Thursday, September 30, 2010

A Giant Pulsating Mind is a Terrible Thing to Waste

Micheal Faraday, a physicist and chemist from the early 1800's, most famous for Faraday's law and his other contributions to the field of electromagnetism, presented a lecture during the Royal Institution Christmas Lectures in 1860. This lecture is one of my favorite reads. Not only for the ingenuity to discover things we now take for granted, but for the language used to describe the technical subject matter. It's like poetry compared to today's standards.

In 1860, Faraday's topic was candle flames. This seems simple, but this one flame, that has provided light and confidence for our ancestors over many centuries, is quite complex and revealing to the structure and characteristics of fire. Faraday called his lecture "The Chemical History of a Candle". If you have the time to read it, I vehemently recommend you do. Your perspectives on flames, combustion, and simplicity itself will be altered.

If you feel so inclined to experience this taste of historical influence, I can provide you with a copy.
Disclaimer: I am not much on reading. I tend to read only technical manuals, research, and anything I can learn something from. This Christmas Lecture provides more than just a perspective on combustion. When you read it, consider the amount of ingenuity, creativity, and genius it took to create the experiments necessary to develop the results. Then to have the skills to evaluate the results and determine a proper conclusion decades before it could be proven is amazing.
This type of thinking is what separates the leaders from the followers.
Another note: I am posting this completely off topic subject because it's my birthday tomorrow and I thought I'd share a bit of something fan-freakin-tastic with you.
Here is an excerpt from Faraday's Christmas Lectures:

I DARE say you well remember that
when we parted we had just mentioned
the word "products" from the candle; for
when a candle burns we found we were
able, by nice adjustment, to get various
products from it. There was one
substance which was not obtained when
the candle was burning properly, which
was charcoal or smoke, and there was
some other substance that went upward
from the flame which did not appear as
smoke, but took some other form, and
made part of that general current which,
ascending from the candle upward,
becomes invisible, and escapes. There
were also other products to mention.
You remember that in that rising current
having its origin at the candle we found
that one part was condensable against a
cold spoon, or against a clean plate, or
any other cold thing, and another part
was incondensable. We will first take the
condensable part, and examine it, and,
strange to say, we find that that part of
the product is just water- nothing but
water. On the last occasion I spoke of it
incidentally, merely saying that water
was produced among the condensable
products of the candle; but today I wish
to draw your attention to water, that we
may examine it carefully, especially in
relation to this subject, and also with
respect to its general existence on the
surface of the globe. Now, having
previously arranged an experiment for
the purpose of condensing water from
the products of the candle, my next point
will be to show you this water; and
perhaps one of the best means that I can
adopt for showing its presence to so
many at once is to exhibit a very visible
action of water, and then to apply that
test to what is collected as a drop at the
bottom of that vessel.

Poetry in common spoken word. FYI, 1 Faraday= 96485.3 coulombs

Wednesday, September 29, 2010

Porting the Honda Head

Back in the December 1971 issue of Hot Bike Magazine, Richard Bean wrote a detailed article about the power potential hidden in the CB750 cylinder head. His article describes the research and experimentation performed by Jerry Branch of Branch Flowmetrics.

The Following is Mr. Beans words.

Next to a whopping increase in displacement, nothing adds horsepower to Honda's multi-cylinder engine like porting. One of the best of the current crop of super bikes, the "Four" still has room for improvements in the ports and combustion chamber.

To find out exactly how and where these improvements should be made, we went to Branch Flowmetrics in Long Beach to talk to owner Jerry Branch about the Honda head. Jerry had just started porting a head for a customer and we were able to gather our information while the final tests were being performed.To test the Honda head, Jerry had designed a jig which would support the head over the port on the flow bench and provide a means of opening the valves in precise .050 steps so that the airflow through the ports and combustion chamber could be measured at different valve lifts. The first test is a guideline test to determine the flow of the stock head, intake manifold, and carburetor. The bench uses a standard pressure measurement rated in inches of water with corrected temperature and barometric pressure to insure that the suction applied to the cylinder re- mains constant throughout the test range.

With the valve held in place by lightweight spring, this test jig
allows valve to be set at any lift to check airflow though port and head.
For accuracy flow bench testing is best.

Air is pulled into the carburetor intake and through the port at varying degrees of valve lift to check the capabilities of the port at any point in the cycle. The first bit of information gained from the stock configuration test was that the Honda 750 head reaches maximum flow at a valve lift of only .250. At the .250 lift point, air flow has risen from zero to 54.8-CFM (cubic feet per minute). Going all the way to .450 lift only increased the flow to 58.7-CFM, indicating that the stock Honda Four engine requires a cam with a long duration, which will open the valve quickly and hold it open at moderate lift (about .300-inches) for an extended period of time to allow complete filling of the cylinder. High lift is not needed and cannot be used effectively until the port shape is improved to a point where the engine will flow much larger amounts of air at high lifts.

