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Honda SL 125 Ran fine, now won't start 2 hours later

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Hello,

I need some help with my '72 SL 125. I just got the bike about a week ago. I am new to bikes but have experience turning a wrench a bit on cars and basic diagnostic skills/understanding.

The bike has been running great. 1700 OG miles, but has been sitting awhile before I got it. PO got it, flushed all fluids, cleaned carb, new chain, adjusted points. Now it's mine. Have been running it around every day, starts right away always.

Last night, I got gas and checked the oil. It was low so I added about .5 quarts 10 w-30. Now, I ran it today to the store right down the street. Ran great, but when I put it in neutral to get off the bike real quick and return some movies, it died. Hadn't done this yet. Started right back up. On the way home, everything was fine but I noticed the idle seemed a bit lower/gradually decreased at a stop. did not die though. Hadn't done that before. I parked it, and went to start 2 hours later and I cannot for the life of me get it going. Got it started for about 2 seconds with the choke on, then it died.

I have fuel flow from the tank to the petcock. I will check spark ASAP. The battery is brand new and the lights come on so I don't think it's that.

Any suggestions?

Thanks for reading the long post, I really appreciate any and all help from you gurus.

:bonk:

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yeah ... check and confirm a good strong spark , new points is the best way

i think this could be fuel related , you should comfirm consistant fuel flow . make sure the fuel is not contaminated . was the fuel tank cleaned thoroughly ?

it does not take much to cause a blockage and check float level

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Have a good blue spark. Tank looks rusty on the inside and I'm pretty sure it was not cleaned really. I put 87 octane in it.

don't know how to check float level. petcock is clean.

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Recharge the battery. When my SL100 would get low on power, the motor would bog and die out. Then check the charging system.

well it is a brand new battery, so not sure. don't have a trickle charger but will get one asap. Maybe all these short trips with the headlight burned the battery out. The lights still dimly go on though so I would think that would be enough power to start it?

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Check your float bowl for rust from the tank. Doesn't take much to start plugging up the small jets. You use a screw driver to spring the clip under the float bowl on the bottom of the carb. Have the gas shut off. Look for particles in the gas in the float bowl. Sounds like you have trash coming in from the rusty tank. Do a search on how to fix your rusty tank. It will NOT run reliably with rust in the tank.

Swiss

If you have a good spark, the battery is giving you enough juice. It sounds like you have run the battery down some but it was not lacking spark when it stopped running on you. Charge the battery, fix the rusty tank and ride.

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alright, I will clean the tank as soon as I get a day off here. I'll try to get a chance to check the float today. going to go with electrolysis unless anyone has a better suggestion. Tank doesn't seem horribly rusted when glancing in there but it is for sure rusty.

could putting 87 octane in have caused this? It was the first time I refueled. I didnt think octane level would change it's ability to start completely. I'm unsure what the PO ran in this. I've had all 2 strokes so I'm used to premix haha

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87 octane is fine and anything more is a waste of money. Low battery and junk in tank - my bet is junk in tank is getting to the float needle and shutting off the flow of fuel. One way to know if it is getting gas or not is simple, as you may know, was the plug wet or dry after attempts at restart. Dry no fuel flow, wet is fuel and usually no ignition.

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so I pulled the carb and cleaned it today. didn't seem very dirty at all. sprayed carb cleaner in slow and main jets. Put it back on and still nothing. after cranking I pulled the air hose and fuel is definitely getting in there. also plug did seem wet I think, but I am a novice so I can't exactly tell. but I for sure have spark so this makes no sense.

Also noted I had to rewire the igniton before. the (+) wire fell off so I had to solder it back on. I have checked the wiring over and over again and it seems fine. bike ran fine after I rewired it. could it have something to do with this? I definitely have spark.

Any ideas? maybe order a new carb? really want to get back to riding.

Edited by 650SL

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did the bike loose power at all when you rode it home? feel doggy? I ask because if you have have ignition and fuel the only thing left is compression. If a valve is not seating = no compresssion. check the adjustment and if you have a tester run a compression test.

what color is the spark plug? should be a nice light tan to gray, not sooty black or black and oily. Which both would indicate low compression.

