Author Topic: Classic Bonneville Racer  (Read 39449 times)

0 Members and 1 Guest are viewing this topic.

Offline Old Scrambler

  • My CB750K3 has been in 39 States & 5 Provinces
  • Old Timer
  • ******
  • Posts: 3,221
Re: Classic Bonneville Racer
« Reply #25 on: March 24, 2014, 07:51:51 am »
Bill..........The frame has already gotten a serious haircut.............time for a shave ;D ;D

Actually I think the few thou of clearance is more likely the result of the HD-studs in your build. our practice session included a loaded head. Dave likes the original machined studs so I removed them from my list of needed parts............but will use the HD-stud-nuts.
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
'63 CL72 Project(s)
'66 CL77 Red
'67 Triumph T100C
'73 750K3 Owned since New
'77 750F2 Cafe Project
2000 Aprilia Pegaso

Offline SF

  • Hot Shot
  • ***
  • Posts: 477
  • I burn gas very well
Re: Classic Bonneville Racer
« Reply #26 on: March 24, 2014, 10:02:03 am »
subscribed
92 wr250 sold
98 zx6r sold
04 zx10r
73 cb350 twin
75 cb550f
75 cb550f
72 r5c
rgid springer bobber project

Offline Bill/BentON Racing

  • Really Old Timer ...
  • *******
  • Posts: 6,691
  • Ex Honda Service Manager, Cert. Honda Tech - Racer
    • BentON Racing
Re: Classic Bonneville Racer
« Reply #27 on: March 24, 2014, 12:47:51 pm »
K, getting ready to pull it to adjust valves, don't like going thru the tappet holes for clearances over .004". Tha blades as they get thicker.....they can fool you....ask me how I know! ;D Also a 350f tank can mount coils underneath still. Also will have to loosen them to remove cover, Bill
BentON Racing Website
OEM Parts | Service | Custom Builds
BentON Racing Facebook
Over 35 years of experience working on vintage motorcycles, with a speciality in Honda SOHC/4 with a focus on the CB750 and other models as well from 1966 - 1985.
______________________________________
1993 HRC RS125 | 1984 NS400R | 1974 Honda CB750/836cc (Calendar Girl) | 1972 CB 500/550 Yoshi Kitted 590cc | 1965 Honda CB450 Black Bomber | 1972 Suzuki T350 | 1973 88cc | Z50/Falcons Pit Bike | 1967 CA100| 1974 CB350 (400F motor)...and more.
______________________________________
See our latest build 'Captain Marvel' CLICK HERE

Offline 754

  • Really Old Timer ...
  • *******
  • Posts: 25,383
Re: Classic Bonneville Racer
« Reply #28 on: March 24, 2014, 04:14:17 pm »
Just bend the 1.26 cent feeler guage..
 So on my A frame I should shave that middle seam,  below the neck. ?
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline Old Scrambler

  • My CB750K3 has been in 39 States & 5 Provinces
  • Old Timer
  • ******
  • Posts: 3,221
Re: Classic Bonneville Racer
« Reply #29 on: March 24, 2014, 04:26:54 pm »
I just discussed this with Dave M. and we are only going to 'dress' it to avoid sharp edges.  That flange adds strength to the neck.
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
'63 CL72 Project(s)
'66 CL77 Red
'67 Triumph T100C
'73 750K3 Owned since New
'77 750F2 Cafe Project
2000 Aprilia Pegaso

Offline Bill/BentON Racing

  • Really Old Timer ...
  • *******
  • Posts: 6,691
  • Ex Honda Service Manager, Cert. Honda Tech - Racer
    • BentON Racing
Re: Classic Bonneville Racer
« Reply #30 on: March 24, 2014, 04:55:22 pm »
Agree, only talking a few thousands, I wouldn't remove it or relieve it much.
BentON Racing Website
OEM Parts | Service | Custom Builds
BentON Racing Facebook
Over 35 years of experience working on vintage motorcycles, with a speciality in Honda SOHC/4 with a focus on the CB750 and other models as well from 1966 - 1985.
______________________________________
1993 HRC RS125 | 1984 NS400R | 1974 Honda CB750/836cc (Calendar Girl) | 1972 CB 500/550 Yoshi Kitted 590cc | 1965 Honda CB450 Black Bomber | 1972 Suzuki T350 | 1973 88cc | Z50/Falcons Pit Bike | 1967 CA100| 1974 CB350 (400F motor)...and more.
______________________________________
See our latest build 'Captain Marvel' CLICK HERE

