Author Topic: 1350cc Pushrod bike  (Read 51921 times)

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Offline JimL

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1350cc Pushrod bike
« on: January 23, 2010, 11:04:02 PM »
Not much to show, yet.  Heads are out getting porting along with bigger seats and valves (oversize CR750 valves fit, from the old 2 valve heads, though these engines are 4 valve cylinder heads).  I don't have enough heads in hand to show what it should look like....these are a pair of spares, while the good ones get fixed up. 

The rear frame section (above the wheel) is still the old Katana parts....that gets chopped off.  I'm going with .122 wall, 1 5/8" DOM for all 4 main frame tubes....I want this chassis STIFF.

Carbs will be 40mm on each cylinder (4).  Cams are out for rework (setting up to run 10-11,000 RPM for peak power).  I had good luck running the 500 up to 11,000 last year, though it ran poorly due to metal going through the carbs and flooding the back cylinder. 

These engines are actually 674cc (though it says 650cc on the block), which equals 1348cc total.

I'll have to move the upper shock mount back, in order to get the engines closer to the swing arm pivot.  It also looks like the front wheel may have to go forward a few inches.  The rear suspension question is still not certain...I'm running out of real estate, quickly.

The engines will be angled, approximately as shown, to allow coupling crankshafts direct using 6" straight cut, spur gears.  Both engines will have starters (working together), and their original ignition triggers and modules.  It uses a single clutch and trans (close ratio 5 speed from the 500, plus lower ratio primary drives to reduce trans and countershaft RPM).  This thing will not be much fun getting off the line.

Because the oil pumps had to "go", and the spur gears would drag in a "bath", the system will be dry-sumped with external pump.  Since the bike will be APS (only), the radiator and various tanks will have to live sideways in the fairings.

Cooling system ditches the original cam driven water pumps for a high output electric.  All electrical is from 2 batteries, contant loss system.

Tomorrow will be temporary bolting up the crankcases, to get accurate measurements before we water-jet the primary drive main connection plate.  If I can get an extra knee installed in my left leg, I might be able to clear the rear carb!  The wheel base is currently identical to the 500cc bike I ran last year.

JimL


Offline Beairsto Racing

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Re: 1350cc Pushrod bike
« Reply #1 on: January 24, 2010, 01:15:03 AM »
Cool project!
I enjoyed looking over your 500 in the line up last year at Speed Week after following the build diary.
I recall you mentioning that the 500 chassis was built to handle 2 engines.
Good luck with the new build.

Scott
2 Club since '02
Sponsored by: Turple Bros.,
Palliser Chevrolet, Hose Headquarters, Bentley's Motosicle Pain Tin, The Window Man

Offline JimL

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Re: 1350cc Pushrod bike
« Reply #2 on: January 26, 2010, 01:31:15 AM »
I've figured out how to keep the wheelbase under control, by angling the engine package down at the back and up at the front.  With the cases bolted together, I found I can position the forks at 32 degrees, with 7.1% trail/wheelbase ratio.  The rear, upper shock mount has to be "flipped" and some frame cut away to clear the rear head and exhaust.  Wheelbase is identical to last years bike, but a little more rake and trail.

I'll have room for about 2 1/2" suspension travel, front and rear.

Working on the crank gear arrangement, I've mocked up the arrangement shown (the center gear is foam board, at the moment).  Using crank gears (connected to each clutch basket gear), and a single central large gear (an extra clutch basket gear), I have much better access to bearing support for the additional shafts.  This eliminates cutting and welding up oil passages, and leaves room to add high pressure oiling to each of the idler gear bearings.

The dry sump pump can run from the forward small idler, because the clutch basket goes away on the forward engine (just the gear will be left behind).

JimL

Offline JimL

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Re: 1350cc Pushrod bike
« Reply #3 on: January 26, 2010, 09:33:43 PM »
Long story shortened.   :-P  Long conversation with an engineer who worked on geared cranks.  Bad way to go for a novice.

He says get connected by Gilmer belt, from one clutch gear to another (mine have damping springs in them).  It'll mean no machining on the cases, but a little more work to make shafts and bring them outside.

Sure glad I wasn't farther along!

Offline JimL

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Re: 1350cc Pushrod bike
« Reply #4 on: February 01, 2010, 01:59:34 AM »
Engines are mounted to my motor plate....2 days to hand carve these parts, then joined with 1" square bar stock.  Still some more fill and weld to do, then start making cover plates with bearing carriers for the belt drive between the 6" gears.  The belt will run on 3-4" gears, to keep surface speed below within reason.

The Katana frame head will be cut away considerably, before I can start bending tubing (need my other heads to move ahead).  Also shown is one of my "reduced" flywheels and my 18T sprocket.  The swing arm pivot is as close as possible, because the rear sprocket will only have 30-31 teeth.  The chain runs will be close, top and bottom, but ok for 2" of travel.  There's a rear view, along the swing arm, showing countershaft sprocket position.

Still have to figure out where to mount and drive the dry sump pump....the belt drive runs backward, so that won't work.

More to come.

JimL

« Last Edit: February 01, 2010, 02:51:39 AM by JimL »

Offline WhizzbangK.C.

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Re: 1350cc Pushrod bike
« Reply #5 on: February 01, 2010, 04:26:37 AM »
Just thinking out loud here. Would it possibly work out better to use a belt to link power from the 2 engines at the trans output shafts? You would have to synch the shifters and use both transmissions, but it could be done. Belt speed would be much lower, and it seems to me that it would simplify fabrication quite a bit. You could probably even adapt late model H-D final drive belt and pulleys. In my mind it seems that it would result in a more robust setup with less stress on all the parts. Maybe use a vacuum booster to help with pulling both clutches.

