89 CRM 250 WITH UNCONTROLLED ENGINE RACING PROBLEM?????
89 CRM 250 WITH UNCONTROLLED ENGINE RACING PROBLEM?????
I'm currently living in South America and have an 89 CRM that has a brand new engine in it (ouch). When I bought it a few months ago it had been sitting for years with low milage. It ran fine for a while but a couple of bearings went south apparently due to moisture corrosion in a humid climate over the years sitting. When I was going over it mechanicaly before the engine was rebuilt, it had a bit of a \"racing engine\" problem occasionaly. After a while it went away, and the engine had to be rebuilt. Now once again this problem has resurfaced after sitting for three months. I will start it up on choke and it seems to be fine, then Ill take off the choke and maybe give it a bit of gas and the idle wont drop down for way too long... then maybe I'll hit the gas again and it will go NUTS screaming at top rpm, even shutting the key off wont shut it down when it's doing that... I have to whack-wack-wack the throttle till it will finally come back down. By that I mean violently twisting the throttle to full and back to ilde several times to get the thing to calm down. So you would think sticking throttle then right? But the wierd thing is that when its idling... I can get it to race without ever actually twisting the throttle to anywhere near full throttle position, it does it with hardly any throttle input at all. I have taken the carb out, cleaned it very well with compressed air and identical problem again, maybe worse.
So, anyone have any good hunch what could be happening here? Am I likely looking at air leaks? It's nuts how it wont shut off when I jerk the key... but maybe that is a sort of heat induced deisel effect? Reed valve problem? Electrical? Floats????
That full racing motor like that is scary... i keep waiting for something to blow, 1000 dollars worth of shrapnel . Anyone????
Many thanks,
Mark...
So, anyone have any good hunch what could be happening here? Am I likely looking at air leaks? It's nuts how it wont shut off when I jerk the key... but maybe that is a sort of heat induced deisel effect? Reed valve problem? Electrical? Floats????
That full racing motor like that is scary... i keep waiting for something to blow, 1000 dollars worth of shrapnel . Anyone????
Many thanks,
Mark...
You sound like your not stupid and i expect you have checked all the obvious things ,,Like 'there is a tension return spring on the cable above the carb slider and its strong enough to return the throttle cable and slider to a neutral position ,(idle)And you have checked the circlip on the end of your carb needle is placed correctly in the carb and is pushed down with the slider as it throttles off ,what about float needle ,, does it seat properly with the correct float hight ,?.Is the seal good on the throttle /slider head.What ever your problem its most defantely something to do with your carb..If its an air problem then youll notice a burnt plug..What color is your sparkplug ,, So , Tell us what you have checked and dismissed and we'll see if you have missed anything out ,, Good luck
<quoted material> You sound like your not stupid and i expect you have checked all the obvious things ,,Like 'there is a tension return spring on the cable above the carb slider and its strong enough to return the throttle cable and slider to a neutral position ,(idle)And you have checked the circlip on the end of your carb needle is placed correctly in the carb and is pushed down with the slider as it throttles off ,what about float needle ,, does it seat properly with the correct float hight ,?.Is the seal good on the throttle /slider head.What ever your problem its most defantely something to do with your carb..If its an air problem then youll notice a burnt plug..What color is your sparkplug ,, So , Tell us what you have checked and dismissed and we'll see if you have missed anything out ,, Good luck
Ha, well thanks for the vote of confidence, hope I dont dissapoint ya. Quickly, yes there´s a spring thats doing it´s job, the slide is working fine. So I checked the plug, the base is kinda dark, coffee color... the arm is the color of a toasted bagel... mm breakfast. Nothing looks too wierd to me on the plug. So this morning I was checking the throttle slide and cable and realized that the slide was not quite re-seating properly, so I lubed up the cable and cleaned out the slide chamber, re-sealed the reed block, checked the rubber boots, everything looked good with the slide snapping back down into place nicely. Result? No change. Could this be electical? I´m used to a 400 4stroke so cant say, but the spark looks weak on this thing... kinda wimpy and small. Tiny in fact... should I replace my coil? How can I test my spark output properly?
Still searching for a solution.
Mark...