Offline Old Scrambler

  • My CB750K3 has been in 39 States & 5 Provinces
  • Old Timer
  • ******
  • Posts: 3,221
Re: Classic Bonneville Racer
« Reply #31 on: March 29, 2014, 04:13:17 pm »
Pics of J&E Pistons.........12.5 to 1 compression for a K-head...........no spark-plug relief..........35mm wide valve pockets. All sharp edges will be 'smoothed' and the pockets will be widened for better clearance. We set pieces of head-gasket on the F2 head to gauge the piston depth in the chamber. Good clearance at the spark-plug and should be OK for depth on the valve pockets.  Did not get an exact measurement, but the piston has about 2mm of thickness at the deepest part of the valve relief.

 





Cylinder will go to Millennium Tech for boring next week along with pistons.  When they return each piston will be marked for a specific hole.  They are already marked to keep the valve-reliefs in the proper places. 
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
'63 CL72 Project(s)
'66 CL77 Red
'67 Triumph T100C
'73 750K3 Owned since New
'77 750F2 Cafe Project
2000 Aprilia Pegaso

Offline joesmotos

  • Enthusiast
  • **
  • Posts: 213
Re: Classic Bonneville Racer
« Reply #32 on: March 29, 2014, 07:24:51 pm »
Just curious..do you use a burette to measure actual compression ratio vs what they tell you it is?

I ended up getting a burette from a medical supply outfit to check mine when the time comes,in the past i never went to that extent but now that i have more time available i figure i will just so i know for myself..

I know when the dragrace guys come out to Bandimere dragstrip in Denver for the Mile High Nationals they run higher compression on the Pro Stock bikes cause of the altitude..i am thinking higher compression would be a good thing out on the salt also..

nice looking pistons though,never had issues with JE myself..

Offline Old Scrambler

  • My CB750K3 has been in 39 States & 5 Provinces
  • Old Timer
  • ******
  • Posts: 3,221
Re: Classic Bonneville Racer
« Reply #33 on: March 30, 2014, 10:57:44 am »
Joe.........the 12.5 to 1 is 'as advertised'.  Dave measures the chamber volume and calculates static-compression (motor is running-in-place) with a known air-factor.  Actual compression is just a guide to estimate the available-cylinder pressure when intake-volume is optimized.  Although we hope to have 13-1 or better compression calculated at about 800-ft above sea-level (the bench in Dave's shop), we are trying to design the airbox to supply sufficient air on each intake-stroke as the bike goes faster versus the usual lack of enough air caused by adverse turbulence or drag on the intake-stream. 
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
'63 CL72 Project(s)
'66 CL77 Red
'67 Triumph T100C
'73 750K3 Owned since New
'77 750F2 Cafe Project
2000 Aprilia Pegaso

Offline joesmotos

  • Enthusiast
  • **
  • Posts: 213
Re: Classic Bonneville Racer
« Reply #34 on: March 30, 2014, 11:18:01 am »
Cool...love to see the finished airbox...will it have some sort of ram air incorporated into it?Always interesting to add those sort of things into the old technology and constraints of OEM frames...you gotta be really creative!..Bet that baby is gonna fly...cant wait to see it..on top of the sound it makes..im already getting excited about going back and we have what,5 months yet?..This is gonna be a hoot..

Offline Old Scrambler

  • My CB750K3 has been in 39 States & 5 Provinces
  • Old Timer
  • ******
  • Posts: 3,221
Re: Classic Bonneville Racer
« Reply #35 on: March 30, 2014, 01:01:59 pm »
Yes, its exciting to 'build' something for a once-a-year event. Especially when you know that a record is within reach..........if the motor stays together ;) ;) ;)

Air-flow to the airbox is planned but is a design in progress. It has to fit either over, or along the side of the motor. The duct(s) also has to fit within a fairing in case I want to run in the Partial-Streamline class. I have my eyes on a slightly modified CR fairing but have yet to place the order.  A stock airbox will fit but may be pushed back somewhat to allow for extended intake manifolds. 

