big red problem continues. PLEASE HELP.

[conig]

OK I have posted on this before and the problem is continueing and driving me nuts. When my big red it running if you gun the throttle the bike will stall as if its running out of fuel or the spark is getting blown out. if you roll on the throttle it will go but still seems lean or down on power.

Here is what I have done to try and fix this and my problem is still prosisting.

1. I have removed all rust from the gas tank and treated it.
2. replaced the fuel filter and line
3. cleaned the petcock with carb cleaner and used an air compressor.
4. cleaned out all pasages in the carb with said compressor and carb cleaner
5. rebuilt the carb with a moose rebuild kit.
6. put a stock size main jet on the pilot jet and a bored out main jet (huge) on the main jet. problem still procists. at this point I have ruled out fuel.
7. replaced the coil.

the problem still prosists as if I have done nothing I also replaced the studs on the headpipe.(just did it becuase they were rusted)

what else can I do? Or what else could cause this? I'm really at a loss here. the only other things I can think of would be maybe a bad choke or my timing chain is worn. Could using the wrong oil do this I don;t think so but I used some from the auto parts store.

Who knows I may have to just sell the bike if I can;t ride it I have no idea what elese could be wrong.

PLEASE HELP ME ANY AND ALL SUGGESTIONS ARE APPRECIATED.

[bigredhead]

Does it smoke when first started ? or when fully warmed up ? black or white smoke ?

Do you have access to a compression tester ?

[bigredhead]

Remove the air filter and poke you finger into the carb *( with the engine OFF of course ) and switch the the choke on / off .. make sure it's opening and closing properly.. might be getting stuck partially closed.

[conig]

no smoke with the correct jets, some black smoke with the above mentioned modified jets. never any white/blue oil smoke.

I have a compression tester but its the wrong thread for the big red. shouldn;t the choke be closed off most of the time? am I just feeling for fuel?

[atctim]

be sure all of the carb vent hoses are open and clear. I personally have seen a vent hole hose run to another vent hole, and it screwed things up on the top end - it would idle fine and run fine, but at high RPM's it would "miss".

[Glenn J]

Make sure your gas cap is vented properly. If that's gummed up, it could be causing the problem.

[Banage]

you may need to get new seals. I have the same problem with my bigred and got seals on the way. Ill let ya know if it helps

[Kintore]

I have a ATC200, make sure yours is FULLY warmed up. Mine does this unless it is all the warm. After it is warm, shes runs like a top and I can gun it.

[conig]

its better when warm but still present if you try to start moving in to high a gear. thats why I wondered if it could be the clutch engageing when its not supposed too.

maybe is is seals or a blown head gasket, vents are clear, gas cap on or off it does this.

[jeswinehart]

Have you checked the timing , valve settings ???


john

[Dirtcrasher]

Still sounds like a fuel problem to me, not wrong oil or blown gaskets or seals. Did you unscrew every single jet, hold them up to a light and check that every single tiny hole is clear?? And that once they are removed every single passage is spotless?? Spraying cleaner in there without removing every jet doesn't do the trick, Is the airscrew and oring new from that kit? did you lightly bottom it and then back it out a turn or so?? Is the choke plunger oring in good shape?? I've had lots of 250CC SX carbs do strange stuff until I finally started going through them correctly. Why not grab a used 30$ carb from someone that worked fine and rule it out?? But, I would do the things I mentioned before if you haven't already.

[broook]

shouldn;t the choke be closed off most of the time? am I just feeling for fuel?

The 85 Big Red does not have a choke as such. It has what is called a fuel enricher. Instead of closing off the air supply as in a regular choke it enriches the fuel supply. If you follow your choke cable to the carb you will will come to where the plunger goes into the carb body. If this is not seating right or if as a previous post sugested the rubber O ring is not working right you will have a rich running condition that will give you the symptoms you describe. It does not have to be out very much to cause problems. Also when you unscrew it make sure there is no dirt on the tip of the plunger needle. this would also cause it not to seat properly.

[conig]

ive checked and rechecked passages and the choke. I'll do it again though and see what I get maybe something is still in there screwing things up. I'll report after this weekend on what I find.

[TeamGeek6]

The first rule of troubleshooting is:

"If youre fixed or replaced everything (fuel system, in this case) and it still doesnt work, the thats not where the problem is."

Compression or ignition. Replacing the coil is wasted money, they rarely fail - thats the first thing everyone tries and it never works. Weak or intermittient spark will do this exact thing because the fuel loads up in the cylinder - makes it look too rich.

Put the stock jets in (or as close as you have), verify the float and fuel level and that compression is good and no air leaks. IF thats all good, its ignition

[350xfromhell]

hey guys,
i'm not saying that this could be your problem but my boss has an 84 big red.it had the same symptoms.i rebuilt the carb,replaced the lines even the crankcase evac.had the correct timing,valves were champ.was charging properly.i even had one of the people on this forum email me schematics.kreemed the tank and put on a aftermarket gas cap.replaced the coil and still had problems.so maybe try this,borrow a service manual.it will have the schematics and readings for everything.get your hands on an ohm meter.and test every prong on the ignition module.if one is off by even a hair,your coil won't fire properly.the one that was on this bike wasn't off by much,but i got another one of ebay and installed it and this guy rides with us every other weekend.like i said i don't know if this could be your problem,i'm just trying to help.