Like I said, just a thought. I've been quite impressed by your work so far, so I'm sure that what ever you decide to do will be top notch.  :cheers:
Ah, this is obviously some strange usage of the word 'safe' that I wasn't previously aware of.  Douglas Adams

Offline oz

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Re: 1350cc Pushrod bike
« Reply #6 on: February 01, 2010, 02:10:07 PM »
Wahoo Excellent!!!
Newcastle born and bred a City built on Coal and Steel and a people built of stronger stuff

Offline 1212FBGS

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Re: 1350cc Pushrod bike
« Reply #7 on: February 01, 2010, 03:47:50 PM »
Jim
shouldn't you be out changing floor mats and gas pedals?
Kent

Offline nrhs sales

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Re: 1350cc Pushrod bike
« Reply #8 on: February 01, 2010, 05:58:12 PM »
So will this be run in special construction class then?

Offline Stan Back

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Re: 1350cc Pushrod bike
« Reply #9 on: February 01, 2010, 07:12:18 PM »
Kent --

I don't think he recalls.

Stan
Past (Only) Member of the San Berdoo Roadsters -- "California's Most-Exclusive Roadster Club" -- 19 Years of Bonneville and/or El Mirage Street Roadster Records

Offline JimL

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Re: 1350cc Pushrod bike
« Reply #10 on: February 01, 2010, 10:43:37 PM »
Whizzbang....I did look at that, but I have the lower primary ratios (2.242:1) installed (and closer, lower ratio transmission gears), so my belt speed will be less on the engine primary reduction than it would be on the end of the trans (trans has overdrive).  This arrangement is about as short as I can get, and certainly the slowest with a small pulley set.  Also, this lets me determine where the engine rotations are, and eliminates the drag of "two overdrives".

I also had the advantage of guidance from people learning to make horsepower through two cranks.  Pictured below are the flywheels (lighter on the "drive out" engine)....not a great pic...sorry.  The front flywheel is quite a bit heavier than the rear; before you ask, I don't know why....just following directions!  That's the good part about bein' not so bright; smart folks help you out, figurin' 'what can it hurt?'

The other problem for connecting output shafts, is the wacky layout on the "left" side of these engines.  The shift drum is on the "wrong end" of the engine, right under the countershaft, plus shift linkage arms, flywheel, starter, starter drive, ignition...all in between the countershafts...gets ugly.

nrhs....yes, "A" class, and it'll be "APS" only, because there is too much gear in too small a space.  There will be things hanging off the bike, all the way up into the fairing, which will make it impossible to enter as a naked bike.  I'm still struggling with the dry sump pump (which is a MUST HAVE due to the rear engine lay down, which would flood the trans if I wet sump).  I may have to open part of the front engine forward case area, to make room for the dry sump pump, bringing the lines out the side of the motor plate.

When I first ran Bonneville in 1969, I was fascinated by Don Sligers dual Enfield.  To my eye, it was perfect, and I've dreamed of building a twin engine bike ever since.  I don't know if it'll work as good as his did, but I'll always appreciate that memory.  That's as good a reason as any to give it a try.  Thanks Don!

JimL

Offline wobblywalrus

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Re: 1350cc Pushrod bike
« Reply #11 on: February 01, 2010, 11:43:04 PM »
Upside down forks used to be exotic but they are more common now and some used ones are showing up at decent prices.  They have a lot more strength and rigidity in the triple clamp area than regular forks.  Just a thought, if a guy could find a set for a bargain, they may be a good idea on a big, long and powerful bike, especially if the salt is wet or rough.

I am learning a lot from your build, especially how to set up the chassis on the bench, how to position things, etc.  This is a nice bike.  Thanks for posting the pictures.   

Offline JimL

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Re: 1350cc Pushrod bike
« Reply #12 on: February 02, 2010, 12:15:50 AM »
Thanks for the tip about the forks...not sure if there are any that would fit this frame head, and any that aren't already wrecked can't be cheap.  I can brace the triple clamps, like we used to do for road race in the old days.

A note about the table; the bolt holding the wheels down (through the tubeless tire stem hole) is "washer shimmed" underneath, between the 3/4" ply and the steel table frame.  The 3/4" ply is raised from the bed and shimmed everywhere for level.  On each side of the wheel contact point, just outboard of the edge of the rim, is a bolt through the table bed and the table frame WITHOUT washers between.  Very small changes in tension, on these two bolts, adjusts the vertical position of the front and rear wheels.  After it's set and "settled" for a bit, finish any adjustment needed, then tap some shims in to keep it from sagging.

It's kind of a poorman's adjustable workbed.  It'll hold shape long enough to get tubing welded, and after that won't matter so much.

Table is on casters, also...really important when building in a restricted space.

Offline John Noonan

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Re: 1350cc Pushrod bike
« Reply #13 on: February 02, 2010, 12:42:49 AM »
Jim,

I am sure I have a good straight set of upside down/inverted front forks with wheel and brakes...if you can come and get them they are yours..pm if interested..


John

Offline JimL

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Re: 1350cc Pushrod bike
« Reply #14 on: February 02, 2010, 01:12:46 AM »
Thanks John....I have to figure this PM thing out.  I never noticed the MY MESSAGES and have been ignoring people for years!  My apologies to everybody....especially the nice fella' from Pulishers Clearinghouse (I didn't hear the doorbell, either!)

 :oops:JimL