1988 Suzuki Quad Runner 250 2x4 Won't Start. Help!

[alexwv1863]

I'm working on my buddy's 1988 Suzuki Quad Runner 250 2x4 and I'm having some issues.  The main issue so far is I can't get the dang thing to start.  When I try craniking it with the electric start, all it will do is grind.  Occasionally it will backfire once at a time.  That doesn't happen every time though.  I have read that some 4 wheelers have to have the hand brake engaged before it will start.  I'm not sure if this is one of those or not.  The carb is brand new, fuel pump works, brand new battery, gas is fresh.  There isn't a choke cable right now.  What am I missing?  What would you recommend me trying?  Also, how is this 4 wheeler's engine supposed to be cooled?  Today was the first day I've actually started going through it.  There are several parts he needs to order.  I'm just trying to get it to start first before any more money is spent on it.  Thank you for your help.   I really appreciate it.

[Hunter19]

First you need to install a choke cable. The grinding noise sounds like a bad starter. You don’t have to apply the break to start the ATV. The motor is a air cool motor. 

[Curtis Underwood]

What I do is take a can of starting fluid and spray a little in the carb and turn it over if it starts running for a few seconds then it is in your fuel or carburetor. If it only backfires and does not run a little for a short time then it is in your ignition system.

The carb, fuel line, fuel filter or tank could be stopping fuel flow. Air fuel misture is also important.
Tis ingnition appears to kill the ignition by turning off the 12 volts to the CDI where most turn CDI off by grounding it.
Hear is a print. That shows you the electrical and how it is wired. if you are getting 12 volts to the cdi on the orange/white lead and it is not firing then you have a bad CDI or you have a bad coil.

 

[Mech]

Fix the choke cable, even temporarily by jury rigging a bit of wire bent to engage with the choke plunger so you operate it down by the carby.

Check the starter is spinning the engine fast  enough(which it sounds like it is since it fires occasionally).

Then coax it into life with choke and very little or no throttle. The choke doesn't work if the throttle is opened much at all, so it sometimes pays when trouble shooting and starting a reluctant bike, to wind the idle speed down a half turn or so. If it doesn't want to start after a few winds and a bit of throttling, then take the spark plug out and check whether it's dry, or soaking wet. Then change your approach by either giving it no choke and some throttle, or choke and no throttle, depending.

[alexwv1863]

Thank y'all so much. Im going to give what y'all said a try tomorrow and see what happens. I don't hear the starter grinding. It's more of a "putt putt" noise where it sounds like it's sucking air, which it actually is from the air box. It made me wonder if it was getting too much air, so I've even tried covering the hole with my hand, part of at shirt. Still nothing. Just thought I'd throw that in there as well. I tried a little starting fluid but im not sure I got anything in the carb bc of how it's placed. He told me he got it to run when he poured gas im the motor. Im assuming I have the lines on the fuel pump correct. I'll take a photo and mark the lines tomorrow as well. 

[davefrombc]

Take the spark  plug out and turn the motor over to see if you have spark a thumb over the  spark  plug  hole  will give you an  indication if you have at least half way decent compression.  There is a service manual  that covers your quad in the downloads section of the forum.

[alexwv1863]

Ok, so I now have this issue and I'm not sure if it's because I took the jets and stuff out of the new carb and put it into the old carb. Im assuming it's the right carb for this bike. I have gas going to the carb but it's spraying out of the back of the carb and the overflow, even the air outtake (not sure if that's the right name). I'm getting compression. I took the spark plug out and held my finger over the plug hole. It seems like it's got enough compression. I think im going to switch everything back to thre new carb. I don't get it. I know it's got to be something simple that im overlooking. I'm going to try to attach a video if I can... This is what happens now since I switched carb parts around from new to old. 

[alexwv1863]

I switched the  carbs and now it acts like it wants to run. Got it to backfire once. I swear it sounds like the mufflers stopped up somewhere, but if you put your hand over the muffler, you can feel air coming out. This new carb isn't flooding like the old one. It's really bugging me. Ugh! 

[Curtis Underwood]

It sounds like it is not firing correctly. You need to get the service manual on it and follow the ignition check procedure.
It could be anything from the Capcitive Discharge Ignition(CDI module), coil, sparkplug, Timing, valves setting, switches, Stator sensor or wiring.

[Mech]

Have you been taking the plug out and checking whether it's flooded or dry as I suggested ?

Are you sure the plug is good ? Once a plug has been flooded they can get a fault where they are real easy to foul after that. They spark when you check for spark against the head, but the spark runs down the porcelain when there is compression making it harder for the spark to jump.