Using this radiused entry on the intake port gives a guide line
reading to determine overall flow rate of the stock and modified ports.
Finished port had 105.6 CFM flow rate!

Jerry also performed a test without the valve installed, but retained the stock 28mm Keihin carburetor. The airflow increased a very small amount to 60.3-CFM demonstrating that the design of the valve is very good just the way it is and presents no large restriction to airflow. The final test on the stock head consisted of removing both the valve and the carburetion and adapting a venturi to the intake port to sec how much air could be pulled through the port under ideal conditions. The test, called an "entry only" test, gave a figure of 77.3-CFM indicating that while the valve does not present much restriction to airflow, the stock Keihin carburetor does.

Jerry decided to adapt a larger carburetor to the stock head and chose a 32mm Mikuni. The Mikuni is a better flowing carb and is still small enough that four of these 32mm units will fit the engine and frame without much modification. The test showed- that the Mikuni installation was good for an increase of 5.9-CFM at the .250 lift point and would allow a further increase in flow to 65.7-CFM at .350-inch lift before the curve started to flatten out again. This is a substantial improvement for a bolt-on part.

A further test with the valve removed and the 32mm Mikuni gave a reading of 71.7-CFM, not too far down from the entry-only figure of 77.3-CFM. Jerry feels that the 32mm Mikuni would be perfect for racing use, or on large displacement street engines. For a stock cubic-inch Honda Four the 30mm size would work best.

The actual porting of any head is done in a trial and error manner using the experience of the man doing the work as the guideline for what must be done. Even with testing facilities like the flow bench, the porting business remains as much art as science. Jerry's first job was to establish the flow pattern of the port so that he could get a clear idea of the areas in which metal must be removed to increase the flow. Porting is not just enlarging the area of the port; such a move will sometimes lower the flow rate and destroy the usefulness of the head.

Most of the shrouding in the combustion chamber was ground away,
giving the Honda head a Hemi-like appearance. Valve sizes and seat
width were left stock. Finished porting job gave a 25.6 increase in airflow.
Illustrations at right show areas were metal was removed to alter flow
around valve guide and improve velocity.

Jerry uses a tiny probe which can measure vacuum in different areas of the port. By inserting the probe into the port, he can find those areas which have less flow and can draw a graph of the flow deep inside the intake port. The first thing he found was that the majority of the air movement was confined to the floor of the intake port. The valve guide area was severely restricting the flow of air in the upper portion on the port and would have to be reshaped to allow an increase in CFM. Also the height of the guide projecting into the port should be cut down about 114-inch. Reshaping the upper portion of the in- take port caused an increase in the velocity of the flow which led us to the second discovery about the port shape. The curve of the port directly behind the guide is too gradual and forms turbulence, blocking part of the area around the valve head with a disturbed wall of air. Jerry ground a deeper curve, almost a pocket behind the guide and flow shot way up. Just the opposite condition exists on the floor of the port. There the curve is tight and causes the air to try and go around too much of an angle to reach the valve. The radius of the floor was reduced slightly and the sides of the port just ahead of the valve seat were opened up about 1/8-inch to form a mild venturi which would further accelerate the air/fuel mixture into the chamber. After these modifications had been made and the port polished smooth, Jerry removed most of the shrouding in the combustion chamber, making the inside of the head look surprisingly like a Chysler Hemi. The valve scat width was left stock.

Reinstalling the head on the flow bench, Jerry set up an open port (entry only) test to sec what improvements had been made. The results were astonishing! Flow in the open port was now 105.6-CFM, an open port increase of 37 percent!

With the valve and 32mm Mikuni carburetor in place, flow was up from 65.7-CFM at .350-inches lift to 73.3- CFM. The best part was that the flow continued to increase rapidly all the way up to .450 lift, drawing 81.5-CFM. In this configuration, the Honda Four engine can make use of a cam with really high lift, getting heavy charging of the cylinder, even at rpm's above 10,000. On the basis of dyno testing on other small displacement, multi-cylinder engines, Jerry believes that the required CFM for maximum use of the air/fuel mixture would be in the area of 75-CFM. This means that the modified Honda engine can be twisted to over 10,500 rpm without running out of air! The final figure for the modified port and 32mm Mikuni carburetor installation showed a 26.6-percent increase in flow, a tremendous gain for the small amount of reworking required.

The final test was with the stock Keihin carburetor on the modified head. Flow was restricted slightly by the 28mm throat on the Keihin, but at .450 lift the engine was still capable of pulling 72.4-CFM over the original 58.7- CFM. Asked to estimate a horsepower increase on the ported engine, Jerry said a 15-percent increase was in the ball- park!

