11-25-2010, 03:32 PM #1
"Bumping" when rotating crank Help me clear this up
I think I know what this is, but I wanted to run it by you guys. I am rebuilding a 96 SLX and it has tow holed pistons. When I was checking the index I noticed a definite bump when rotating the crank in the case. It was like turning an electric motor. slight resistance and then it goes to the next bit a resistance. Is this the stator hitting each one of the magnets, of are the bearings oblong?? I cannot remember is this is normal or not. It has been a while since I rebuilt one of these engines.
Last edited by friscoboater; 11-26-2010 at 07:08 PM.
11-25-2010, 08:00 PM #2
The magnet is one peice,it shouldn't have intermitent resistance.
Do you have the flywheel off ? Bendix out ?
I'm guessing rusty bearings.
11-25-2010, 08:17 PM #3
No the flywheel is not off. All I have done is take off the heads. This engine is super clean and there was no water in it at all.
11-25-2010, 08:24 PM #4
- Join Date
- May 2008
Are you saying it has a increase in resistance, or it hits a 'hump' where its harder to turn, then it wants to fall over a bit?
How many times does it do it per revolution of the crank? Does it happen when a piston hits the top or bottom of a stroke? Or is it at some point where no piston it at the top or bottom?
If its seemingly random, it has to be something funky with the stator/flywheel area... Or POSSIBLY a lower crank bearing. If its when the pistons at hitting top and turning back around, its a crank bearing.
11-25-2010, 09:00 PM #5
It is exact. as you turn it you feel the bumping as you turn the crank. I will shoot a video.
11-25-2010, 09:06 PM #6
Better off taking everything off the cases (flywheel-cylinders) inspect all the peices and see how the crank turns over. Especially after it burned 2 pistons,there might be debri in the cases. And it would be a good time to replace the crank seals.
11-25-2010, 09:48 PM #7
I think you might be right. I have never rebuilt a bottom end, just torn them apart to sell the parts. I am so scared I will not get it sealed correctly, or not get the stator timed right.
Here is the video
11-25-2010, 10:04 PM #8
- Join Date
- Oct 2006
- Cleveland OH
I'm leaning towards the magnets.
Remove the flywheel and see if it still feels that way.
Also, you can see what the stator timing is set at. (should be aligned with the case halves "seam")
What spark plugs were installed in that engine?
What CDI was installed?
Have you inspected the carb filters yet?
11-25-2010, 10:09 PM #9
I have not got that far yet. That is on the too do list tomorrow. The CDi is bone stock and he was running 7ES plugs. How hard is it to get the stator back on correctly?
11-25-2010, 10:25 PM #10
- Join Date
- May 2008
Pull the flywheel, since you need to do it to split the case anyways. If it goes away, great. If not... Its likely theres stuff in the rod bearings. Bearings might just need to be cleaned off, or they could be bad. Split the case and do a visual inspection, along with moving the rods by hand to feel the play and action on the bearings.
Regardless, it will probably run for a while as is. It might just 'go away', but its not a good sign.
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