fosdyke

Hi Sounds like your autolube system may be faulty or maladjusted and feeding too much oil into the mix. Check your settings for the throttle and 2 stroke oil pump set up - if you don't have a manual here's what to do: 1. Check the lower throttle cable is adjusted to give 0.5 - 1.0mm of freeplay (adjust with adjuster on top of carb) 2. Slowly turn the twist-grip to remove all freeplay - atthis point the throttle valve should start to move. Check the position of the circular mark on the face of the oil pump pulley aligns with the protuding guide pin - adjust if necessary. 3. Check the stroke setting (if necessary) - operate the pump via the plastic pinion and note the movement of the plunger (if no pinion is fitted you have to use the kickstart (remember to take the plug out!!) the maximum gap should be between 0.20 and 0.25mm (use feeler gauges). If adjustment is necessary you will need to get shims from a dealer. If this makes no difference you could have a crankcase leak and are burning gearbox oil - check the transmissing fluid level regularly to see if you are 'burning' oil. Good luck

:D Well done Lisa - keep riding :D

New engine fitted and bike back on the road within a week - much to the 'other half's' delight! Danidge - check out my replies in the workshop forum! - BTW is your bike making any 'unusual' noises - loud rumbles that could indicate major mechanical wear?

Sounds like a valve timing problem to me - have you checked and reset the valves?

OK so we know the kickstart works, and we know that it will go if you push it which suggests that you have 1. A spark 2. Some compression 3. Fuel reaching the plug You now need to check that everything is set up right - don't take anything for granted, the guy you bought it from may have rebuilt the engine - but he could have set it up wrong: Check: 1. Points gap and condition (if its not CDI) 2. Ignition timing 3. Remove and clean the carburettor - that means taking ALL the jets out and blowing them through with compressed air. 4. Compression - can't emphasize this too much - on a 2 stroke you need more that 100psi to get it to run real good 5. Auto-lube system is functioning 6. Reed valve (if fitted) isn't sticking Keep me posted - change the plug for a new one and use fresh petrol.

Hi 50psi seems really low 150 - 175 would be normal - as Yoda says check that you are using the compression tester correctly - and make sure you crank it several times with the throttle fully open. You are going to have problems starting it if the compression is under 100psi. Did you check the bore & rings for wear when you re-built the engine? And did you use new oil seals - could be an airleak on the PTO side. Don't take anything for granted - use a new plug, and fresh (that means straight out of the pump) petrol, with a thimble-full down the bore - see if you get a 'pop' - and check the timing - I cranked away for half an hour once before I realised the woodruff key had broken (common on a rebuild). Keep me posted

Hi A rebore would be the quickest and cheapest option, but as some of the other guys say with a good tune up the RXS will eat most other 125's for breakfast so why bother - 'if it aint broke - don't fix it'!!!

Hi Check iginition timing - if you have the 3 magic ingredients the bike should run, maybe not good - but it will run, but if the timings out it'll never go even if you pour petrol or starting fluid into the pot! As for checking leaking seals - and use this at your own risk! - one favoured method is - when the bike is running squirt starting fluid onto the seals and observe if the engine speeds-up indicating an air leak. I would strongly recommend having a fire extinguisher handy if you are doing this though!!!!! But try the timing first.

Hi Just a thought - have you checked compression with a gauge? - could be piston damage. Otherwise if you have changed the plug I go with the timing chain.

Hi Check the ignition timing - if the bike has a flywheel magneto the woodruff key could have broken and put the timing out - it's happened to me a couple of times - and no matter how much you kick it - it just aint goin to go! On the bright side - if you can get the magneto off (you need a special puller) the keys are dirt cheap! (buy extras I did!)

Hi Sounds like one of the oil seals has gone. Is the bike using 'gear-box' oil ? If you can't get it to idle it could be an air leak in one of the seals on the Power Take Off side - but if it is using oil it sounds like a gearbox seal. Check the spark plug for colour to see if it is oil fouled - if necessary disconnect the auto-lube system (if it has one) and use a 20:1 mix in the tank - see if that makes a difference. If its an oil seal - fraid its and engine dismantle job - but they are not too difficult on the small engines - and if you are going that far I would consider doing the bearings at the same time.