On the exhaust side of the chamber, very little need be done other than polishing around the guide. This resulted in about a 10-percent increase in the area of the port just behind the guide. In normal practice, the exhaust should be capable of flowing about 85-90 percent of the intake rate. Jerry recommends that using straight pipes with megaphones, a flow rate of 85 percent be maintained. Since the Honda exhaust port comes very close to this in its stock state, very slight reworking is all that's necessary.

There you have it. If the extra power is wanted, it's available with porting. Those of you running large displacement Honda Four engines at the races would stand to gain the most from porting and polishing the head The results speak for themselves!

Monday, September 27, 2010

Barn-Find Beemer (sort of)

I didn't really need another project right now, but some bikes you just don't pass on. Especially not one you've been cultivating the lead on for a couple years.

This all started about 3 years ago when I was catching up with a long-time friend of my Dad's. He collects tractors, cars, radios, pipe organs, cameras, etc but I never knew before that he was into motorcycles. He was checking out my bike at the time and telling me about all the places he had been on his BMW bikes over the years. While we kicked around stories he mentioned an odd bike in his shed. A BMW with a volkswagen engine in it. The story was that he'd bought it about the time he stopped riding bikes, some 15-20 years ago. He ran it around his property a few times, but never bothered to tag it, and it was relegated to the barn fairly shortly never to be touched/started again. I was intrigued and told him I'd catch up and come over sometime and see it.

A year and a half or so went by and we hadn't seen each other again until I randomly caught up with him. He asked if I was still interested in seeing the bike. I hadn't forgotten about it, but I didn't have a garage at the time and wasn't going to take on a project like that, but I told him I'd see him soon. I got his number that time, though, and his eMail address. About 8 weeks ago I finally got a meeting set up to dig through his stuff and see this bike. It was in the back of an unlit barn, covered in boxes and blocked in by other bikes, but from what I could see I knew I needed a better look atleast. So 3 weeks ago I spent a good chunk of a Saturday helping him extricate the bike for pictures. Here's what I found.

For starters, this is the yard in front of this particular shed (one of several):

In addition to the 15 or so VW's left he parted out and scrapped another 21 he said. There's a shed full of VW engines and parts. There are also a number of Mercedes cars piled up and a building full of Mercedes engines and parts. Parts everywhere. My kinda guy.

When I got there on Saturday we started with the tour of the place. Besides the cars you can see, and the several dozen tractors not in the pics, here are some of the fun pictures.

On "the terrace" which is a lean to on the back of one barn were these two bikes. A 1961 or 1962 R50/2 BMW:

and a 60's R69S parts bike (those are his high socks, not mine):

In the corner of that picture you can see some of the stacked Mercedes car engines. Below the bikes, packed in between several tractors, was this 37 Mercedes car:

So that more or less sets the tone of the place, but it is one of those hordes you'd have to see to understand. The bike I came looking for was in this unassuming barn:

Opening the sliding doors that don't have sliders yet (he's only been there for like 30 years) I found this collection:

My camera decided to turn-off the antishake and I didn't know it until I got home, but you can't see the bike in this shot anyway. It's behind the silverwing on the left, under some boxes and a sheet. The bike on the right is his special bike. A 1960's R69S that he rode everywhere. We pulled it out first to make room to work in there (it's not for sale, I tried):

After we dragged the silverwing, stuck calipers and all, from the shed we revealed the BMVW for the first time in well over a decade.

Here's the BMVW out in the daylight:

I was kind of blown away with the quality of the work done on this conversion. The frame was stretched atleast 4" to fit the extra two cylinders, and BMW's don't use round frame tubes (oval) but I couldn't find any evidence of the work. They must have used pieces of another BMW frame to do it. Too cool. I know car-engine'd bikes aren't everyone's thing, but this is the classiest one I've seen. I had to have it. Here she is about to be unloaded from the trailer:

I can tell you this, I'm not changing hardly anything on the bike. The 80's aircleaners have to go, in favor of something older, and I'd like to make the turn signals a bit less obtrusive, but other than that all I want to do is make it run. The patina on it is great. Work's gonna be slow on it for now, I do have other bikes and projects that I need to finish first, but I wanted to share the barn-find pics with you guys. I need to get the engine loosened up, free up all the cables and controls, and preform the standard BMW maintenance that hasn't been done on this bike ever (like taking the trans out and lubing the input splines, crucial on the old airheads).

No idea how it'll ride, but damn it's a conversation piece isn't it?

Sunday, September 26, 2010

Got caught in 10%

Sometimes a little rain is relaxing.

Friday, September 24, 2010

Where the F is my Jetpack?

With such talk about jetpacks and futuristic junk pertaining to certain builds, this little diddy popped up on my radar. And it is spectacular.

More Pictures of the New Project

These bike photos are ripped directly off of Saint Motorbikes Blog because I didn't have a camera and Jeff stole one from one of his kids.

