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Hey guys, new here, but haven't found ANY answer to my specific problem on a Suzuki dedicated ATV forum, so here's to hoping!
I acquired a 95' Quadrunner 250, 4x4, (LT4WD) for practically nothing with no spark. The PO had tossed in a used stator which didn't fix the problem... so I went all routes (though cheaply) to narrow down the initial problem of no spark.
Plug, coil, CDI (caltric) and stator w/pickup (caltric) were purchased and installed. And it RAN, but bogged horribly and would not rev past 1/4 throttle.
I checked fuel flow, vacuum lines, all the normal stuff, no issues. I decided to check the valves and cam... well, there was one problem. The cam was 1mm under the lowest spec in the manual. So, in-came a new cam, Stage 1 Hotcams... also threw in a new set of shindy valves, lapped them, replaced the valve seals, and the timing chain.
Back together again (w/stock airbox and new oiled filter). Now it idles even better, still boggs at 1/4 throttle, but will rev past it if you hold the throttle open for a second. Ahaha... success!
So I was able to ride it above 1/4 throttle once I had momentum... could shift through the gears, all was good as long as I kept it over 1/2 throttle. Took a long enough ride to break in the cam properly at least so I won't have to worry about that.
Now, I start fiddling with the carb. It's clean as a whistle, stock, with stock jets (new replacement Mikuni jets). Same problem.
I start thinking, maybe this is fuel related and the bike is having an issue transitioning from idle jet to main jet... so I LOWER the needle by raising the clip 1 spot. Now it revvs up in neutral with no bog, but it boggs about the same trying to ride it. So I move the needle down again with the clip on the top slot. Better, but still has a bit of bog at 1/4 throttle.
The last bit of advice I got was to ditch the CV carb... so I sprung for a brand new Mikuni VM30-83 round-slide. Bolted it up, blew into the vacuum tube to fill it with fuel (no vacuum port on this one) and she fired right up... but there is still a bit of bog, it's just masked by the fact that I'm not waiting for the vacuum diaphragm to open.
So I feel like each little step brings me closer, but not perfect. I'm now wondering if this is still in-fact a carb tuning issue (I have some jets I can fiddle with and maybe lean-out the idle jet a little.) OR if the cheap-a** Caltric Stator/Pickup is what's causing these issues.
I have a 95' KingQuad with 400 miles on it... like new.. runs like a top... I've tried both the stock QR and the Caltric CDI boxes on it, and it revvs up and runs like a champ.
The only unknowns between the two systems are the carb, and the stator/pickup. My next step in troubleshooting is to rip apart the King Quad and test it's CDI on the Quadrunner... but considering there is no change to how it runs I doubt it will lead to a solution.
HOWEVER... I tried the stock CDI just recently after running the Caltric this whole time, and the bike runs like garbage. Hardly idles, and won't rev up at all. So, that is my one smoking gun telling me that it's either the pickup coil or the stator itself.
Has anyone had a problem even CLOSE to this? I can't image the carb would be causing this many issues, especially going to 2 different ones, both with stock jetting to OEM, and exhibiting the identical symptoms... the only change is when different CDI's are plugged in, or when the needle valve leans out the mixture.
Also, I checked the piston, rings and bore when I had it apart and they're like-new... no scoring, rings are loose, cylinder is still round and has honing marks still int he bore. Stock piston, stock bore size and it has 160psi compression. Battery is brand new, and I've tried 3 different R/R's, none of which change any symptoms, but slightly vary the charging voltage by .2-.5 of a volt depending on which unit. Also tried a new coil which changed nothing.
ANY help would be appreciated. Too much invested to not get it running right.
By John Ford
i ordered a keihin carb for my 07 trx 90 and it fits nicely but the new cable they sent is way too long and i can't make it work. the old honda cable cap [that fits on top of the carb] is too small to fit. the keihin cap is approx 3/4 or 19mm. honda cap is more like 1/2 in. the keihin has a rubber boot on the cap where the throttle cable goes through . i don't know how to find the right length [most cites don't give the length]. i'm not sure how cables fit into that boot and do i need to add the length of the boot to the cable? the old honda cable is 28 inches total, but the cable movement is only approx 2'' which would not be enough to reach the actuator block on the keihin. looking to find a throttle cable compatible with the keihin. any help, please.
By Roy Anderson
I have a 2002 Suzuki LT-F500F, and am a first time atv owner. I rode two wheel bikes for many years, and now, two months in to being a new at owner, am just not enamored with the thumb throttle, and I’m wondering if anyone has tried a conversion to a typical twist grip throttle as found on all motorcycles? If so, how do you like it?
Can anyone point me to a good set of instructions for changing front diff oil on a 1987 Suzuki LT4WD? I can almost guess which bolts are drain & fill... but I've been wrong before... 😆
I found some partial posts on other forums and they linked out to dead images and whatnot. Any help appreciated.
This thing is running pretty good, got the front brakes back to life, electric start works fine, seat cover fixed up, plastics stitched back together...
BEFORE (last week):
Problem: The ATV starts and runs at idle perfectly. But as soon as I open the throttle, the engine starts to slow down until it stops. On the attached video you can hear the sound of how it works: see video below
Prehistory: there is a Polaris Sportsman 500 1998, which for about 1.5 years stood in repair, including also replacing CDI with one taken from the same ATV. Finally, the vehicles were on wheels, traveled several kilometers and overheated - forgot to fill the antifreeze Came back home in small moves. The next trip started well, but after 10 km there was a feeling of a small drop in power (even as the vehicle got warm completely) but still drives. Next trip - the situation is repeated. The next test of ATV through time and a huge loss of power from the very beginning. The engine sneezes, does not want to go more than 5 mph.
What has been done: the carburetor has been replaced with a new one (inexpensive, $ 40), a new spark plug, a new ignition coil, the engine head has been removed, the piston is in good condition, valves were corrected - but the problem was definitely not in them.
Ignition control unit is suspected. Who faced similar? Please help in solving the problem.
Thanks in advance.
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