Bad seals on the crankshaft,the engine is sucking air from the seal and it leans the mixture,had the same problem on my KTM and I just replaced the seal on the ignition side.All problems solved!
For those of you who are still wondering. Many people where correct on the air leak, air is getting in somewhere most likely near the carb. But to find exactly where the leak is, have the bike idle and then spray starter fluid or WD-40 on the carb manifold, if it revs up high, theres your leak. You could also use propane, do not ignite!
Wow!!! So many nasty comments!!! Interesting problem. Troubleshooting this one could take time. I know you sold it but the next person to see this may gain some info from it. I am going to believe that this bike ran good at some point prior to this thus eliminating tuning. In saying this, that does not mean it can't be carburetor linked. I will rule that out temporarily. We must consider the fact that this is a 13.5:1 compression ratio engine (give or take depending upon the year). So basically what that means is it requires GOOD FUEL (Premium for sure). Fuel will cause detonation which can cause symptoms that are similar to this. I would do a compression test just to verify what the condition of the motor is. Compression numbers on a good engine will vary from 165 lbs to 200 lbs. Anything over 200 lbs is probably related to considerable port work, after market pipe and over bored carburetor. This type of compression would require a high octane race fuel. If you have a test showing less than 125lbs on a 250, it will cause various engine tuning issues. Anything below 100 lbs will cause fouled plugs and probably excessive engine smoking. Lower compression is usually harder to start also. If the engine is good, make sure the fuel is fresh and the lines (including vent/breather lines) are clear of debris. Remove the carburetor and take off the float bowl. Clean thoroughly with carb cleaner. You may as well check the needle at the same time. If it has an indent where it seats on the seat, it is probably time to change it. The float level should be level when the carb is upside down to ensure proper dispersal of fuel. See tuning manual for schematics. Once done and filled with fresh gas test it again. If the problem persists, then we would have to move to any leakage in a seal that can introduce air into the system. Check carb boot for cracks. It is a difficult test on a bike for crank seal leakage. On a lot of 2 strokes where the seals are accessible, you can spray ether around the crank seals and the engine will rev or die showing potential for a seal problem. Electrical could also be a potential. Suzuki has a power jet controlled by a solonoid. This does not appear to be the case here. The TPS should not cause this, yet, I have seen strange things caused by TPS units. There is a test proceedure listed online for testing the TPS. It never hurts to be sure. The CDI unit is also an option. I do not know of any way of testing a CDI unit in your garage. Coils are a definite. As coils become old the windings and internal components become weak. I am not sure of the numbers, but once again, resistance tests and ground tests can be done on a coil. The funny thing about coils is they don't always quit, sometimes they just get weak and the problems they can cause in this state are unbelievable. This guy warmed his bike up, with a shoddy coil, this is exactly one of those ghost problems that could be caused by a coil. We need to understand, the bike does not go out of tune!!! Jets and carburetor components can become dirty with varnish and debris and in some cases parts can become worn. Trying to tune a worn out motor can be frustrating and will never end. Things to check are the simple things. Make sure ALL VENTS and BREATHERS are clear of obstructions. Clean the air filter. This is a silly one. I have seem engines run terrible and the guy is trying to tune it up. Pull the seat off and a forest is growing in the air box!!! The bike needs air to run. Removing air makes the AF rich. The bike will run like crap if it is to rich. It will also loose power and have the potential to become scrap metal if it is too lean. Never lean a bike out with a filthy air filter to make it run good. When you finally clean the filter, it will probably run lean and potentially melt a piston. Granted, it may run REAL GOOD after you clean the filter, for a brief time until it has a meltdown. I know I am forgetting some things, but I hope this may help someone and I hope it explains that problems develop and are not to be addressed by tuning. Oh... unless severe elevation or temperature change is a factor.... for another time!!! Cheers!!!
It's getting puffs of air in the fuel system somewhere, sometimes people reuse the reed cage gasket and it has a crack that's hard to see. Try looking for where are could be getting in.
playstaionRLZ- just a note. More oil added to the same quantity of gasoline does not make a " rich mixture " It makes the mixture leaner as " lean " is defined as less and rich more. More diluted oil means less gas-hence lean.
