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Bonneville Salt Flats Discussion => Build Diaries => Topic started by: JimL on December 01, 2011, 10:53:29 PM



Title: APS-PG-650 prep for 2012 Speed Week
Post by: JimL on December 01, 2011, 10:53:29 PM
This'll be short because the bike is primarily an engine change and a little tune-up on balance, CG, and aero.  Most important; at last SpeedWeek Tom Evans saw my adjustable chain run guide, and asked me to post a picture.  This guide came about because I had difficulty feeding chains through this bike.  The Suzuki swingarm tends to feed the chain into the wedge ahead of the sprocket.  It instantly jams the wheel and can be a struggle to free.

Then a bike at ElMo had a chain break and jam the wheel.  I decided to try to do something about the issue, and this is what I've made.  It's simply an adjustable shelf that feeds the chain off the sprocket and keeps it going forward, instead of into the "wedge".  I hope I never need it at speed, but it sure is easier to put on the chain these days!

Also shown is my gantry for loading, unloading, or work-positioning the bike.  Due to long wheelbase and low clearance, I had an awful time loading/unloading or working on the bike.  Also, I have heavy tabs welded to the frame tubes and I bolt the bike down to a floor bracket for all transportation (quick and easy on the return road).  It is a little difficult to get lined up perfectly, so this gantry lets me drop into the bracket.

It works great for single-handed loading/unloading, and I've added hoops on the outside of each fender to catch the tires for a raised work position.  I'll make a positive stand that uses my ground stand "pass through shaft", to lock the bike in the work position with the gantry swung out of the way.

Regards, JimL



Title: Re: APS-PG-650 prep for 2012 Speed Week
Post by: Beairsto Racing on December 02, 2011, 05:11:22 AM
Jim,

Thanks for posting, that's a great tip about the chain guide. :cheers:
We are building a new swingarm for the Double and will add this to the design.

Cheers,
Scott


Title: Re: APS-PG-650 prep for 2012 Speed Week
Post by: Koncretekid on December 02, 2011, 08:04:01 AM
I try not to lose the chain when changing sprockets, of course, but if I have to remove the chain, I usually clip on another used chain and pull it thru.  Then to replace the new chain or cleaned chain, simply clip onto the used chain which is still in place and pull the new one onto the sprockets.  You just have to remember to bring an old chain with you, even if it's just a piece of cheap industrial chain, sufficiently long to clip the ends together.

As for the gantry, I am thinking of building a simple tube frame that will fit in my trailer or can be removed to place over the bike and use a come-along to pick the bike up.  I'm sure it's been bone before.  Any photos out there?

Tom


Title: Re: APS-PG-650 prep for 2012 Speed Week
Post by: edinlr on August 14, 2012, 11:14:47 PM
Congrats on the new record Jim. 150.176 on a 116.54 record, awesome. :cheers:


Title: Re: APS-PG-650 prep for 2012 Speed Week
Post by: wobblywalrus on August 15, 2012, 12:21:16 AM
That is a good record, Jim.  It might be there awhile.


Title: Re: APS-PG-650 prep for 2012 Speed Week
Post by: edinlr on August 16, 2012, 12:44:14 PM
Not likely, I am sure Jim is targeting a certain Triumph in as many classes as he can.


Title: Re: APS-PG-650 prep for 2012 Speed Week
Post by: JimL on August 19, 2012, 01:06:47 AM
Thanks fellows....that first run was pretty weak at 140.7 but I didn't have the get-up-n-go (in several ways) to do it over.  The bike was showing 160+ by the tach, on the return run, which makes sense with quarter speed in 158 range and mile at 159.616.  This is almost exactly our best speed last year on two of our runs, despite jumping compression to 14.3:1.  This will take some puzzling, I am afraid.

Not good to feel stuck!  I am itching to get this thing faster, but not sure where to scratch. :?  Have a good BUB and build season.

JimL

P.s.  Forgot to mention.... The gantry is awesome....so easy to load and unload and nobody hurt this year!  Also nice not needing tie downs during the event....just the two shouldered bolts that lock the bike to the trailer at the frame tabs.


