Topic: Classic Bonneville Racer

[Jerry Rxman Griffin aka MuthaF'er]

Merry Christmas Dennis. Hope Santa brings you a successful dyno run! 

[Lostboy Steve]

Before I get too old, I want to make it out there. I just want to ride something, I dont even care if its a dilapidated moped, just to run the flat would be amazing to me. That, and glamis.

[johno]

Hi Den,
when you said you run 125 main jets, was that Mikuni or keihan  numbers?

When I sais I was going to run 125 as well my mind wasnt on the job and I was thinking Keihan numbers which is 110 in Mikuni.

Keihan to Mikuni coversion ;  I bought 3 sets of jets to start off.
120 =107.
125 = 110
130 = 115

so I will start with 110 mikunis
johno

[cbornotcb]

Hi Den,
when you said you run 125 main jets, was that Mikuni or keihan  numbers?

When I sais I was going to run 125 as well my mind wasnt on the job and I was thinking Keihan numbers which is 110 in Mikuni.

Keihan to Mikuni coversion ;  I bought 3 sets of jets to start off.
120 =107.
125 = 110
130 = 115

so I will start with 110 mikunis
johno

110 seems a bit miniscule mate,,,
Standard Jetting Specifications
Carburetor # TM32-1
Venturi Size 32   
Main jet 250(VM4/042)    
Pilot Jet 45(VM22/210)    
Needle Jet Q-2    
Jet Needle 5FP17   
Throttle Valve 4.0   
Air Jet None

Tiny

[Old Scrambler]

Tiny..........I think those are the numbers for TWO-strokes   But the TM models are different from other Mikuni carbs and tend to run high numbers.............I use a 165 main on my 243cc Triumph T20.

I refer to Mikuni numbers on my RS34s.................The motor ran very nicely on 125s but was too rich to carry the load in 4th and 5th gears. Also have each size down to 100........BUT........I prefer to tune from rich down to 'just right' rather than be lean and burn a piston

[Old Scrambler]

After following the encouraging but overall bad news about Mr. Johno's experience in Australia..............I have formulated a flexible plan for the  Classic Bonneville Racer (CBR) to make another attempt at setting a record.......or at the least, exceeding 150-mph..........at the Bonneville Motorcycle Speed Trials (BMST) running from August 29th to September 3rd. 

I've been occasionally running the motor while parked on my hoist in the garage. A new front fender with significantly more aerodynamics and 'salt-guard' protection is in the works. The oil tank will be mounted more inward of the frame, and the shocks will be somewhat stiffer. I have visually inspected the pistons and the head/valves with the assistance of a SNAP-ON mini-cam inserted through the plug holes.  All looks good with minor carbon deposits on piston #4. I am hopefully upgrading the electrics by installing new Dyna 5-Ohm coils, new wires, and new resistor caps to go with the already installed Dyna-S ignition.  I have order some new TYGON 5/16-inch ID fuel line to match the twin petcocks. I expect the bike to be back together and ready for a dyno-tuning session by mid-May.

Today I found out that the dyno-equipment I was planning to use was sold to another dealer some 80 miles from me. So, plan B was put into place for a session at a Ducati dealer in Milwaukee, about 45 miles away from my garage. The service manager who runs the equipment was a former Honda tuner with quite a bit of drag-racing experience.  I plan to make several dyno-runs, with and without the air-box, to get a base of whats going on before we make changes...........one at a time   Besides have spare plugs, plenty of race-gas and several sets of jets, I expect to be taking plenty of notes during the sessions to keep track of what works and what to stay away from.  If we find that the RS-34s are just too big for this motor, I have access to a set of CR31s or TMR33s. 

 

 

[Jerry Rxman Griffin aka MuthaF'er]

Sounds like a good plan. The Duc plan MAY be better too.

Question though, why resistor caps vs standard Dyna wires? 