Theres a number of things 1. Take your carb apart and givet ot a real good claeaning..... whaile your at it play around with the jets and float hight. 2. If you are using pump gas that could be another problem try av gas you can by it at and air pot " BRING A METAL CAN OR THEY WILL NOT LET YOU BUY IT!" the ethanol in pumped gas eats thr fuel line causing the carb to gum up the ethanol gums it up to so try a clear fuel line you can get some at Lowe's or home depot. 3. Cheak your oil and fuel mixture that could be another problem the less lubrication you got in the motor the worse the outcome will be for you my uncle had one be for he died now its mine so cheak that. 4. Air leak in the carb might need new seals for because the ethanol in pumped gas eats then. 5. Cheak the air box and filter for dirt this also might be the preblem it might be sucking dirt in from the air. I hope rhis helps you have fun riding.
jaydaintith oh well thats good, I was only worried because my friend said it meant to bike was going to blow up, but I looked it up and found out thats not the case
If you look under the left side of your motor there should be oil on your frame and that means it's the crank seals and or crank bearings. When they are bad what it does is it sucks air into the motor and pushes out the exuast.
I agree Its an air leak Most likey the ignition side crank seal.Its an easy fix Just need a flywheel puller and a new seal and a deep socket that's the size of the seal to lightly tap it into place.Good luck bud
Unless you mixed it really rich, it shouldn't be smoking like that. My guess would be that it's running off of bottom end oil because one of the crank seals is shot. probably the clutch side since the clutches are in oil. Other than that the bike seems responsive, which means it isn't the carb or the spark plug like the other idiots on here would like to think. I don't understand why someone would comment on something if they don't know what they're talking about.
By the sounds of things you dont know what your talking about yourself.... it's a 2 stroke.. they are supposed to smoke . Why would you comment If you dont know what your talking about?
moto mix obviously you know nothing he knows it supposed to smoke but not a lot if it smokes a lot it could be a bad crank seal sucking in transmission oil
so it wasn't pluming smoke or loosing oil, long ago. My guess is the throttle spring has been cut to make the throttle lighter, the idle mixture is probably off so someone has the slide sitting higher than it should, float level probably too high too causing a bit of flooding too for good measure. So, as the engine is idling the incoming air can raise the slide, then idle increases, usually caused revs to continue to rise. Really interested to see what you find, my seal had popped out, worn
When a 2 stroke starts to run outta fuel they tend to rev up on their own. maybe your floats are to low and just when it starts to starve of fuel the floats reach low and start to fill the bowl causing that effect. cant hurt to dble check your float height adjustment.
You have an air leak somewhere. It could be in the intake tract, base gasket, or crank shaft seals.If you have excessive smoke and you have mixed the fuel correctly it may be drawing oil through the right side crank seal. A good leak down test should reveal the problem.
Needs potential new Reeds or if that's not the problem maybe it's not getting enough air flow. Idk I'm not a mechanic just know these helped my 89 rmx250 same engine
I can tell you now it isn't the clutch side, crank seal. if it is a crank seal it will be the ignition side crank seal. It could also be a gasket that has gone bad and is getting air from places it doesn't need to be getting it from. Get some WD-40 and spray it around the cylinder base gasket and the head gasket, if it has any effect on the idle. replace the top end immediately. If that has no effect, spray around the reed boot and check your throttle cable routing.
It is a caburetor problem... I had same on a 2002 RM 250 The tank of carburetor is too empty...So the bike 'eat' air + gas by the tank.. It is the float valve who is not ok and doesn't gige too much gas. Open caburetor , and gently twist the 'arm' of the float. Not easy to do, because if you do too much , your acarburetor will 'piss' gas.
seals just give low crankcase compression, hard to start, bad idle and low power down low. I'd suggest checking float height and that the jets are the right size but they too don't just make a bike rev up and down by itself like that. To me it has to be the carburetor slide, the solenoid opens and shuts a bypass circuit but haven't seen one on mx bike, all mine are too old but from RGV days they wouldn't effect the idle like that, they were for off idle to mid range. Let us know what you find.