Here we are testing out the new oil/rocket tank on Tesla, Jeff's new project. I wanted a vertical oil tank to sit between the twin carb setup on the hardtail CB frame to free up some space behind the seat post and get rid of some of the void above the transmission.

This is what I came up with. 2.5 qt's of cappuccino capacity. It looks really odd off the bike, but fits right in on the frame.

Some other things on the bike are a new girder, some bar end levers, a leaf spring seat, and a Cycle X twin carb setup. I had been wanting to build this girder for quite some time. I liked the look of the side mounted springs of the old solid leg girders, but wanted a more modern feel while riding. With that in mind, I used two air shocks set with 50 psi each. For now, that gives it a good tight feel and a travel distance of 2.5 inches. The bar end levers fit the bike nicely and the leafer seat keeps with the lines and doubles as a moon bounce.

I really like the way the oil tank turned out on the bike. The bungs follow the angle of the seat tubes and it fits perfectly between the carbs. This is Jeff's favorite angle on the bike. Looking at the header pic on his site, you can see a pattern. Hmm? New header pic?

Since I am currently banished to working in a shed, Jeff offered me some space in his garage to do some work. I left last night a little before 2 am. The day before that was 3 am. Before that, 1 am. Thanks Jeff for the space and harassment!

I have a little slice of concrete right next to Tesla, the primary patient in Jeff's stable.

After getting 3 hours of sleep I woke up exhausted but I knew it was worth it. The best thing that came out of last night was this killer Pillow Hawk! Ohh and an evil twin to my left. He's not all that bad but he does remind me of someone. I just can't put my finger on it.

No, wait. I figured it out.

Thursday, September 23, 2010

First Day of Autumn

Grab your bike

Snag your friends

And hit the road (maybe with a few less windshields)

Fall is the best riding seasons in my opinion. By far the best scenery, the best weather, and the most ambition to get a few more miles in before the real cold hits.

Wednesday, September 22, 2010

New Project Teaser Photo

Hardtail with a new girder design. The size of my little escort is deceiving.

Thursday, September 9, 2010

My GrandPappies New Toy

My Granddad called me up a little while ago and asked me if I knew anything about the old military harleys used in WWII. We talked for a while about his old bikes and the one he was looking at. In the end it turns out the bike he had found was a hodge-podge of different parts and wasn't really what he was looking for. But at the root of the conversation, he was looking for a vintage motorcycle with a sidecar to putt around in. He's going on 84 and is as sharp as a fresh edge on sheet metal.

I took a look around and found a few things within his budget. In the end, he settled on a bike that reminded him of something he saw quite often during his time in Okinawa. The bike he is picking up is a 1977 BMW R100/7 with a nice sidecar. When he was in Okinawa, there were probably quite a few knock off's of the old BMW boxer engines floating about.

The 77 beamer has full luggage, windscreens for the hack and the bike, muddies, floorboards, new rubber on all three corners, and a pile of extras. The paint is in great shape and he's pretty happy about the whole thing.

Here are a few small pictures of the bike. I have to pick it up for him so I'll snag a few more pictures then. I'm going to go through it a bit, make sure things are kosher and then take it for a spin.

Nice looking bike! In a little bit we'll get something up about John's new find, which is also a BMW... Sort of.

Thursday, September 2, 2010

Souping-up a cheap seat hinge

We picked up a seat pan off eBay for the Hot-Rod Honda build. The pan is great, real thick and fits just right. It came with a free seat hinge, and the price was right but the hinge left a lot to be desired. For one thing, the tolerances were pretty sloppy with some washers to take up the slack. Secondly, the steel hinge rode on steel shoulder-bolts, which is ok for a little while but that will wear out way too fast for frequent riding. This is a budget build, and it wouldn't seem right to spend more on a seat hinge than the hardtail, so let's see what we can do with this freebie to make it usable.

Here's the patient. The shoulder bolts are very nice with precision shoulders, which will come in handy.

First order of business, if we're going to run bushings we need more room. We hogged the existing holes out to 5/8" on the mill and moved the center a bit closer to the hinge to it didn't punch through the edge. After that, we made a tube to weld in. The ends are bored to 1/2" on the lathe and it's just a bit wider than the existing hinge to leave some room for weld.

Slipped the tube into the hinge and welded around it. After the tube was fully welded we milled out the excess material in the middle until only the bearing reliefs were left. A little grinding and it looks like it was one piece again. Even though the material in the middle gets cut away, the tube ensures that both bushings will be perfectly aligned.

Now that there's enough material for a suitable bushing there needs to be room for a flange on each bushing to take care of side-thrust. The lathe made short work of reducing the width of the center piece by .060" on each end.

Whipped up some nice bushings with flanges on the lathe. Here is the new and improved kit. The end result is that it fits like a glove, and moves much much smoother. Here's a hinge that'll provide years of solid riding and didn't break the budget on this build.