This link is dedicated to helping those who are in the midst of resurrecting an “Old School” motorcycle for the purpose of vintage motorcycle racing. Those bikes with points and condensers instead of electronic ignitions. Those that have carburetors rather than fuel injectors. If you are on such an honorable mission, this is the place for help.
Table of Contents: 1) Building Race Bike, 2) Wheels & Tires for Vintage Racing, 3) Shocks,
Building a CB350 “Stocker” Race Bike
This is a quick recommendation list based on what I know about racing and the 350 Honda:
This document and included links are based on 350k Honda OEM parts on a CB350K, CL350K or SL350 Honda manufactured from 1968 to 1973. Upgrading brake hub, brake plate, spokes, rims, forks & parts, etc… will require different parts than linked below and will be covered in another document! The concept of racing a “stocker” includes the fact that there isn’t much required to be changed to race them. As 50 year old motorcycles, there are some things that are best replaced as updates due to aging and mileage.
Consider this: The natural evolution to a 350 (actually manufactured as a 325cc motorcycle where 350 was a model number, look at the front of the cylinders for the 325cc identifier cast into them) Honda stocker race bike is to become a Vintage 1 Class (WERA) and/or 350 Sportsman (AHRMA) and/or other 362cc souped up class vintage race motorcycle. As such, one might consider that there are five versions of the race bike. At the same time is should be noted that this author has enjoyed “double digit” racing a 350 stocker for more than a decade.
- A bare-bones basic “run what ya brung” basic motorcycle that meets minimum qualifications to pass technical inspection. This could literally be your average 350 Honda that ran well enough to ride on the road, that was stripped of things allowed, hopefully had race compound tires put on it, then taken to the track.
- A basic bike prepped for racing, updated with most or all of the things listed in this article, and ready to race in one of the many stocker classes in the world as a bike that has been refreshed for racing
- A transition bike that may have one or more of the upgrades to make it ready to receive a souped up motor as described in the Vintage 1 or 350 Sportsman classes. Once you’ve built a basic prepped bike and are racing regularly, you might find yourself making this transition naturally to upgrade the bike as your skills increase.
- A fully upgraded V1 or 350 Sportsman bike that is capable of performing with the almost doubled horsepower motor installed in the frame. The motor upgrade for this type bike starts at around $3,000 and that is with the racer doing the upgrade labor on the motor themselves.
- A special configuration bike for the AHRMA Lightweight Production Novice class: It is a very original looking bike with mandatory street features left on the bike. This class is for newbies and is the least expensive and least time consuming because it is so close to the way it was sold on the showroom floor. Note that bike version #5 would chronologically be between #1 and #2, if your bike is ever to take that path.
Understanding this path makes it easier to put your priorities in perspective. What is described in this article is bike #2, a basic prepped race stocker 350 Honda built from 1968 – 1973. One important note includes that there are TWO TYPES OF CB350. This article references the CB350K, CL350k, and SL350k two cylinder bikes. Beware that when shopping for parts that there is a CB350F (four cylinder) Honda that does not qualify in the classes mentioned herein.
Consider this: Moving forward on a tight-budget-basis will mean increasing your chances to complete a stocker race bike. It is otherwise quite possible to prevent, or significantly delay, completion of your race bike build by exceeding your budget before completion. I recommend aiming for a complete basic prepped bike to get YOU to the track, develop experience and understanding that will allow you to appreciate later upgrades as your budget allows. Any parts that are replaced with upgrades can be sold to future racers and increase your financial resources for your race bike.
My best recommendation includes making the bike a runner and testing it on the road. Looking for issues that you want to know about by the time the motor is apart. Proper Shifting, unexplained leaks, working carbs and any engine issues that will need to be researched while the motor apart are best to know before the motor is apart.
As soon as you buy ANY vintage motorcycle, get a VIN verification completed by your county police. In the state of Georgia, at Georgia T22B form is required and the July 2013 or later version is required. T
Having this completed means that you are working on a bike that is yours to keep and not something that someone else can rightfully take away from you.