Chassis-building for this type of competition allows us to be quite creative.  No need to be street legal or worry about cornering or brakes.  It just has to go in a straight line with NO speed-wobble.  Then a good deal of effort goes into avoiding turbulence and drag. When you get into speeds well over 100 mph the aero-design effects horsepower and speed. The air has to be mostly pushed to the side to avoid excessive drag off the rider's back and to eliminate upward 'lift' at the rear.  The really fast guys have an expression..........."Its not how you open the hole, its how you close the hole."  What that basically means is that a poor shape and/or tail-design can require more power to overcome drag than the power it took to open the hole in the air at the front.   
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
'63 CL72 Project(s)
'66 CL77 Red
'67 Triumph T100C
'73 750K3 Owned since New
'77 750F2 Cafe Project
2000 Aprilia Pegaso

Offline Old Scrambler

  • My CB750K3 has been in 39 States & 5 Provinces
  • Old Timer
  • ******
  • Posts: 3,221
Re: Classic Bonneville Racer
« Reply #36 on: May 03, 2014, 07:40:59 pm »
A small update....................Ordered a lot of parts........some have arrived including the reinforced valve cover and the latest primary and cam-chain tension designs from CYCLE-X.  Expecting the valve-train items any day now...........and the special grind cam should be here in a couple of weeks.  We've been fitting various wheels and today decided on a pair extracted from some off-brand bike. But they are lighter and stronger than another other 18-inch & 19-inch combo we know of. We also have started to align the frame with the swingarm and forks to get everything as straight as possible.........notice the laser-beam ;)
 [imghttp://][/img]

We are working with a small tank and will remove part of bottom and tunnel to allow room for coils and air-flow.
Before:



In Process

« Last Edit: May 04, 2014, 05:41:44 pm by Old Scrambler »
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
'63 CL72 Project(s)
'66 CL77 Red
'67 Triumph T100C
'73 750K3 Owned since New
'77 750F2 Cafe Project
2000 Aprilia Pegaso

Offline bwaller

  • Really Old Timer ...
  • *******
  • Posts: 7,041
Re: Classic Bonneville Racer
« Reply #37 on: May 04, 2014, 05:21:52 am »
Important work indeed Dennis. There is only one picture open, are there two more?

I watched a couple TV episodes about five or six motorcycle teams from the UK that made the trip to Bonneville, and all the trials & tribulations involved. It was well done and fun viewing.

Offline Old Scrambler

  • My CB750K3 has been in 39 States & 5 Provinces
  • Old Timer
  • ******
  • Posts: 3,221
Re: Classic Bonneville Racer
« Reply #38 on: May 04, 2014, 05:50:39 pm »
OK..........fixed the pics..............The tank must hold a minimum of 5-Liters.  We have restricted the shock-stroke to about 2.5-inches. Now hunting for some short springs. 



Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
'63 CL72 Project(s)
'66 CL77 Red
'67 Triumph T100C
'73 750K3 Owned since New
'77 750F2 Cafe Project
2000 Aprilia Pegaso

Offline Old Scrambler

  • My CB750K3 has been in 39 States & 5 Provinces
  • Old Timer
  • ******
  • Posts: 3,221
Re: Classic Bonneville Racer
« Reply #39 on: May 05, 2014, 05:39:45 pm »
Tires arrived a few days ago from separate vendors...............Bridgestone Battlax BT-023 110/80ZR-18 on the rear and a BS Battlax T-30 110/80 ZR-19 on the front.  I bought them through Amazon.com for the best prices.  Those are the narrowest and tallest tires I could find with the desired speed-ratings. The front is a W-rated tire on the order but came with the Z-rating on the sidewall.  I think the difference between the BT-023 (the 19-inch is no longer available) and the BT-T30 is a vary slight change to the tread design. I am running a 2.5-rear rim and a 1.85-front.

The shocks are new Mullholand units that Dave sourced a few years ago at a swap-meet. The proper rear axle with adjusters arrived today so now we can proceed with a rolling chassis.  We have to measure sag when we fit the shock springs and take an educated guess about springs and oil-weight in the forks...........again.......only about 2.5-inches of travel is desired...........but it has to be dampened properly. By rule, a working steering dampener will be fitted from the lower tree to the frame. 
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
'63 CL72 Project(s)
'66 CL77 Red
'67 Triumph T100C
'73 750K3 Owned since New
'77 750F2 Cafe Project
2000 Aprilia Pegaso

Offline Greg H

  • When two cams is one too many .
  • Hot Shot
  • ***
  • Posts: 366
  • Still crazy after all these years .
Re: Classic Bonneville Racer
« Reply #40 on: May 11, 2014, 01:50:37 am »
Very interesting build  8). Looking forward to seeing how the motor turns out  :) :).

