Ricco

Signs of needing a decoke: The carb is standard as is the air filter. Plug is nice tan colour. Oil pump adjusted correctly. When cold, the engine 'burbles' terribly when I get to around 4k revs and won't rev through this. This is accompanied by quite a bit of smoke coming out of the exhaust. This eventually clears (a mile or two) but then, when I get up to around 50mph (6.5K) revs it smokes badly for 2 or 3 miles, before clearing back to normal. It's not using gearbox oil so I've ruled out the problem being bad oil seals. These symptoms may or may not be down to coking up but I didn't think it was a bad place to start! I've no idea when it was last decoked, I bought the bike last year, I've done 2.5K miles on it. By the state of the baffle and all this smoke I'm getting, it's probably been a fair while or maybe never!

My Rs125DX is showing signs of needing a decoke. No problem removing the exhaust but when I tried to remove the baffle the first bit came off but the rest of it is stuck inside. Seems a previous attempt at this caused the baffle to snap, just where the thinner part meets the thicker part. Neither the exhaust nor the baffle are available to buy so it seems that I'll have to do the best with what I've got. I was thinking of pouring petrol or similar into the pipe then blocking off both ends and allow it to sit for a day or two. Then, with a hammer and broom handle or similar, knock the stuck bit out of the exhaust pipe. Clean the baffle up then repair it by welding. Any other ideas, or is there something more effective than petrol to use? Thanks for any replies.

Having sprayed wd40 into the spark plug cover it's now run without a hitch for several weeks. Simple fix!

It doesn't happen anywhere consistently. It can be when I start it up, when I'm going slowly through traffic, or when I'm going fast down a dual carriageway. I had a similar problem to the one you described in the past, solved by installing an inline fuel filter, the inside of the tank is rusty. This is different, it cuts out very sharply, to nothing, whereas when I had the dirty fuel problem it would struggle to a stop over a few seconds.

Thanks, I've just wd40'd it, see how that goes.

I wonder if anyone can help: Over the last few days a problem has developed when I'm riding my bike. Most of the time it runs perfectly. From time to time though the engine dies completely for just one or two seconds, then comes back to life and runs perfectly again. It doesn't feel like fuel starvation, had this problem in the past and it died more slowly. I took the carb off though and cleaned it, although the jets looked clear. Any ideas what the problem might be here? Thanks.

I have a new chain and sprocket kit for my bike. My previous bike had a separate cover for the front sprocket but the RS125 just has one cover on the left hand side, that covers everything. I know the clutch cable locates under here plus the clutch push rod. There's also the neutral switch, I think. I'm comfortable removing the gearshift lever, all the bolts are free that hold the case. I'm nervous though. If I go ahead, remove the bolts and gear lever, manage to get the cover off, am I likely to have a load of things fall out not knowing where they came from, or how to replace them? Any help appreciated!

Thanks for the replies. Is there any reason why I couldn't remove the wheel and then tyre, cut out just the offending spokes and replace them, rather than face the cost of a complete rebuild?

My '82 RS125DX has 5 loose spokes on one side of the rear wheel. While it's not affecting the ride I'dlike to fix this and it may possibly be an mot fail? I've tried to adjust them but the adjusting nipples are rusted solid. I've tried a bit of wd40 and 3 in 1, clamp the spoke with mole grips close to the nipple and worked them backwards and forwards but no joy. Any hints or tips how I might free these?

It is a bit tricky but I carried my last bike around for 4 years without it falling into the cut! Basically I welded a rack across the back of the boat, 4mm steel channel. A shorter piece of the same slots into this, pivoting to allow for variations in the towpath height. It's a bit tricky, the boat is 6 foot 10 wide, bike is 6 foot 4, with rear light assembly removed. I also need to remove the front footrest assembly, this interferes with the rudder steering, and wedge the rear brake pedal down with a block of wood. I've been through hundreds of locks without a problem but you do need to be careful, it's a bit tight. I know it's not the best environment for a bike but needs must, and I always cover it.

Cheers I live on my narrow boat, different places around Cheshire, near Nantwich at the moment. Might drop into the bike shop in Middlewich, they seem quite helpful.