Insure and register the bike! Liability only insurance gets you the ability to register the bike to ride on the road. The road becomes your test track. This is really important! Without a place to legally test ride your bike, your bike budget could be gobbled up with “police encounters”.
My best recommendation includes making the bike a runner and testing it on the road. Looking for issues that you want to know about by the time the motor is apart. Proper Shifting, unexplained leaks, working carbs and any engine issues that will need to be researched while the motor is apart are best to known before you start to dismantle it.
Things that can be left on the bike until convenient to remove:
Fork Ears: These can be used as number plate mounts?
Electric Starter Motor: Removing this will require removing the left/port engine case cover, cleaning both gasket surfaces, adding a new gasket, etc… Probably best to save this modification for the engine overhaul where you will have to do all things all over again, if done before.
Charging system: The alternator rotor and stator can be left on the engine through your first racing season without a doubt. Leaving the charging system fully functional means not having to worry about charging your battery will be one less thing to make your learning curve steep. Also, for your first season, your racing skills will be a limiting factor, not any excess weight or spinning mass. If by chance your charging system has the original “Orange Fin” Zener diode, REPLACE IT AS THE FIRST THING BEFORE STARTING YOUR RACE BIKE PROJECT. They are also another item that is not “if” but “when” they die. And when they die, they take your battery down at the same time. 2 weeks shorted, a lead acid battery doesn’t have much of a chance for recovery. Never connect a lithium battery to a system with an orange fin, 50 year old, Zener diode!
Stock Exhaust: Unless you have a show condition exhaust system, you can consider using the original exhaust for racing. If it’s show condition, sell it for more race bike resources??? The CL350 exhaust offers the benefit of ground clearance, but does make access to the left/port carburetor difficult. The stock CB350 exhaust system is a little low, but if your bike came equipped with after market mufflers, they probably clear the road better when leaning. Both stock exhaust system are heavy and you will eventually want to replace them with lighter systems.
Stock Battery Box: It’s a little high on the center of gravity scale, but if you find that to be an issue, consider a lithium battery.
The stock seat: especially the early model (rear flip) seats are fairly low and close to the frame. Eventually you will want a fiberglass seat that hugs the frame close and low as possible.
Stock Foot Peg Assembly: Some race classes like the Production Lightweight Novice class with AHRMA require the stock foot pegs be used. If you do have to keep the stock foot pegs, CUT THE SIDE STAND PORTION OF THE ASSEMBLY OFF! Simply removing the side stand bolt will leave the portion I am speaking of. That will hang down and dig into the track, throwing you off the bike!
Things you may want to take off the bike:
Handlebars and bar mounts
Front and rear fenders
Turn signal and tail light assemblies
Rider Foot peg Assembly
Speedometer and speedo cable
Headlight, turn signals
Side covers and a breather (However, if you remove the rubber “velocity stack” from the air boxes that is all you need on your carburetors for velocity stacks)
Chrome Lift Handle (for use with center stand)
Clean and Rebuild carbs
If the front end is already apart, replace ball bearings with tapered steering bearings upgrade, stay with stock forks and replace fork seals and fork oil and mount the front end back on the bike.
Use existing wheels/hubs/spokes to get it on the road for complete engine/transmission/carb testing
(Hold off on stripping rear fender until you have a “trick” LED tail/brake/license plate setup for street testing)
Items to refresh/replace on your basic prepped stocker race bike, 350K Honda:
Fuel Tank: Unless you have a pristine tank interior, line the tank with POR-15 Cycle/ATV Kit
Chassis & Control Items:
Tapered steering bearings (“The first modification to a race bike.”, Buff Harsh, and I totally agree!)