Ha, well thanks for the vote of confidence, hope I dont dissapoint ya. Quickly, yes there´s a spring thats doing it´s job, the slide is working fine. So I checked the plug, the base is kinda dark, coffee color... the arm is the color of a toasted bagel... mm breakfast. Nothing looks too wierd to me on the plug. So this morning I was checking the throttle slide and cable and realized that the slide was not quite re-seating properly, so I lubed up the cable and cleaned out the slide chamber, re-sealed the reed block, checked the rubber boots, everything looked good with the slide snapping back down into place nicely. Result? No change. Could this be electical? I´m used to a 400 4stroke so cant say, but the spark looks weak on this thing... kinda wimpy and small. Tiny in fact... should I replace my coil? How can I test my spark output properly?
Still searching for a solution.
Mark...
Welcome, still sounds like the slide is in the worng way round (180 degrees).
I had similar with my AR80, killed the ingition and it kept screaming, pulled the plug cap off and bounced off all for walls of the garage.
Other option and possibility is to check the crank seals, if the left one is gone and is drawing oil in, then perhaps thats enough to make a diesel type effect.
Is an odd one and keep us posted with your findings
I had similar with my AR80, killed the ingition and it kept screaming, pulled the plug cap off and bounced off all for walls of the garage.
Other option and possibility is to check the crank seals, if the left one is gone and is drawing oil in, then perhaps thats enough to make a diesel type effect.
Is an odd one and keep us posted with your findings
Well thats an idea allright, 180 out. I think though, that the fact that the problem seems intemitant would rule that out. Seems that if it were something that concretely wrong, that the problem would be consistent, allways the same. I will though certainly check that, and thanks for the new idea. The seals are a negative, cuz this thing has all new engine seals, and it even did this with the old seals... seals changed, problem stayed.
Could this be an electrical phenomena? My cdi gone breserk? Doubtfull.
Thanks,
Mark...
Could this be an electrical phenomena? My cdi gone breserk? Doubtfull.
Thanks,
Mark...
I have heard of similar before & the fault was an air leak, caused by a perished inlet rubber, possibly not the problem in your case as you would have possibly have noticed a perished inlet rubber whilst checking the Carb slide.
But its worth noting that an incorrect fuel mixture eg. too much air could cause the engine to race! you state the engine is fine when on choke? eg getting extra fuel!
possible causes of too much air are
1. Blocked or partially blocked Carb jets? if the bike has been stood for a while, the jets can become partially blocked from dried up fuel. Is there any crap floating in the Float bowl?
2. Air leak to inlet system? check all joints between carb & Barrel, one way to confirm this is to spray WD40 or similar over the joints when the engine is running & see if idle speed changes.
3. Airleak to Crankcase? are both crankcase halves joined properly & sealed? any damage or cracks? Is the base gasket sealing? You could try the WD40 test on these areas!
4. Leaking Crank shaft oil seal?, you state these seals are new but are they fitted correctly & is the Crank shaft running surface damaged?
Most of this work would have been done during the engine re build but its often worth double checking that something has not been missed.
I would be surprised if Electrics would cause a intermittent fault as electrics would normally work or fail completely!
Good luck with the investigations.
But its worth noting that an incorrect fuel mixture eg. too much air could cause the engine to race! you state the engine is fine when on choke? eg getting extra fuel!
possible causes of too much air are
1. Blocked or partially blocked Carb jets? if the bike has been stood for a while, the jets can become partially blocked from dried up fuel. Is there any crap floating in the Float bowl?
2. Air leak to inlet system? check all joints between carb & Barrel, one way to confirm this is to spray WD40 or similar over the joints when the engine is running & see if idle speed changes.
3. Airleak to Crankcase? are both crankcase halves joined properly & sealed? any damage or cracks? Is the base gasket sealing? You could try the WD40 test on these areas!
4. Leaking Crank shaft oil seal?, you state these seals are new but are they fitted correctly & is the Crank shaft running surface damaged?
Most of this work would have been done during the engine re build but its often worth double checking that something has not been missed.
I would be surprised if Electrics would cause a intermittent fault as electrics would normally work or fail completely!
Good luck with the investigations.
Hi Radish,
I have seen this before on my mates mark1 and he spent a long time going through everything, the carb, accelerator cable until...
...looking at the power valve - it had become gummed up because he was running it on a low quality oil. I would certainly check this.
Let me know how you get on.
B.
I have seen this before on my mates mark1 and he spent a long time going through everything, the carb, accelerator cable until...
...looking at the power valve - it had become gummed up because he was running it on a low quality oil. I would certainly check this.
Let me know how you get on.
B.
