Minor 250r issue I've never figured out...

[Dammit!]

This has been going on occasionally with my '86 R for a few years now.

Every so often, usually after sitting a good while, it's a bear to get it to rev. It will start just fine but giving it gas results in an immediate bog. I have to lift the choke slightly to keep it from stalling. It takes several minutes of attempting to give it gas and using the choke to keep it alive before it finally revs and acts normal. Once I get there it runs fine and doesn't do it again for the rest of the weekend. Even sitting outside on cold desert nights.

I just started it for the first time since Easter and it took a good 7-10 minutes to get it to rev. At one point it even revved up out of control like it was held wide open. I had to pull the plug wire to kill it. The switch didn't do anything (that was a new one, its never done that before).

I know it's overdue for new reeds. I just replaced the stator and flywheel. I know it's jetted pretty much spot on. I know the 2-cycle oil I use is not known to be good for storage (Klotz Super Techniplate). Maybe it's gumming up or something. I don't know.

Any ideas what the cause might be or has anyone else experienced anything similar with a water pumper?

[tundrawillie]

turn the petcock off and run the gas out before storing

[RoscoW]

Do you use stabilizer in your fuel ? The absolute crap gas these days will go bad in a couple months, gels up into a white sludge. I've been running stabil in every tank I mix up cause I'm not sure how long it will sit in the carb between rides.
Just a thought.

Ross..

[4cylinders]

hey, the fuel in the crankcase goes sour. it takes a while to refresh it. chain saws do the same thing.

[NINJA]

You are experiencing a temporary lean condition due to ethanol in your gasoline. Either the fuel in your floatbowl has absorbed enough water from the atmosphere to cause this or it has gelled in your tiny jet orifices causing a temporary lean condition. When you trike wouldn't shut off with the kill switch, that tells the whole story right there. The combustion chamber operating temp was so high that it was being ignited by a glowing hot carbon deposit instead of the spark plug. Drain your bowl if your trike is going to sit longer than a couple days. Everyone with a 2-stroke is going to have to start doing this. gas these days is chit!

[Mr_RPM]

The combustion chamber operating temp was so high that it was being ignited by a glowing hot carbon deposit instead of the spark plug.

so why would pulling the spark plug cap turn it off? if the spark plug was not igniting the fuel then why would removing its electrical connection make a difference then just hitting the kill switch?
Im not disagreeing im just clueless. lol im not a 2 stroke guy really

[NINJA]

so why would pulling the spark plug cap turn it off? if the spark plug was not igniting the fuel then why would removing its electrical connection make a difference then just hitting the kill switch?
Im not disagreeing im just clueless. lol im not a 2 stroke guy really

Because the deposit wasn't large enough to sustain a high enough temperature without the added assistance of the spark from the spark plug. If he'd held onto the kill switch for an extended period of time, it would have accomplished the same thing. It could also be that the deposit had enough time to burn off, so pulling the plug wire was coincidental in the termination of combustion.

As an afterthought, is the kill switch functioning properly and completely? Is it possible that added vibration from RPM could cause a temporary short to ground? This could be in the wires or the switch itself. This could explain the kill switch not stopping the engine.

[Mr_RPM]

I was thinking the same myself just wasn't sure. pulling the plug was most likely a coincidence and holding the button down would have done the same.

[Dammit!]

Kill switch is a brand new OEM one.

I use 100LL AV gas (shoulda mentioned that sooner). I haven't run pump gas in it since several years ago.

When it revved out of control it scared the absolute **** outta me too. Luckily I had already been trying to get it going for a few minutes so at least it wasn't stone cold at the time. I always figured it was just a fuel thing of some kind but the electrical problems I started having last year got me to wondering about it.

[harryredtrike]

id go with the reeds sticking a little after sitting.maybe they are getting stiff.

[Mr_RPM]

Sounds like gum or grit in the main jet and or pilot jet , the kits are cheap on ebay or just soak it in carb cleaner . After the dunes i allways run the carb dry at idle but at the end it goes lean and starts revving weird witch i don`t like but i never have any problems the next time out ! I put a kit in my `85 round slide 34mm and ran it on my tecate and man what a diffrence that tecate purrs like a kitten and does`nt dump out the overflow anymore ! Oh , i like VP 114 and MC-1 @ 50:1 STAYS CLEAN !!!

I have always been told running the engine out of gas on a pre mix 2 stroke is very bad because as it runs out of gas your also starving the engine of the much needed oil lubrication thats in the gas.
I would just drain the carb with simply removing the float bowl.

[JayBone]

Yahoo had news saying yesterday they are going to add more ethanol to gas. I think it was up to 15%. Just to let ya's know.

[250rAL]

You know there's a drain screw right? I've never had that problem and mine sometimes sits for months between uses with the same old gas in it.

[RodKnockRacing]

You know there's a drain screw right?

exactly what i was thinking of saying

[factoryX]

funny, this happened to me at the dunes a couple times right before it melted a hole in the piston, and jetting was spot on. I usually run ethanol free premium but the gas in it was left over ethanol pump gas.

[3Razors]

Yep, there is NO ethanol is avgas. Which makes it great for storage. The revout problem after sitting for long term is if you dont turn the fuel valve off and either run the bike out of gas or remove the drain nut the the gas/oil seperates and the oil itself will gel up and cause some clotting until it loosens up and clears outs.

[NINJA]

Of course it could be your flywheel side crankseal going bad.

[fabiodriven]

Of course it could be your flywheel side crankseal going bad.

Wouldn't the problem happen all the time if that were the case?

[NINJA]

Wouldn't the problem happen all the time if that were the case?

No, many times I've seen a 2-stroke do it sporadically, often when cold.