I'd suggest getting a new plug, trying it and checking regularly whether the plug is getting wet or not.

And.. suzukis seem to like to start up with very little throttle. If they are trying to fire as you wind them over, and you then open the throttle, you will hear it get more reluctant to crank.. Close the throttle right down to very little(I mean the tiniest bit possible), and they often burst into life.

[Curtis Underwood]

Mech is correct.  Answer these questions.
When you lay the plug against the head with it removed and turn the engine over do you see a sparking as the engine turns over?
Is the spark from the Plug's anoid(Center of ceramic) to the ground point.  
When you remove the plug after trying to start it, does the plug look black, brown, gray or wet?
The color of the plug tells a lot. 
Here is a link that gives pictures of what to look for when inspecting spark plugs. 
https://besthomegear.com/how-to-read-a-spark-plug/
 

[alexwv1863]

Yes, I've checked the old spark plug and the new one and they both have spark. The last time I checked it before I quit for the day, it appeared a little wet and it was starting to get carbon on the end. I rigged up the choke with a wire for the time being, I tested the stator and it also appears to be fine. I couldn't find the orange and white wire that goes to the cdi box, but I'm going to look more tomorrow. Im also going to go through all of the wires and make sure none of them are naked or burnt. Im running out if ideas. When I put my hand over the back of the carb, it starts acting like it's going to hit and start. Doing this I started getting a little smoke and the engine started to get warm to the touch. I bring this up bc it's a first so far. I also need to check the rectifier. That's another thing I haven't tested. 

[davefrombc]

I suspect it  is a fuel  mixture problem..  Have you played with the mixture screws? What notch is the main jet needle  in on the slide?.  Is the idle air screw turned all the way in?.  It  usually  is anywhere from  11/2 to  2 1/2 turns out from  lightly seated.  Have you  downloaded the service manual from  the  downloads section  Here?  you  might get some idea  where to  start on carb settings in it.  If you're getting spark the rectifier  and rest of the ignition system  is likely ok.. getting any kick from the motor when  you choke it with your hand over the inlet is  usually because there is something plugged or badly miss set on the carb. or an air leak  on the inlet making  it far too lean

[Curtis Underwood]

If it is getting fire as you have indicated. Then davefrombc is correct.
I would start with chapter 5 and go through the carb. Then I would go to chapter 3-3 page 40 and back the idle stop screw out so it is set at minimum idle(this screw forces the throttle needle up giving it more fuel when screwed in (this changes the amount of fuel it gets at idle). Then I would go to 3-3 page 41 and make sure the free play is correct. If this is set to tight it can open the throttle and since these start best at idle it could cause it not to start.
This carbs air fuel mixture is set by gently screwing the pilot air needle all the way in(gently Do not tighten it will damage the needle) and factory setting is to back out 1 1/2 rounds. That is what the manual calls for. This sets the air not the fuel. What this pilot air needle adjustment does is to allow the correct amount of air for the amount of fuel that is being sucked through the idle jet(the only way to change the amount of fuel going throught the idle jet is to change the size of the jet, so the air is adjusted for proper mixture).
Make sure you check the throttle valve needle this is what allows fuel for higher speeds(if it is not set correctly or is damaged it will allow fuel to pass at idle causing to rich of a mixture that can not be adjusted out using the Pilot air valve). On most ATV carburetor the Throttle needle has small cut out rings or slots that a clip fits into that is used to set the air fuel mixture when machine is running above idle. I do not know where the old carbs throttle needle was set at but the new carb needs to be set at what old carbs needle was set to.
Also is the new carburetor a Original engineerd manufacturer (OEM) carb or is it one you bought that says it is a replacement carb?
The problem with carbs that are not OEM is they most of the time are not set for the size ATV your buying for. These are made to replace a lot of different carbs for different size ATVs. Most of the time they are set mid range and have to be adjusted for each ATV.
I have run upon some of these cheaper carbs that can not be adjusted to run correctly. I tried everything including using the old jets, setting the throttle needle to the setting of the OEM etc. When I run upon one that I can not get to set correctly I send it back and order from different manufacturer.
One example is my own Yamaha 350. I had a float sticking causing it to flood. So I sent for a new carb off of Ebay. I tried everything. Oh I could get it to idle but not rev all the way and could not get the power it should have had. So I ended up finding a used carb off a 350 and rebuilding it. My old carb had a nonreplaceable seat for the float valve so I had no choice but to replace the carb. The new carb is still setting in a box with a lot of old carbs that I use for parts(the warranty ran out even before the carb came in) warranty starts the second you pay for it and if it takes 4 weeks to get it in then it is out of warranty. So 45$ wasted.