Offline 754

  • Really Old Timer ...
  • *******
  • Posts: 25,383
Re: Classic Bonneville Racer
« Reply #41 on: May 11, 2014, 09:47:38 am »
You got parts on the way, should get them in a few days..

I hope the pistons are thicker than 2mm in the pockets..( not sure what general rule is on that)..nice slugs..
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline bwaller

  • Really Old Timer ...
  • *******
  • Posts: 7,041
Re: Classic Bonneville Racer
« Reply #42 on: May 11, 2014, 10:24:10 am »
I have to agree with Frank about the crown thickness at the valve pocket. Going back I see you mention not getting an exact measurement, but 2mm seems pretty thin. I'm no expert but when I had mine made I was advised to use a minimum of 0.170" at the VP and 0.100" VP to ring groove.

I know this isn't J&E's first attempt at making a piston, so you can take this with a grain of salt until you hear differently...or get an exact measurement  ;)




Offline Old Scrambler

  • My CB750K3 has been in 39 States & 5 Provinces
  • Old Timer
  • ******
  • Posts: 3,221
Re: Classic Bonneville Racer
« Reply #43 on: May 11, 2014, 04:34:39 pm »
No expert here, either ;D ;D ;D Any and all advice is constructive :)

We have made a few changes regarding the valve-train...........so tomorrow we will be ordering a few things from a source not known to me from these pages.  But the products sure are nice and they make Dave happy. Secrets will be revealed when proven to be successful. The super-flow valves will need lash-caps and the beehive springs will have plenty of clearance to get the spring-pressure up without guide/seal interference.  The little Ti-retainers look like something from a jewelry store 8) 8) 8)

Pistons will be measured for pocket thickness along with setting up to enlarge the valve pockets......not deeper, just wider.

Frank, Thanks..........will look for the parts in the mail. 
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
'63 CL72 Project(s)
'66 CL77 Red
'67 Triumph T100C
'73 750K3 Owned since New
'77 750F2 Cafe Project
2000 Aprilia Pegaso

Offline Old Scrambler

  • My CB750K3 has been in 39 States & 5 Provinces
  • Old Timer
  • ******
  • Posts: 3,221
Re: Classic Bonneville Racer
« Reply #44 on: May 17, 2014, 04:44:40 pm »
Thanks for the parts, Frank. One mount and the plug will get used on the build.

We measured the valve pockets at about 6mm for piston top thickness.........so all is well.

Selected Yamaha 550 Secca wheels as they are light, strong, the correct size (19x1.85 F; 18x2.15 R) and they fit the swing-arm with plenty of room for the sprockets we plan on using. The brake-plate stay will align with one of the lugs on the swing-arm. We did have to make a shim-plate to align the sprockets so now looking for 8-mm longer studs.  Now I feel comfortable to order sprockets in 1-tooth increments starting at 45 and going down to 39.  Now this may sound optimistic...........but according to the speed calculator with a 25-inch diameter tire, IF the motor will pull 9,000 rpms in top gear, we should be hitting speeds of 150 to 180+ mph depending on the final drive ratio. I plan to start with an 18 / 43 combo, so a little over 150 is possible.  DID you SEE the IF..........

Rear Wheel alignment


Shim-Plate


Moved the oil-filler to inside of the frame-rail and made the tank about an inch narrower


Inside of oil tank


Little by little................I would never get this done by myself.  Dave builds between customers at his salvage yard and putting a few of his own bikes together.
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
'63 CL72 Project(s)
'66 CL77 Red
'67 Triumph T100C
'73 750K3 Owned since New
'77 750F2 Cafe Project
2000 Aprilia Pegaso

Offline johno

  • Expert
  • ****
  • Posts: 1,083
Re: Classic Bonneville Racer
« Reply #45 on: May 19, 2014, 01:52:03 am »
Good progress Dennis, well done.  Funny thing I have never cut up a Honda oil tank so I love the pic.

I am installing the new pistons tonight in a mock up only to check clearances and have a look at the shape and chamber. Will do this cos the dynoman JE pistons are different to the JE pistons we have all over the top crown.  I'll have a look this week and make the decision on the crown shape. How are yours progressing ?
ciao johno
cheers johno
GRASSHOPPER SOHC HONDAS ARE THE MEANING OF LIFE.