[Iprefer3]

Only time I've ever had an engine scream like that is because it was sucking air through the base gasket

[MTS]

Sounds to me like it could be a combination of a few things, First thing that comes to mind is Excessive Oil in the crank Case after sitting...It still is a fluid...Drips down a bit Over time i would think...Combined with the lead in the av-gas...Could cause problems...Even Sticky or Gummed up Jets or needles in the carb...Excessive Carbon build up...I'm just speculating...haven't had a chance to play with av-gas. Another thing i Just thought of....Could be sucking small amounts of Trans fluid between the case gaskets...Recently had a run in with an R...That Did something similar.

[ktmbk]

I've always had similar issues with my 250r in the past. After sitting for months (year?) I have to let her warm up for a long time before she will rev properly, as I'm do I blip the throttle and each time and she'll rev a little higher. It's as if I have to clean her out, she also smokes like crazy untill it's done
I've always thought it was the old junk premix sitting in the case. New gas, cleaned carb, new plug, new crank oil never helped with mine.
As for the reving, sounds like a air leak, had that problem with another R engine (which also had the cold reving issue by the way). The engine wouldn't die with a hot spot exactly when you pull off the plug cap.

[factoryX]

well when I got the head off, there was no carbon build up any where, it had burned off Like it had ignited or something lol. And what was more weird was the cylinder walls being in okay shape so I don't think jetting was the issue.

Here is the piston
http://i55.tinypic.com/fw4q2w.jpg

and here is the cylinder wall.
http://i52.tinypic.com/33bz33p.jpg

there is a little scoring but my god, a hone and its good? Would a air leak cause this?

[MTS]

Looks like a case of WOT Way lean...With PUMP gas...Imo

[factoryX]

it was running sweet, but I should of drained the crap gas.

[Rjfabwerx]

Don't you guys have the option to buy gas without ethanol added? They separate it here...I buy gas that has no ethanol (beknownst to me by a sticker label) and mix with hp2 and never had any problems before...My friend has been doing something that I'm still not sure about, I'm not a risk taker like him...he's mixing like Xylol or something into his gas to boost the octane...has the same ingredients as the store bought octane boosters...running it though his 350 Warrior and his 2002 Chevy pickup and claims the difference is phenominal...Kinda off the topic, sorry...I'm goin with maybe your reeds are sticking also...the idea of geling also makes sense...Reeds are fairly cheap, carb kits are pretty cheap...maybe just do both if you can and drain your bowl between rides like these guys are sayin...Not helpful at all but I just want to be part of the conversation, haha...good luck!

[factoryX]

I do, but bend is one of the only places where you can get it in oregon.

[Mosh]

well when I got the head off, there was no carbon build up any where, it had burned off Like it had ignited or something lol. And what was more weird was the cylinder walls being in okay shape so I don't think jetting was the issue.

Here is the piston
http://i55.tinypic.com/fw4q2w.jpg

and here is the cylinder wall.


http://i52.tinypic.com/33bz33p.jpg

there is a little scoring but my god, a hone and its good? Would a air leak cause this?

That was lean..Hottest part of the cylinder is the exhaust side..You can tell the front of the piston was gettin hot.
What carb jetting and pipe were you running?

I would bore that cylinder. It has gotten hot enough to throw it out of round, and it looks like you have some ring clipping also.
Make sure you relieve the ports when done.

[Dammit!]

Yep, there is NO ethanol is avgas. Which makes it great for storage. The revout problem after sitting for long term is if you dont turn the fuel valve off and either run the bike out of gas or remove the drain nut the the gas/oil seperates and the oil itself will gel up and cause some clotting until it loosens up and clears outs.


I was figuring that was the most likely culprit. Is Super techniplate known for that? I've heard it's not a great storage oil but I never heard why. Klotz is not supposed to seperate but I know gas will evaporate and leave the oil behind. Same thing I suppose.

I always turn my gas off but never bother to drain the bowl. Guess I'll have to get in the habit of doing that and see how it goes.

[Mr_RPM]

or just go outside and start it up a few times a week, alot more fun! =P

[Dammit!]

or just go outside and start it up a few times a week, alot more fun! =P

Not when your garage is 120 degrees. :lol:

[Mr_RPM]

Not when your garage is 120 degrees. :lol:

ouch, I don't think i could do Arizona haha

[3Razors]

I was figuring that was the most likely culprit. Is Super techniplate known for that? I've heard it's not a great storage oil but I never heard why. Klotz is not supposed to seperate but I know gas will evaporate and leave the oil behind. Same thing I suppose.

I always turn my gas off but never bother to drain the bowl. Guess I'll have to get in the habit of doing that and see how it goes.

Ya, all the oils will do that with enough time, the gas seperates and leaves then basically you have a puddle of oil in your carb bowl. Klotz isn't the best for storage as its a mix of 80 percent synthetic and 20 percent castor oil. Synthetic oils have an acidic property that attracts moisture which leads to rust on the crankshaft/bearings in long term storage.

[breastman569]

I was figuring that was the most likely culprit. Is Super techniplate known for that? I've heard it's not a great storage oil but I never heard why. Klotz is not supposed to seperate but I know gas will evaporate and leave the oil behind. Same thing I suppose.

I always turn my gas off but never bother to drain the bowl. Guess I'll have to get in the habit of doing that and see how it goes.

Doug,
I was having the same problem, i would start the bike before going and i couldn't get to go more the 1/4 throttle without killing it, so after pulling the jet i could see a film over the jet, so after each dune trip i just empty the bowl and spray some carb cleaning up there just to keep it clean. oh and im using caster 927 and still does it so dont think it just klotz that does it.
Ryan