Suzuki king quad 300 idles great but Boggs when you apply throttle

[97kingquad]

10 hours ago, DayBreakJim said:

My king quad had this exact same issue and it ended up being tight intake valves and my carb leaking gas into the throat. 

I'm thinking the intake valve as well. In going to try adjusting it tonight. 

The stator is charging (sometimes overcharging) I've replaced the resistor and coil, plug and air filter, eventually I'll have gone through the whole bike. But a fues issue doesn't make sense to me because it runs like it's deprived of air not fuel 

10 hours ago, Gwbarm said:

This has turned into a very interesting thread curious to see whats really wrong.

You guys are doing great!

Lol me too

[97kingquad]

12 hours ago, Mech said:

Mmm well, sucking on a pipe is easier than adjusting the valves or swapping heads.

I will try this when I'm off work. But I am just puzzled. I don't think it is a fuel issue because it runs better with more air so wouldn't that mean there is enough fuel?

11 hours ago, Mech said:

Have you ever noticed that anything that buggers up the vacuum, like air leaks or tight valves, seems to effect them more at idle than when they are revved up ?

The bike runs fine at idle it's only when the rpm start to climb 

[97kingquad]

11 hours ago, JustRandy said:

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.

So what do you suggest I do? I plan to keep the bike for a while if not indefinitely. So if I am going to get it running right I feel I might as well fix everything along the way. 

The CV carb is that a different style or is it a part? 

I'm not too inclined when it comes to mechanics but I'm not a loss either 

I've never touched a bike up until I tore into this and my ltf250 so any advice or input is appreciated.

 

Also thanks for all the help this far. It has been a big help (especially getting comfortable with taking out my carb and the small components) 

I feel pretty confident with everything but the internal engine now 

[Gwbarm]

First place i would start Do you have an OEM carb or is it aftermarket, thats the first thing i would do make sure you have the correct carb on it if its aftermarket look for an OEM on ebay and rebuild it, if you plan on keeping it. One step at a time until we get it figured out.

[97kingquad]

6 minutes ago, Gwbarm said:

First place i would start Do you have an OEM carb or is it aftermarket, thats the first thing i would do make sure you have the correct carb on it if its aftermarket look for an OEM on ebay and rebuild it, if you plan on keeping it. One step at a time until we get it figured out.

As far as I can tell yes it is OEM. Everything matches up to OEM diagrams 

[Gwbarm]

If its OEM id should have markings on it Mikuni, Kei Hin not sure which carb came on it , no markings its probably aftermarket. I know you have cleaned it but if it is OEM get a carb kit and rebuild it to get the fuel issue eliminated. If not OEM i would look for one on Ebay. I have had so much trouble with non OEM carbs.

[97kingquad]

3 minutes ago, Gwbarm said:

If its OEM id should have markings on it Mikuni, Kei Hin not sure which carb came on it , no markings its probably aftermarket. I know you have cleaned it but if it is OEM get a carb kit and rebuild it to get the fuel issue eliminated. If not OEM i would look for one on Ebay. I have had so much trouble with non OEM carbs.

Ok I'll check it out tonight 

[JustRandy]

2 hours ago, 97kingquad said:

So what do you suggest I do? I plan to keep the bike for a while if not indefinitely. So if I am going to get it running right I feel I might as well fix everything along the way. 

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?

2 hours ago, 97kingquad said:

The CV carb is that a different style or is it a part? 

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.

2 hours ago, 97kingquad said:

I'm not too inclined when it comes to mechanics but I'm not a loss either 

You seem inclined to me if you're adjusting the slide needle.  You just need to learn some more.

2 hours ago, 97kingquad said:

I've never touched a bike up until I tore into this and my ltf250 so any advice or input is appreciated.

Also thanks for all the help this far. It has been a big help (especially getting comfortable with taking out my carb and the small components) 

I feel pretty confident with everything but the internal engine now 

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.

[97kingquad]

1 hour ago, JustRandy said:

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.

Eventually I'd like to take it up a notch but for the time being I am more focused on getting it running right and knowing that everything is 100% before I jump into adding other things or upgrading multiple parts, I am going to check the valves now if I can get to it. I'll keep everyone posted. 

I'm checking this thread often through the day as this damn bike is on my mind all day lol 

I just can't get over it running better without the airbox cover. It doesn't make sense to me,

 

Maybe the exhaust valve is stuck open so I don't build any back pressure? Idk. But I'm gonna check and I'll post some pics 

1 hour ago, JustRandy said:

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.

Also kinda flattered me when I read that lol thanks 

[Mech]

There are diaphragms in the fuel tap and the fuel pump 97, and if they get a small hole in them the fuel gets sucked down the vacuum hoses and straight into the engine. They run rich.

[97kingquad]

20 minutes ago, Mech said:

There are diaphragms in the fuel tap and the fuel pump 97, and if they get a small hole in them the fuel gets sucked down the vacuum hoses and straight into the engine. They run rich.

I'll check that next, I'm checking the valves right now and I don't have a feeler gauge but the valve on the spark plug side (I assume the intake) seems pretty tight. I feel a slight wiggle but not much at all and I know the spec is 1-3 mm so I think the intake valve is okay, (I will go back with feeler gauges when I can get a set) 

But from what I can tell intake is good, now I just have to get at the exhaust

 

[JustRandy]

4 minutes ago, 97kingquad said:

Also kinda flattered me when I read that lol thanks 

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.

