 used external blocks to hold the cam bearings, and these blocks were slid into the ends of the heads. The 360 used a much more modern design with the cam bearings directly in the head, eliminating a ton of precision machining. They also massively simplified the cam chain tensioner. For the record, I think I have built about ten CB350 engines, with no. 11 in my garage awaiting for me to finish this GS1100e that continues to frustrate me.

I also don't know recall why the 360 engine was not reliable, as I had already moved into 4 cylinder bikes by the time the 360 was out. I did piece together a 360 out of parts for my girlfriend/future wife to get her around campus. That was totaled after she was hit by a car, and I moved her onto a GS450, which was lightyears ahead of either the CB twins.

 

[Dave8338]

I've got a 360 Honda engine sitting on the shelf in the shop. As for weight, that thing is a REAL PIG ! ! ! I'm not concerned for the strength of the frame. It will flex a little. Keep in mind that the single back bone and down tube is larger in diameter than the twin tubes of the GS bikes. Braced correctly and tied back tight to the engine, you can create a whole new stress member, the engine, that Suzuki never did.

Yamaha pulled it off in the Virago series of bikes. Worked GREAT. :-$

Inverted forks in the plan?

 

[AJ]

I've got a 360 Honda engine sitting on the shelf in the shop. As for weight, that thing is a REAL PIG ! ! ! I'm not concerned for the strength of the frame. It will flex a little. Keep in mind that the single back bone and down tube is larger in diameter than the twin tubes of the GS bikes. Braced correctly and tied back tight to the engine, you can create a whole new stress member, the engine, that Suzuki never did.

Yamaha pulled it off in the Virago series of bikes. Worked GREAT. :-$

Inverted forks in the plan?

Don't know about the 360, but the 350 frame also tied to the cam cover with a pair of triangular brackets. I suspect this was done for stiffness.

 

[Racing Geek]

What kind of KTM do you have? I wanted a 525 and ended up getting a DRZ400E with a street title. Still dream about the KTMs though.

It's a '98 KTM 400RXC. It's an older bike but it's still a blast to ride. This pic was before it went into street mode. The Camaro behind it was another project.

I've read that the 360 was less successful than the 350. Can't remember why. The only real difference I can think of is the 6 speed it needed because Yamaha and Suzuki had one.

To my eye, the biggest changes were the cam and the transmission to 6 speed. The 350 used external blocks to hold the cam bearings, and these blocks were slid into the ends of the heads. The 360 used a much more modern design with the cam bearings directly in the head, eliminating a ton of precision machining. They also massively simplified the cam chain tensioner. For the record, I think I have built about ten CB350 engines, with no. 11 in my garage awaiting for me to finish this GS1100e that continues to frustrate me.

I also don't know recall why the 360 engine was not reliable, as I had already moved into 4 cylinder bikes by the time the 360 was out. I did piece together a 360 out of parts for my girlfriend/future wife to get her around campus. That was totaled after she was hit by a car, and I moved her onto a GS450, which was lightyears ahead of either the CB twins.

I've also read that the oiling at the top of the motor wasn't as good as the CB350 and that's why there were never many people that raced them.

Don't know why the link to the Triumph manifold didn't work, but here's a photo. It's something like a "log manifold" like 850 Combat suggested.

I suppose that one could work if the spacing is right. The S&S one I have looks more like the picture below which is why I mentioned needing really sharp turns for it to work. I wonder if that older Harley manifold you posted about would have the same or similar port sizes as the GS? Hmm...:-k

It's fun how this thread is evolving... going from "What the f**? This is crazy!" to actually trying to think creatively about how to pull this beasty off. RG, I think you've handled the criticism pretty well.

Back to the technical, I had not noticed how you had cut the back bone of the frame to shoehorn in the engine, but now see you've really gone to town with it. How much clearance do you have to brace that, especially because the tank tunnel is already tight? Are you planning to form a tube around it somehow? You'll need to close the bottom of the box for stiffness.

Also, will you be able to get your cam cover off for valve adjustments? And where the h@ll are the coils going to go? (ok, those are small fry questions, but inquiring minds want to know! )

In the photo showing the top of the motor, the two holes you see along the edge of the cut is where the stock upper motor mounts where fro the 360 engine.

The tank will be custom so I'll have as much room in the tunnel as I want. I do plan to close off the bottom of the tube with some plate and I'll be adding a brace like this. The bar used for mock up is 1" conduit. The coils will be placed on the inside of the brace underneath where the gas tank would go. If you where to kneel down next to the bike you could probably see them poking out under the tank but they should otherwise be out of sight. Note that the front part of the brace will be a tighter curve then what is picture. I couldn't get it any tighter without severely crimping the tube.

This is all the metal except the backbone pieces I cut off of the frame. Plasma cutters are wonderful!

I will be using all the GS engine motor mounts (2 in back, 1 on bottom, 1 in front) and I'll be make the breather on top into a motor mount to further brace the back bone. I'll be adding a brace going directly between the upper shock mounts to better support the shocks and give me something sturdy to sit on. I'll also be using some plate steel to gusset the frame in a few areas.

I will not be able to remove the cam cover for a valve adjustment unless I totally redo the backbone or I live with having to remove the engine every time the valves need adjustment. I've decided I would rather remove the engine every time since I shouldn't have to remove it very often.

I've got a 360 Honda engine sitting on the shelf in the shop. As for weight, that thing is a REAL PIG ! ! ! I'm not concerned for the strength of the frame. It will flex a little. Keep in mind that the single back bone and down tube is larger in diameter than the twin tubes of the GS bikes. Braced correctly and tied back tight to the engine, you can create a whole new stress member, the engine, that Suzuki never did.

Yamaha pulled it off in the Virago series of bikes. Worked GREAT. :-$

Inverted forks in the plan?

Yes, the stock 360 engine is a pig. That's why I think the 350# wet weight is actually a little generous of an estimate.

Since the F2 forks have been recently rebuilt with stiffer springs I plan to leave them alone. If I ever run across a RS125 front end or something similar, I would consider swapping the F2 forks for that. That opens up all kinds of issues with what I have currently so it would have to be a pretty good deal though.

 

[boontonmike]

That car was my first car. Mine was an 86 Iroc-Z in white. I miss that thing. Looks like we have quite a bit of tastes in common. Nice Ktm by the way, looks real clean. I would love to see the street wheels on it too.

Looks like you are on the right track with the frame modding so far. This may be a case of jumping to conclusions, because it looks like you know whats going on. I have a little faith in this.

 

[Racing Geek]

That car was my first car. Mine was an 86 Iroc-Z in white. I miss that thing. Looks like we have quite a bit of tastes in common. Nice Ktm by the way, looks real clean. I would love to see the street wheels on it too.

Looks like you are on the right track with the frame modding so far. This may be a case of jumping to conclusions, because it looks like you know whats going on. I have a little faith in this.

Mine is an 87 IROC-Z. A lot of chassis (braces galore), suspension (Koni shocks and adjustable everything), brake work (Corvette), and obviously the wheels are Corvette (18x10.5 with 295 rubber front and back). It will be for sale in the Spring.

The KTM won't be taken out until we get a good rain to wash the salt away and there is room in the garage. Is there a "post pics of your other rides" thread? I'll put some more pics of past/present vehicles in there.