Tylerman

Well work continues, I replaced the front brakes/springs, fork seals, greased everything in the front hub, and the replacement clutch hub arrived. Alas when I removed the old hub I noticed that the flat roller bearing between the hub and basket is smashed and deformed, causing the new hub to spin eccentrically. So although I have all the parts including a new clutch pack, I gotta wait for yet another part to put it all back together. I also found the retainer clip on the kickstart shaft had snapped, so I replaced that. Lastly I have a replacement oil window, as both tanks I have leak at the window. Slowly but surely she is being beaten back into roadworthy condition.

Well now that it runs so smoothly I can justify putting a little money into it. I ordered a replacement clutch hub, throttel cable splitter (kinda jerry-rigged right now), brake shoes, fork seals and a oil sight glass (whats in there now is cracked and leaking). The original paint is sharp enough to keep, although the frame could use a re-spray, and the rear fender is shot but it keeps the rain off as they say so until more money comes up, it stays. Once its rideable I'll title it and be off on my merry way.

Little two strokes can be finicky sometimes, if you kicked it over many times it could have too much fuel in the combustion chamber (my son does this with his dirtbike a lot), just pull the plug and give it a couple swift kicks to blast the fuel out. Don't rule out compression loss, when I started working on my RS100 a few weeks back it tested with plenty of compression but no spark, when I finally got a spark and tried to start it the rings stuck to the piston and compression was lost. Ended up having to re-ring it and replace all the associated gasket to get it running again. Good luck.

Oh I worked over the clutch, but not in a good ay apparently. However, the sumbitch is idling now! I took the entire intake section apart and started putting it back together from scratch. Top End This is just prior to assembly with the correct rings and gaskets Carb and Reed Valve Assembly I remade the three gaskets on the right with rubber sheet material, cheap tech! When the day started it looked like this No compression, but oil tight and waiting for me to figure it out. Now it is at this stage I was missing a sidecover bolt, all I had was a screw which was WAAAAY too long, so I improvised a little spacer setup The motivation for putting all the extras back on (intake snorkel, airbox and filter) was because if it needed the filter to run, and I had the parts, why bang my head against a wall if I didn't have to. I cut a new filter from some oiled foam, stuck it in, botled it all together, kicked it over and it started and ran steady and smooth. A little idle tweaking and it sat there putting like it had been running every day instead of sitting in my carhold in pieces. After I got it running I swapped out the old front end and fender with a better condition one I had laying around Old Front New(er) Complete front swap minus the wheel, so I went to the trouble of cleaning and greasing the upper and lower bearings on the stering stem. I gotta tell ya, whoever came up with the design for those forks was a sadist, they are an absolute bitch to put together. Anyway, Bad news is the clutch is not engaging but I am not totally suprised by that, a clutch is the least of my concerns. The wheel will spin at idle but it will not engage enough to ride. Like I said it started and settled into a steady idle once I had the intake system completely installed, pulling the clutch cover off is no big deal. I am pumped!

Looking at it again, there is a gasket at the reed-valve to cylinder junction, duh air leak possible there, gotta go get some more gasket material. Gonna try like hell to get an idle out of this bike today.

OH motherhumper, a local shop I hang out at has a gasket making plotter/software setup and I had them cut me a new base gasket. Twenty minutes of wrenching the top end off and on, gave it a couple kicks and compression is up to 102psi. Well that seems too low still but I'll give her an honest shot. And it started. I have had this bike for nearly four years and it has never started. Now I have that sense of anticipation in my chest. My mouth went dry as I watched the flywheel continue to spin. It dies within seconds, ten to twenty at most, and stalls out when I give it throttle, and I am still frustrated that compression is so low. There is no intake tract, just the hard connection from the carb to the reed valve, with an o-ring and a phenolic plastic (I think) spacer in between. Both look to be pretty clean, the o-ring is still pliable and shows no cracks but I'll get a new one. I am also going to go through the carb AGAIN to see if there's something I missed. One other thing, I have the original snorkel and airbox but no filter element. The entire assembly is on the shelf, the mouth of the carb is open. It should still run in this condition, though, yes? I have had a two stroke with old crank seals but they didn't become a problem until the bike was warmed up, several minutes of riding, this sputter/stall seems to happen too quickly for that, although I cannot completely discount them as a culprit. Any advice is helpful.

