running lean??

[pfo186]

hello all.
i've been tinkering with my carbs for some time now, as i've had problems with my bike running lean. i did that bonehead move that a bunch of ppl on here have done and broke the tip of my needle air screw off in the hole. i found the smallest drill-bit i could find from a special parts store and just drilled a hole straight through(after countless attempts and fails using other methods found on here), the hole is only a little bit bigger than what it originally was. please take a look at the pics i attached and tell me if you think it looks lean still, it still looks slightly lean to me. but i'm not sure.

thanks for the help!

 

[Onetype]

Hard to tell from the picture or maybe its just my eyes. It should be a tan, brown or grey color. If your that concerned about it you can always richen it up a tad bit. Better rich than lean.

 

[ace68]

going by the carbon on the plug it doesnt look too bad. since they took the lead out of petrol,its harder to read plugs now.

 

[xschris]

As long as it idles ok and had no dead spots at take off you should be ok.

 

[pfo186]

it idles high, almost like there is an air leak. i tightened all the clamps good, and even packed grease in any areas where an air leak could be possible, so i dont know why it would be idleing high still. i put the picture of the pipe on there also because it looked a little too blue to me and i know thats a sign of running hot.

could the original stock jets be jacked up causing it to run lean? would buying new stock jets be worth it? (i think i would only need the main and pilot?)

thanks for the help

 

[xschris]

When I had this happen to my carbs I had to replace them. I could never get them to work right. I know others on here have drilled out there mix screw holes but never said if they got them to work

 

[drewpy]

what exhaust/air filters are you running?

 

[pfo186]

pretty sure those are stock exhaust (as you can see in the pics) and use the original stock air filter. i even sprayed the layer of foam with super tacky motocross air filter oil ( doesn't drip off the filter over time). is there something with the stock exhaust (baffles?) that could be making it run a bit lean?

thanks again for the help guys

 

[drewpy]

those exhausts remind me of Jardine! not standard

I think you may need to run a bigger pilot and keep the mains ( one of them is rich the other lean)

 

[pfo186]

really? shit, i always thought the exhaust was stock. one cylinder is lean, the other is rich?? how can you tell? does this mean the carbs need to be balanced?

any recommendations on pilot jet sizes and best place to get them?

 

[pfo186]

i found some pilots on mike's xs. stock is 42.5, and i ordered a 45. will these pilots work?

 

[ace68]

Bigger means richer,but ive gone too big and that can be a problem too. 45 should be ok.

 

[drewpy]

I can tell, because the inner ceramic on the spark plug is too white indicating a lean mix, the carbon on the edge is near the cylinder which keeps it cooler.

unless you switch off your bike's engine doing over 4k revs, (called a plug chop)you will be in tickover mode when switching the engine off.

This is the last state the bike was running and the fuelling mix, so the weak mix is pilot.
The carbon is from mains, but is protected from burning off due to the large heat sink (the cylinder head)

I would go 45's. This is not a prescriptive answer as carb tuning is black art and each bike is different!

 

[TheFoggie]

Blueish pipes would tell me shes is running lean, as lean engines run hotter. Changes in exhaust piper colour is from excessive heat.

I agree with drewpy. The ceramic around the electrode is white, if it was running rich it would be black too like the outside edge of the spark plug.

 

[pfo186]

So I put in the 45 pilots, and it runs maybe slightly better. But still a little lean unfortunately. Also, one cylinder is def running hotter than the other. What could cause this if there is no air leaks? Point timing, carb syncing? Leaky exhaust?

I'd appreciate any feedback
Also, some help with what I should do with the jetting to richen it up some more or direct me to a guide so I can read up on it. Not sure if i should just up the pilots again or if the mains need changing also
Thanks again!!

 

[rodeofan5656]

im havin the same problem on mine! the right side header pipe is blue, and the other is just a darker color, kinda brown. maybe the XS400s have problems with the right side bein lean? i have an "open airbox" setup, and have to run with the petcock on PRI or it wont run right. but still, the pipes blue and sometimes turns a darker blue while warmed up..

 

[drewpy]

yep, some fit bigger jet on the right side. Prob as the inlet flow starts from the left carb.

 

[sambishop]

do you have to just wait on ebay till our carbs are for sale or can you get away with using other carbs?