Yamaha RXS100 alleged "2-stroke-itis"

[Dan79]

On rare occasions my 1990 Yamaha RXS100, which I have owned about a year, decides to lose power then fall asleep with about 10 seconds warning whilst running.

This occurs without fail on the A14 at about 60-65 mph whilst trying to overtake a 4-axled tipper truck laden with loose rubble. Joking aside, the common factor is wet weather combined with a hot engine - never done it in summer, dry weather (hot or cold) nor immediately after setting off. This results in panicked cut-up manoeuvre of the lorry I just overtook followed by bouncing in and out of rabbit holes on the hard shoulder. 3 times in one year is a bit much and it's only a matter of time before both my luck and the bike's luck run out and we both get flattened by a Dutch turnip wagon.

My local motorbike garage fobs me off with "it's a two-stroke they don't like wet weather" in my opinion that's a cop out since I bought the damn thing to ride in the winter, that's what they are for.

Benefit of the doubt though - has anyone any other explanations for this or suggestions for prevention of "two-stroke-itis".

[Alexio]

Well I don't know loads about 2 strokes but "itis" medically speaking means inflammation of. You might just need to pull over and wait for things to settle down? I can't think of why rain would affect a 2 stroke like that though, logically I've always thought that the wet would simply make for an engine being cooler rather than anything else.

But, sometimes I have to pull over and wait a while on my 4 stroke CG engine before performance gets back to where it was when I ride for hours and hours. It's all very weird.

Maybe water / moisture is getting in to your air box or fuel somehow?
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will never give up his CG. I look at my fuel gauge more as a progress bar than a fuel gauge.
G: With my GSXR I do often effectively use it as a scooter with a clutch in town.
ms51ves3: why does it need 500 miles? Are you teaching it how to be a piston?

[ms51ves3]

Wet weather and cutting out points to the electrics. Not great at the best of times on an RXS but even worse if they're wet.

When it cuts out, have a look to see how wet the plug cap and the ignition coil is. Sounds like they are getting soaked and shorting somehow.

[unitybiker]

sounds like your getting partial seizure .your doing well wringingits neck.remember its a 100 ,the rain may effect two strokes but the common factor each time is the speed,if it usually goes a lot faster and is modded then check your oil pump for air leaks and correct oil ratio adjustment,sometimes the accelerator/oilpump cables can get stiff and throw the adjustment out .

[27cows]

I encountered this scary phenomenon just once - and it was down to dodgy alternator wiring and led to me having to ride 30 odd miles home with the flywheel cover removed - so no clutch, no gearchange (3rd all the way) and the flywheel spinning at 9000 revs two inches from my leg I managed the whole journey without stopping LOL

I'd bought some bits for next to nothing, including a stator. Don't know why I decided to try it out as the one on the bike worked fine. But I never used it again after that incident and I've never experienced anything of the kind before or since.

Wet weather is never a problem for my RXS. Electrical grease is marvellous stuff

[Kickstart]

Hi

I would agree that it sounds electrical, and no reason a 2 squeak should suffer more than a 4 stroke in the wet.

The other possibility for it cutting out after a period at high revs would be a blocked fuel tank breather (or blocked fuel filter, same effect). However this would cause problems in the wet or the dry.

All the best

Keith
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[bladerunner]

agreed it sounds more electrical as it does it only in the wet. I'd suspect that the plug is getting water on it or the ht lead or cap are arcing out to earth and after a few seconds the heat from the engine could dry off the water enough to clear up again. 2 strokes do sometimes suffer this a little more as the plug sits on top of the head exposed to spray off the front wheel more than a 4 stroke but thats not to say it's a 2 stroke thing at all and a new cap or rubber pipe over your ht lead should stop the issue for you.

PS if it's one of those old metal ht caps you have plz throw it in the bin anyway...what a stupid idea that was!!!
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Current bikes...cbr929, KDX200's, Rd125lc mk2, RGV250's

[Kickstart]

Hi

Just another thought. Does the RXS still have the original airbox or does it have a K&N style single filter?

