200 "auto x" fuel issue... at my wits end... :(

[Taiser]

So I've been working on my "AutoX" for the last week or so because my new parts arrived and I thought it would solve the issue but it didn't... :wondering

It idles fine but seems to be starving for fuel when you give it throttle. It runs about 80% fine at half choke when warmed up with the odd backfire, makes good power but with the choke off it backfires like crazy and if you goose it too fast it stalls. I have checked EVERYTHING I can think off and it's not helping... don't know what else it could be at this point... The motor is from a 83 200. Everything else is stock 200x except for a cobra pipe. I can see a bit of jetting change needed but not to the point where it does this much.

Here's what's been done.

-updated the carb to a "el-cheapo" 200x carb from e-bay... no difference (switched them back and forth a few times as well)
-updated the main jet all the way up to a 118 (about 3 numbers higher, did one at a time)... no difference
-raised the needle to it's max height... no difference
-checked and adjusted the timing, cleaned the spark advancer and gaped the pickup coil... no difference
-compression test is fine
-fresh fuel, good fuel flow
-spark is good and strong
-all coils checked and within spec...

Not sure what's left. I probably have a spare CDI I can try but I can't see how that was the issue. Did the 200x have a different CDI setting than the regular 200's? Don't think so. All the other conversions I have seen were just plain drop in's. I'm thinking I might pull the spark advancer from my 200x engine and try that, but the one in the machine now seems to work fine. I'm at a loss now for what's left to try... any ideas welcomed... :confused:

[danbur55]

did you check for any vacuum leaks around intake? what about valve clearance as well as cam lobe lift

[Taiser]

Yep, checked for leakage, adjusted the valves. Didn't check the cam itself but the lobes didn't have any wear that I could see when I did the valve adjustments. Engine makes good power as long as the choke is on so I don't think it's anything mechanical (engine wise)...

[DohcBikes]

Is the top end atc200 or 200x? Sounds like atc200. What's the smallest main jet you have tried? What carb model did you get?

Since you are able to raise the main jet size AND the needle with no change, there's a chance you are starting out too rich.

The atc200 takes smaller jets and a smaller carb than the 200x.

[barnett468]

Hello;


Did it ever run well?

Did it run well with the previous carb?

When did it start to run poorly?

What is your elevation?


What size is your pilot? The fact that it sounds like it runs better with it on suggests a low gas level in the carb and/or lean pilot jet for starters. A good pilot size might be around 38.

What upgrades are done ie., high comp piston, high perf pipe etc.?

As Dohc asked, what is the carb ie., keihin, mikuni, round or oval bore, what EXACTLY is the id size of the inlet of the carb?

If they gave it a "PZ" rating on Ebay like PZ22 or PZ26 etc., what was it?


I would do the following at this point.

The following gas level test eliminates the need to check the float level and is more accurate. It should also be done PRIOR to jetting.

GAS LEVEL - Check the actual gas level first by doing the following:

1. get a small 10” long piece of clear plastic tube.
2. connect it to the float bowl drain fitting.
3. hold it close to the carb with the open end even with the top of the carb.
4. open the gas valve on the tank and drain screw on the carb bowl.
5. the gas in the tube should be from even with the bottom of the main carb body to 3/16” below it. If it is outside this range, I would correct it.

If your gas level is high but you have plastic floats you might need a new float or possibly heat that one and bend it. Flying might have ideas.




What size is your pilot. the fact that it sounds like it runs better with it on suggests a low gas level in the carb and/or lean pilot jet for starters.

What upgrades are done ie., high comp piston, high perf pipe etc.?

As Dohc asked, what is the carb ie., keihin, mikuni, round or oval bore, what EXACTLY is the id size of the inlet of the carb?

If they gave it a "PZ" rating on Ebay like PZ22 or PZ26 etc., what was it?


I would do the following at this point.

The following gas level test eliminates the need to check the float level and is more accurate. It should also be done PRIOR to jetting.

GAS LEVEL - Check the actual gas level first by doing the following:

1. get a small 10” long piece of clear plastic tube.
2. connect it to the float bowl drain fitting.
3. hold it close to the carb with the open end even with the top of the carb.
4. open the gas valve on the tank and drain screw on the carb bowl.
5. the gas in the tube should be from even with the bottom of the main carb body to 3/16” below it. If it is outside this range, I would correct it.