Rear Brake Shoes (Optional as rear brakes can get you in trouble, consider using originals)
Fork oil (7 wt)
Shocks: This is a rider/budget restricted item. There are $1,200 shocks and $100 pairs to chose from
Clip-ons (33mm forks OEM, 35mm is the standard upgrade)
Fiberglass seat (Personal preference item but make sure measurements match your frame)
Plastic rear fender (From later model Honda, cable tie mounted forward of frame tubes)
Rear Sets foot pegs and controls
520 Chain Conversion (35T sprocket on rear seems to be trick, 15, 16, & 17 tooth fronts)
Metal Valve Stem Caps (SCI Link to Follow?)
Perches and Levers (with Dog Leg Levers) in Black Includes new Adjusters
Your approach is up to you. Options include running the 50 year old rubber cam chain tensioner for the first season as only a minor risk, if the rubber roller looks good behind the cam chain tensioner. But this is not recommended. After street testing your engine/transmission consider installing the Teflon cam chain slipper tensioner upgrade with the Tsubaki/Camillia flat slide chain or new OEM rubber tensioner wheels. This does require a complete motor tear-down and splitting the cases. So long as you’ve tested the shifting capabilities of your motor and are confident they do not need replacement, then this could be the last time you are in your lower end.
Those with the early engines 1xx and 2xx serial numbers will want to replace the kick start mechanism at this time as well unless you want to leave your bike as a push start only engine. The early model kicker is a matter of when it breaks with use rather than if it breaks.
If during your street testing you have no issue with blue smoke from the exhaust (having someone riding behind you is helpful) then using your existing pistons/rings is an option. You might consider this as one of your determining factors is the rubber wheel on the cam chain tensioner looks good too?
Kicker upgrade if necessary (eBay)
Teflon cam chain slipper tensioner (Bore-tech?)
Tsubaki/Camillia flat slide chain (Bore-tech?)
Piston/Rings/Wrist Pin/Circlip (Check the rules you plan to race under. 1.0 fourth over are linked)
Lithium Battery The 8 Cell Battery is what I run with. 5, 12 minute practice sessions and no recharge!
THE ULTIMATE RACER’S CARB REBUILD KIT Take a close look at all you get and what little you pay!
Or, 2 BASIC Carb kits
Inevitable Shopping List (PARTS):
Carb Boots and Gaskets, if needed
Float Bowl Seals (Always a good idea to have spares as the gasoline soaked ones don’t go back in till dry)
Fiberglass Cafe Seat (be sure to compare measurements to frame size)
Exhaust System (Mac to Jemco) (***5PA)
Wheels/Rims & Spokes (***5PA)
Inevitable Shopping List (TOOLS AND SUPPLIES):
Some form of air supply, tires (I like the Craftsman BoltOn Compressor Attachment)
Leatherman Multitool (I feel naked without it)
DIY Guy Tools and Supplies:
(***5PA) = Indicates that this topic, unlike for street bikes, is not a matter of just a link but rather is worth a 5 page article on the topic
Other documents: Some already completed!
35mm fork conversion for 350K Honda race bikes
Exhaust System (Mac to Jemco) (***5PA)
Wheels/Rims & Spokes (***5PA)
Upgrade Considerations: AFTER you have a completely refreshed race bike and are looking to enter the transition bike category, you will find yourself considering the following upgrades.
Alloy (aluminum) Rims, based on your hub/brake plate decision, must match spoke count and array.
Spokes, New spokes, properly laced and trued, nice upgrade. (***5PA)
Front wheel brake set up (***5PA)
Rear wheel/brake set up? 350 Rear wheel/brake/hub is what this document/links is based on!
The SL350 Rear hub with CB200 brake plate is as trick as it gets, on a budget. (My entire 2017 season)
Front end? The 33mm (stock) front forks, could work fine for the first season. I ran one for the first 5 years. THERE WAS A NOTICABLE BENEFIT with the 35mm 1974 CB550 forks & triple tree configuration.
You’re not expected to push that hard your first season. 35mm is inevitable.
What engine mods for first season?
