coffman Pipe on 750sxi

[Ryan Stewart]

Really? that guide i posted makes me think it is too rich because it dies, not hesitates.

And i was thinking..... Low screw is for idle to 1/4th throttle. then the Low jet takes over. Then from there the High jet takes over. then finally the High screw.

So if my idle to 1/4th works great.
And my WOT works like a champ.
Wouldnt that point to my Low jet specifically?
And the fact that it Bogs down specifically means too rich. Or possible my popoff.
So what if i went back to 65 / 125. and maybe go to talller springs.
Thats my mindset at least.

Trust me when i say this. I was at the lake for 4 hours , coming back to shore to take the carb off and tune down the screws. I think i did it like 30 times, doing a quarter turn at a time. I did that with high and low screws starting at 2 turns going down to 1.

 

[Ryan Stewart]

Oh, another question real quick. Im testing out the 4 sets of springs that i have. And i notice my tallest ones prevent the needle from moving at all.
And the two medium sized ones only let the needle move a little bit, like barely any up and down movement.
And the cut springs seam to give it the most up and down movement.
Is it intentional that the needle barely shifts up and down?

 

[sleeper sx]

When it dies it's too lean, stumbles it's too rich.

 

[Ryan Stewart]

if thats the case, i can only guess its my pop off, or i need a bigger lower jet, im pretty sure 2 turns on my low screw didnt work . on size 85

 

[Ryan Stewart]

guess ill take it out and play with it some more. im not sure what is causing it to instantly plummet when i give it gas passed 1/4th throttle.

 

[sleeper sx]

Ryan iam going threw same chit with my sxi, I'm running 44's

 

[bandit88]

Im putting 44s on mine shortly. Have the manifold, just waiting on the carbs.

Ryan, when you were dialing the screws out, did the problem change at all? Better or worse?

 

[Ryan Stewart]

Hey guys. Better news...

So i put in a set of Lightweight springs... Taller than the cut ones, but they seam lighter.
I also changed back down to 75 Low jet, from the 85 that i purchased.
Then i set my screws to 1 1/2 turn Low, and 2 turns High.

When i put it in the water today, it was worse than ever. Lots of low end hesitation to where any gas would cause it to die.

So I put the Low Jet 85 back in , left the lightweight spring it... and IT ALMOST ran like a champ.
Theres just this slight hesitation in the low-mid throttle.
I could actually squeeze the trigger 3 times then WOT and it took off.

So my issue is definitely with either my Low Jet or my pop off. because changing from 75 to 85 was such a big difference.
And the lightweight spring seamed to help allot too.

So should i.... buy a 95 Low Jet. and a 135 High jet.
Currently im at 85 Low Jet and 125 High jet.
Or maybe cut this new lightweight spring down a bit too?

 

[bandit88]

Dont go that big on the jets, will be WAY to rich. What is your altitude? I took mine out and tuned some more yesterday. Ended with 1 turn out low, 80 pilot, 40G spring (the shorter one), 125 main, 3/4 out high. Perfection. Im at 6000ft. So if you are near sea level, the 85 pilot should be on the money as that will raise fuel a little in all of the range. How are your water lines into the pipe again? You may just be getting too much water in and it needs to clear out and that is the hesitation you are feeling.

 

[Ryan Stewart]

Very possible. Water goes from Head to first stinger on pipe then it exits from the middle of the pipe and i bought a T to split it to the end of the pipe near muffler and then right into muffler. I have no idea if thats correct. Also no pisser. You dont think it needs to go higher on the low jet? It seamed to do wonders going from 75 to 85. Almost seamed fix . That, and conjunction with that lighter screw.

Hmmm. Could it be lack of water in the pipe? It seamed really hot. Uncomfortably hot , but i can hold my hand on the engine after testing a qUick tune test. how do i make sure its passing water when on lake. Garden hose i know works.

 

[Ryan Stewart]

I didnt go as low as 3/4 on high. But i did test 1 turn. Same symptoms . Except i couldnt go top speed, so i was worried it was too lean.

 

[Ryan Stewart]

Drats. Im seeing some oil on the seam of a weld on the bottom of the pipe. I cant tell if its a leak yet or if it got splashed or dripped. From user error. Im guessing a small crack might also be the cause.

 

[bandit88]

A crack will definitly cause issues and that pipe looks like its been welded before, but also that water routing is a major issue. Without a pisser all of the water is going into the exhaust. You want the exhaust as dry as possible without burning up the couplers, so a fine mist. I would unplug the hose going into the resonator and run that to the pisser, then put a restrictor, like a carb main jet, in the stinger so it only gets a small amount of water. Should be a whole different beast.

 

[bandit88]

Here is a pic

 

[Ryan Stewart]

Okay. And why would i want to restrict water flow as it leaves the exhaust? To me that sounds like it will build up water. Ps thanks for your time and effort with all this.

Here is a pic

 

[bandit88]

You just want to restrict the amount going into the stinger, but since its T'd and the rest is going overboard, water is still flowing and cooling the motor/pipe. You just want a fine mist going into the exhaust stream to lower temps so it doesnt burn up the rubber couplers. With the amount thats going into it now, is choking the motor out. And no prob, troubleshooting this stuff is my thing. I like working on mine almost as much as I do riding it.

 

[Ryan Stewart]

You just want to restrict the amount going into the stinger, but since its T'd and the rest is going overboard, water is still flowing and cooling the motor/pipe. You just want a fine mist going into the exhaust stream to lower temps so it doesnt burn up the rubber couplers. With the amount thats going into it now, is choking the motor out. And no prob, troubleshooting this stuff is my thing. I like working on mine almost as much as I do riding it.

I had know idea i could be flooding the exaust with water. I dont quite understand how putting water into the muffler/ end of the pipe will drown out the motor's performance. To my understanding all of that is done in the engine. But spraying too much water into the stinger causes it to drown out?
Ill be fixing that ASAP then. Can you please show me where I can get this restrictor? specifics would be great due to my lack of knowledge.
And too late, I already bought a 95 and 135. Ill test the 95 out for fun though, see how it works.

 

[Ryan Stewart]

https://www.blowsion.com/quick-disconnect-water-restrictor


This?

 

[bandit88]

Yep, that would work. Otherwise, I just go to the hardware store, get a plastic hose barb splicer and thread a main jet into it. Basically the same thing as this: https://www.watcon.com/fuel-system/fuel-restrictor/return-fuel-line-restrictor.

 

[Ryan Stewart]

Alright. I dont have extra jets, or a threading kit. So ill just blowsion it. As long as that works. I think im nearing a resolution soon . Do some more welding, regulate the water at stinger, ill test the 95 low jet for kicks.