[johno]

I'll be there with you mate,   wish I could start my engine occaisionally, just to let the neighbours know I was home 

I'll be interested to see where you end up with the timing, I know you have started with 38 deg, I wasnt game enough and started with 35 deg same as the factory engines and they had 11:1 comp ratio where mine was 12.2 to 1 so I started at the factory 35 0n first engine then on second engine backed off to 33 deg to start low and bring it up.....just never got it back up to 35   had a few other issues with a bad apple in the barrel !

sometimes  dyno's raise issues  but at the end of the day they dont lie.    I get a rush just being around the dyno shop.

[Old Scrambler]

Jerry.............I have long-term plans to upgrade the entire system with something programmable. We have location options for the coils and will need to route custom-length wires to avoid getting in the way of the air-intake duct(s). The long-term plan involves a bigger (close to 1000cc) motor and building a partial-streamline fairing and tail section. The first part of the plan is just to get this motor running at its best and prove that the chassis will perform at higher speed.  Today I finally got the pic-proofs of last year's event (Scooter Grub, the official photographer, had a heart attack) and I can see that the shocks sag with my weight..........and I need to lose more weight or get a smaller, lighter & shorter, rider.  I'll post the pic when I get the official print. 

[Old Scrambler]

Johno..............We have re-set the spark to 35-degrees and anticipate dropping into the 20s depending on dyno results.  Right now I am spending time trying to get an official sponsor involved in this project. After 3-trips to the salt-flats my van needs new front brakes and rotors, and my trailer fenders look like swiss-cheese

Last week I started exercising and walking to try and get my weight down to 190-lbs. or less. Maybe land-speed racing will be good for my health............I seem to remember feeling good at 185

[Jerry Rxman Griffin aka MuthaF'er]

Jerry.............I have long-term plans to upgrade the entire system with something programmable. We have location options for the coils and will need to route custom-length wires to avoid getting in the way of the air-intake duct(s). The long-term plan involves a bigger (close to 1000cc) motor and building a partial-streamline fairing and tail section. The first part of the plan is just to get this motor running at its best and prove that the chassis will perform at higher speed.  Today I finally got the pic-proofs of last year's event (Scooter Grub, the official photographer, had a heart attack) and I can see that the shocks sag with my weight..........and I need to lose more weight or get a smaller, lighter & shorter, rider.  I'll post the pic when I get the official print.

Naw, the shocks weren't sagging, the salt was just building up 

[Old Scrambler]

Dyno Test...............WOW..........did I learn a lot

When I firgure out how to get the paper to post as a pic...............you will see the results.

The basic day..............sunny and warm, about 80, and low humidity...........This was a DYNOJET machine run by a local H-D shop in West Bend, WI.  Discovered a broken needle clip on #1 so minor repair but all was well. RWHP was showing high 60s and touched 70 on some of the early runs. They had trouble with the A/F snifter so only got one good run in with it working...........we were right on with 125 Mikuni jets in the RS34s. We had the timing set at stock to start and then played with it. We are now somewhat retarded and found 5-hjp

We then removed the 16-inch exhaust pipe clamped to the 4-1 header and discovered another 1,000 rpm at about the same peak power. The best run was abruptly stopped because the tech knocked the ignition wire off of the battery at 9,600 rpms.  On another run we played with exhaust length and lost a few ponies, but held clean rpms to 11,000.  The tech ran most tests in 4th gear and a few in 5th. Top indicated speed with the extended pipe was 148 mph at the 17/45 sprocket ratio.

The tech is an off-road racer and hill-climber. He was impressed with what we brought in and said it ran much stronger than he expected. He now plays a lot with stepped-diameter exhaust pipes. He thinks we could find another 5-hp by using a reverse-cone megaphone..........Dave and I just happen to have some candidates for the job. Dave and I could tell a few other mechanics at the shop were taking note at the high rpms emitting from the sound-room in the corner.   

76.24 RWHP translates to a rounded 98-HP at the crank. On another day and a different dyno the numbers will change. The tech said they tested their dyno by taking a known bike to other H-D dealers with DYNOJET equipment. All test were within 2-hp.

So now we have a base from which to make minor tuning changes at the salt-flats.  The motor sounds good and needs plenty of air. We started with the air-box........then completely removed it..........then installed the top only.  The stacks into the top of the box added 5-hp vs no stacks.