Well eBay bit me, I have waited four weeks for a std set of piston rings to arrive from Singapore, but gave up and bought a set from a shop in Georgia and had them in two days. Buttoned everything back up, gassed up the tank, scrambled to put a fuel line on the crossover with gas flowing out, cleaned the gas off of the bike, tested compression, 90psi. Dangit, I went cheap and made my own base gasket and I think that is the problem. I did reanneal the copper head gasket, no trouble there I've done it on other two strokes. I'll figger this thing out or die trying.

Throttle cable adjustments are next. If you have a service manual it should outline the procedure. In simple terms, you want to ensure the throttle slide (piston, whatever you call it) inside the carb is in the FULLY closed position, geez its been a while since I've done this and don't have a book in front of me, tighten/slacken the screw adjuster on top of the carb until the slightest movement of the cable moves the slide, then tighten/slacken the screw adjuster at the grip until you can turn the grip just a tiny bit before you feel the cable start to pull, that should set a good baseline. I don't know about the DT175, if it has an oil pump your manual will tell you how much slack to set in the cable for that component, some manufacturers allow for some slack, others want it tight. After this reset your idle speed using the appropriate screws on the carb. If adjusting your throttle cable doesn't help, you may have a crank seal going bad, I don't know the history of your bike if it has sat a long time the seals can dry out and leak.

I dig the color, sort of an electric yellow. Also like the wheels, would love to find a set for my RS100, but alas a drum front.

These things "tear down the road"? I'll believe it when I see it, but I am looking forward to it regardless.

Grrr, well the saga continues, I received the 1st overbore (0.25) rings, still too big. Its been two weeks now and I am waiting on the std rings now. Process of elimination.

That's slick looking, I had an 81 Maxim550 and always wanted the Seca model. +1 on the rain, though, I only did it a few times but the water killed it each time. I would even have to wait 1/2 an hour or so after washing it to be able to start it up again. Of course YMMV

Tampa Bay area, about 120 miles from Daytona. I am thinking, as I have nothing but free time, about going during the week to avoid the crowds. We'll see. As to the RS100, I got the rings but apparently I was wrong, down in the bore the ring ends overlap so they are too big. As I cannot find the information on the correct size I sucked it up and ordered both a set of standard and 1st overbore (0.25) rings. Seems that rings here in the US run about 30 to 40 bucks, but if I get them from Singapore they are $20 including shipping, it just takes longer to get them. I can wait. I also managed to wrangle the gas cap off, the inside looks clean and rustfree, so that's one less thing, ya know.

Cool, thanks. Looks like he's out of service for a few more weeks but I still need to finish the top end rebuild on this bike so I can wait.

I'd love to, but the economy struck me down so I am trying to get it running on the cheap if you will. A $10 set of rings is cheap and easy, beyond that it goes back into the corner and I get started on another project until funds become more available. Ironic, huh, I have the time but not the money right now, as soon as I get the money I will no longer have the time.

Thanks Git, I have a pretty thorough service manual that I have been using that has those specs. I just remember from having rebuilt a couple Kawasakis that those manuals gave bore and piston diameters for the common oversizes and was hoping to find something for this Yammy. I am thinking it is the second overbore to 0.50" and have ordered new rings for it. I hope thats it, otherwise I cannot justify putting the effort into this bike to replace the crank seals.

That's my best guess right now. Hopefully unsticking and cleaning up the rings will get me by for now. The more I think about it, the bore looks very fresh (still hatching visible) and there's very little carbon on the head or piston, for 15k maybe it has been gone through before.

Grrr, no luck with this one. Once I finally got everything buttoned back up I found that I have a mere 90psi compression. I pulled the top end and the rings were stuck to the piston something fierce. Took about twenty minutes to get them both off, I took my time trying hard not to snap them. Now that they are free and cleaned up, I'll snug everything back together and hope that's work to get it to fire. Quick question for the gurus. The piston is stamped with a "5" adjacent to the arrow indicating piston front. I cannot believe that this thing is on its 5th overbore, although it does have over 15k on the clock, but the manual does not give piston dimensions and to make matters worse there is a "0000" inked onto the outside of the skirt of the cylinder. So I am at a loss to determine what size rings to order if'n I end up needing to. Any way to determine what size I've got?

