CB175 Race bike FAQ
Here I will try to outline the basic steps necessary to build a competitive race bike listed in approximately the order you should follow to get the job done in the quickest and most economical manner.

1. Remove all unnecessary equipment, lights, kick stands, rear fender, gauges (except tach) etc. Get a race seat....save about 10 lbs. Remove heavy ass stock front fender. Remove stock front pegs and mounts.

"De-tab" the frame (grind off unused mounts).

Get clip ons and proper levers etc to fit them.

Make rear sets using the stock passenger peg mounts.

2. Drill and lockwire oil drains, oil filler plugs, axle nuts, brake mechanisms, exhaust mounting nuts.....and/or....everything

3. Replace all the worn cables, hoses, bushings, gaskets etc.

4. Get race tires...Dunlop or Avon

5. New rear shocks (not oem type), pull apart front forks, clean them and put in some heavy weight fork oil like 20 wt.

6. New brake linings in the front ( preferably a whole new larger front brake..... CB160 front brake works better than stock 175)

7. Freshen up the engine with new pistons and rings, disassemble and clean the engine, check the cam bearings.

8. Consider some carbs.... either new Keihin PE24 race carbs or Honda SL350 K1 24mm carbs (will require a bit of work to get them on)

Clean up the ports with a dremel.

9. Exhaust.... tough one....guys in the NW are running everything from custom made systems to straight pipes. I've done a lot of dyno testing on exhaust and so far it appears that it doesn't make a whole lot of difference what type you use. Local sound limits will probably do more to determine what type of system you use. I make my own 2 -1 systems, very light, lots of work, maybe good for max 1hp over something you could throw together yourself. I hate making them to sell because I have to get about $400 to make it worth my time and no one wants to pay that much.... I do however make and sell the megaphone sections.... <http://www.jrbranson.com/BikeParts/CDR-Parts.htm>

10. Consider replacing the stock points with a pertronics electronic ignition....the guys at Group W have the info and parts on that swap. You'll want to go to a "total loss" ignition system. Meaning you remove the alternator stator, starter, solenoid, key switch etc and wire it up so it just runs off the battery. Typically a charged battery will let you run all day. (saves a ton of weight). Use a CL175 starter motor block off plug to plug the starter motor hole.

11. Camshaft....I run a megacycle 122-20 cam....we have guys running stock head and cam that go very fast so it's not necessary. Also an engine with a stock cam tends to be a lot easier on the valve train. Grind/polish off the weld seam between the exhaust valve head and stem ( the heads are welded on)....it must be smooth and shiny....this prevents stress risers that sometimes cause the exhaust valve head to break off and do lots of damage. Find new or aftermarket valve springs

12. Lace up some new wheels using alloy rims.... Excel makes WM2 size rims in 18" that will work (about $130 each). <http://www.buchananspokes.com/> can make any spokes you need to adapt rims to brake hubs.

13. Buy some synthetic oil and use it.

Your target weight at this point should be around 240-245 lbs. The stock bike weighs around 300 lb...so you are talking a decent performance increase just from the weight reduction.

Advanced Modifications.

1. The stock liners can be bored out to about 190+ cc. Problem is there are nothing but crap pistons out there to do this. I have designed some very nice pistons in 56 and 57mm (202cc and 209cc) but they are very expensive. Figure about $400 for a set of pistons, rings and wristpins. The 57mm size requires some extensive modifications to use....larger liners, boring crankcase to fit larger liners etc.

The stock pistons in 1mm oversize are a good place to start, they are cheap, light and good quality. Stay away from the common "Hap Jones" 3mm (55mm) overbore pistons...they are crap and produce about 8:1 compression.

2. Big ass front brake....like from a Honda 305 superhawk (200mm diameter), or a Honda 450 (has 40 spokes so it will need a new rim). Or go with a CB160 brake worked up by Vintage Brake...details here: <http://vintagebrake.com/>

3. PVL mag/cdi ignition..... needs no battery...works like a 2 stroke dirt bike. Requires quite a bit of modification and screwing around... I make the parts to install one....once again...not cheap, you'll probably spend about $450 by the time it's all done.

4. Fiberglass/Plastic fuel tank...whatever you can find that fits. Typical stock tank weighs around 8 lb., typical glass tank around 4.5 lbs. Get a glass front fender.

5. Remove, lighten...remake out of aluminum everything you think you can manage.

6. Replace stock tach with light weight electronic tach.

7. Pony up for someone to build you a custom exhaust system

8. Move on to serious expensive engine modifications...porting, stainless oversize valves, heavy duty springs.

9. Consider a larger front end....something 33-35mm, ( I use a Honda CB550/4, VTR250 is also a good choice)

Target weight for the bike at this point should be around 220-225 lb. The bike can be taken down to around 205 -210 lbs but it starts getting expensive and requiring a lot of work.

Big thing is step by step. Do what you can, when you can. There is a huge amount you can do without spending much money....just depends on your tools and your time. Get friendly with your hacksaw, grinder and welder.