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Discussion Starter · #1 ·
So I did the well documented dyna GL1000 ignition mod on my '68 CL175. Everything went fine - piece of cake, started easy, thought I was done. Problem is now I have a massive dead spot right around 4k rpm. No amount of adjusting seems to have any positive impact.

I've installed dozens of electronic ignitions on other bikes and never once had anything other than complete success (although I've never had to machine a rotor down before). But like I said, everything seemed to go just fine.

Any ideas on what I could be missing or what could be happening? Could I have somehow messed up the rotor slots or something?

This is my CL175 ahrma race bike, which I've just been running on points (which everyone advised against) and it ran just fine.....but I wanted it to run more than fine and get modern, as well as be able to ditch the rotor and stator.
 

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Patrick and Zeke had a similar issue with one of thier 175 builds ( different pickup (dyna?)but same hall effect type pick up and magnet rotor) iirc ( the post was years ago) they had the pickup floating left and right with the cam at some rpm (harmonics?) And needed to take a little extra off the back of the rotor so that the magnet stayed in line with the pick up.
 

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Discussion Starter · #3 ·
That's interesting...I have the exact same ignition they used (dyna ds1-3).



Patrick and Zeke had a similar issue with one of thier 175 builds ( different pickup (dyna?)but same hall effect type pick up and magnet rotor) iirc ( the post was years ago) they had the pickup floating left and right with the cam at some rpm (harmonics?) And needed to take a little extra off the back of the rotor so that the magnet stayed in line with the pick up.
 

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Discussion Starter · #5 · (Edited)
Yes I have seen this thread....now I'm trying to find the thread where they're having problems - EDIT: I found the post. Yes this could possibly be the same problem. Gonna check it out tomorrow! Thanks!
 

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Yes I have seen this thread....now I'm trying to find the thread where they're having problems - EDIT: I found the post. Yes this could possibly be the same problem. Gonna check it out tomorrow! Thanks!
Could you post a link to this please ? I've searched but not found the problem ( and solution ? ) thread.
 

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Discussion Starter · #7 ·
I'm afraid I can't seem to find it again!! But I will say, the solution is a little unclear as I am not sure how to shim behind the rotor without interfering with the little "thumbs" of the advance weights. I'm afraid I may have machined the rotor too short :(
 

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Not sure if this will relate to a 175 but here's my experience with the dyna on my 450. I drilled one magnet out because they must not have been set exactly 180 degrees apart and the timing light would show two flashes.

http://www.hondatwins.net/forums/55-engine-discussion/83137-misfire-mystery.html

I noticed the gap was bigger than spec so I was going to try to make a new plate to get the pickups closer and see if it would work again. Switching back to points seemed like such a improvement I left it as is. After reading hondamans explanation on how they work I wonder if they just degrade with time. I wonder if all the Hall effect units are the same.
 

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Thanks for the link. I spent a long while reading the CB200 thread trying to find this, didn't think to look in the CB175 thread :confused:

I ordered myself the Dyna kit this morning, this info will be invaluable. I have the Charlies place ignition in my other 175, and that works fine, but as the Dyna is around a 100 USD cheaper, seemed worth a try. Charlies instructions state that the charging circuit must contain a voltage regulator, or the unit will get fried. I have fitted a modern combined reg rec to both bikes, which is what I think they recommend. Using standard ( pattern ) ignition coil on both bikes and Motobatt gel batteries.

Only problem with the Charlies Place kit was that tightening the rotor bolt locked the advance mechanism, stopped it advancing, motor very flat until I'd spotted this. Needed a shim under the rotor retaining bolt and washer.
 

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Discussion Starter · #11 ·
I was able to shim it to where I believe it is a perfect fit - no end play yet the advance works as it should - still have the misfire. Put the points back on again just to triple check and the misfire goes away. Now I'm very disappointed.
 

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I now have my Dynatek ignition fitted and running well. I've covered most of this in my project log, apologies for any repetition here.

First job was to cut the rotor down to size. Not having a lathe ( or the ability to use one even if I did ), I used a hacksaw and files to modify the rotor. I used the advance and retard on my spare 175 engine to get the dimensions correct, more of that later.







I then fitted the ignition pickup plate and bolted down the rotor, again on the spare engine. Fitted just right, minimal endfloat, just enough to allow the advance and retard mechanism to operate freely.



I then tried a trial fit of the points cover. It fouled the pickups, so I had to modify it by cutting a section out and covering this with a stainless steel plate, held on with JB Weld.



I then removed the left hand pickup module, as only one module is required for the CB175 twin, unit being originally intended for the four cylinder GL1000. Then fitted the unit to my K4 engine. First snag - no end float clearance at all, retaining bolt and washer locked the rotor in place so advance would not work. So I swapped the two advance mechs around, and ended up with too much endfloat. Solved this by dismantling both mechanisms, and swapping shim washers around until I got the end float reasonably right.

Next snag. With the right hand module in the correct position for firing at F mark, it fouled the right hand plates retaining screw. I wasn't happy relying on just the left hand screw to retain the ignition plate in place, so I ground down a cap head M5 screw, plan being that this would just nip the edge of the plate. I'd ground it down too far, so I added an M5 washer under the screw head. Tightened this down and cracked the pickup module. So I removed this and fitted the spare left hand module in its place. Also tidied the wiring, and made up a wiring strain relief that would actually fir under the points cover.



Had a bit of brain fade at this point. Timed the ignition with a test lamp, so that the light went out at the F position. Engine reluctantly started and ran, badly, no power. It then dawned on me that I should have timed it so that the test lamp came ON at the F mark. Engine much happier now ! Also, in this position, both plate retaining screws fit without interference.

Refitted the modified points cover, along with a gasket trimmed to clear the ignition pickup module.



And went for a test ride. And again today. Engine started first kick from cold. Previously, it has taken several goes before it would start, then much juggling with the choke to keep it going. Admitted, part of the improvement is probably because I've raised the carb needles one notch, suspecting a weak mixture.

Bike now pulls really well, no flat spots or misfires right up to 10K, idles nicely even when cold. There is an audible rattle from the ignition, caused by the rotor tapping against the retaining washer / bolt. Maybe if I shimmed it even closer this would go away, but as it's running well I think I'll leave it as it is for now.

However, I'm not completely blasé about all this . As well as my mobile phone and RAC recovery membership ( and Carole Nash recovery cover ), I have inserted the following tools and parts into the bikes tool box :D

 
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Thanks for the guide, i'll be doing this soon to a CL200. Quick question, why didn't you just sand down the top of the pickup/plate rather than cutout the points cover? I would imagine theres plenty of meat in that plastic casting to make some room.
 
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