Title: Re: APS-PG-650 prep for 2012 Speed Week
Post by: wobblywalrus on August 20, 2012, 01:05:47 AM
Jim, why not put your engine data into PipeMax with your rear wheel horsepower multiplied by 1.1 and use the option to calculate volumetric efficiency?  This can tell you if the engine is already about as good as you can make it be. 


Title: Re: APS-PG-650 prep for 2012 Speed Week
Post by: DND on August 20, 2012, 08:56:41 PM
Hi Jim

Not sure how you bumped C/R , if a taller piston dome was used maybe it hurt the flame travel or flow in the chamber.

The higher C/R for use in the thin air might be off set by the other mods to the piston, everything is a trade off.

Don


Title: Re: APS-PG-650 prep for 2012 Speed Week
Post by: wobblywalrus on August 20, 2012, 11:44:44 PM
This is what I am hinting about with volumetric efficiency.  Lets say you are between 110 and 115 percent with a NA gasoline engine.  The motor is very efficient and it is hard to gain anything without losing something else. 


Title: Re: APS-PG-650 prep for 2012 Speed Week
Post by: JimL on August 21, 2012, 10:12:56 AM
Yes, piston dome is higher than last years engine.  Mile 2speed is much better, but apparently no help past 10,000 rpm in 5th gear through the 3rd mile. 

Also, These pushrod heads have the intake ports very low, designed to keep the carbs out of the riders knees in the original shaft drive configuration.  This may be the classic case of "trying to make a silk purse out of a sow's ear", as grandpa used to say.  Certainly a very compromised design, to the point I cannot get the intake lengths even ( or short enough) due to the intake port position so close to the cylinder block.  Rocker arm geometry is also poor due to low valve cover design.  I read, somewhere, that Honda wanted this to be an automatic trans bike suitable for lady riders.

Of course, it's a lot more fun to be an "armchair engineer" so I can complain about the design! :lol:  this is always a fun hobby....we just have to keep changing things or we'd be bored in our old age.

Thanks for the good advice/insight.
JimL


Title: Re: APS-PG-650 prep for 2012 Speed Week
Post by: edinlr on August 21, 2012, 11:12:39 PM
Jim,  I have to wonder if you are getting enough fuel.  With 250 dirt bikes running up to 50mm carbs and fi and all the 1000 fours having big units, this might be an issue on top.  Years ago we starting running dual Holley dominators when all the experts said it was too much, and yes the cars picked up hp.


Title: Re: APS-PG-650 prep for 2012 Speed Week
Post by: JimL on August 22, 2012, 10:21:38 AM
Probably right....I like the idea of a pair of pro-series 41s (currently have pro-series 39), but cost and fitment issues abound (the larger body is a problem for this engine design).  Behind all the "stuff" we've done to this bike is still the problem of small money and short on knowledge.  What I have works fairly good, but I could screw it up if I go the wrong way....and break things I cant replace.

I haven't figured out the flaw in the Navaho rug, and it's making me cautious. :?

Regards, JimL


Title: Re: APS-PG-650 prep for 2012 Speed Week
Post by: Koncretekid on August 22, 2012, 07:45:56 PM
Jim,
Congratulations on your successful record run.  Maybe the CX650/500 motors aren't perfect, but they have a lot of potential with 4 valve heads compared to our old British bikes, and seem to outperform anything Harley can throw at it!  I'll be on my way to BUB on Friday morning, albeit without (yet) having started it  up after total reconstruction after Loring.
Tom


Title: Re: APS-PG-650 prep for 2012 Speed Week
Post by: wobblywalrus on August 22, 2012, 08:20:13 PM
Most of the hotter Hinckley Bonnevilles use 39 mm flatslides that have 36 mm choke diameters.  This seemed too small of a carb to me.  Some talking to experts and figuring shows me that peak flow through a single carb on a single cylinder only happens for a small portion of the combined intake and compression cycle.  Carb size is not as important as maintaining proper flow velocities, flow inertia, and acoustics, is what I gather.   


Title: Re: APS-PG-650 prep for 2012 Speed Week
Post by: RidgeRunner on August 22, 2012, 09:45:53 PM
     I think you are gathering well.  PM sent.

             Ed