Well crud I broke the clutch hub, and am hoping some JB Weld will hold it together temporarily. The new kick shaft assembly came in, so that is all ready and waiting to go in, the clutch plates are cleaned so I am just waiting for the hub repair. I only need the hub to work temporarily, if the bike runs well and I can title it (no small task in itself) then I will be tearing down the engine entirely, anyway. Cleaned and waiting patiently...

Here she is, BTW. She's rough but everything spins freely. And yes that is the wrong tank, from a CS-3 I think. As I stated above the correct tank is locked for the time being.

Well as I predicted the economy forced my company to give me some free time, a lot of it, and I have gotten into this RS100 pretty righteously. I did implant the good coil and now I have spark! Problem is with the pliers/kickstarter I cannot spin the engine enough to get it to start. To compound that I found out that the clutch plates are now sticking so I cannot push-start it. Then I found a replacement kickstart shaft! Problem is it is in Seattle, so I have to wait for it to get here. Luckily I don't have to split the cases to install it, and since the clutch plates are sticking I will have a chance to correct that at the same time. Problem is the original good condition tank I have is locked, and I don't have the key nor do I want to risk damaging it by prying to cap off. So now while waiting for the kick shaft I am trying to find either a replacement key (the code is still stamped on the keyhole) or a decent locksmith that might somehow have a blank. The iggy swith is NOS and does not match, nor do I have the key for the seat/helmet lock but I am not too worried about that now. But I'm close, man, real close.

I'm sure this has been asked many times, but does anyone in Central Florida know of a decent shop to cut a key for an old bike? My RS100 has a tank from a CS-1, and I found a correct replacement tank on eBay but I inadvertently locked the cap and now cannot remove it. I emailed the seller and he does not have the key. The tank is in good shape and I don't want to distort the neck by wedging a screwdriver into the catch, and the code is still stamped into the keyhole. Hell if I could even just order the correct key would be fine. Any help?

A lot of small-bore japanese bikes with 6v electrical systems work the same way, the lights (except the tailight and neutral) will not work unless the bike is running, in fact most electrical stuff on it work work for diddly unless you are actually in motion. In other words, with the bike running, at a stop, you will not be able to use your horn and all lights will be dim. Weak electrics are standard.

Is there a throttle lock on the throttle grip? On my old HD Sportsters it was a screw device on the bottom of the right hand control, basically you twisted the throttle to the speed you want, then using only your thumb twist that screw until tight. It is basically a set screw designed to bind the throttle assembly in an open position allowing you to rest your right hand. It is possible that a P.O. cranked the throttle while it was tightened and grooved the throttle tube by mistake, which is why you can accelerate but not decellerate.

Howdy, new guy here in Florida. I don't know if all the bikes I listed in my profile show up on the bottom of this post, if not I have a small collection of bikes from several different spots, some Kawasaki dirtbikes along with a pair of dissassembled H1s, a pair of Ducatis, an old Honda scrambler and a 74 Yamaha RS100B. I used to own an 81 XJ550 Maxim, and I still lust after the Seca version of that bike. Just wanted to intruduce myself. As for the RS100B, it does not run, but cannot be far from it. It is in original racing green paint and chrome, although most of the chrome is rusted away. Compression is good, it clicks through the gears, I thoroughly cleaned the carb, but it lacks spark. I replaced the contact breaker and condensor with new, found a supposedly good used coil although I have not installed it since the old one still tests OK, I basically don't put much time into it but with the economy threatening to grant me more free time than I want I might dig back into it in the hopes of making it run again. Worst thing about it is the kickstart shaft is smooth, and a replacement has not surfaced. A good pair of locking pliers has sufficed to this point, but that is, of course, not a permanent fix and I don't want to weld a kick lever to it. Replacement of course means splitting the case, which means I would be feel guilty and stupid if I didn't do the crank seals and bearings, and bead blast and paint the cases and cylinder. So for now its just trying to find spark, all the rest will wait. It is actually original enough that I would like to restore it, although building a ts125 replica would be cool, too. Anywho, hello again, I will probably lurk more than post, but hey, I'm basically a nice guy.