If your gas level is high but you have plastic floats you might need a new float or possibly heat that one and bend it. Flying might have ideas.



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http://www.freesmileys.org/smileys/smiley-laughing025.gif (http://www.freesmileys.org/smileys.php)

[Taiser]

Thanks for the ideas.

The carb size got me thinking, so I put on a known good carb from a 185. It won't even run with that carb on!!! With full choke on it will barely idle!!! :( I'm really starting to think this is a timing issue. I'm giving up for this weekend. I'll switch out the pickup coil and spark advancer for the next attempt at fixing this.

[6speedthumper]

Are you running stock X or S jet sizes in that bad boy?

[Taiser]

Kept the original X carb. The replacement was also an X carb knockoff and the jets were for an X as well. I'll be ripping out the 200 carb that I just tried in there, it obviously doesn't work and it's not the problem. Also thinking of rebuilding the original x engine and putting it back in, but that's not my first choice, the auto is much more fun and way more convenient in the winter without the clutch, especially when I get stuck in the snow!!! :)

[Taiser]

Spent the week testing things, last resort now is to actually pull the cam out and check the specs, it's the only thing that's left!!! If I have to rebuild an engine, I might as well rebuild the original "X" engine and bench the Auto until I have more time to look at it! I'll see if I can post some pictures when I pull out the cam! :)

Too top it off, I noticed a pool of gas under my minty 250 Big Red! Carb is soaked and dripping down the engine! WTF? Probably a stuck float? Anybody know of carb leak issues with the 85 Big Reds? Mine has extremely low mileage so I don't know why the carb would start leaking out of the blue, especially since I haven't used it in about a month!

[captain2207]

Not sure if this applies here but,on my v65 magna it used to backfire on deceal and if you absolutely romped on it.it was running to lean,about half turn out on piolit cured it.maybe try that.

[cap]

Some things to check>

Possibly air leak around the carb intake, spray carb cleaner while running around this area and listen for rpm change.
Pull petcock out of tank and check filter, replace fuel line with inline filter and new line.
Make sure tank cap is venting.

Also the 200x ran a 24mm carb vs 22mm on the 200 correct?

[Taiser]

So I decided to pull the engine... :(

http://i1312.photobucket.com/albums/t533/taiser350/ATC/DSC02099_zpsfe385f73.jpg (http://s1312.photobucket.com/user/taiser350/media/ATC/DSC02099_zpsfe385f73.jpg.html)

Since there is nothing much left that it could be. It's not a intake leak and fuel flow test was fine. Compression is also fine but consensus is that the cam or valves might be worn out enough to cause the issue... I tried both carbs, the 200x original and a new one + a standard 200 carb. It wouldn't even idle on the regular 200 carb! :(



http://i1312.photobucket.com/albums/t533/taiser350/ATC/DSC02100_zps79cc35b3.jpg (http://s1312.photobucket.com/user/taiser350/media/ATC/DSC02100_zps79cc35b3.jpg.html)

Here she is in all her "glory"...





http://i1312.photobucket.com/albums/t533/taiser350/ATC/DSC02102_zpse54358b3.jpg (http://s1312.photobucket.com/user/taiser350/media/ATC/DSC02102_zpse54358b3.jpg.html)

Pulled out the cam... super clean, no pitts, no scores, nada!!!! $%^&*()





http://i1312.photobucket.com/albums/t533/taiser350/ATC/DSC02103_zps2e1584c6.jpg (http://s1312.photobucket.com/user/taiser350/media/ATC/DSC02103_zps2e1584c6.jpg.html)

Checked the lobes, they are a hair worn off but still in spec. Don't trust these calipers too much, but they are good for a good quick check.




Double checked with old faithfulhttp://i1312.photobucket.com/albums/t533/taiser350/ATC/DSC02104_zps31addad8.jpg (http://s1312.photobucket.com/user/taiser350/media/ATC/DSC02104_zps31addad8.jpg.html)

Double checked with old faithful, calipers were bang on, she's within spec!!! I'm going to pull the top end off and replace the valves and cam anyways. Not going to bother with the piston or rings. Compression is fine but since the cam is close to being out of spec, maybe the valves and tappets are all just hairs off enough to cause the issue. At least then I'll be sure it's not the damn motor!!!