[Curtis Underwood]

There is one other thing you need to check. The rubber boot that the carb mounts to. that mounts to the intake on the head. Check and make sure there is no cracks in that boot. I have had them crack on older machines and allow more air flow which changes the mixture.

[alexwv1863]

So far I have checked the carb, the needle setting, the air flow needle. All of those are set correctly according to the manual. The needles aren't damaged at all. It is a Chinese brand I think. I know for sure it's not OEM but it's made identical to the factory original. Im not for sure if the jet holes are the same, but visually they look close to identical. It's still doing thr same thing, except now the 4 wheeler jumps a little like it's trying to start. That's thre best way I know how to describe it. I guess I'm going to check the timing next. Oh, the intake boot is fine, no cracks or tears. I ran into that issue with an arctic cat im working on that I cannot for the life of me get to run. That's a whole nother story for another time. Will update what I find next. 

[Curtis Underwood]

I think this sounds like it is flooding. The fuel air mixture has to be right for it to run. Flooding can be caused by the wrong Idle jet, the float set wrong and/or the float needle not shuting fuel flow off.
Try turning the fuel off and empty the bowl of fuel. Then check the plug and make sure it is not wet and is still firing. Then with plug out turn engine over to help remove any fuel still in the cylinder. Then Put spark plug back in. Do not turn fuel on. Take your starting fluid and spray for about 1 second into carb throat do this whille turning engine over it should start and run for a few seconds. I it doen't then you either have the valves to tight or it is out of time.

[alexwv1863]

I took the head off the jug on the motor because I'm thinking it's out of time.  I didn't get your last message in time.  Now my issue is this: someone has been in the head of the motor and didn't put a gasket or gasket sealer back.  There has been water in there sometime before because several of the bolts were rusted.  One good thing is the timing chain is tight and nothing inside there is rusted.  I tried looking for timing marks on the chain, but I really don't know for sure what I'm looking for.  I see the marks on the cog.  I'm going through the repair manual now, but I wanted to ask you guys what you thought, and if you could tell me what I need to be looking for.  Before I took the head off, I tried cranking it over, it would get that shimmy like it's about to crank, but it just won't hit.  That's what led me to think it may be out of time.  Then, when I took the head off and saw someone had been in there before, it furthered my suspicion.  I might add that I've never tried to set the timing on a 4-wheeler.  I really appreciate all of your all's comments and trying to help me.

[Curtis Underwood]

The timing chain has no marks on it and it does not matter how the chain itself is placed on the cogs. The timing chain being tight is not a sign that it is not bad or worn. You have a timing chain tensioner that tighens the chain this will have to be losened to make adjustments or to check the amount of wear on the chain. Consult the manul on how to check the chain. The marks on the cam cog, if there is two one on each side of the cam shaft or cog is the timing marks like so -o- they need to be  aligned with them horizotal head or it could be just one mark and that would be aligned with a mark on the head. There is a small plug cover on the engine that is used to put the crank shaft into the correct position.
You need to read the manual on the proper way to check the time. Different atvs use different markings on the crank and cam. Also you need to make sure it is on the proper stroke they can be set 180 degress out. The manual will give you the instructions on checking/setting the time.
Those bolts being rusted is not that great a problem unless they are weakened where they would break. I would probably just clean them up good.
I gave general information because it will be a day or so before I can check the manual and give you specifics. I am dealing with some personal family medical issues so when I can I will get back to you.
 

[davefrombc]

It's great to  have members here who  can give specific help  information  Curtis. Ones like myself  can  only give general information and hints of where to look,  mostly from  pre-computerized, carburetted / points and condenser automotive days,  with a smattering of electrical wiring.  Beyond offering guesses  of where to  look and help finding manual  downloads and general  mechanical  info.

Beyond that,  I  have to dig into the manuals myself .

[Curtis Underwood]

Davefrombc. Thank you. I have a degree in electronics and my Father was a master mechanic. I worked with him from time I was knee high to a grasshopper lol. I worked as a mechanic in service on hellicopters and then on trucks and cars for a few years. Then I decided I had enough of low pay(back then it was low) so I went into Industrial electronic. I am retired now, got burnt out doing electronic repair, 45 years of it is way to long and have a hobby that is trying to turn into a business of working on small engines. These electrical prints, ECM/CDI electronics are simple on small engines though the manufactures are tring to make them complex so shade tree mechanics can not work on them. I started out just doing some work on friends mowers and Atvs. I have never advertized but now have about 75 - 85 people that use me to repair everything, mowers, Atvs, motorcycles and Boats. But I draw the line and work only on smaller engines. I have had people wanting me to work on Trucks and cars because they know I know how but I am to darn old to do all the crawling around on them.
As for parts and manuals I use the internet to hunt down what i need and sometimes I have to purchase those manuals.

