Is there anything simple to do to increase compression. My old Honda CB125S has low compression. Hard to start when cold but runs ok when warm. Shoot a little oil in the cylinder and the compression comes right up, so think the valves are ok. Top end gaskets cost more than the bike is worth. I'm afraid to ask what a set of rings costs. Anything simple to help? I once put STP in a bike. Helped the compression, but the clutch never worked again. ;-) Live and learn. Other options? Thanks, mike -- Return address is VALID but some sites block emails with links. Delete this sig when replying. .. Wanted, PCMCIA SCSI Card for HP m820 CDRW. FS 500MHz Tek DSOscilloscope TDS540 Make Offer Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121 Bunch of stuff For Sale and Wanted at the link below. MAKE THE OBVIOUS CHANGES TO THE LINK ht<removethis>tp://www.geocities.com/SiliconValley/Monitor/4710/
March 20, 2005 1975 Honda CB125S2 1-Cylinder 4-Stroke 125cc Trade-In Value (Good Condition) $300 Trade-in Value is what consumers can expect to receive from a dealer for a trade-in unit assuming an accurate appraisal of condition. This value will likely be less than you would receive from a private party sale because the reselling dealer incurs the cost of safety inspections, reconditioning and other costs of doing business. Trade-in values are based on clean units in good condition, with all original standard equipment. Mileage/condition and additional equipment may have a substantial impact on the value shown above. Maybe you might want to clean the bike up, polish it, make it look nice and sell it for $300 plus whatever the prospective private party would be willing to pay? compression, but the clutch never worked again. ;-) Live and learn. Go down to Walmart and buy a few quarts of Valvoline VR-50 Racing Oil? It's 50-weight oil. Your clutch won't slip like it did with STP. It just won't disengage properly until the engine is really warm. Maybe the heavy 50-weight oil won't circulate when the engine is cold, so you can keep the engine warm with an electric heater under the bike. Of course, if your float bowl overflows gasoline and the heater ignites it, you might burn your garage down... Want to learn mechanics and fix it yourself? Run down to your local motorcycle salvage yard and find a Clymer's manual for little single cylinder Hondas. Motorcycle salvage places don't just buy wrecked bikes, they buy new old stock from dealers. The first motorcycle I ever built was from new old stock or NOS, as it's called by the afficionados of Ye Olde Crocke. Good motorcycle salvage places might even have NOS for your CB-125, ya never know what you're going to find... You'd probably pay about $5 to $7 for the manual. Study the manual. Learn how to find top dead center on the compression stroke so you can line the piston and valves up properly before taking the cylinder head off... Acquire a few good tools. Spend a few hours on Saturday taking the cylinder head off and and de-greasing and scraping all the carbon out of it. Box up the cylinder head and cylinder and piston and take it down to a local good independant motorcycle machine shop and have the machinist measure the cylinder and piston to see if the cylinder needs to be overbored instead of just honed. If you don't need an overbore, standard rings will fit. If you need an overbore, you need an oversized piston and oversized rings... Order the parts and wait... The next Saturday with all parts ready, reassemble your CB-125 and enjoy it for years to come...
Yeah, but we're up to $71...unless I need to have it bored and buy a new piston. Then I really should do something about the rust in the gas tank. Then it needs a real headlight, and a new battery. And the oil leak needs fixed. Will need a new tire soon... And a weekend of greasy fingers to do it all. That's just too much to put into a $20 bike that still gets me from one garage sale to the next... I was looking for a quick fix that might help some...maybe... mike -- Return address is VALID but some sites block emails with links. Delete this sig when replying. .. Wanted, PCMCIA SCSI Card for HP m820 CDRW. FS 500MHz Tek DSOscilloscope TDS540 Make Offer Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121 Bunch of stuff For Sale and Wanted at the link below. MAKE THE OBVIOUS CHANGES TO THE LINK ht<removethis>tp://www.geocities.com/SiliconValley/Monitor/4710/
You obviously haven't seen THIS $20 bike ;-) OK, help me out here. The bike doesn't burn oil. I have low compression ~60, but squirting oil in the cylinder brings it right up. I interpret this to mean: Valves are ok, Oil ring is ok, Compression rings not doing their job. I don't understand how heavy oil will help this??? STP has some stuff in it to ungunk the varnish on the rings??? Maybe there's something I can let soak in the cylinder to loosen gunk on the compression rings without messing up the clutch??? Wishful thinking, I know, but sometimes wishes come true. I'm looking for the motorcycle equivalent of duct tape... Have the manual. Got the tools. This wouldn't be the first, or second, or third motorcycle engine I've rebuilt. It's a simple matter of cost/benefit plus a pinch...ok a ton...of lazy. This bike has a lot of other issues I outlined in the previous post. But it still gets me from here to there. Had a chance to buy a whole engine for $15 last year. Still kicking myself for being too lazy to go home to get the car. mike -- Return address is VALID but some sites block emails with links. Delete this sig when replying. .. Wanted, PCMCIA SCSI Card for HP m820 CDRW. FS 500MHz Tek DSOscilloscope TDS540 Make Offer Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121 Bunch of stuff For Sale and Wanted at the link below. MAKE THE OBVIOUS CHANGES TO THE LINK ht<removethis>tp://www.geocities.com/SiliconValley/Monitor/4710/
Heavier oil will help to seal worn compression rings and piston skirts against the cylinder walls, raising the compression, but heavier oil isn't really indicated for a small bore engine like your Honda which really benefits from a light grade oil's circulating ease... Not that I know of... You may be right. The compression rings may be stuck in their grooves. A product called "Rislone" may still be available. You add it to the oil and it works gradually to free your piston rings. I can't say what it might do to your clutch plates... You might also try some Marvel Mystery oil in the gasoline. MMO works good to help lubricate valve guides and valve guide lubrication makes old carboned up engines run a lot smoother---for a while... Another trick we used to do was pour very light oil down the throat of the carburetor while running the engine at a very fast idle. It would smoke like crazy, but the oil helped to loosen up sticky valves and stuck rings. Of course that will ruin your spark plug, and once the spark plug is ruined, you might as well sell the bike to Mark Olsen for about $80... Think of that. You will have quadrupled your money on the Honda, and you can go out and buy 4 more $20 CB-125's...
