Confirmed popping through intake, Timing off? |
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Confirmed popping through intake, Timing off? |
corsepervita |
Jun 2 2010, 10:20 PM
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#1
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Member Group: Members Posts: 327 Joined: 18-April 10 From: Redmond, OR Member No.: 11,631 Region Association: Pacific Northwest |
Ok - so I've sealed up all the potential exhaust leaks except the one possible leak coming from the back of my muffler which may be small - unable to tell.
However, I started noticing a popping noise. I recall it a few times when I first started driving the car but it was so small I couldn't really make out what the noise was. The other day after fixing the exhaust I rolled down the windows and listened more carefully. The same odd "poof" noise I heard behind me was audibly from the engine area. I had my wife get in the car while the car was cold and blip the throttle while it was in neutral to see if it would do it again - it did. It was unmistakably some sort of pop from the intake. It's more of a "poof" than a loud "bang" ... I've heard the noise before on my 924 when the exhaust was partially torn apart - but that was a HUGE lack of back pressure. So that kind of (lack of)back pressure wasn't there since the exhaust is complete, no leak at the heads anymore, and as well only a small one up near the muffler - but even then it's tiny. I remember hearing that popping through the intake is either running too rich, timing off (retarded) or a huge exhaust leak. Since the popping on decel seems to happen very frequently - and just as much so (sometimes more) after the exhaust leaks were taken care of, I'm noticing this more as well. Since decel popping would be culprit to a lean condition - and intake popping would be culprit to a rich condition (at least as far as I know, I may be off on that); My assumption would then be my timing is off? (since obviously you can't have both lol) Wanted to bounce this off everyone here in case I'm crazy. Again - new to working on these little air cooled engines. I'm gonna go put it back up on stands tonight and crawl under and check. A family member also suggested I may have valves that are too tight, but I recall Jim saying he already adjusted the valves and they were adjusted to the .006" mark they were supposed to be at. I plan on replacing the pushrod tube seals here soon - he sent me a procedure on how to do it (i also found a wonderful article on the forum about it) so I will end up double checking them anyway. Any ideas? I'm gonna go get a pot of coffee going and go get it up on stands once I have a brew going and get acquainted with the car some more. |
corsepervita |
Jun 3 2010, 04:13 AM
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#2
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Member Group: Members Posts: 327 Joined: 18-April 10 From: Redmond, OR Member No.: 11,631 Region Association: Pacific Northwest |
Valves are out of spec.
Now... correct me if I'm wrong but I'm using the same method of checking valves as I would my 250. Rotate the engine till you can see the rockers at their low point on the cam lobe. You rotate it till you see it push, then keep going till you see no more movement (when the rocker is at it's neutral point) then measure the clearance. Obviously when the lobe is doing it's job you can't measure clearance, that would make no sense. Once the lobe is away and the rocker is at furthest point, measure clearance. Continue for each valve, so on and so forth. At least that is the method I use on my 250 Ninja, this seemed no different, unless i'm crazy. Indeed, I Could be. And wouldn't dispute it. IF that is the correct method... then indeed, we are out of spec. My intake valve on one side was .006" then the other side was .009" - mind you it was closer to .008" but I could BARELY fit a .009" in there, that's way off. Now I know these engines on this model are supposed to be .006" all around unless at some point they were adjusted to .008" intake and .006" exhaust? I'm not sure. But it seems the one side is off. I didn't get to measure them all, it's almost 3:00am and I doze off a few times inbetween checks and figured I may as well come back inside before I fell asleep and woke up drooling under the car with oil all over my face. (IMG:http://www.914world.com/bbs2/uploads_offsite/i225.photobucket.com-11631-1275560030.1.jpg) |
VaccaRabite |
Jun 3 2010, 07:11 AM
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#3
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En Garde! Group: Admin Posts: 13,465 Joined: 15-December 03 From: Dallastown, PA Member No.: 1,435 Region Association: MidAtlantic Region |
This picture shows the valve being dead nuts correct. Inner valves are intake. Outer valves are exhaust. intake valves are set to .006. Exhaust is set to .008. Zach |
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