Offline Old Scrambler

  • My CB750K3 has been in 39 States & 5 Provinces
  • Old Timer
  • ******
  • Posts: 3,221
Re: Classic Bonneville Racer
« Reply #46 on: May 19, 2014, 06:37:05 am »
We will know a lot more in a few days............all motor parts should be on the bench by the end of the week.  Did your initial pistons have the J&E logo inside?

We weighed the pistons and found a 4+gram difference from lightest to heaviest.  They will all get lighter when the valve-pockets get wider to fit the 35mm intakes.  Dave noticed the J&E letters on the heavier pistons were more visible than on the others............so we assume the weight difference is on the underside of the faces.  After Dave polishes the sharp edges away on the crowns...........he assures me they will all be equal. BTW............we do not require plug-reliefs in ours due to clearance in the F2 head :) :) :)
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
'63 CL72 Project(s)
'66 CL77 Red
'67 Triumph T100C
'73 750K3 Owned since New
'77 750F2 Cafe Project
2000 Aprilia Pegaso

Offline Old Scrambler

  • My CB750K3 has been in 39 States & 5 Provinces
  • Old Timer
  • ******
  • Posts: 3,221
Re: Classic Bonneville Racer
« Reply #47 on: May 29, 2014, 04:47:15 pm »


Kinda cool to have my initials and a special number.............Its a first for me 8) 8)



Quite a bit more 'meat' than stock......................
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
'63 CL72 Project(s)
'66 CL77 Red
'67 Triumph T100C
'73 750K3 Owned since New
'77 750F2 Cafe Project
2000 Aprilia Pegaso

Offline johno

  • Expert
  • ****
  • Posts: 1,083
Re: Classic Bonneville Racer
« Reply #48 on: May 30, 2014, 05:25:54 am »
Hi Den,
The cam specs look good, based on your engine discussions I reckon you have nailed the cam. the key features , lift , duration and LCL  will be perfect.

Every engine combo is different though and for mine I felt the X12 would have suited mine the best and I was thinking of going megacycle x12 as I need more lift (as high as possible to suit Mikes ports) but one  of the forum folks helped me out with the 125 / 75 so didnt need to buy another cam as I also have spread of cams up to 310 duration to try on the dyno.

You probably noted a post on Treys thread where I have calculated all my top speed gearing at 9,500 RPM, that was because on all the cams I put into the dyno simulator two things happened to nearly all the biggish cams .

After flattening The torque curve started to dip down at around 8,500 RPM and the HP flattened from 8,500 to 9,500 RPM before continuing to climb up to 11,000 plus.     Both those dips and flattening curves are significant events to me in terms of drivability in top gear, hence my gearing selection.  with all the big cams the only differnce from big to the biggest cam was the amount of torque and hp by say 7HP BUT all the curve dips were identical at those RPM's  ;)

Why I like your cam Den is the LCL may be the key to stopping that dip in both the curves. Interesting stuff.
It is forcast for a weekend of rain next two days If I get house bound I will have a play on the dyno simulator and send for your interest.
GRASSHOPPER SOHC HONDAS ARE THE MEANING OF LIFE.

Offline Old Scrambler

  • My CB750K3 has been in 39 States & 5 Provinces
  • Old Timer
  • ******
  • Posts: 3,221
Re: Classic Bonneville Racer
« Reply #49 on: May 30, 2014, 07:42:13 am »
YOUR INTEREST in my project is GREATLY APPRECIATED :) :) :) :) :) :) :)

By spreading the lobe-centers we hope to avoid valve interference on the OFF-stroke. We are opening shorter valves so the lift was increased to approximate the K-type lift. We hope to keep the valve-faces flush with the chamber to maintain flow and help the motor get through the 8,500 flat spot.  BTW.........I have noticed that flat-spot in 5th-gear many times on standard K-cams and the 41A-grind, as well as the F2 cam in a K-head.  However, no flat spot on the original K0 models. I attribute that to spark timing and the 16-tooth front sprocket. We are mounting our CBR600 ignition on the points-plate to retain adjustment options.

We have discussed taking the bike to a dyno-shop..........but everyone around here uses the fly-wheel style dyno popular with H.D. builders. We are still looking and maybe will get a chance with one of the portable units at Road America. 
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
'63 CL72 Project(s)
'66 CL77 Red
'67 Triumph T100C
'73 750K3 Owned since New
'77 750F2 Cafe Project
2000 Aprilia Pegaso

 

;