Suzuki Quadmaster 500 Ignition or Carb problem - Backfiring

[JohnnyBAtv]

Hello Everyone and thank you in advance for any advice you can provide. Also this is my first post. I have read some other posts regarding backfiring of this type of quad, but my issue adds another layer of complexity.

My quad which I purchased from a gentleman who couldn't figure this issue out thought he had it licked, as well as I did. He had replaced the carb with a brand new one and still had the same issue.

Here is the issue: Initially the quad ran great, didn't have any backfiring issues IF the ignition switch was turned all the way to the second click which is the lights on position. It would start and run fine. However, if the quad was run on the first ignition click - lights off, it would backfire and not run.

So the solution to the problem was simply to run the quad with the lights on.

Now, even if it is run with the lights on it backfires and sputters. It will not accept any throttle. It will backfire and surge if throttle is applied.

Thank you for any advice.

[XWrench3]

the first question i have to ask, seems obvious, but have you tried a new spark plug? the spark plug is still the weakest link in the ignition circuit. mostly because of all the varying conditions it is asked to operate in. if so, i have to tell you, honestly, from the description you are providing, it sounds like you have an electrical problem. as a former mechanic for more than 30 years, i can tell you that more than 75% of all electrical problems can be traced back to a faulty ground. there is an easy way to tell if this is the problem however. but, the difficulty can be made worse by how much of the quad is covered in plastic. the quick check is to simply run one single jumper wire to multiple locations. it needs to start at the - side of the battery, then onto a good frame ground (sand off the paint, and apply dielectric grease (available at any auto parts store). from there, to the engine (same thing, sand off paint) then up to the cdi box ground WIRE, and finally to the ignition coil ground WIRE. if this does not cure it, the problem is most likely not a ground problem. there is always a chance that the stator could have a problem, as that is where all electrical power is generated from. and you could also have a defective switch. if the jumper wire fixes the problem, it will be very tempting to just stop there. but you really NEED to find the cause and repair it properly. if it is corrosion, the chances of another connection being corroded nearby, possibly in the same connector, is very good. and just ignoring it is simply asking for more trouble. which will most likely come when it is most inconvenient. like riding by yourself, after dark, miles and miles from home. or in the middle of a swamp.

[ScottBarry28]

Jet kit? I added jet dyno jet kit to my bike. I didn't account for exhaust. Blew out stock muffler. Added HMF works great. Let me know whats on your bike I will ask my Mech.

Scott

[JohnnyBAtv]

Thanks for your responses! I have been out of town, but will be able to look into the quad soon. I'll post any info I uncover.

Edited December 7, 2012 by JohnnyBAtv
Plural

[XWrench3]

the biggest thing is to be calm and be thorough. getting upset will either cause mistakes, or worse. if something gives you a lot of trouble, walk away from it for 10-15 minutes, drink a soda, clear your head, and go back at it. if it still gives you trouble, walk away from it for the night, post on here what is giving you trouble, and see if one of us can help. i have seen a lot of damage (and i have been there myself on some of my own things) when you struggle with something you do not understand. i remember doing a brake job on my first car, and getting so mad i took a rubber hammer to the body! it did not help fix the car, but it let enough steam off that i could think clearly after a while. it took me 2 weeks to fix the dents, and the paint never did really match. i have seen hammer holes in crankcases on some customer machines. totaling the quad is one way of fixing it, but i do not recommend it! it is NOT cost effective!