13 minutes ago, 97kingquad said:

I just can't get over it running better without the airbox cover. It doesn't make sense to me,

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.

 

21 minutes ago, 97kingquad said:

Maybe the exhaust valve is stuck open so I don't build any back pressure?

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.

2 minutes ago, 97kingquad said:

I feel a slight wiggle but not much at all

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.

[97kingquad]

3 minutes ago, JustRandy said:

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.

 

4 minutes ago, JustRandy said:

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.

That was actually a very helpful video for me. Thank you lol I'm gonna watch a few more to help with my tuning skills, 

And for the valves am I able to access both from the same side of the engine or is the rubber  plug on the opposite side of my engine also supposed to come out?

[JustRandy]

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

[97kingquad]

1 minute ago, JustRandy said:

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

It wiggles a bit now and I can hear a light clicking now, I'll get it back together and fire it up. Stay tuned 

[JustRandy]

6 minutes ago, 97kingquad said:

It wiggles a bit now and I can hear a light clicking now, I'll get it back together and fire it up. Stay tuned 

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

[Mech]

The clearance is in thousands of an inch, not millimeters.

You should barely be able to feel or hear the play, but there should be some.

One millimeter is forty thousands of an inch..  to give you some idea of what's required.

[JustRandy]

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.

[97kingquad]

1 hour ago, JustRandy said:

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

So I took it out a couple turn and it bogged worse, then I turned it in a few and it got slightly better but I still think maybe worse than before. But it runs better with no movement? I'm gonna keep playing with it a little bit

 

1 hour ago, JustRandy said:

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

It wiggles a bit now and I can hear a light clicking now, I'll get it back together and fire it up. Stay tuned 

1 hour ago, JustRandy said:

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

After

[Mech]

"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."..

Oh.  And you say they have a problem with their valves..  I wonder why you would get that impression.

[JustRandy]

40 minutes ago, 97kingquad said:

So I took it out a couple turn and it bogged worse, then I turned it in a few and it got slightly better but I still think maybe worse than before. But it runs better with no movement? I'm gonna keep playing with it a little bit

 

It wiggles a bit now and I can hear a light clicking now, I'll get it back together and fire it up. Stay tuned 

After

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?

[JustRandy]

31 minutes ago, Mech said:

"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."..

Oh.  And you say they have a problem with their valves..  I wonder why you would get that impression.

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

 

[97kingquad]

19 minutes ago, JustRandy said:

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?

I will double check but I believe that's what it was set to when I last touched it

[97kingquad]

15 minutes ago, JustRandy said:

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

 

Okay well if I'm gonna mess around this much how do I go about replacing them?

 

[Mech]

Better to set them correctly 97, and not have to replace them..

I though you wanted to get it going, not wrecked.

[97kingquad]

4 minutes ago, 97kingquad said:

Okay well if I'm gonna mess around this much how do I go about replacing them?

 

By that I mean do I have to take the engine out 

1 minute ago, Mech said:

Better to set them correctly 97, and not have to replace them..

I though you wanted to get it going, not wrecked.

I do, but if you think the valves are going to cause an issue down the road anyway I might as well know how to replace them if not do it now. 

Also I'm a dumbass. I was looking at the exhaust end. 

(As I said before it's my first time digging into an engine lol)

[97kingquad]

3 minutes ago, Mech said:

Better to set them correctly 97, and not have to replace them..

I though you wanted to get it going, not wrecked.

I also think you guys were right about him knowing something's off (maybe) because the intake valve screw cap is stripped, lucky I have one on my parts bike but I don't want to leave the engine outside without one so I want to put the stripped one on the parts bike. Any ideas to get that guy off there? Also I broke my half inch ratchet lol I will have to grab one somewhere. 

[Mech]

I have never had any problem with the valves in the ten regular customers bikes or the two I have had..

It's important to get them set right, and then they stay set for years.

If you mean the socket won't grip the plug, use a single hex socket, and give it a tap down onto the cap to seat the socket and disturb the O ring under there.

If you give them more clearance than they are meant to have, they will hammer into their seats and self tighten.

If you set them correctly, the ramps on the cam lowers the valve gently and you will have no problems.

[Mech]

You should check the hoses for fuel, and you should use two spark-plugs as I suggested earlier to check the spark is strong and consistent.

[JustRandy]

4 minutes ago, 97kingquad said:

By that I mean do I have to take the engine out 

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.

4 minutes ago, 97kingquad said:

I do, but if you think the valves are going to cause an issue down the road anyway I might as well know how to replace them if not do it now. 

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.

4 minutes ago, 97kingquad said:

Also I'm a dumbass. I was looking at the exhaust end. 

(As I said before it's my first time digging into an engine lol)

The smartest people are those who are quickest to admit they're wrong.  They will be right eventually.

4 minutes ago, 97kingquad said:

I also think you guys were right about him knowing something's off (maybe) because the intake valve screw cap is stripped

I could see someone backing the valve screw out to get it running and putting it up for sale.

7 minutes ago, 97kingquad said:

Any ideas to get that guy off there?

Vice grips.  Big ones.

8 minutes ago, 97kingquad said:

Also I broke my half inch ratchet lol

How the heck?!?