Bargos
'Daybreak Boys', West Sussex
'Daybreak Boys', West Sussex
Well sports fans... im running out of ideas here. I have checked or done the following.
sprayed carb cleaner on all connections and got nothing except a slight increase when i hit the joint going from the back of the carb to the horn that connects it to the air cleaner. No reaction from any engine seals.
checked the power valve for proper function (it´s clean and working and does not seem to affect the problem much closed or open)
thouroughly checked the slide assembly, it´s orientation in the carb, and for proper seating along with the throttle cable return.
dissasembled, cleaned and blew out the passages on the carb twice
new spark plug.
I HAVE NOT DONE THE FOLLOWING:::
replaced the pilot jet (I hear these can lead to so-called erratic running)
confirmed proper float level or needle and seat function
anyone think of something else?
still plugging away at it
Mark...
sprayed carb cleaner on all connections and got nothing except a slight increase when i hit the joint going from the back of the carb to the horn that connects it to the air cleaner. No reaction from any engine seals.
checked the power valve for proper function (it´s clean and working and does not seem to affect the problem much closed or open)
thouroughly checked the slide assembly, it´s orientation in the carb, and for proper seating along with the throttle cable return.
dissasembled, cleaned and blew out the passages on the carb twice
new spark plug.
I HAVE NOT DONE THE FOLLOWING:::
replaced the pilot jet (I hear these can lead to so-called erratic running)
confirmed proper float level or needle and seat function
anyone think of something else?
still plugging away at it
Mark...
Mark,
Just an idea - are you sure the throttle slide is closing properly?
Its just that it sounds like everything is fine until you open the throttle and then it goes mad, so it has to be part of the system that operates once the throttle is opened and doesnt close again.
Are you sure it isnt the throttle cable getting caught further along than the twistgrip? Might be worth removing the grip and to see if you have any slack in there that could cause the problem.
Let me know, cheers.
Keep plugging away at it - we will get it sorted for you. What does agermaney think...?
B.
Just an idea - are you sure the throttle slide is closing properly?
Its just that it sounds like everything is fine until you open the throttle and then it goes mad, so it has to be part of the system that operates once the throttle is opened and doesnt close again.
Are you sure it isnt the throttle cable getting caught further along than the twistgrip? Might be worth removing the grip and to see if you have any slack in there that could cause the problem.
Let me know, cheers.
Keep plugging away at it - we will get it sorted for you. What does agermaney think...?
B.
Bargos
'Daybreak Boys', West Sussex
'Daybreak Boys', West Sussex
Mark,
Hi, i also have a mark 1. Not had this problem on this particular bike, but have seen it a few times on 2 strokes...
I see you've checked the plug, however this could still be the problem, i would try a new one and/or a \"colder\" spark plug. The carbon sitting on the plug and \"glow\" hot which will cause the fuel to ignite and continue running the engine even if all the switches are off.
I know you've changed the plug, but unless there is something \"glowing\" or spraking in the combustion chamber, the engine will not run. There is no spark created if the engine switch or ignition is off, therefore it can't really be anything else if this happens.
You can check the coil, by connecting an Ohmeter across one the terminal and the output wire (cap). This should read around 4.7kOhms. It's unlikely to be the coil though i would think.
Hope this helps, let us know how you get on...
SMB
Hi, i also have a mark 1. Not had this problem on this particular bike, but have seen it a few times on 2 strokes...
I see you've checked the plug, however this could still be the problem, i would try a new one and/or a \"colder\" spark plug. The carbon sitting on the plug and \"glow\" hot which will cause the fuel to ignite and continue running the engine even if all the switches are off.
I know you've changed the plug, but unless there is something \"glowing\" or spraking in the combustion chamber, the engine will not run. There is no spark created if the engine switch or ignition is off, therefore it can't really be anything else if this happens.
You can check the coil, by connecting an Ohmeter across one the terminal and the output wire (cap). This should read around 4.7kOhms. It's unlikely to be the coil though i would think.
Hope this helps, let us know how you get on...
SMB
Well, there is carbon in the combustion chamber also. Seems since I changed the plug and that had no effect, that if the carbon is a problem its in the combustion chamber. That though, is not what is causing the thing to race like a maniac, that is air and or gas. The carbon is only a sub-symptom. I gotta get on it again with that carb spray and look a little closer. I got a tip on thumpertalk to take off the ignition cover and hit the crankseal directly... that might reveal something.
Im past tearing my hair out on this, no hair left.
ciao
Mark...
Im past tearing my hair out on this, no hair left.
ciao
Mark...