Author Topic: Why Are my Points Breaking/Snapping?? (Read 8788 times)

MCRider · « **Reply #50 on:** May 15, 2012, 11:05:12 AM »

bolling: The part number for the CB350F in question sb center digits 333, not 300 which is for the CB750. Unless there was some part upgrade i missed. Though they do look similar and maybe you were just using them as an example?

lucky · « **Reply #51 on:** May 15, 2012, 12:59:48 PM »

I would just go get a brand new points plate COMPLETE with condensers, points etc.,. and install it.,,,,,,,, DONE.

Forget about it.

As far as you telling the truth, I believe you. But someone else may have told you something that was not true. Its possible.

I thought you were playing a joke on us.
That is what guys do at motorcycle shops during the day for fun.

andrewk · « **Reply #52 on:** May 15, 2012, 01:20:03 PM »

I'm betting on bad condensors, too. That makes the point absorb all the load of switching- points welded up/broken- repeat until something fails.

OEM points and condensors are expensive, but worth it.

Green Goblin · « **Reply #53 on:** May 15, 2012, 01:54:04 PM »

Condensers are also brand new, but they definitely were not purchased through the dealership. Where would I be able to find a brand new points plate?? I've searched but only found used ones for sale. I also read about the plate being out of alignment, I didn't check that, but will after work.

MCRider · « **Reply #54 on:** May 15, 2012, 01:56:38 PM »

Quote from: Green Goblin on May 15, 2012, 01:54:04 PM

Condensers are also brand new, but they definitely were not purchased through the dealership. Where would I be able to find a brand new points plate?? I've searched but only found used ones for sale. I also read about the plate being out of alignment, I didn't check that, but will after work.

Got mine for CB750 on eBay. Took a chance with the middle priced one and it was a TEC, so happy camper.

andrewk · « **Reply #55 on:** May 15, 2012, 02:26:26 PM »

350F is a tough animal to find NOS parts for, and a lot of things are discontinued, like the points plate.

Buying a used one can be ok if it hasn't been beaten up, but most of them have to some extent. You might be stuck working with it, aligning it etc. If the threads in the holes are ok, this should be fine- the points plate doesn't really go "bad" but it can cause you headaches if the holes are stripped or if its bent badly.

You can still get OEM points though- service honda has a pretty cheap price- http://www.servicehondapsn.com/fiche_section_detail.asp?section=121191&category=MOTORCYCLES&make=HONDA&year=1974&fveh=2901

If you're plate is in servicable condition, I'd clean it up, put new OEM points and condensers on it, check the alignment, and go from there. Maybe inspect/clean/re-lube the advance mechanism while you're there too.

If the cause of the breakage were in fact because they welded together, you'd want to investigate all possible causes of point failure- shorted coil, power not shutting off, etc.

Hope this helps

MCRider · « **Reply #56 on:** May 15, 2012, 04:48:20 PM »

Quite a few good looking used ones on eBay from $15 to $65 dollars. I looked at them all. I'd go for any of them to eliminate the variables. A little points file, contact cleaner and should be good to go.

Gotta admit, I still don't see any way in the world that break could have occurred. May be there is magic in the world... good and evil.

Spanner 1 · « **Reply #57 on:** May 15, 2012, 04:49:34 PM »

AND the pivot pin looks smaller... wish the OP would clarify....... oh well

Green Goblin · « **Reply #58 on:** May 15, 2012, 05:06:55 PM »

Sorry Spanner1, I thought I posted a reply to your question! I'm not sure about the original point that broke, but the second one that broke 100% had the pin inserted into the corresponding whole in the points plate.

I think I may have found the culprit. I rode the bike to work today (about 5 miles, with a very casual, slow route home if something were to fail) and just took the points cover off to inspect. It appears something is hitting the point? So I took the cover off, "massaged" it, and then grabbed a black sharpie and colored the whole area that could be touching the point. I'm going to put the point back on and ride home, hopefully there damage won't get any worse!

Spanner 1 · « **Reply #59 on:** May 15, 2012, 05:21:15 PM »

Well that kills my theory

... Must be a poltergeist with a tiny hammer under your points cover, see no other explaination

lucky · « **Reply #60 on:** May 15, 2012, 06:18:50 PM »

Can you post a photo of the points cover front and back? Thanks.

madmtnmotors · « **Reply #61 on:** May 15, 2012, 07:18:48 PM »

Quote from: Green Goblin on May 15, 2012, 05:06:55 PM

It appears something is hitting the point?

My first thought was that something is bouncing around in there, loose bolt, broken pieces of previous point set, advancer spring, gremlin? Take all of the ignition parts out and inspect all components for possible damage/failure.

scottly · « **Reply #62 on:** May 15, 2012, 08:07:55 PM »

If the points had welded together, the point on the broken part would still be welded to the other point. Even if there were something jamming the point arm from opening, the phenolic part that rubs against the point cam should fail first.
My best guess is that the point gap was adjusted by bending the point arm, thus cracking it.

Anybody else notice the 1/4" bolt and mutilated adjustment slot in the point plate? (Not that it's related to the points breaking; just an observation)

Spanner 1 · « **Reply #63 on:** May 15, 2012, 08:37:11 PM »

You mean you don't bend the moving point to set the gap ?... the other 1/2 is fixed, its held by the screw ..... huh

( All conjectures are game at this 'point' ( pun ) ... ).