Totally modified involves taking it down and apart for the following upgrades:
About the author as a vintage motorcycle racer:
Raced a Norton with AHRAM in 1996 while running for state representative, maintaining the interactive attractions at Coke Olympic City during the Olympic summer of 96 in Atlanta. Was married at the end of 96 and let go of racing for about a decade. In 2004 that same Norton race bike came back up for sale. Early 2005, with the help of a British race partner, reentered racing with WERA. Norton racing was replaced with Honda CB350 racing the following year to take advantage of the reliability factor, leaving a lot of wrenching behind.
A decade of racing later, having gradually evolved the race bike to a mechanically upgraded race machine, I look forward to leaving my self-named nickname of “Crash” behind. Averaging 1.5 crashes a season over the past 11 race years is something I attribute to having NOT refined the bike as fast as my racing skill set.
Using the information above will hopefully help many future racers get up to speed with their race bikes. Get your bike to version 1.0, the sooner the better. Either way, if you’re already thinking about it, get yourself on the track and have some fun.
Wheels & Tires for Racing (In only three pages)
I was inspired to jump on this topic when a future racer with a bike that is almost ready for the track showed up with stock 350 wheels, painted black, and sporting a Kenda Challenger on the rear and a Michelin Gazelle on the front. Although acceptable for the road riding, not what I’d recommend for a newbie to learn to race with although I might have in my early budget racing days.
My history includes some racing with Dunlop, but mostly with Avon which are the best tires in the rain, based on many vintage racers experience. 2017 was my first year running the Continental Road Attack 2 CR and racing has changed all for the better.
Knowing what I know now as a street rider, the tire is the part that rides on the road. As a racer, the tire is the part of your machine that “sticks to the track”. In the bias belted tire world, stickiness of the tire is a fairly literal term. Even after a complete regular racing season on the Continental Road Attack 2 CR I’m amazed at how the softness/stickiness which is not so evident is replaced by some out and out awesome radial technology.
The tire’s forgiveness in tire pressure is another amazing factor. I recently went out on the track without having checked my tire pressure. Experiencing a known slow leak-down on both the front and rear over the course of the season, I simply inflated to my 26 rear and 24 front at the beginning of each race day. Upon returning to the pits, I allowed the tires to cool under the canopy on the relatively cool 78 degree day. Prior to my next practice session, I checked and tires were at 22 and 16. The amazing part is that I felt nothing out of place.
A bias belted tire would have been steering for me at those low pressures with a noticeable handling issues. Buff Harsh, the Honda Research Analyst that worked with Continental to create these amazing tires, has reported that they can be run with less pressure. I’m sure it’s for liability reasons that is all that is stated. I was still surprised about not having any feedback that let me know my tires were so low on air pressure.
For other racers like me who might “race on the cheap” I have this for you to consider. Just like the steep price of the transponders @ $415 new, the amortized price for 10 years of use with 6 races a year comes out to $7 a race weekend. $360 for a set of two tires delivered to your door that last 5 years averages $6 per race weekend. More than 5 years are expected from the Contis based on the original release of the Road Attacks and the total absence of “Conti Take-offs” after more than 5 years in production means that racers will soon be taking off their tires only because the idea of running a set of race tires more than 6, 7 or 8 years will be unnerving. This will be more a factor of “the way we’ve always done it” than any indication from the tires themselves.
Cheap Jack is recommending that newbie go strait to the tire they will be “scrubbing off” for years to come, from the start. Among the returns should include having the same old leathers that don’t get chewed up by crashing 1.5 times a year on average? This takes the leathers amortization down to penny per race weekend, so long as you don’t eat your way out of you leathers. Clip-ons, throttles, exhaust pipes, belly pans, and missing out on racing until you patch your bike back together are other factors to take into account. For those, like most, that put money into the aesthetics of their machines, you can just imaging the savings if you don’t have to replace tanks, seats, fairings and the paint jobs that go with such repairs.