All the best

Keith
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[lexx86]

i am still having the same problems with my rxs. i have taken of the circular side panel to reveal tha there was water in the throttle control. still no joy starting it tho. two stroke is full as is petrol. what a to do?

[Kickstart]

Hi

From the circular side panel I am wondering if it is a YB100 rather than an RXS100 that you have.

However, firstly do you have a spark?

All the best

Keith
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[lexx86]

[Kickstart]

Hi

Assuming you mean backfires from the exhaust then sounds like it has dumped a load of fuel down there. Could be the engine is really badly flooded (same for the exhaust, but at least you can take the exhaust off to drain it out). It is worth checking the timing though.

If you mean backfiring back through the carb then definitely check the timing and also check the condition of the reed valves.

All the best

Keith
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[lexx86]

i have had a mechanic re-adjust the reeds and replace the fuel an oil lines. they have been primed as well as far as im aware (if he hasn't he is a sh1t mechanic) how do i check the timing?

[Kickstart]

Hi

Not really much to adjust on the reeds. Reed stops can be bent out further but unlikely to need bending to correct anything. Reeds tend to be pretty much maintenance free until you bin them.

Not sure how he would prime the oil line if the engine isn't running. You get prime the line to the pump easily enough but not really from the pump to the engine.

All the best

Keith
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[lexx86]

[Kickstart]

Hi

Did it seize and stop, or just die? What is the plug condition? Do you have a spark? What have you done to the idle mixture screw? What do you mean by a makeshift air filter?

All the best

Keith
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[27cows]

The RXS is almost unbreakable. The only thing that ever stops it running is ignition problems, in my experience. You can have major bore wear, non-standard pipe, no air box at all or a K&N or the original full of water, air mixture all wrong, water in the fuel etc etc and it will still start and run (not necessarily very well LOL).

I think this problem is very likely to be caused by water in somewhere, probably the stator components. Failing that, look very carefully at the ignition coil and make sure the HT lead is OK, particularly where the plug cap screws on, and that the orange wire isn't damaged and no water has got into the bullet connector.

[lexx86]

[Alexio]

If water in the electrics is the problem then you need to be attacking your bike with lots of WD40
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will never give up his CG. I look at my fuel gauge more as a progress bar than a fuel gauge.
G: With my GSXR I do often effectively use it as a scooter with a clutch in town.
ms51ves3: why does it need 500 miles? Are you teaching it how to be a piston?

[27cows]

And once you get it sorted, keeping the water out with electrical grease

[MaybeGuy]

1990 energy induction RXS's are CDI, not points.

try the sparkplug, check the carbs set up right etc.

the one i built did this sometimes too. it was a fucked float valve. I tried cleaning it out, but it was worn and scored so i just replaced the whole carb for a tenner from the breakers rather than buying a new one and waiting for it to arrive.
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Blue_SV650S wrote: it was a sh1te wheelie, but it proves that he can get it up in 3rd and can do angles. In summery, mattsprattuk is a gobby little sh1tebag, dopehead tw4t, but sadly for all of us, he probably isn't THAT full of sh1te!!
Kickstart wrote: Hi I tend to agree with Matt. All the best Keith

[27cows]

RXS carbs last virtually forever...unless a previous owner has fiddled. I can't ever remember having a problem with a worn carb component. Sediment needs to be cleaned out maybe every 10-15,000 miles. The tickover needs a minor tweak now and again, that's about it.

[MaybeGuy]

your right. it CANT be the bikes problem, it must be you! RXS's are invincible. im sorry for doubting them
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Blue_SV650S wrote: it was a sh1te wheelie, but it proves that he can get it up in 3rd and can do angles. In summery, mattsprattuk is a gobby little sh1tebag, dopehead tw4t, but sadly for all of us, he probably isn't THAT full of sh1te!!
Kickstart wrote: Hi I tend to agree with Matt. All the best Keith

[27cows]

[Dan79]

Thanks for all the advice