Confirmed popping through intake, Timing off? Options

[corsepervita]

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]

The feeler gauge being bent like that will give you a false reading. You don't need to drop the HEs to adjust valves, and the muffler just tucks up behind the bumper. No need to remove bumper or valance.

I actually just put it there so i could take a picture and show the clearance. I got at it with the feelers at a different angle so you don't bend them.

I took the HE's off so I could mostly verify my job I did on sealing up the exhaust was done properly since it was my first time doing heat exchangers. It does make the procedure a bit easier. But I want to hunt down the exhaust leak as well. I do believe I found it - it did appear to be the muffler as well.

I did figure out how to get the muffler out without taking the bumper off as well, lol it took me a few but I finally went "Hmm... ok if i turn this at this angle... AHA!" lol glad I didn't take off the bumper!

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)

You have that backwards.

Thank you - I wasn't quite entirely sure, thank you for the correction.

http://www.914world.com/bbs2/index.php?showtopic=28758
From the classic forum. Good info. I see you were tired and had the clearances backwards. Intake .006, EX .008 is the correct clearance. Very good article and good read.

(IMG:style_emoticons/default/agree.gif)

The Krusty method of adjusting is the way to go! When i had my 2056, i set them all to .006 and that worked fine for me ...
(IMG:style_emoticons/default/cheer.gif) Andy

PS: I have no idea what a '250 Ninja' is but remember that on a T4, each cam-lobe is shared, so whatever method you are used to might not work correctly here ...

Hm - it's a motorcycle, kawasaki ninja 250. Basically you'd rotate the engine until the lobe was rested at a point that it wasn't moving that rocker arm, you knew at that point you could insert a feeler gauge to check the valve clearance.

I understand these are a different valvetrain, however, at some point the cam lobe is moving onto do it's job with another valve, so at some point the one you're looking at will be at the low point of the lobe where nothing is happening, this is where you check your clearance, correct? But from my understanding you go to TDC, check them, then rotate it, check it again, etc...

It seems from what I've read from Capt'n and his post is sort of similar, you just rotate the engine till you sort of see what the diagram listed in his post shows up (not necessarily tdc or anything specific) so that means those particular rockers are at their low point on the lobes (doing nothing, ready to check clearances). Please correct me if I'm wrong, just trying to make sense of it since it's new to me. I'm used to doing motorcycles - so the concept is similar but these are ol' pushrod engines which i've not ever done before.