Hi Are you sure that the kick start is kicking over the engine? test for compression with the kickstart - you can do a simple 'rule of thumb' by taking out the plug, putting your thumb over it and cranking it on the kickstart - if it blows your thumb off compression is good and the kickstart is operating ok. As the bike runs when you you push it its reasonably ok - but 2 strokes are fussy, everything has to be about right or they just don't go: Check 1. Fuel is reaching the plug 2. you have a good (blue) spark 3. You have at least 120psi compression (@ full throttle) If you have all of these it should run - it may not run good, but it should run - after that check points gap, ignition timing, clean and reset the carbs, check the auto-lube (if it has one id working) - and put a couple of hundred miles on it. You may find after a while some of the niggly problems go away as crank seals soften. Good luck

Hi 650 - 700cc of SAE 10/30 should do the trick!

Don't know if it helps but certainly on the YB100 it points to the exhaust port.

Ok you know the drill - its those 3 things 1. Spark 2. Fuel 3. Compression If you've got all of these it should run (unless your timings miles out!!) If you are new to bike mechanics but reasonably handy try this website http://www.dansmc.com/ You don't have to agree with the guy's political sympathies but his 'online course' is simple and methodical - it's got some of my bikes going just through a process of logical progression. Good luck

Hi Just had similar problem with my YB100 - Are the plugs oil or carbon fouled? If carbon then check your air filter, or change the element. If oil - try doing a compression test 120psi + is ok, anything less and you could be looking at a problem with rings or an oil seal. Do you have any 'unusual' noises coming from the engine that could indicate something more serious? Good luck

Thanks for the tip..........yes MSR did have one, and hopefully it will be delivered before the weekend, so if the engine is good it could be back on the road for the weekend! I did do the fork seals on an old RS100, similar to the YB, I seem to recall fitting them back in the bike first, but maybe my memory is fading....you could try that or putting them in a vice to free-up one pair of hands!!!

Hmmmm I was lucky my forks were ok - so beyond checking the seals I didn't dismantle any further, but I will consult the learned manuel to see if it has any tips. And as a postscript to my original post - having completely dismantled the engine I have found that it was big end failure that trashed the induction disc - and one half of the crankcase.........so I am busy sourcing a replacement engine...booo hooo. Still on the bright side I have more than doubled my array of spare parts!!!!!

Ok - don't know if this will be of help/cheer you up: If the valve stem oil seals or the valve stems are worn then you will be burning oil, particularly noticeable when you first start up by a cloud of blueish smoke from the exhaust. If you are mechanically handy - you could re-lap the valves yourself all you need is a can of paste, a 'lapping' tool and a lot of patience! If your valve guides are worn this is a job for a local engineering company who maybe able to fit new sleeves - or you could consider a new cyclinder head. Explore all the possibilities unless your garage give you a blinding quote on the repair! Good luck

Hi Hope someone can help me with some ideas. I have a 1989 YB100 purchased from ebay and lovingly restored over the last 2 years including new bearings oil seals etc. It has been running reasonably well until about a week ago, when it started 'breaking' spark plugs - a new plug would run for only a few miles and die - ie weak or now spark. The colour of the plug was dark grey/black but not oily suggesting a rich mixture. I adjusted the carb and oil pump to try and acheive a leaner mixture - but no success, and today on a ride out it went through 3 plugs and finally died completely and had to be trailered home! An initial strip down indicated damage to the piston by a plastic substance which could only be the induction disc valve. Sighting through the induction port seems to comfirm this - so I have a job to replace this as well as the piston, with possibly a rebore as well! There may be another cause of the disc valve damage which I may find on further dismantling, but has anyone heard of this happening before - and was the 'plug destruction' a symptom of the impending failure? I am interested in any thoughts on this and how to improve the mixture settings on this bike for th future. Thanks Geoff

Hi Hope someone can help me with some ideas. I have a 1989 YB100 purchased from ebay and lovingly restored over the last 2 years including new bearings oil seals etc. It has been running reasonably well until about a week ago, when it started 'breaking' spark plugs - a new plug would run for only a few miles and die - ie weak or now spark. The colour of the plug was dark grey/black but not oily suggesting a rich mixture. I adjusted the carb and oil pump to try and acheive a leaner mixture - but no success, and today on a ride out it went through 3 plugs and finally died completely and had to be trailered home! An initial strip down indicated damage to the piston by a plastic substance which could only be the induction disc valve. Sighting through the induction port seems to comfirm this - so I have a job to replace this as well as the piston, with possibly a rebore as well! There may be another cause of the disc valve damage which I may find on further dismantling, but has anyone heard of this happening before - and was the 'plug destruction' a symptom of the impending failure? I am interested in any thoughts on this and how to improve the mixture settings on this bike for th future. Thanks Geoff