more carb confusion

[unclejtl]

sorry, been searchin, but a little confused ? just got a 86 xr200. test rode good, just up and down the rr tracks (about sea level). took it to our place in the desert and it ran bad at most anything more than 1/8 throttle...

uni filter

no baffle

all else stock 112 main 38 pilot

c-clip middle groove

2 1/4 turns out

now in my reading, I need a bigger pilot...40 I assume, but reading charts, I need to go down on the main as our place is in randsburg, ca and is roughly 3500ft. the riding flucituates a bit on elevation. weather last sat was around 50 degrees. before I go buy jets, can I get some expert advise? thanks

Edited February 6, 2012 by unclejtl

[Chuck.]

3500' is not enough to require rejetting, if also a hot day just drop the needle one groove. I've often run sea level jetting on hot summer days at 5000' and just suffered the blubbering or dropped the needle. This observation is supported by the jetting guides in several Honda Service Manuals. After many XR200s, many modded, I've never needed to increase the size of the pilot jet.

Sudden crappy running is usually caused by a dirty carb, old bikes that sit a lot collect crud in the tank and carb. Check out https://www.thumpertalk.com/forum/showpost.php?p=8896796&postcount=1.

Needing 2 1/2 turns on the mixture screw is a bit much and does indicate a larger pilot jet, but before changing I suggest a good carb clean and checking the float level. On one bike last summer I had a 1mm low float level, and after raising it to spec the mixture screw went from 2 1/2 to 1 7/8.

[unclejtl]

thanks chuck,

I took the carb off and opened it to see what jets were in it. it looked spotless inside. I will do it again to check passages.

when riding the bike, there was nothing put popping after 1/8- or so, throttle. not any responce from the main circut???? if it was the needle, wouldn't it have picked at wide open on the main?

[Chuck.]

The XR200 carbs are jetted for best operation which is borderline rich, rather than borderline lean like other carbs. What confuses carb symptoms is the circuits all overlap; the main jet affects all the way down to the pilot. I installed a one size richer main in a bike that had run one needle clip rich for years. It suddenly had a rich low speed with very rough throttle response from a closed throttle. Turning the mixture screw in helped but caused popping on decel. The fix was dropping back to the original main jet, I suppose I also could have dropped the needle back to stock.

As the link explained there are two very small discharge ports for the pilot jet that can become obstructed by debris. Hard starting from cold is one indication of an obstructed discharge port.

[unclejtl]

ok, it's soaking today and will put it back together tonight.

thanks

[4strokeridertt]

Check your wiring. A loose or corroded connection may have just enough flow at idle speed but to much resistance to fire correctly.

[Chuck.]

When you clean the carb make sure you can see light thru those two small discharge port, you will need to remove the pilot and mixture screw to sight the ports. I had a very small bit of debris in one of the ports that took a lot of work to dislodge, the symptoms were difficult cold starting along with unsteady idle. I also back blow all of the passages with carb cleaner.

Checking/adjusting float level: I'm right handed so here is how I check the float level. Hold the carb by the engine end in your left hand in its normal position. Slowly rotate the carb CCW until the float contacts the needle (almost 90 degrees), measure the distance from the float bowl flange to the bottom of the float, should be 12.5mm (1/2"). I've encountered jetting issue if the float level is lower than 13mm.

[unclejtl]

great, thanks. it's soaking now, will look tonight. seems to me when I took it apart, i could blow thru it all. will check the level and any loose connections.

what's weird, is that when I test rode it, it ran great and pulled hard, way better than my 2001 (it was all stock, baffle snorkle, etc) parked it, two weeks later take it up to the desert and it starts and idles, but runs like crap.... well, I don't know the history of the maint either ?

[unclejtl]

well, pulled it outa the carb dip, cleaned everything, checked all passages. the float level was set a little high, 11.5mm, set it to 12.5. put it all back together and rode it down the road... ran like it did when I test rode it... which is good. I wish I had rode it here when I got home from the desert, before I took it apart.

air/fuel screw is still around 2.5-2.25 turns out. I could not find the o-ring that was on it. not sure where it went, but installed another I had that fit.

i'm wondering if I did something wrong the first time I pulled it apart to see what jets it had in it. that was done after I bought it and before I went to the desert?...anyway we'll see what happens when I go back to the desert the weekend of the 17th.