| Author | Message | ||
     Anthonye |
Could a backwards piston make a noise similar to valve noise or rod noise? The noise is worse when warm and when the engine is laboring. Also, it is there when I rev it up but much worse slowing down. I figured a bad rod bearing but after taking the engine all apart (and I mean completely apart!) the only thing I found wrong was a backwards piston (and that took a couple of days of staring before I noticed it). Opinions anyone. Tony | ||
| Ratbuell |
Check your wrist pin and bushing for wear. I just replaced the bushings in my S2 for too much play. Haven't fired it up yet - no time to finish wrenching, and I'm *sooo* close! - but it had what sounded to me (in car terms) like a rod knock. bbrrraappp, only on light loads or coast down. On the backwards piston...personally, I dunno. I suppose anything's possible, and I'm sure they're oriented for a reason. Definite maybe?  | ||
| Bluzm2 |
This is a question I've been wondering about for a couple of months. I've done 3 top ends and one rear cylinder so far this spring. As I was installing the rear cylinder job I got to wondering what the difference is. The "arrow" is suppose to point to the front of the bike. That means it's pointing to the exhaust port on the front cylinder and the intake on the rear. Both pistons are the same yet they go in the cylinders 180 away from each other. Is there something in the way the pistons are made that requires them to be installed this way? Or is it a crankshaft rotation thing and loading of the same side f the piston during the power stroke? Oh Pammy! You out there? Just curious... Brad | ||
| Bad_karma |
I though the piston pins where off set for noise purposes. Piston at top dead center moving around in the bore. I have read in the V8 world you can rotate the pistons to get a small amount of torque increase. Joe | ||
| Anthonye |
I just re read in the service manual that the pistons are to be installed with the arrows pointing towards the front. They even make a special note of it. I have read car pistons are oval shaped when viewed from the top, the skirts are wider at the bottom than near the rings, and the wrist pin is off set to one side, all of this just a few thousandths of an inch and done to prevent noise and piston slap. Maybe with new pistons in tight cylinders it doesn't matter which way the pistons go in, but my engine has 32,000 miles (I bought it used 7 months ago) and the noise is becoming very annoying and cheap sounding and getting worse. I am at a loss in that the backwards piston is the only thing I can find wrong. |
