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1972 Honda SL100 update

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I posted about my newly acquired SL a couple months ago. It was a non runner and I was not having good results. Turned out to be low comp due to bad valves, and upon teardown found cyl damage. New 2-over piston, rings, valves. Got her running, but only for a minute at a time. Bad battery. New one and it's running but the clutch is stuck. I know, should have checked that out, but....non runner. Broke it loose pretty easily.

Finally got to run it a few miles and the carb did not seem right although I had it squeeky clean. Plug was black velvet, but it really was not running all that bad and started 1 kick. Researched the jets and found the pilot to be a 42, book 38, main 110, book 105. I'm not sure it's the orig carb. even though 1784 mi. I going to drop the pilot down to spec, and probably the main too.

I've run into a confusing issue re the float level and the clymer spec. Clymer sez .49 in which cannot be right for this carb. 1/2 in would not be possible with those 1 in brass floats. The spec for the cb100 is .945 in, and that might be doable. Anyone care to hazzard a guess re correct number? Thanks.

Clymer has scared me a little here. I'm referencing table 1 in chapter 7 of the period Honda singles 100-350 manual. I guess the SL100 has a 658A carb, but I don't know how to find that number. Mine looks like the type 1 ref in the manual. I hope my experiences with this ride can be of help to others. Tom

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I would like to resurect TomSL100's question about the correct float level for SL100. My Clymer book must be wrong too. My '72 SL100 has a 658A carb also. I just soaked my carb in cleaner and put a new gasket set in it. The carb overflows out the overflow tube. I want to check the float level, but .49 does not seem realistic either. Do you think I may need to replace the needle and seat?

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At least with my XL175 you get the float level not by holding the carb up side down . the procedure is to set it with the carb bore vertical and when the float contacts the needle and before it compresses the spring in the needle that is when you measure.

This is the procedure from the factory service manual. I suspect that the 100 may be the same way. It is different than just about any carb I have worked on over the years.

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Glenn,

That is how I am holding the carb to measure the float level. The float tab just barely contacts the spring loaded needle. The Clymer book stated .49", TomSL100 stated .945",

and I read on another thread here quite a while ago .826" (I can't find that thread again). What is the correct level? It sure is confusing. I guess I need to spend another 50.00 on a Honda service manual on ebay.

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the procedure is to set it with the carb bore vertical and when the float contacts the needle and before it compresses the spring in the needle that is when you measure.

You measure from the notched area on the carb body to the bottom of the float. I made a gauge out of stiff paper wide enough to clear the floats but narrow enough to sit on the carb body. The spec from my service manual for sl cb cl 100 and 125 is .826 (24mm).\

If your level is close and you have fuel overflow it is either a dirty/bad float needle jet or a cracked overflow tube. The tube was cracked on my bike causing it to leak and I was able to solder it up.

Edited by drturnip

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Thanks ya'll. I'll go with .826" as the correct float level. I'll check the overflow tube closer, never thought about that. The needle and seat looked good, but I'll check that closer as well.:busted:

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You measure from the notched area on the carb body to the bottom of the float. I made a gauge out of stiff paper wide enough to clear the floats but narrow enough to sit on the carb body. The spec from my service manual for sl cb cl 100 and 125 is .826 (24mm).\

If your level is close and you have fuel overflow it is either a dirty/bad float needle jet or a cracked overflow tube. The tube was cracked on my bike causing it to leak and I was able to solder it up.

Thanks to drturnip for the tip about checking the overflow tube. Mine was cracked so since I do not have a solder gun, I ordered a new float bowl and that cured the leak. My float level was right close to the .945 instead of the .826. I'm not sure it would of adjusted to .826.

I was hoping that would cure my hard starting problems and it did not. It still takes about 10 to 15 kicks to get it started cold. Would timing be a possible cause for that. Or might that still be carb issue?

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timing if too far advanced will create hard starting as will a clogged pilot jet in the carb, or too low a float level, valves too tight, worn points, or a coil going south.

Edited by Motosprtman

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timing if too far advanced will create hard starting as will a clogged pilot jet in the carb, or too low a float level, valves too tight, worn points, or a coil going south.

Moto, this is what I have done so far. Adjusted points with a continuity light and set to .014". Then hooked up a timing light and adjusted the points according to the clymer book. Had to move the points quite a bit for that. Put the carb in Berrymans carb cleaner. Replace carb gaskets, un-clogged pilot jet with jet cleaner wire. Float level is approximately .945 best I can tell. Replaced condensor but have not replaced points yet. I do have a new set. Spark plug seems to have a nice blue spark. I adjusted the valves to .002 for

both in and exh.

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Oops, I got interrupted before I finished. Anyway, this weekend I'm gonna replace the points and reset the timing by continuity light. Try and start it. If that doesn't help then I'll hook up a friends automotive timing light to my 12 volt charger ( I need to get a new timing light for these Honda's). Adjust the timing and see if it starts easier. Am I missing anything?

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Oops, I got interupted before I was finished.

So, hopefully this weekend I'll install the new points and reset the timing. Do ya'll recomend setting it statically or with a strobe type timing light? How do you know if the advance mechanism is working properly? The SL100 has know tach so do you guess at the rpm? Thanks in advance.

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The advance assy is so easy to remove just take it out disassemble lube and reassemble. 4 screws and one bolt. You really don't know until you tear it down. If it's sticky it will give you grief.

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best to use a strobe once you have it running and at idle. The post on making sure your advance mechanism is not stuck is very good advice!

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Apparently, I'm not going to let this thread die. I have gotten past the hard starting issues stated before, but now out of the blue it has started having a sticky clutch. It'll crank up and go to shift into first and the bike will lurch forward and die. It is like I didn't even use the clutch. I'll roll it down the driveway and stick in 1st gear, then shift to 2nd and you can tell it is not shifting with the clutch. I've tried several methods to try "to break free". One- rolling the bike back and forth in gear while operating the clutch in and out. Two- adjusted the clutch adjuster nut on the right engine cover per the owners manual. Three- I had a new clutch cable so I put it on. None of this has helped. So I guess it is time to drain the oil and pull the right engine side cover. Is there something to look for? Maybe a broken clutch mechanism of some kind? Any help would be appreciated.

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This is real common on these bikes. There may be some clutch basket wear causing the plates to hang up, or the plates themselves might be sticking together. That's what mine does before it's warmed up. I just work the clutch back and forth a few times before I take off. After it's warmed up it's never a problem so I don't worry about it.

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Apparently, I'm not going to let this thread die. I have gotten past the hard starting issues stated before, but now out of the blue it has started having a sticky clutch. It'll crank up and go to shift into first and the bike will lurch forward and die. It is like I didn't even use the clutch. I'll roll it down the driveway and stick in 1st gear, then shift to 2nd and you can tell it is not shifting with the clutch. I've tried several methods to try "to break free". One- rolling the bike back and forth in gear while operating the clutch in and out. Two- adjusted the clutch adjuster nut on the right engine cover per the owners manual. Three- I had a new clutch cable so I put it on. None of this has helped. So I guess it is time to drain the oil and pull the right engine side cover. Is there something to look for? Maybe a broken clutch mechanism of some kind? Any help would be appreciated.

Dose the clutch lever fell like there pressure when you pull it in?.

Inspect the grooves the clutch plate fingers slide into. Both inner and outer

Possable cuases

Worn Clutch Basket

Worn Center Basket

Broken Pressure Plate

Broken or Burn up Clutch Disc

Broken or Burn up Steel Plate

Just Google worn clutch baskets that give and idea what look for

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