Cafe Racer Forum banner

1 - 20 of 61 Posts

·
Registered
Joined
·
28 Posts
Discussion Starter #1
I've finished the dry-build, including handling upgrades (tapered rollers in steering head,new shocks,rebuilt forks,fork brace,18" wheel on front).Now the frame is sitting bare with all unused lugs& center-stand removed and it's decision time on whether or not to weld in some frame braces.From what I can find out, the KH500 has bracing/gussets that earlier models didn't have, but I can't find any information on how effective it is. I found a copy of Denco's suggested bracing, and I've read Tony Foale's articles on frame bracing, including specific recommendations for the Kawa H2 750 (agrees with Denco's ,a little more complex), but both of these are dealing with the earlier frames. Anybody here have KH500 experience,would extra bracing be worth the effort for a street bike (stock engine with improved intake & Wirges chambers, no racing ,just fast riding once in a while).Any other mod.'s that work to suggest?
 

·
Registered
Joined
·
23,287 Posts
I drag raced a kh500 for a while, denco ports and chambers, big carbs, but otherwise a street bike.

the KH500 frame is braced in a very heavy way. Were I to do it over and had unlimited time and energy to weld everything in I would use an early h1 frame and brace it the way Tony Foale and Tony (Nicosa - Denco's Drag-on Fly) would have done it instead.

However if you are starting from a bare KH500 frame it is an excellent starting point - it is just a heavy frame.

What frame are you using right now? There is a difference between the 1969-1972 and the 1973-1975 frames as well with the later frames needing less bracing. Also how much hp are you making and what is your riding style? an H1 loves a point and shoot style, and if you are looking to be more gran prix than stoplight hero I would brace the frame anyway.

Though to be honest, if I was going to build another triple it would probably be an h1 in an s3 frame - which is about as badass as you can get short of an h2 in an s3 frame.
 

·
Registered
Joined
·
23,287 Posts

·
Registered
Joined
·
23,287 Posts
One final thing though - when I went to a rear slick on my kh500, I did brace the stock swingarm (this was long before I told the world on the triples board about fzr400 swinger conversions)heavily. Under hard launches the swingarm had a tendency to wrap and send the bike off in one direction or another. After bracing that wet noodle, it worked awesomer.


BTW: this is what a road racing 1971 h1 frame looks like, bracing is done by Todd Schuster of BMW racing R90S fame:



 

·
Registered
Joined
·
28 Posts
Discussion Starter #7
Thanks for the info & links Geeto. Between what you say & Scrambler73's comments, I'm inclined to see how it works without the X-members in the downtubes for & aft of the engine, the biggest part of what I was considering. I'll put some gussets aft/below swingarm pivot tube, and a cross-member on the top rails aft of the shock mounts for now. Welded a 16 ga. plate under rear of gas tank to mount electrics on/ brace. You're right about it being a heavy frame, feels about double a Triumph oil-type frame; putting the bathroom scale under one wheel at a time,looks like the finished bike(dry)will come in under 350 lb. This is the only frame I have, and haven't rode the bike yet,it came home as a pretty rusty/dusty mix of mostly '76 KH500 parts with '73 parts, including a '73 engine as a spare/parts. I'm mounting the '73 carbs on the '76 engine w/ stock jetting for that year except the main jets, have a set of 100's & set of 102.5's to go in, (depending what's required when it finally runs)so I'm hoping for close to the stock 60 HP,maybe a tad more if the chambers help as claimed by Mr. Wirges. As for riding style,I like to try to cut a fast curve,but out here on the prairies there ain't many of those to practice on, so I make no claims as a GP rider,maybe an inspired wannabe?
 

·
Registered
Joined
·
23,287 Posts
wirges chambers are shit. not all as the 1969 hand built ones hanging from my ceiling are excellent, but 95% of them are not those and thus shit. The reason a wirges chamber is shit is that it has a large internal baffle that streaches almost all the way to the front of the pipe. It gets caked up with 2 stroke gunk, chokes down the exhaust, and all of a sudden you lose power. If you are going to run wirges pipes I suggest you cut it open, remove said internal baffle, and weld it back up. If not you should at least have it boiled out so it isn't caked with crusty-ness.

I strongly urge you to brace the stock swingarm, just a piece of sheet over the pivot and stock brace to box it all up. Works wonders.

your finished bike will weigh over 400lbs. if the bike isn't level when you are weighing it you aren't getting an accurate reading. The only way to scale a bike is to use certified scales and have both tires on the scales at the same time. in a pinch you can do it one at a time but you have to pick the opposite end up at its furthest point so the bike is level when you weigh it.

If you have a strong beam you can hang stuff from go get some industrial or sportsman hanging scales and weigh the bike like that - cheaper than real car/bike scales and will be more accurate than bathroom scales. A good sportsman scale for weighing a 300lb or less deer costs $45.
 

·
Registered
Joined
·
1,220 Posts
quote:Originally posted by Geeto67

in a pinch you can do it one at a time but you have to pick the opposite end up at its furthest point so the bike is level when you weigh it.
Geets, why would you need to lift the other end to get an accurate reading? I know, I should have been paying attention in geometry class. Or maybe physics class? I don't even know what subject I'm ignorant in here.
 