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didn't seem to lose power to me, but I went literally right down the street. the idle just seemed to be gradually going down at a stop. one thing I did notice is that I checked the oil days before, and it seemed low but not extremely low. then a few days later it was pretty much empty. no leaks seen.

Also I didn't clean my carb extremely thoroughly or anything. just a few quick sprays with carb cleaner. but it looked really clean. and again I'm not 100% sure the plug is even getting wet...seems pretty dry to me with a small amount of moisture? again I am a newbie.

plug looks like this:

photo2jqj.jpg

Uploaded with ImageShack.us

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plug shows a rich condition, that may be due to low compression. The loss of oil would worry me - without a leak it must be being consumed, and that means worn piston rings, only way to make sure is to get yourself a compression tester, it simply screws into the spark plug hole and has a gage on it, then you kick it until the needle stops moving, and that is your compresion resding. should be at least 150lbs.

Now then back to the plug looks dry..... maybe you are not getting fuel and the pilot jet is clogged remove it from the carb and hold it up to daylight, you should be able to see through the very small passage. Also was there gas in the float bowl whe you removed the carb? if not the float needle is stuck and telling the floats that the carb is full of fuel when in reality it is dry (sticking floats) a sticking float needle is most often caused by a rusty tank.

Edited by Motosprtman

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My SL100 had very similar symptoms. Almost as if it was an electric bike. As the battery ran lower and lower, the bike slowed, then stopped.

Fully charge the battery, then give it a try.

I would get a couple of new spark plugs. They are pretty cheap and I'd rather use a new plug than a cleaned out one.

A hill makes starting a bike much easier.

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Much like your car, the battery only serves to start the bike, once running the alternator part of the stator provides ignition and also charges the battery. I could go out ot my SL125 right now with a very DEAD battery, connect it to the charger for 10 minutes or so and leave the charger connected and it would start. Disconnect as soon as bike is started and wa-la. They do need a fully charged battery to start only.

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thank you both for all of your continued replies. So I squirted some starter fluid into the carb inlet and it started and died. cleaned the carb yet again, nothing. yes there is fuel in the float bowl. going to go to sears right now for a trickle charger so I can see if it's the battery. and I have a new plug I'm using too.

I'd like to hope with 1700 OG miles the valves aren't toast but I guess you neer know. it starting with the starter fluid seemed promising that its a carb issue...

Edited by 650SL

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ok so I charged the battery some, still nothing. Cleaned the carb for the 3rd time too. It fired up then died when I put the carb on but maybe that was just some remaining starter fluid, I don't know.

I've ordered a carb rebuild kit and will try that. but the jets looked clear to me and I sprayed the hell out of it with carb cleaner.

I guess I will try a compression test while I'm waiting for the kit but the compression feels pretty good to me.

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Alright did a compression test. Getting 140-150. that's with an adapters so I know that makes the reading a tad lower.

So that's low, but not at-death's-door low, right? should still be able to start it with those numbers?

Also, I called a local SF Bay area shop here to see what their quote would be on a top end job on an sl 125, just to see before I possibly attempt the job myself. They basically laughed at me, said it's not economical on that bike and told me to get a lifan and they'd install for $750. HA! Seems ridiculous to me, top end is fairly straightforward on a single like this isnt it?

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Rust in the tank is bad news...usually what happens first is a few flakes of rust will keep the needle and seat from closing and the carb will flood. The bike might run okay at open throttle, but at idle and low speeds it will stall as the float bowl overfills and the mixture gets rich.

Usually a bike starving for fuel (Plugged gas line or needle and seat) will increase the idle RPM (lean mixture) before it stalls, but when the needle can't shut the gas off it'll slowly bog down to a stall.

First thing I'd try is removing the float bowl, remove the floats and clean the needle and seat. New one's are good too, but with rust in the tank it's only a matter of time until you do it again.

just a shot in the dark..

Sparkle

Edited by patuca
shitty spelling

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