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Discussion Starter #1
Another newbie here. I am usually a Suzuki auto (sidekicks mostly) kind of guy but I recently got a 91 quadrunner in pretty decent shape, The main issue was some rust repair to the frame, which I've done. I picked it up non-running but a spark plug fixed that and it ran but would not idle. I took the carb out, gave it a quick clean and made sure all passages were clear. Adjusted the pilot screw to 2 turns out and it ran pretty good for the most part but still had an erratic idle and would sometimes shut off after idling for a few minutes.

After a quick ride I pulled the plug again, it was carbon fouled pretty bad. I took the carb out and adjusted the pilot screw to 1 3/4 turns out and re assembled. The bike ran perfect after this for a day or 2. It still wouldn't start with choke, and even a small amount of choke when idling will kill it.

Most recently, I replaced the choke cable as the other one was broken on the handlebar end. I replaced the choke cable and it started up quickly as usual, but then a short time later it started to be very hard to start and will often stall in gear when slowly applying throttle. I think the choke might have been stuck on a bit, but I have it adjusted perfectly now so the correct amount of tension is on the new cable. It will also not start without giving it throttle.

Here are some videos of how it is running now. It will idle all day if you leave it but if you slowly give it throttle in gear it's sure to die. WOT is perfect the bike pulls great (for a 250 anyway lol). It seems the first bit of throttle is really killing it.

video-1599522777 - slow rev

video-1599523522 - WOT

video-1599523629 - slow speed maneuvering

Considering these issues what should I be zoning in on to check out. Plug is still carbon fouled by the way, it actually flooded really bad last time I tried to start it and would not fire until I pulled the plug and cleaned it up. Even when cold the bike will not fire without at least 1/2 throttle and no choke. It will never start with choke it seems now.
 

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The first thing I’d do is pull the carb and do another cleaning. I suggest doing a ultrasonic cleaning if you have the means to get one done. Next I’d buy yourself a carb rebuild kit and rebuild the carb. I’d recommend a Shindy rebuild kit. Once all that is done, I’d check your valves to make sure their still within spec. Hard starts are often a sign of worn or out spec valves. And welcome to the Forum.


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i think I'm going to try the "home brew" carb clean mentions in the FAQ. I'll try this before spending the nearly $50 on a new kit. I will check the valves but I don't think that the issue because in my experience that makes for hard cold starting, but this thing went from starting instantly dead cold to hard starts and Stalin the next.
 

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20146
image.jpeg


Broke the carb down last night and gave It all a bath in the boiling home brew. Very unpressive results. I could not get the float off. If you see the pic I posted its clear someone already messed up the end. Any ideas on how to get this pin/Hinge out? I thought about the die grinder but you guys night have a better idea.
 

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Well I got that pin out after and broke it all down and submerged it in the mix as mentioned previously. The carb came out looking brand new.

I also checked and slightly adjusted the valves, they were within spec but intake was on the tight end. Very difficult to adjust them compared to other atvs I found. Not in a good spot...

so I put it all back together to factory setting with the fuel screw 2 turns out and it started up very easily. But then it would not run with the choke off... I turned up the idle a few turns but it still ran poorly and would stall sometimes in gear. When fully warmed up it would not run idle at all. Previously it ran very strong past 1/4 throttle but now it coughs and backfires at WOT when warm.

I know you said get a carb kit but all my jets look perfect and so does the carb. Does anyone have any input at all?

20167
 

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The float height is fairly critical on those. It only has a .5 mm tolerance. The metal plate needs to be 12.5 mm to 13mm. If it is even slightly to high it will idle like crap and slightly to low it will get up to about 1/3rd throttle and start sputtering.
 

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Discussion Starter #7
So I didn’t really do much else but put in some fresh gas and clean the spark plug. Seems to be running well now!
 
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