JustRandy

It was an olive branch. man. You suspected a torn diaphragm in the pump so coupled with possible corrosion I figured I'd back you in your interest in the pump. But you're so determined to be a miserable turd it's impossible to get along with you. No. I never thought the pump was the problem. If he has a bad valve then what do you recommend? No they never cause problems that I know of. I have the one in the picture. But cleaned up. Wish you'd stop sabotaging the thread. What if it's mechanical?

Not just a, but the. And notice the corrosion. So it's probably worth taking the pump apart for a cleanup anyway.

I think this is the fuel pump: A valve inside the pump: And the petcock

Don't feel bad I missed it too. There's too much going on in this thread lol People crank those caps on too tight. They think because it's big it needs torqued down. Same with oil plugs. Luckily they don't cost much.

Wait a minute.... you haven't even gotten the cap off the check the valve? It didn't click in my head until now lol I agree with Mech there. I don't use feelers either but I know what .001 feels like. It's the faintest clicking noise you can possibly make. .003 is a lot louder. Basically .001 is the smallest gap you can make and still have a gap.

Anyone can claim anything online. But I don't see how anyone could work on engines for 50 years and not know a worn valve won't hold a setting. It's usually the guys bragging about how much they know who don't know much. I wonder how you have lived so long and not have learned that too. You're a mystery, Mech.

Setting them to spec is only important for getting all your cam duration. When I had a bad valve I'd have to stop on the side of the trail and back the screw out a turn then get going again. I made the gap huge so I didn't have to do it again for a while. It ran fine with only small loses in power in the upper rpms. I pulled many loads of dirt like that until I got time to tear it apart and replace the valve. But if you're sure you have a gap now and that didn't fix the problem then something else is wrong. Yep it's a fun quad and I wouldn't trade mine for anything.

Once the valve starts wearing, they will not stay set. So setting them right is a waste of time. A worn valve will eat up .001 in 5 minutes. Anyway he said he didn't have feeler gauges. Evidently you've never seen a worn intake valve like the picture I posted or you'd know all this already.

No you can just take the head off. I'd get a service manual since it's your first time. I think they're on here for free. And get a piece of cardboard and punch holes in it so you can put the bolts in the holes so you can get them back where they came from. The right thing to do is take the head to a shop and have them cut the seat. Then order a Vesrah valve that's made in Japan. I don't trust the metal from China. The smartest people are those who are quickest to admit they're wrong. They will be right eventually. I could see someone backing the valve screw out to get it running and putting it up for sale. Vice grips. Big ones. How the heck?!?

I get that impression because just about every suzuki engine I have seen from that era had a bad intake valve. Try to keep up. Here's one from a king quad up in NY

So it didn't wiggle before but now it does and it's not running better? Did you put the carb back how it was stock?

For diagnostic purposes it doesn't matter how big the gap is so long as there is a gap. I used to set it something like 1/8 inch just to get some work done and by the end of the day it was tight again.

Clicking now after you adjusted it or was it clicking before?

Be sure there is a gap. Wiggle it up and down. You should feel some gap and hear a clicking.

My friend who found the quad has done all sorts of mechanical work on atvs and mowers but I've never seen him tinker with the needle clips so if you can do that then you can do anything else. Lots of good mechanics haven't even finished high school. You may not get a job working for NASCAR but I'm sure you can learn to fix your stuff lol My high school teacher was a big influence on me. He gave me a piece of paper that said it's not your aptitude that determines your altitude, but your attitude. Persistence and determination alone are omnipotent. With the lid on there is a stronger vacuum signal to the diaphragm on the cv carb plus more vacuum to suck gas out of the needle jet hole. More likely the intake valve is stuck open and combustion pressure is going backwards into the carb. I've never seen a bad exhaust valve on these engines. If there is no wiggle then that indicates the valve is worn. Can you back the screw out a turn or two until you feel some wiggle then see if the engine runs better? Don't forget to tighten the nut.

