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The Points Situation: Modifications Necessary for Honda CB350, CL350, SL350, CB360, CL360 & CJ360 Ignition Points

Posted by Brenden on 5/16/2018 to CB350 / CL350 / SL350
Ignition contact points are a critical wear item that are changed out on a regular basis. The ignition timing of the Honda CB350, CL350 scrambler CB360 and CL360 scrambler (as well as the SL350 and CJ360) must be spot on for the motorcycles to run well. A major piece of ignition timing accuracy is the precision of the contact points you are using. Regardless of brand, all the old stuff made in Japan was pretty tight tolerance right out of the box. You could pop them on the bike, adjust them perfect and be on your way. 

We are now 40+ years later and the supply of NOS (New Old Stock) ignition points for the Honda CB350, CL350, CB360 and CL360 (as well as the SL350 and CJ360) has pretty much dried up. Original Japanese stuff is starting to command a real premium as supply is scarce. In fact, the last remaining Japanese manufacturer stopped production a few years back and any old stock from the 70's has been pretty much depleted (unless someone out there has a giant stash in some forgotten warehouse). 

Initially this worried us, as no ignition contact points means no running engine and thus no motorcycle riding. So, for the last year we have been testing & developing various replacement ideas and trying to come up with an affordable solution that will keep your bikes running and on the road. We have been working on an electronic ignition system to replace the contact points (stay tuned), but we know that is not for everyone and that there should always be an igniton points option. 

The good news is that we have been able to source new supply of ignition points (made in China), which are copies of the old Nippon Denso Type 48 points that are used in the Honda CB350, CL350 scrambler CB360 and CL360 scrambler (as well as the SL350 and CJ360). Yet, quality control of these ignition points is inconsistent between sets, but when properly modified their accuracy is greatly improved. When I say quality control, it is in terms of manufacturing variance regarding tolerances and precision (how sloppy are they made). Let's not confuse this with material quality, nor let's not project the assumption that because the parts are made in China they are garbage, which is not the case. After testing, the material quality seems on par with the Japanese stuff, but rather the tolerances in some areas are too loose and others there is not enough adjustment. With some simple DIY modifications, we can bring precision of these new points up to an acceptable level, maximizing their full potential on your bike. It is just going to take a little elbow grease and we are going to show you how to do it and provide the tools and parts to do the job correctly. 

There are four key mods that need to be performed on these ignition points to ensure smooth operation and accurate ignition timing for the Honda CB350, CL350 scrambler CB360 and CL360 scrambler (SL350 and CJ360 too). All of the following modifications should be performed on both the left and right sets of the points. These new ignition points are available as a matched pair or part of our ignition rebuild kit

1) Shimming The Cam Follower: The cam follower (that elbow shaped piece of phenolic) pivots on a shaft and is retained by an "E" clip up top to the points base plate. We have seen that there is excessive up and down play of the follower on the pivot shaft. This means that as the points open and close, the follower can float up or down on the shaft which changes where the contact surfaces touch. Such movement can cause the the contact surfaces to change position to one another and thus change the ignition timing of the engine while it is running. As the engine RPM increases the issue is multiplied. 

The solution is to shim the cam follower on the pivot shaft to remove as much up and down play as possible. We have included a specific shim washer, one for each set of points, to do just that. There is a mixed assortment of shims pre-installed on the points from the factory which are part of the inconstancy issues. Some are plastic, others metal, sometimes there is one, two or even no shims at all. Regardless of what you find, remove the "E" clip and slide the cam follower off of the pivot shaft, removing any washers that are there and discarding them. Now install the included shim washer on the pivot shaft so that it will be sandwiched between the base of the pivot shaft and the bottom of the cam follower. This is the only shim that should be used.

2) Lubricating The Cam Follower Pivot: While the cam follower is removed from the pivot shaft it needs to be lubricated. We like to use white lithium grease on the shaft, inside the hole on the cam follower as well as a light coat on the top and bottom surfaces of the follower where it touches the shim on bottom and the "E" clip on top. Wheel bearing grease can be used in absence of white grease. Reassemble the cam follower on the shaft and install the "E" clip (be careful not to launch it across the room as you'll never find it). Finally mop up any excessive grease that may have squeezed out of these areas as to keep it from being flung around the ignition chamber when the engine is running. For a part that moves thousands of times a minute, they amazingly come dry from the factory.

3) Cleaning The Contact Surfaces: Points are just an electrical switch; the contact surfaces tend to be dirty with corrosion, causing a poor connection. This is due to parts sitting in warehouses for years exposed to humidly or other conditions prime to cause oxidation. The solution is simple and is an old-time trick to clean up dirty points. Use a 1/2" strip of 220 to 320 sandpaper folded in half. Open the points by hand and place the sandpaper between the contact surface (rough sides facing out) and let the points close on the sandpaper. Then pull the paper out from the points. Repeat this a dozen or so times, as the goal is to remove the oxidation from the contact surfaces but not take out a lot of material. You will see shiny spots on the contacts where the paper is cleaning the surface, continue till the surface is clean and shiny. Do a final wash with rubbing alcohol.

4) Enlarging The Points' Mounting Holes: The holes that have been stamped in the points base plate to mount them on the timing plate are not only too small, but not exactly stamped in the right location. This means that when attempting to adjust the points to set ignition timing there is not enough movement of the points on the timing plate for proper adjustment. Some sets do not allow for enough movement to let the points properly open. Others have the opposite problem where the points are always open and never close. Regardless each set of points needs to be test fit on the bike to see which way the mounting holes need to be enlarged. We have included a small round file for just such a purpose. The points are made of fairly soft steel so filing the holes a little larger is easy. On average we need to remove about 1 mm or .040" of material on one side of each hole. The goal is to elongate the holes to allow enough motion back and forth to properly set the ignition timing. It may take a little trial and error get the holes sized just right.

The below video shows in detail the ignition points mods and how to do them:


Once all four mods are done to the ignition points, set the ignition timing on the engine per our Ignition Timing Video

For now, this should keep your Honda running properly. At the time of writing this, we are attempting to source better ignition points built at a higher tolerance control level as well as finishing up the testing stages of our electronic ignition. Stay tuned for more information as we have it: subscribe to our newsletter or follow us on YouTube, Instagram and Facebook.

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