Now that you’re going to put the right tires on your vintage bike, let’s talk about wheels to put them on. I found my ideal wheel/brake configuration in the same round that I came across the Continental Road Attacks. Again, consider that I am running the CB350 in the “stocker” class with only 1.0mm over-sized pistons, OEM designed lower compression barely reaching 90 mph.
The front wheel/brake configuration on “Black Bullet” is a stock 350 with nicely worked in set of modern brake shoe material. Michael “Mercury” Morris at Vintage Brake has given the 350 front front brakes honorable mention and I’m here to agree with him.
The rear wheel hub/brake is a hybrid setup that takes some time to create but is off the shelf (eBay) OEM Honda based. To lighten and de-tune the rear brake system I used the later model SL350 squared off hub. Shopping NOTE: Early SL350 hubs are nothing more than a CB350/CL350 rear hub. Look close for the concaved squared off hub!
The SL350 brake plate is a cable operated system from the factory. After a little experimentation, I came up with a way to turn the 1mm overlap that prevents the CB200 rear brake plate. The CB200 is a rod operated brake system, like the CB350/CL350 system. Using a rotary tool and sanding bands/drums on both the SL350 brake hub and interior of the CB200 brake plate, a smooth and even removal of about 1mm of each leaves enough clearance to allow the two to mesh quite nicely. I did run with a thin film of grease between the two, just as a precaution. I had no issues all season long.
I’ve also cut away, using a band saw, the non reinforced sections of plate to allow inspection and cooling on the track. Flipping the brake cam so the brake arm is in the upward position makes access to the rear-set brake rod and de-tunes the brake function by taking the brake arm from operating in the 7 o’clock to 5 o’clock position which is optimized at the tangent and moves the operating range to more like the 1 o’clock to 3 o’clock range. In this setup, the more brake that is applied, the less leverage is made available to the brake shoes. Having received many a pat on the back for rear wheel lockup recoveries, this is a subject near and dear to this racer’s heart.
Both these wheels represent my first fore into non OEM steel wheels on originally trued spokes that hadn’t been touched since the factory. I don’t recommend that any newbie in the future boast such a claim, now knowing that truing even the OEM spokes and wheels would be better, safer, and leaving the racer with more control, better feedback from the bike, and a better learning curve to boot.
Rims, converting from steel to alloy/aluminum, means less spinning mass/weight at the outside of the wheel, which leads to faster acceleration with the same amount of torque applied. Its almost like a horsepower upgrade without messing with the motor. Once you decide to make such an upgrade, the question becomes… “what width do I buy?”. This is a bit of a conundrum. The Continental website states that the 100/90-18 requires a 2.5” width rim and a 2.75 for the CR that I race. However, Mr. Buff Harsh has stated on the WERA BBS Vintage section that the same tire is asking for a 1.85” or 2.15” width rim under the heading of “Conti race tires now available”. Th e tire has proven very forgiving in low pressure situations. Safety Note: Checking your tire pressure before each ride shows you care about everybody that gets on the bike.
I spent the entire season with my Contis on 2.15” rims and had absolutely no issues whatsoever. However, even with only about 1/8” of chicken strip indicated, I can only imagine the performance I could get where the edge of the tire was beefed up with that last bit of rubber being reinforced with shape that a 2.5” rim would offer. As such, while writing this article, I just ordered 2, 36 hole, 2.5” aluminum rims with 18” diameters of the shouldered design to be delivered to my door for painless price of $206 for both rims including S&H. (since mikesxs.net offers free shipping on orders over $100). I’m taking the 2017 season tires and giving them new lease on life for 2018. You may want to consider going straight to the finish line with 2.5” rims?
Spokes connect the rim and the hub. Having raced on 50 year since they were trued wheels, OEM design seems to hold up in the stocker racing mode. If the spokes AND nipples are in good enough condition to come apart without destruction, they may be worth tapping/cleaning/lubricating and reusing?? New OEM specification spokes should be a bit better , and if you want to pay three times as much, Buchanan spokes are the racer’s industry standard.