Spanner 1 · « **Reply #64 on:** May 15, 2012, 08:42:51 PM »

I think it's time the OP explained exactly how he gapped the points and set the timing on this bike .... like, before anyone else even has another suggestion...... let's wait

And can we see a pic. of the rest of the bike, just curious !

Green Goblin · « **Reply #65 on:** May 15, 2012, 10:58:37 PM »

I set the pouts gap by loosening the screw and sliding one of those thin gap measuring tools in between te points. I can assure you I didn't bend anything! I'm sure you guys have seen everything, but I do have experience working on cars so I have a basic understanding of what should and shouldn't be done. I'll disassemble the assemble and check for extra material that could be bouncing around. Thanks again for all the suggestions guys, it's greatly appreciated.

I'll post a picture of it when I get home, thanks for the interest.

lucky · « **Reply #66 on:** May 16, 2012, 08:28:54 AM »

Quote from: madmtnmotors on May 15, 2012, 07:18:48 PM

Quote from: Green Goblin on May 15, 2012, 05:06:55 PM
It appears something is hitting the point?

My first thought was that something is bouncing around in there, loose bolt, broken pieces of previous point set, advancer spring, gremlin? Take all of the ignition parts out and inspect all components for possible damage/failure.

Very good possible explanation Madmtnmotors!!! A bolt or screw inside that area bouncing around?

Green Goblin · « **Reply #67 on:** May 16, 2012, 08:38:27 AM »

I don't have a great pic of the bike, but here's one that a friend took of me on one of our recent cruises. A fairly basic cafe, but I did 90% of the work in my garage (besides a portion of the wiring and sewing the seat cover).

Green Goblin · « **Reply #68 on:** May 16, 2012, 08:41:18 AM »

Quote from: lucky on May 15, 2012, 06:18:50 PM

Can you post a photo of the points cover front and back? Thanks.

I'll take a picture of the points cover when I get a second. Upon first inspection I ruled out the possibility that the cover could have been bent, but after spending some time really checking it, there could be a slight bend. I've "massaged" it and covered the area that is potentially hitting the point with a black sharpie to determine if it is hitting. Hopefully that'll solve the problem!

Bodi · « **Reply #69 on:** May 16, 2012, 08:51:20 AM »

Something is fishy. The points gap should be adjusted by loosening the screw slightly (so the points plate is held in place but still moveable) and using a flat blade screwdriver twisting between the little notch in the points plate and between the two bumps in the backing plate to move the plate against the snug screw. In your first picture the notch is way off to the side of the two bumps on the tight side. It looks like the other points set is adjusted way tight as well. I think that these are not actually 350-4 point sets. That doesn't explain the breaking - possibly the geometry is so different that it's over stressing the arm somehow?

Green Goblin · « **Reply #70 on:** May 16, 2012, 12:50:21 PM »

Ya the first photo was taken after the first set of points broke and I didn't know what those two markings were for. I'll take a picture of the points plate now that I have everything a bit better adjusted too. I am pretty sure that the points are for a CB350F, but they were Daiichi points which I have now been told are cheaply constructed points.

westondc · « **Reply #71 on:** May 16, 2012, 02:32:18 PM »

random guess here... could it be that the part of the advancer that the points ride against be warn down in its low spot (the point where it causes the points to close)? this might cause the point to snap closed hard when it connects with the other side of the point, even when gaped correctly. if the advancer hasn't been properly lubricated at the area where the points ride then it could have warndown over time.

it would be a good idea to remove the spark advancer, clean it, and measue the spark advancer lobe with a caliper micrometer to see if its meets spec

Drewery · « **Reply #72 on:** May 16, 2012, 03:20:59 PM »

Just checked this post as I am in the process of changing points myself. I had points break on me once, for what it's worth. On the highway at about seventy miles an hour and the sudden loss of power almost had me over the handlebars. Could points break twice on a bike? Possibly. I don't remember the manufacturer that made mine but it's possible on of them simply produced a bad batch. I'll be interested to see how this post ends. Hope it's a happy outcome!

bollingball · « **Reply #73 on:** May 16, 2012, 03:25:17 PM »

Quote from: westondc on May 16, 2012, 02:32:18 PM

random guess here... could it be that the part of the advancer that the points ride against be warn down in its low spot (the point where it causes the points to close)? this might cause the point to snap closed hard when it connects with the other side of the point, even when gaped correctly. if the advancer hasn't been properly lubricated at the area where the points ride then it could have warndown over time.

it would be a good idea to remove the spark advancer, clean it, and measue the spark advancer lobe with a caliper micrometer to see if its meets spec

The points don't ride on the advancer it is behind the points plate. I think the word you are looking for is (cam) the points cam lobe.

Ken

lucky · « **Reply #74 on:** May 16, 2012, 04:27:04 PM »

Quote from: Drewery on May 16, 2012, 03:20:59 PM

Just checked this post as I am in the process of changing points myself. I had points break on me once, for what it's worth. On the highway at about seventy miles an hour and the sudden loss of power almost had me over the handlebars. Could points break twice on a bike? Possibly. I don't remember the manufacturer that made mine but it's possible on of them simply produced a bad batch. I'll be interested to see how this post ends. Hope it's a happy outcome!

This is the first I have ever heard or seen of this.

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Author Topic: Why Are my Points Breaking/Snapping?? (Read 8788 times)

bollingball