Remove the spark plug and pour a little Marvel Mystery oil in the plug hole then rotate the engine slow and then move the piston to the bottom and fill the cylinder the Marvel Mystery oil and let it set a few days. it may help and can't hurt. good luck
Lazy buggers you are what with all that yanky now how you are still a pack of jews who wouldnt spend a sent. L
Shoe fits and I'm wearin' it all the way to the bank. Thanks, I'll give it a shot. mike -- Return address is VALID but some sites block emails with links. Delete this sig when replying. .. Wanted, PCMCIA SCSI Card for HP m820 CDRW. FS 500MHz Tek DSOscilloscope TDS540 Make Offer Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121 Bunch of stuff For Sale and Wanted at the link below. MAKE THE OBVIOUS CHANGES TO THE LINK ht<removethis>tp://www.geocities.com/SiliconValley/Monitor/4710/
The rings are shot.... and need to be replaced in order for you to bring it back to normal.... you may also have some of the compression leaking out the valves too.... if you are going to do a ring job, I would also get the cylinders honed out, and while yo uhave it apart, check for a valve job.... parts aren't all that expensive and since you are already there, it may behoove you just do the whole area... Good luck Fwed
Fred probably figures that the few dollars he might spend on Marvel Mystery Oil or Rislone to free up the piston rings is a major gamble, but it's his money and his bike (shrug)...
Quoting from a few lines up: Please give me your reasoning, based on my experimental results described in the above paragraph, on the valves being bad. That's the point. I'm NOT gonna do a ring job. The damn thing runs. I'm just looking for a duct-tape quick-fix to make it better if it exists. If it don't, that's ok too. I'll continue to ride it like it is. Did I mention that I'm NOT gonna do a ring job? People seem to have a problem understanding that I'm NOT gonna do a ring job. There's no possiblilty that I'll do a ring job as long as the thing gets me from here to there. It's a $20 bike and I'm trying my darndest to keep it that way. Thanks, mike Who's NOT gonna do a ring job...but did risk $2.79 on some Marvel Mystery Oil ;-) I would also get the -- Return address is VALID but some sites block emails with links. Delete this sig when replying. .. Wanted, PCMCIA SCSI Card for HP m820 CDRW. FS 500MHz Tek DSOscilloscope TDS540 Make Offer Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121 Bunch of stuff For Sale and Wanted at the link below. MAKE THE OBVIOUS CHANGES TO THE LINK ht<removethis>tp://www.geocities.com/SiliconValley/Monitor/4710/
It's a complete waste of time and money, and only the gullible try it. Jeez. First - the name. They might as well call it Snake Oil. Secondly, the survival of the boring bar and other machine tools into the 21st century suggests that there is no quick miracle cure, whatever Marvel says.
This is my bet as well. A top end strip, new set of rungs, or even soak the gummed ones for a few days.....
That's the point. I'm NOT gonna do a ring job. The damn thing runs. I'm just looking for a duct-tape quick-fix to make it better if it exists. If it don't, that's ok too. I'll continue to ride it like it is. Did I mention that I'm NOT gonna do a ring job? People seem to have a problem understanding that I'm NOT gonna do a ring job. There's no possiblilty that I'll do a ring job as long as the thing gets me from here to there. It's a $20 bike and I'm trying my darndest to keep it that way. Ok... well I missed that since when I read the post, the person who replied never copied that in there.... soooooooooooo.. if you aren't going to do a ring job, then you will have to live with the problems you have and yes marvel mystery oil will help, but like you say, its only a "duct tape" fix and will not last... Enjoy the thing while you can...... As for me, well I would just plain fix it right..... oh... and as for valves.... based on personal experience, I was losing compression thru an exhaust valve since it sat for a very long time and needed to have head work done.....after that, compression problem fixed.... Fwed