There was some rust when I unscrewed the valve seat, plus bits of what looked like epoxy. I guess someone must have put expoxy in the tank sometime (badly). I don't think we smashing lots of nuts and bolts around the tank would have helped much, but there you go. I received the carb repair kit. Unfortunately, the float valve in the kit is a larger diameter so won't fit. I'm a bit stuck. There are no legible markings on the float valve so I've really no idea what I'm looking for. One option is to get a copied carb from China for 20 quid delivered. Hopefully the float valve and needle will fit mine or otherwise, I could put the whole carb on. I'd rather not introduce Chinese to this bike if at all possible. Otherwise, is there a place in the north west where I could physically take the part so someone knowledgable could identify something suitble to use?

Yes that's the one I saw. No guarantee that it fits (see previous post) but Wemoto have said they'll take it back if it doesn't fit. Got to be worth a go. God it never ends does it! If there is, how can I get it out?

Thanks I saw that, but was put off by how long delivery takes. I'm still using the bike most days, having to take the carb off half the time! I've just noticed that Wemoto are offering a carb repair kit for the 1975 RS125. My Haynes manual suggests that all the RS125's have the same carb. Emailed Wemoto to confirm but they can't, say they can't access the OEM diagrams, whatever they are. Anyone know what these diagrams are, could I maybe find them on the net?

Apologies for this being a bit long winded, thought it best to explain in full. I've had a Yamaha RS125DX for a month now. I've had one of the 2 following problems quite regularly since: Either: Petrol flows from the carb overflow when I stop, engine floods. Or: Bike runs fine for a couple of miles then bogs down and dies. This happens quicker if I rev the bike harder. After waiting a minute or two the bike starts again, same thing happens a couple of miles down the road. I think both problems are caused by the same thing: The float needle isn't moving in and out correctly. It's either doesn't move far enough up and fuel overflows, or doesn't move down enough, not allowing enough fuel. Does this sound about right? I've cleaned the carb out loads of times. The tank was rusty inside when I bought the bike so I cleaned it out and fitted an inline filter. I cut the first one up after a couple of weeks, there was very little stuff inside it, I'm fairly confident the petrol getting through is fairly clean. I want to replace the float needle and its seat but I'm really struggling to find one. The Haynes manual lists the carb as a Mikuni VM 24 SH. Neither Wemoto nor Yambits sell this carb repair kit, and my wider search came up with a blank. I could buy a complete new copied carb from China for 20 quid delivered but don't really want to put any Chinese stuff on it, you know? I would expect the parts I want are probably the same on some other Mikuni carbs, which may have repair kits available. Is there any way I can cross reference the needle and seat against other carbs to see if they will fit? Any other ideas? Many thanks.

OK thanks, I have the manual, I guess that will describe how to check for crankshaft movement.

I was hoping to not hear that, such is life sometimes! There's no obvious bearing noise at the moment. I bought the bike following it being laid up for 2 years, I guess that's what did for the seal. I haven't done many miles since I bought it. Do you think attempting to change the seal with the engine in situ would just be a waste of time?

My Yamaha RS125 is throwing out white smoke when I start it up, and for the first few miles of a ride, before clearing up. It's using gearbox oil. Seems the right hand crank seal has gone. Does anyone know if the seal can be replaced by removing the clutch assembly, or is it an engine out job and split the crankcases? Thanks for any replies.

Thanks, I know they share many of the same parts, that should work out nicely.

Yes, Yamaha RS125DX, eighties model. I'm thinking of going to view one that's for sale. The forks are covered by gaiters (spelling?), probably hiding pitted forks. If I know the diameter underneath I can work out how easy (or not) it might be to adapt my rack to suit. Would possibly save me a wasted trip. Cheers.

I've been tootling along on a Suzuki GN125 for 6 years now but now is the time to get something a bit more interesting. I've decided on an RS125. I live on a narrow boat, I carry the bike on the back on a rack I designed and had custom built. Basically it's 4 inch steel channel, the bike is secured by a front fork sliding into another fork built into the rack. My first question: My existing bike has front forks of 32mm diameter. I've searched for ages on the internet but can't find out what the diameter of RS125 shocks are. Does anyone know? Second question: The tiller steering on my boat is likely to be interfered with by front footpegs on the new bike. The GN has foldable pegs which alleviates the problem but I believe that they are fixed on the RS125. Any ideas how I might adapt the pegs to make them foldable, or removable? Thanks for any replies.