Symptoms of bad crank seals?

**Auto_Demon** · 07-17-2013, 10:45 PM

so my trike was running fine one day and the next it would run until it warmed up and then just bog and die then you couldnt start it again till it cooled down. it wont idle either. carb its clean, new plug, running 32:1 stock jets. Motor has never been touched, stock exhaust on it. My friend thinks it could be crank seals and I keep denying it because I dont want to take the motor out but I need to know before I buy anymore upgrades for it

**rg97** · 07-17-2013, 10:49 PM

First of all what bike? I know its a two stroke, cause of the 32:1 comment. If you had bad crank seals, the motor would puff LOTS of white smoke when it runs. This happens because the bad seals let transmission oil into the crankcase and it gets burned with the other gas. I had that same problem on my shee when i bought it.

**Auto_Demon** · 07-17-2013, 10:52 PM

sorry i forgot the most important. its an 85 250r. and it doesnt smoke bad at all. perfect amount actually. im thinking its either the cdi box or the stator

**rg97** · 07-17-2013, 10:59 PM

Lots of smoke = crank seals. Your seals are fine. There are people on here that are real experts at this kind of stuff, so i can only help you to a degree. If you think its the cdi or stator, see if you have a spare one and put it on, then try.

**82 250r** · 07-17-2013, 10:59 PM

1.Replace the stator.

2.Make or buy a leakdown tester and test for air leaks. Bad crank seals will make it run lean all the time...it doesn't sound like that's your problem.

**sweetip2000** · 07-18-2013, 12:14 AM

I just went through this on a turd of a bike I bought from some azzhole on CL. Says it just needed the carb cleaned. Yeah right..... this turned out to be the biggest waste of money in parts from hot swapping part by part. Then Flying W jumped in and it turned out to be a 15 page thread on the same symptoms you have. Anyways W walked me through the troubleshooting and he really helped me nail down what the culprit was. You need a multimeter and test the resistance between the stator. In my situation it was a real curve ball because the resistance on the stator was good but there was a bum connection in the white quick connect clip coming off the stator.

When I disconnected that white clip it started up all the time which it didn't do so that was resolved but the bike would not want to start after it was hot.

I opened the cover and looked at the stator. Part of the stator was discolored. So what the conclusion was. The stator would get too hot after running for a while.
Bike would run but when you shut down it wont kick over again until it cools down.

I cant guarantee that's your problem but if I can save you the $$ that I wasted at the bone yard it will only help you and others. Thank you Flying W. You are the man. Good luck.

**yaegerb** · 07-18-2013, 12:20 AM

Only way IMO to determine if you have a crank seal going out is to perform a pressure test.

Here is a link to educate yourself further...
http://klemmvintage.com/airleaks.htm

Also, harry klemm built my pressure tester. Give him a call, for a small price he can build you one too. Or if you have the money, motion pro sells an entire pressure test kit for about 250.00.

After you read the article, any other questions just ask.

**threewheelin-feelin** · 07-18-2013, 12:35 AM

just my opinion but a bad crank seal on the stator side would not cause it to blow white smoke. i do not believe your dealing with bad crank seals. sounds electrical to me as well. stator and also ignition coils also will cause a motor to cut off and not start when hot. you may want to test to continuity on the ignition coil once its hots. thats a easy place to start. dont forget there is a pick up coil on the stator that should be tested as well. and if you can best results will be to run it till it dies and then test every thing

**82 250r** · 07-18-2013, 02:38 AM

Unfortunately, testing a stator with a meter can be a waste of time... especially with the symptoms described by the OP.
If the bike starts, and runs for a time, the stator can also pass an ohm test.

If it we're mine, I would replace the stator with a known good one to eliminate it as your problem.

**jb2wheels** · 07-18-2013, 12:08 PM

When I bought my 85, it was beautiful but would not rev or "clean out". It would start 1st or 2nd kcik every time but just would not run out.

I chased everything. Carb. Coil. Exhaust flange. Pressure test. I even replaced the RH crank seal despite a good pressure test. I even checked the stator and it was in spec.

I finally llistened to what others who have been there before were trying to tell me. Specifically, they said the water pumper Rs were sensitive to the stators being on the low end - anything under 150 Ohm even though the spec is like 50-250. Mine was 130ish.

I replaced my stator and the problems went away. My favorite trike to ride.

**Auto_Demon** · 07-18-2013, 12:48 PM

Ok well i have an 86 cr250r for parts so ill swap the stators and see

**Auto_Demon** · 07-22-2013, 05:19 PM

Update: i ran the bike till it died and checked for spark as a friend said i should and it didnt have spark after it died, is this a sign of a bad stator, cdi box or ignition coil?

**threewheelin-feelin** · 07-22-2013, 05:31 PM

could be any. you need to test all 3 when hot is you can. the bad part is if i remember correctly from my manual there is no way to really test the cdi box for sure

**ceaserthethird** · 08-01-2013, 05:44 AM

Any updates ? Keep us posted!

**Mosh** · 08-01-2013, 09:41 AM

Personally i would not buy any parts. You have Identified a no spark issue. In My experience with many 250R's, stators just Die..They don't run then stop then come back to life in my experiences. I find more intermittent CDI and Coils or connection issues cause a run then not run condition due to lack of spark than anything. Remove the CDI from the rubber holder and run the trike till it quits..Smack On the CDI with a plastic screwdriver handle and see if you get spark again. If so, suspect CDI or Connections. Also the stator wires up under the tank tend to lose terminal tension and any slight amount of heat will jack resistance up and cause no spark. Check that as well.
I also find that the spark plug boot gets loose where it threads to the coil wire lead and you can trim back the coil wire and re thread the old boot back in for a tight connection.
Lastly, remove your stator cover and see if your flywheel is all rusty causing a lack of gap, for the pick up coil. If so, wire wheel the flywheel on a bench grinder and paint with clear coat and adjust your pick-up coil gap to .017"

I have a feeling you will find a CDI, Coil or connection problem first.

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Symptoms of bad crank seals?