[alexwv1863]

Yea I agree. I really appreciate your all's input because it does help out. I don't have a whole lot of experience working on ATV's, but I am increasing my knowledge daily these past few years. I did figure out how to set the timing last night. Im currently waiting on the gasket sealer to set up so I can tighten the bolts to the cam shaft cover. It didn't have any type of gasket on it. That was a blessing in disguise taking that cover off. Had I not, it would've led to problems down the road. I'm not sure but I think it was out of time. I have the correct marks lined up. Just waiting for when I can adjust the valves. There was oil inside one of the wire connectors. I can't remember what it goes to at the moment but it definitely isn't supposed to have oil in it. I have the manual downloaded and have been looking thru it. Sometimes other people can explain the solution better than the manual can. Thank y'all again. 

[alexwv1863]

Just thought I'd give y'all an update on this HOT Sunday. I've had a time the past few days. I had bought a brand new set of feeler gauges. Couldn't find them at all anywhere thurs, bought a new set Fri. Went to set the timing Fri eve (I figured out where I need to look for the timing marks), some everything like I was supposed to. Then when I try to start thr 4 wheeler, it sounded like crap. I ran out of time Fri night, so I looked again at the manual, even printed off the specs.i tried again Sat, and no luck. Still sounded horrible. So, I was going to try again and realized that instead of 0.06mm for the intake & 0.11 for the exhaust (those are in the middle of the specs range it states), I added an extra "0". Now I'm only admitting my error on stupidity so anyone else whose done this won't feel alone. Lol! The sad part is it took me 2 times to realize this. I've got myself so confused. I bought a different set of gauges today because I thought I didn't have the right ones in my first set. I really hope I figure out what I need to do by tomorrow morning. 

[Curtis Underwood]

I just had a Honda in for repair and found a problem that might be part of alexwv1863's problem.
The honda came in with a charging problem. It would not charge the battery and would drain the battery if left connected. I started trying to figure out if the rectifier/regulator was good or bad. Lol 😂  The darn regulator checked good checking it using the method in the manual. All 6 Rectifiers checked .570 ohms forward and open reverse test. So I said must be the stator but since I am an Electronics tech I know that ohm tests do not allways prove true. I decide to check the Alternating voltage from the stator by starting the vehicle and measuring the voltage with engine running and that is when I ran into something that might be giving him a problem.
You see by the time I had tested the system I had started the machine about 6 times and the battery was down to about 70 to 80% charge level(battery came in and was not full charge). Now It would not start (turned over fast) and acted just like he is describing his is doing trying and sounding like it would fire occasionally.
Well I started trying to find out why the honda would not start and read the manual on what was supposed to read what on the CDI/ECM. It turns out that the CDI module on this honda has to have 12 volts supplied to it for it to fire and according to the print on alexwv1863"s machine it also has to have the 12 volts supplied. I measrued this voltage at the CDI and found it had while turning over only 9.5 volts. It stated in the manual it had to have 12.5 +- 2 volts for it to operate correctly.  So it had low voltage. So I charged the battery and it started right up. I checked the voltage again at the CDI and it had 12 volts turning over and 13 volts at battery.
The problem was the battery did not have high enough charge to prevent a voltage drop when the starter was turnung engine but it did show firing at the plug. I think what it was doing with the plug out was not dropping as much voltage and allowing it to fire but with the plug in the engine was harder to turn and so had a greater voltage drop.
So it is possible that he has a voltage drop from his battery during turning over the engine causing it not to fire properly.

BTW it turned out the rectifiers were good but the regulator part witch there is no check for in the manual, was bad so it was a bad regulator/rectifier. I proved this by checking the AC voltage from the 3 legs coming from the alternator to ground and got 37 volts AC on each leg. Then pluged in the old regulator to the stator with the battery connection disconnected at the regulator and check the DC out it had 6 volts DC output so regulator was bad. Bought a new one and fixed his problem. I am stubborn because I have to prove what is bad and why before I order parts. I am not just a part swapper.
 

[Curtis Underwood]

opps, Did not see your coment above. For some reason while I was writing my comment you last comment was not showing up. You are correct to set the valves at .06mm and .11mm Reason being to loose will cause lose of rpm and power. But to tight will cause blow backs in carburetor. But be aware of what I said above your CDI uses 12 volts and if this gets low it will make it not start or hard to start.