Sounds like you have an intake manifold leak behind the carb. Air comes into the engine behind the carb and draws gas out of the main jet tube and it runs on it own. Carb & reed gasket replacement should be a good start
Air leak in the carb... get some carb cleaner and spray it all over the carb while it's running and on the motor and if it idles up then u have an air leak. Spray it on the motor to and see if u got a leak
That is a very weird situation, never seen or heard a bike just rev up and down like that. Did the crank seal fix it? i can't imagine how it caused the problem, the air leaks that make a 2t run faster have to be between the carbie slide and reeds, after that the leak would cause crankcase compression loss, lower idle and stall, not rev up. I had a crank seal fail and it wouldn't idle or have any power below 2000rpm, it leaked air into the oil and not oil into the crankcase from memory,
Yea it was leaking oil from the bottom. I pulled the clutch cover to find out the crank seal was bad. Im putting the new seal in today so hopefully it works.
its in the carb whats going on is ur get to much gas the flowts in the carb are not working right it will make it do that. the nidal valve is sticking in trun making it run like that.when it is running like that tap on the side of the carb with hammer just tap not hit hard to let the nidal valve drop back down in the valve seat. see if that helps.
My guess is it would have been, anything from air leak, to carb float or (if bike is equipped) power valve lose or something? surge is usually loss and regain of fuel. But good news is you traded the problem haha cheers!
i have a 1990 rm 250. and id say you got an air leak some where. could be something easy like a base gasket or a cracked. carboot but that is bad im thinking its one of your crankseals that are leaking.
Well, I was hopeing its something easy. Iv cleaned the carb and it all looks good. Same thing with the reeds. Would the throttle cable cause that or the gasket that goes in the top of the carb were throttle screws in.
id check the throttle cable and carb just to make sure but if its a real problem id say crank seals(busted), reed valves(cracked),exhaust valves (maybe the small spring is busted) , id run a compression test if i had no other answer
Blooder291 2 stroke has valves too you idiot. A 2 stroke isnt a valveless engine. I have 2 rm 250 engine took appart on my kitchen table right now dont you think i know them? Intake valve=reed valve: opens with vacuum and closes with positive pressure. Exhaust valves: opens with high engine revs. You should really get information before you try to make somebody look stupid.
***** 2 cycle engines are in fact valve-less engines. It isn't valves that perform the intake and exhaust actions of a 2 cycle engine. The piston in a 2 cycle engine, acts as an intake and exhaust valve on a 4 cycle engine, there are 2 ports in the cylinder walls on a 2 cycle engine. one for intake ( carburetor side of the engine ) and one for exhaust ( expansion chamber, aka exhaust side of the engine ). As the piston travels through its cycle, the spark plug fires. Fuel and air in the cylinder have been compressed, and when the spark plug fires the mixture ignites. The resulting explosion drives the piston downward. Note that as the piston moves downward, it is compressing the air/fuel mixture in the crankcase. As the piston approaches the bottom of its stroke, the exhaust port is uncovered. The pressure in the cylinder drives most of the exhaust gases out of cylinder. As the piston finally bottoms out, the intake port is uncovered. The piston's movement has pressurized the mixture in the crankcase, so it rushes into the cylinder, displacing the remaining exhaust gases and filling the cylinder with a fresh charge of fuel. Now the momentum in the crankshaft starts driving the piston back toward the spark plug for the compression stroke. As the air/fuel mixture in the piston is compressed, a vacuum is created in the crankcase. This vacuum opens the reed valve and sucks air/fuel/oil in from the carburetor. Once the piston makes it to the end of the compression stroke, the spark plug fires again to repeat the cycle.
Can the rite crank seal be changed without spliting the case? I thought it mite be the cyliniod that's in the carb too but wont find out till I get back home.
Hello. any suggestions on the following problem with a Suzuki RM 98 2t water is mixed with oil, which is the problem? and what would be the solution? thanks..
Are you leaking any oil? If yes where? First place I would look is the carb boot if you not leaking any oil and by the sounds of the bike running like that you should have a big oil leak!
Well first your bike needs to be jetted bad!!! Next it could be the flywheel gasket or the throttle cable is just to tight. Also the compression seemed way down and your bike needed a new top end (Pistons and Rings) Also clean the carb. After that you should have a decent running bike.
Ich würd mal den kompletten Vergaser reinigen inklusiv allen düsen und dann müsste das problem normalerweise behoben sein ..... Ansonsten ist es das Auspuffventil im motor und des gibts nicht einzelnd zu kaufen da musst du dir n neuen Zylinderkopf kaufen wo des mit dabei ist ......
I love how people just keep running poorly bikes expecting them to magically fix themselves with more revs!😂 Just tear it down you billy bob and start from there .
Well seeing you didn't let it warm up at all....I would say the problem here is the rider, you caused this damage by kicking it and then just taking off
