catkrazy
Posts: 368
Joined: 9/25/2008
From: Marion,Arkansas
Status: offline
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quote:
ORIGINAL: LiveForMud
you have to remember that exhaust flows in pulses... high pressure pulses surrounded by low pressure areas as the exhaust gas moves through. those low pressure areas causes the sucking effect... and the more free the exhaust flows, the easier it is for stuff to work its way into the exhaust at low rpm since the exhaust gases travel slower. and with single cylinder engines there's a lot more time between pulses as compared to something like an 8 cylinder engine.
also, the stock muffler has a lot more interior volume than an aftermarket muffler... which means the exhaust pulses are slowed down a lot more than the smaller volumed aftermarket muffler. with a given flow rate of something through a pipe, the larger the diameter of the pipe the slower the stuff moves... on the other hand the smaller diameter the pipe, the faster the stuff moves. slower pulses have longer times for the sucking effect before the next high pressure wave comes out. one thing you can do is go to a smaller diameter snorkle pipe on the exhaust to help speed up the pulses again as they leave the exhaust... but you'll pay in terms of loosing a little power. or you'll just have to keep the rpm higher while you're in the deep to keep the stuff out.
btw, if your exhaust valves (or intake valves for that matter) are too tight, your engine won't run at all. if the valves can't sit hard on the seats, it can't build compression. this is why many people are afraid to adjust their valve lash themselves because unless you have a little experience you'll get it too tight and it'll either run like crap (won't idle and will have very low power when you get on it), or it won't crank at all.
Great read!!! Thank you for the time to write that here. It all makes perfect sense. The larger diameter snorkle I welded could very well be the culprit,along with the other variables you mention. For now I'm gonna stay with the after market pipe. I tested it back to back witht he modified stock pipe, and the back pressure was almost non existant with the aftermarket (supertrapp) pipe. I'll do some experimenting with the snorkled pipe, and see what I can do do increase the performance of it (may take a few months,lol)
I have no issues going deep with the supertrapp. It idles beautifully completley underwater. I just got a little worried when it died last weekend(due to a bare wire grounding against the frame)I was thinking then "What if " I've sense went back, and checked all the wiring (completly removing plastic, and anything in the way) to make sure there were no other bare wires.
I did adjust my inake valves about a month ago, and then adjusted my exhaust valves last night. (Only one exhaust was out of spec) The intake valves were a different story, both were close to being too tight! which is weird, because most of the time its rite the opposite?
Again thanks a ton!
CK
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"OLD SKEWL" Lil Ole 03 500iM, Locker'd, Lift'd, Law'd, Pipe'd, Snorkle'd, Rad Relocate'd, Clutch'd, Jett'd, Filter'd
Gori!la'd, Spacer'd, 4.0 Gear'd, and one Kick A$$ Gear Reduction!
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Exhaust valve to tight? - 
RE: Exhaust valve to tight? - 
JK