[alexwv1863]

What about when I have the battery hooked up to the charger while trying to start it? The charger I have is also a jump box. Im having a really hard time understanding which gauge I need to use. Im not finding the measurements I need on the gauges. I even bought a different set today. The attached photo is the set I got today. The other set seems to be smaller but I don't have it with me right now. I just want to get this one running so I can move on to one of mine that I have to work on. 

[davefrombc]

The set you show there is a 2 step  set.  Each blade has 2 sizes on it . The outer end will be the thinner one .. You'd use the . 010-012  to set the valve at .010.  Then  to  check if it is too  tight at what you felt is .010 you'd drop to the .009 -.010 to see if it was moderately snug on .010  but  slid easily at .009.  Then  to  check the other way to see if you had it too loose you'd go to the .010 - .012  to see if it  slid through the gap  on the .012 portion of the blade ... Precision  Go  ( setting ok) or  No Go (setting too tight or too loose)

Gauges like those are used when  settings are required to be precise and allow a quick  check of the setting when the critical dimension is to the plus or minus side of  center.  Most feeler gauges are single  size for the whole blade. To  check  go or no go with them   you'd try the sizes above and below your desired one to  check accuracy .  Use the gauge with the gap  you want on the outer part of the blade .. if critical  is closer  use the  .010 -.008 gauge if tolerance is .001, or the .010 - .012 if critical  is looser for example . those  blades allow checking with .oo1 or. 002 tolerance levels .

 

 

Edited May 23, 2022 by davefrombc

[Curtis Underwood]

If your battery on the bike is down  the jumper battery may not bring the voltage up enough due to the connections, jumper battery state and wire size of the jumper cables so voltage drop may not raise up to a point of being good.
The best thing to try is charging your battery, then starting it. Check and note the battery voltage before starting at the battery (should be 12.5 to 13 volts) then after it is started check the voltage again (this should be 13.5 to 14 volts at idle(just higher then the volatge noted before) and as the rpm increases this voltage should increase to a maximum of 14.5. This tells you you charging system is working. Your voltages may be slightly different as long as the voltage running is higher than the voltage with ignition off your charging system is working. Voltage readings depend on the meter you use which can differ from meter to meter so your meter may read 12.3 before starting and 13.3 running which would mean your charging system is working.

[alexwv1863]

I'll keep this in mind whenever I get it to actually run. The engine only turns over and doesn't run. I haven't got it to start at all yet. Right now im trying to get the valves adjusted right. I didn't get to work on it today because it has rained literally all day. Hopefully tomorrow I'll be back at it again. Before I messed with the valves, it would turn over but not run. It's got good spark, brand new charged battery, good spark plug, brand new after market carb that's adjusted to spec, good fresh gas. What else can I check? There's a couple of posts that I need to check what they suggested. 

[Curtis Underwood]

This is what I would do with a machine that has had all this done.
1. I would set the valves.
2. Recheck the time making sure the timing chain tensioner is set so that the chain is tight and timing marks line up.
3. Close off the fuel to carburetor. Drain bowl. Leave fuel Off.
4. Check the oil level and make sure it is not thin which would indicate fuel in the oil. If run with fuel in the oil several things could happen. Engine damage from lack of lubrication, fire due to fuel in oil chamber. If oil is good do the following.
5. Turn engine over spraying a small amount of starting fluid in carb and see if it starts for a few seconds. The reason for this is to ensure you have everything set correctly before actually running the engine. If it does not run a few seconds then you have a firing problem or the carburetor is not allowing fuel/air to get through the throttle air control. I have actually done this with the carb off and it would fire off for a second but that is not advisable be cause a back fire could start a fire with carb off.
6. If it runs for a few seconds then I would take a clear hose and attach to the drain port on the carburetor and run it up the side of carburetor. Open the drain screw and turn the fuel on. The clear tube will show the fuel level in the carburetor and if the float is set correctly. Below is a pic of a Honda carb showing where the fuel level should be on most all the carbs.
The fuel level should never get higher than 1/8 inch above where the bowl meets the carburetor if it does then it will flood and have fuel blowing back out of carb as the video you posted showed. Most carbs use where the bowl meets carb but some are 1/8 inch higher due to the way the carb is made. So check you manual for the proper level if it is shown otherwise use the picture belows level.
7. If it shows the correct level screw the fuel drain screw in to shut it off, remove the clear hose and put the drain/overflow hose back on.
8. Start the machine it should start and run. If it does not run then you have to start finding out why and most likely will be carb problem because it ran using the starting fluid.
This is how I check one that I am having problems with and I usually find the issue faster doing this. Taking short cuts by not doing a step will cause you to miss somthing and you will end up going over and over the same things and still not finding the problem.