·
Registered
Joined
·
28 Posts
Discussion Starter #10
Yeah , I've seen mention of the clogging baffles in Wirges chambers; I've got a buddy w/ a hot caustic tank @ work, so was planning to get a cleanout before the paint & install. If a guy didn't want to cut& remove the baffles, I wonder if a yearly caustic-clean& paint would keep ahead of the crap build-up? With the boxing in of the swingarm, do you think 16 ga. would be OK, or go to 1/8" plate? Weighing the thing, I wondered if 350lb. was too good to be true, have to line up something a little more sophisticated and see what I get.Thanks for the info.
 

·
Registered
Joined
·
1,763 Posts
Steve, it's physics. Weight is a measure of the force exerted on a given body by gravity, specifically the acceleration due to gravity. Weight measured at an angle other than in the direction of gravity (even if different by a few degrees) is not being directly affected by 100% of the acceleration due to gravity.

Personally I'd rather have an enormous balance to find the mass, and calculate weight at a given altitude. But anyway, real world. Bathroom scale.

Support the wheel not on the scale with a block of wood the same height as the scale and do not hold the bike upright. It must be free-standing and level to get the best results. Record measurements for both wheels and add them. Your measurement will be as accurate as your bathroom scale, which could be very inaccurate, indeed.
 

·
Registered
Joined
·
3 Posts
quote:Originally posted by Geeto67

Though to be honest, if I was going to build another triple it would probably be an h1 in an s3 frame - which is about as badass as you can get short of an h2 in an s3 frame.
Geeto, can I pick your brain on this topic? I'm interested in building a cafe bike, have a bunch of H2 parts. I love the idea of a newer/better frame and uprated swingarm and fork.

What can you tell me about the relative merits of the better 'donor' frames for an H2 motor. And can you give me some idea how well an H2 motor would bolt up in an S3 frame?

Thanks in advance,

N., FNG
 

·
Registered
Joined
·
23,287 Posts
although there are some key differences between the h1 and h2 motors, dimensionally they are almost identically, at least they are in the mounts (h1s are rubber mounted h2s are not though).

if you want to see whats involved in putting an H motor in an S frame it doesn't get clearer than this:

http://kawtriple.com/mraxl/khconv/400to500.htm


when cody built his cafe bike he used a kh500 frame. cut a lot of it though. this was the end result, used every trick in the book including my favorite the fzr swingarm:

http://thekneeslider.com/archives/2007/09/03/kawasaki-kh750-2-stroke-triple-cafe-racer/

Depending on how much work you want to do I have seen h series motors in the following bikes: s3, '90's ZX400R, 1990 FZR400, 1988 ZX600R ninja.

Additionally the first gen EX500 front end slides right into the stock H2 triple trees. There is also an easy conversion to EX500 calipers if you want to keep your spoked wheel, but you have to find 5.5mm kz650 discs.
 

·
Registered
Joined
·
23,287 Posts
here is how to stuff an S series into a 1987 zx600:

http://kawasakitriplesworldwide.com/phpBB2/viewtopic.php?f=17&t=11248

Depending on how skilled you are and how much of the work you are willing to undertake here are a few simple guidelines that may help:

1) tire size: you are not going to find a bike whose chain line matches up perfectly. But if the stock size is under 150 width, it is a matter of playing with offset sprockets to get it to line up rather than drag racing style outer bearing supports, offset motors, or other more complex solutions.

2) metal frames: a lot of 80s and 90s sportbikes use an alloy (or steel in the case of the fzr) wishbone with a bolt on steel under cradle. If you can weld aluminum then great but the really new stuff doesn't have that much of an engine cradle if at all. Plus the older the sportbike the wider the engine case usually.
 

·
Registered
Joined
·
4,721 Posts
Does anyone think this frame is correctly braced and gussetted?

The extra stuff.

If not, why?





[/quote]
 

·
Registered
Joined
·
5,780 Posts
It looks pretty good, to me. It has some extra tubes and that is always good, and some extra pieces that look like they are intended to be gussets, too. I also see where some tubes make triangles. I heard that triangles are good and squares are bad. So, based on tubes, gussets and triangles, I like it. I would race that frame even if it did have a 2 stroke motor in it.

Ken
 

·
Registered
Joined
·
23,287 Posts
I don't know, why don't you ask Todd Schuster since he built it.

Hack if you don't know who Todd Schuster is - just Google Bmw R90S Butler and Smith.

It may not be the only way to brace an early h1 frame, but it is a pretty good way.

Dude we get it already - you want to be super king dick of frame design around here. You have a hell of a lot of experience doing this (or so you tell everybody) I am sure, but just based on your piss poor attitude I concede you nothing.
 

·
Registered
Joined
·
4,721 Posts
So you really do not know anything about frames and truly haven't even grasped the foale info.

I actually do not need to ask anyone to know the things which are added, yet technically quite wrong.

You?

Well, I didn't expect you to know since you don't understand even what a radial weld is. That's why I didn't ask you, directly.
 

·
Registered
Joined
·
23,287 Posts
Boring.

The best part part about all this is you have yet to explain any o the info you laud over others. Never claimed to know what a radial weld was, so what, you haven't explained what it is and others have asked you directly.

Not going to argue with you on the internet, I read foale's book, hell I even picked his brain at mid Ohio, and I am satisfied with what I know. I am not the schmuck trying to pick a fight with a know it all on the Internet, you are. Besides I am I'll equipped to fight with you on the net, I have too many teeth and a modicum of dignity.
 

·
Registered
Joined
·
23,287 Posts
But please, don't let me stop you from criticizing Todds work on the net, or Daytona winning rider David Goldstein who commissioned the frame.

Do I think it has shortcomings? Well you'll never know that will you.
 
1 - 20 of 61 Posts
Top