We continue to study and paper-plan a Ram-Air system.  First we will try for records........then experiment for more  

[scottly]

Hey Dennis, do you have a scanner? It's the best way to turn a paper print into a digital jpg.
76 RWHP out of that size motor is pretty darn good! 

[johno]

Your a lucky bloke to have a decent play on the dyno

Reading your post was like getting a dose of salt fever, good drugs  give me more.
cheers Den .....johno

[Old Scrambler]

Hope this copies OK..........

I don't see it.  Opened the scanned image in photo-viewer.........copied image.........click paste..........NOTHING

[scottly]

Dennis, attach the pic using the "Attachments and other options" button under the text box. Click on it, then click on the browse button, find the pic, click on it to high-light it, then click on open; it will show up it the browse box, then click on post.

[Old Scrambler]

Scotty.............Thanks for offering the help..........it just doesn't work on my 'puter'. When I highlight the file image, it disappears. When I click on Open and then Post.............it remains blank.

Anyhow............we had 45 lbs. of air in the rear tire and noted how hot it was (and sticky) after each run on the dyno. Dave guesstimates  another 2 HP would have registered if we would have lowered the air-pressure in the tire.  BTW, the tech remarked how well the clutch and tranny worked with no slippage.  Its a stock tranny with HONDA plates and Barnett HD springs.  We did a total of 15 pulls of which 8 were at 9,600 rpms or higher.

Today I will drain the oil and install fresh BRAD PENN 20-50w motorcycle oil. Its my new recommended lube with a good amount of zinc for these old motors and clutches.

[Old Scrambler]

Maybe this will work...........


The lower end dip was the tech giving it full throttle in top gear.......and



Indicated top speed was with the pipe extension.............so should increase with a mega......and a tail-wind

[Old Scrambler]

This pull was in 4th gear and clearly shows the 11,200-rpm declining power.  Also is consistent showing when the cam comes on RAPIDLY at 6600 rpm..............from this data it looks like my shift point should be between 10,500 and 11,000



To get close to these numbers at Bonneville we will need a lot of AIR

[Old Scrambler]

10 weeks or so to get things buttoned up.............New front fender was just inspected for fit............its ugly right now so no pics.  New reverse-cone mega will be fitted after July 10th.  Should give me another horse or two.  Ram-Air is in the works. My friend Brian Sheridan is helping me design a new system for better flow and more available air at high rpms. I may have to change the tank to get it narrow and have the intake ducts flow along the outside of the tank............near my arms. I am meeting with an advanced-degree air-flow student working for a Ferrari race team to pick his brain. Who new that a square or rectangle flows very much more than a round tube?  I'm still stoked from the dyno-runs...............the motor wants to rev and we are building more power.

I have pre-registered with BMST..................I have to order advance-discount passes for each crew-member and/or guest.  If anyone is planning on two or more days on the salt.............my $40 cost for the 5-day pass is a bargain.  Let me know ASAP..................Jerry, your already counted.

[Jerry Rxman Griffin aka MuthaF'er]

 

[754]

I can remember being on the salt in 09 I think, with a forum member from Wisconsin.
 His name as Dennis, and as he looked around at everything.. He said.. This looks like fun, I think I want to try this....

[Jerry Rxman Griffin aka MuthaF'er]

Frank, you gonna show up?? Join us! Bring Derrick down too since you guys are neighbors. Couple more 750's on the Salt.

[Old Scrambler]

Yes,Frank..........I recall saying that..........and now I'm doing it    Let me know if you want a pass..............and you can have 1st chance at the bed in my van if you don't want a hotel room. I stay at the Quality Inn because they have a good breakfast at 6-AM   The Motel 6 is almost next door with lower rates.

For anyone planning to join the fun........Yes, the bike is tuned and ready to ROLE.........I plan on arriving on Saturday, August 29, and running the CBR on Sunday and Monday. I also have the Triumph Tiger Cub to run but preference is for the 750 record

[754]

I will see,  everything is upside down here......
 There will always be a nice hard patch of dirt, at Bend in the Road... ..lol...