GP1800R #3: Easy $50 Free Flow Exhaust 

The pipe needs to be 3.5" (that is the diameter) the section i got is 1 foot long and cut a few inches off because the 45 angle needs to be closer to one side than the other. If you can find a pipe like this you can do it but i dont think you can without getting it custom made. Its much easier to just cut it with a hacksaw.

The exhaust is mixed with water from the water box, so in theory, it cant get any hotter than the boiling point of water of 100c.... mine held up just fine for over 100 hours before i switched to a thru hull exhaust for no reason other than me wanting it.

@@ZF5foraWhiteGuy 👍

I was. I moved last year. Im in san diego now.

It didn't make any noticeable difference to me without a cooling upgrade.

Nothing has changed with where the exhaust exits. You're just deleting the resonators/mufflers between the engine and the exhaust exit. No different than replacing a muffler on a car with a piece of straight pipe.

Rear thru hull exhaust you have to cut a hole in the hull. Free flow you do not.

T'd into the MAP sensor line. Works fine

@@ZF5foraWhiteGuy ok. When I did this is has a huge dead spot in the throttle. For now I have just capped the t and it runs fine. Guess I’m gonna try the iat adapter. Or maybe a 2psi spring. Not sure what’s in it now. I have the same one as you. Any thoughts?

@@ckpk41605 i believe i used either the yellow or white springs, which arlre 8psi and 11psi. 2psi is too low im sure. You probably have a dead spot because its open at idle or right off idle. So a stiffer spring should fix your problem.

Link is in the description

@@ZF5foraWhiteGuy Thank you

My elbow wasn't smashed, make sure the tubing is inserted into the elbow as far as possible.

@@ZF5foraWhiteGuy well i actually meant theres a bit of a bend in the elbow to where its not a perfect circle in the tube..just hope it dont restrict air flow..mine looks identical to urs..the pipe i bought from ur link was lots smaller than the one u have ..i didnt have to cut anything..think it was like 11 inches

Or was i suppose to cut?..

@@SlayerHawkX on the aluminum elbow i cut one side so the bend was a little closer to the one side like in the video. I didnt cut the silicone elbow. Loosen the clamps and mess with the positioning, the silicone elbow wasnt "smashed" on mine or kinked as im interpreting that. The aluminum pipe was certainly not smashed unless you got one that was damaged somehow.

@@ZF5foraWhiteGuy ​ i done this...works fine..but theres a horrible noise at 3 k rpm and below..i went ahead and got riva stuff.and sounds much better..and believe has much better back pressure...i actually gained a mph or so..BUT IF UR BROKE LIKE I WAS THIS WORKS JUST FINE FYI to ppl out threre

Junk. Waste of money. One is completely broken and the other i use as a portable speaker sometimes but its nothing compared to a decent JBL. They basically tacked them on and forced me to buy them. It was a weird altercation with the saleswoman and i eventually caved. She threatened to not sell me the whole ski without them. Because there was a waitlist.

Top speed is still limited, I didn't notice much difference other than a volume and tone change. However I prefer to get the supporting mods out of the way before going for power in all of my builds.

@@ZF5foraWhiteGuy OK. I've done all stage two except the free flow exhaust and just wondered if it was worth it performance wise. I'm not really looking for a noisier ski but if it gave me a couple mph I might think about it. I saw one guy on RU-vid reattach the resonator to cancel out the drone but probably still quite a bit louder. Thanks for the video.

@@dwaynef17046 IMO, Id say only do the free flow exhaust if you're also going to do a water box.

Link in the description

It came with the "audio package" from yamaha but it was completely pointless. It was just 2 shitty waterproof Bluetooth rechargeable speakers and mounts. Terrible speakers, no bass, could hear them over 20mph and one of them stopped working in 2 weeks so i just took them off. No speakers on it now

This effectively is the exact same setup as any other aftermarket free flow exhaust. Neither of which changes the principle of why water doesn't backflow into the engine, because water won't flow uphill.

@@ZF5foraWhiteGuy thanks, but water will go rise in level if there is back pressure. I am concerned about flooding the engine if my ski has to be towed. I know this is off topic from your video, which I enjoyed. I was here trying to learn about the exhaust system. Thanks again.

@jstone1211 towing or stationary, it wont change the fact that the ski wont sink. It has nothing to do with back pressure keeping the water out... think of it as setting a pool noodle with one end in a pool and the other end on the pool deck, water wont magically move uphill without a vacuum drawing it out. Since the engine is above the water line, there is also no possibility of siphoning... your question has a lot to do with fluid dynamics, however i can assure you, this modification will have absolutely zero impact on the ability of water to enter the engine.

@@ZF5foraWhiteGuy thanks for your reply. I am staying stock for now as I am new to Jet Skis. I did look at the exhaust on my waverunner. seems like water could be pushed up into the water tank in the system. again thank you for your reply.

Haven't been riding or changing much on my ski lately been busy with work. Hopefully get some more time late summer.

@@ZF5foraWhiteGuy Awesome I got 81mph with the mods you posted!!!!

The baffles were replaced, not the water box. The water box is still in place.