For the CB350 front wheel using OEM specification spokes, Sirius Consolidated offers these CB350 front spokes for your consideration. For SL350 rear wheels, SCI offers these SL350 rear spokes which I have used to lace up a 2.15” aluminum rim to with great results.
In 2017, Black Bullitt has been laced with Buchanan spokes on the rear with the Honda SL350 hub/CB200 brake plate (cutaway) and non-Buchanan spokes on the stock OEM Honda 350 front hub/brake plate wheel. Not a spoke broke all season on either wheel.
If Buchanan is within your budget, “Spoke Angel” is a great resource with excellent customer service and will see that you get exactly what you ask for. So, get it right the first time and so will she. She will need to know what type of rim and hub you are looking to lace together. If further information is required, she’ll let you know.
Last, but definitely not least in the wheels & tires department would be bearings. Those originally and never messed with spoked wheels that I raced with did get minimal attention in the bearings department. That attention was nothing more than prying open the bearing seals and placing a couple drops of PB Blaster onto the what is now more like wax rather than what was 50 year old grease. Turning the bearing’s inner races using an axle allows the PB Blaster to work it’s way into the grease and rejuvenate it. Placing your thumb into the inner racer before and then after the PB Blaster treatment will let you know all you need to about what you have just done to the old bearing/grease.
REAL WORLD BEARING NOTE: The OEM bearings are sealed ONLY ON THE OUTSIDE. Removing the bearings will reveal that the seals are not present on the inside of the bearings as the concept was that the weather sides of the bike are protected. As such, any wheels that spent time off the bike, without an axle in them, may have spent time weather exposed making condition inside the bearings unknown.
Conversely, NEW front wheel bearings and NEW rear bearings only cost about $10 a set. Slide hammer type bearing removal tools start at around $30 and make a nice addition to your tool arsenal. Although once PB Blasted, there have been no reports of bearings locking up, the ability to replace the most strategic parts of the “wheels go round and round” of a 50 year old motorcycle just seems to makes sense. Bearing removal tools may very well be an item that your local Auto Zone, Advance Auto Parts, or NAPA may have available for loan or rent?
(In one page, or less)
I have absolutely no information to offer in the line of shocks. I am still racing on the shocks that were on the bike when I bought it. They are RedWing shocks from the 1970s or 1980s that I assume were NOS when Seg Niebuhr configured the bike back when he owned it. Seg was one of the original authors of the document string that I and many 350 Honda racers used as a reference to learn about 350 Hondas for racing purposes. http://www.eurospares.com/350faq.htm
Of all the parts that I have upgraded on Black Bullit, shocks are not one of them. I have upgraded swing arm bushings this past winter. However, the shocks have not been identified as an issue… yet.
I can tell you that new or NOS shocks are better than the 50 year old originals. I can tell you that there are $1,200 shocks and there are $100 shocks. It is important to keep in mind the rules for the class you will be racing in. “Expansion Chamber” shocks are not allowed in WERA 350GP class as the technology was not available during the era that the class is designed around. So, if you’re looking at shocks other than your basic dampener cylinder surrounded by a coil spring, it probably is not going to be “legal” for your class of racing.
However, although I can’t give you any recommendations as this is an area that I have not yet researched nor invested in, I have heard of names like Hagon, Progressive,
It is important to note that the CB350/CL350 Hondas have a shock span of 12.5”. The shocks need to be eyelet on top and clevis on the bottom! If the original OEM exhaust is being used on a CL350, then very narrow shock coil springs must be employed to fit inside the concavity of the OEM shocks. On that note, the OEM exhaust system are very heavy and best replaced with something like MAC or Jemco exhaust.
Making everything else about your suspension system behave as it should will offer more forgiveness in the area of shock absorbers.
If you find any information that would be helpful for future racers, please contact me.
Stone Mountain, GA
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