My friend found one on craigslist and he knew I'd always wanted one so I gave him a bottle of scotch for finding it and reimbursed him cash. I think it was $800 like you. Then I tore it down and rebuilt it. I didn't even play around riding it. I just tore it apart and put a high compression 69.5mm piston, sport cam, new valves, replaced the carb, disabled all the safety crap like no diff-lock in high range or not starting in gear, added winches and lots of stuff. fixed the plastics and racks, and welded stainless plate to the entire bottom. On down the line I got a regulator from Rick's that can handle 50 amps. I also discovered the LT4WD cdi has a higher rev limit so I'm using that. Pretty sure I can exceed 11,000 rpm. So I don't know what you want to do. Do you want to do what I did? Or do you just want to get it running and start riding right away? It's a Constant Velocity (cv) carb. When you push the throttle you're actually just opening a butterfly valve and the engine vacuum raises the slide. I'd rather have a mechanical carb where I control the slide directly with the cable rather than relying on vacuum. It's a simpler more reliable design that's easier to tune. There are no vacuum diaphragms to fail. You seem inclined to me if you're adjusting the slide needle. You just need to learn some more. You're just scared of the unknown but it's not that hard. Navigating the misinformation is the hardest part because you don't know what you don't know. I'd be shocked if your stator is bad because no one has abused their charging system more than me. I have a dump trailer with a 5000 lb winch and have dumped many many tons of dirt using that stator. That's why I got the biggest regulator Rick's has. If your stator is bad it would have to be some kind of fluke. As I was saying I could check your intake valve in less than a minute. Just take the inspection cap off and wiggle the rocker up and down. Do you hear a faint click? Can you feel any gap? Pull the cord to rotate the engine while wiggling the rocker looking for any gap at all. If there is a gap then it's not your problem. If there isn't then you have to take the head off and cut a new seat. Or replace the head with one of your spares. If you need an example then try one of your other quads first so you can see what a gap feels like. Or try the exhaust valve because the gap is bigger. The order of diagnostics dictates being sure the engine is mechanically sound before moving on to the fuel system. And the intake valve is a common problem on all those old suzuki engines from the 230 to the 250 to the 300. They're all the same head and I have a box full of worn intake valves. So I'd definitely want to rule that out. You could also clean the corrosion out of the fuel pump and then you can inspect the diaphragm. Mech was thinking it's sucking gas directly into the engine through a hole in the diaphragm. You could rule that out by sucking on the vacuum hose or taking the pump apart. I'd take it apart anyway because it probably has corrosion. The petcock is another common issue. It's vacuum actuated but I fixed it so it's either on or off but don't remember how because that was 12 years ago. I'm sure there are threads about it. Everyone here is interested in the solution to this puzzle so we all have your back whatever you decide to do.

Reminds me of Ben Franklin's speech at the constitutional convention. "I confess that I do not entirely approve of this Constitution at present, but Sir, I am not sure I shall never approve it: For having lived long, I have experienced many Instances of being oblig’d, by better Information or fuller Consideration, to change Opinions even on important Subjects, which I once thought right, but found to be otherwise. It is therefore that the older I grow the more apt I am to doubt my own Judgment and to pay more Respect to the Judgment of others." https://constitutioncenter.org/the-constitution/historic-document-library/detail/benjamin-franklin-closing-speech-at-the-constitutional-convention The only sure impediment to truth is the conviction that you already have it.

Yep it's like a speaker box with a big hole in it is just as loud as a sealed one at high frequencies because the air doesn't have time to get out before the speaker cone changes direction. When the piston is moving fast the air doesn't have time to leak so even though the valve is open it doesn't change the cylinder pressure so much. But in this case the cv carb depends on engine vacuum to open the throttle so I'm not sure how that would work out if the intake valve is open during the power stroke. At idle the butterfly valve is closed and blocks the impulses, but when the butterfly valve is open the slide feels the pressure from combustion. That may explain why no carb adjustment makes a difference. I hate cv carbs so I'm no expert on them. I have a 250 that's bored close to a 300 and it stretches the head studs and blows the head gasket out. When it happens it whistles, but increase the rpms and the whistling stops. The king also whistles sometimes when I'm lugging but increase the rpms and it stops. Max cylinder pressure is usually somewhere in the lower midrange depending on cam duration. You're not making real power if you're not stretching head bolts lol

The symptoms seem perfectly consistent with worn intake valve. Other owner said it was bogging and he parked it until selling it to 97 who tinkered and got it running for a few days. Then he parked it and it wouldn't start when cold which is exactly what a worn intake valve would do. Now the valve is open so much that no amount of tinkering will work. The only part I can't envision is the the CV carb because I threw mine in the trash the minute I got the quad and replaced with a 28mm roundslide from some suzuki bike. So I'm not sure how the valve being open all the time interacts with the cv carb. But with mine the valve did produce a mild rich condition and usually when I see bad valves I also see a lot of carbon. So removing the airbox lid could help.

Yeah I'm curious too. Wish I could do something to speed it up lol

Yep, sure is. But I could check the valve in less than a minute. Just spin the cap off with a 17mm wrench and wiggle the rocker while pulling the rope looking for any gap anywhere. Super quick.

I suppose anything is possible but the fuel pump isn't very strong to begin with. I sometimes have to blow in the hose from the gas cap to pressurize the tank to get fuel flowing. Seems like a hole sufficient to consistently deliver fuel to the intake would shut the pump down completely. Seems like it would also foul plugs. Also the symptoms would vary with the amount of fuel in the tank since more fuel means more pressure. If that turns out to be the problem I will have definitely learned something.

Oh you think it's sucking fuel directly into the intake through the vacuum hose? It's possible but I doubt it would pump to the carb with a torn diaphragm and it probably wouldn't run at all.

If it were lacking fuel then why would it run better with the airbox lid off?

I'm pretty sure it's the valve man. I suspect the guy knew it when he sold it. Anyway the first step is to be sure you have good compression by being sure the valves are set right before tinkering with the fuel system. I wouldn't bother with exhaust valves. You can if you want but I've never seen a bad one.