Originally Posted by
Lille-bror
Hi all.
How do you test, if you have a defective front bearing?
I've read about allowing the engine run at idle speed at then spray some oil between the flywheel and front bearing. If the engine stops, its because of a defective front bearing because the engine sucks air through the bearing.
I tried it on this monday engine that just flame randomly. Could it be because of a defective bearing?
As you can see in the video, its flames right after spraying oil on the bearing.
Defective engine
I wasn't sure if the method was reliable, so I tested it on my BTT engine with brand new bearings (only broken in). Guess what, it flames in the same way as the other engine after I sprayed oil on the bearing.
So, did I make the oil/bearing test correct?
Lille-bror, Unfortunately ,you have done the test correctly. On the Werks Engine ( assuming EVERYTHING else is mechanically sound) that front bearing is the cause of all your random flaming and tuning issues. I have been there done that with the Werks engines. Running a much hotter plug will help reduce the issue but the fact is its still MASKING the problem...leaking front bearing... Notice I did not say BAD front bearing. Bearings in these engines are not seals... And this issue is by no means isolated to Werks engines. In fact your BTT just proves that point. I have tested for vacuum leaks on brand new never ran nova plus 4's. The first 2 tanks 250 cc's they passed the break cleaner test with zero issues. By tank 3 the engine was studdering. On the 4th tank, 500 cc's i could kill the engine instantly. This was with brand new nova 17011 bearings. So by the time we finish the break in process we are already masking a leaking front bearing with carburetor jetting. This problem is becoming more and more common place over the last couple years for many reasons. Fuel with less oil content / Engines that turn massive rpm / Running a lean bottom to get run time,which in turn requires a small idol gap. Dirty air filters.