Honda Xr70 running rich????

Question

Hi, I was wondering if I could get some help with my sons xr70. It seems to be running rich, it doesn't run good once it's warm, no power and sputter's a lot. When I take the plug out it is jet black. I have played with the air/fuel screws on the side of the carb. and it really doesn't make any difference. There is one screw on the other side of the carb. that is turned all the way in, if I back it out a little bit I start getting gas running out the overflow tube from the carb. Any info. would be appreciated, I am a long way from a dealer and I really want to get this fixed.
Thanks Nate

Answer 1

1. Make sure the choke is off. These have an air/butterfly choke that you can see if you remove the duct that goes from the airbox to the carb.
2. leave the air duct off and try running the bike. If it runs fine then air filter is dirty.
3. turn off fuel valve on fuel tank and run the bike if after a short time starts running better then the fuel level in the carb float bowl is too high
4. refer to this webpage http://houseofmotorcycles.bikebandit.com/partsbandit/oem_schematic_view~schem_dept_id~380274~section_dept_id~1~section_dept_name~OEM+%28Stock%29+Parts~dept_type_id~2~model_dept_year~1997~model_dept_mfr~Honda~model_dept_id~375050~model_dept_name~XR70R.asp
5 If level is too high then you're in a bit of trouble because the floats on these do not have an adjustable tang. You have to get the rebuild kit.
6. turn screw 5 all the way in and back out about 2 turns. this is the idle mixture screw turn screw 7 most of the way out and turn back in until you see part 6 (carb slide) start to move up. turn screw 7 an aditional turn in. this is the idle set screw. run the bike again.
7. if it's still not ok then take off float bowl (part 4) and make sure both jets (parts 19 and 20) are in place. Once in a great while these back out from motor vibration. If you tighten them just turn them a little past snug. Remember that they're brass and break a lot more easily than steel will.
8. low compression will never be the cause of a motor running too rich.
9. buy some carb cleaner. there are two (or maybe one) tiny brass air jets in the front opening of the carb at the bottom. Tilt the carb so these jets are facing up. gently spray a little carb cleaner onto these jets so there is a pool of carb cleaner sitting on top of them. The carb cleaner should drain through these jets and out a port in the fuel jet channels in just a second or two. If not then take a small piece of COPPER wire and try to clean out the holes

That's all I can think of. If none of these things fixes the problem....Then I should retire from my job.

good luck

Answer 2

2000 Honda Xr70

Answer 3

About 30k miles on it, so it doesn't need rebuilt, it is a Honda. It probably needs the carbs cleaned and the valves adjusted, I think that alone will be $400-500 US. Unless somebody has re-jetted it there is no reason for it to be rich unless a float is stuck. Carb cleaning will fix that.

Answer 4

Check the cyl compression. Below 80psi and you need piston & rings and/or cyl bore.
The screw your talking about is on the float bowl. It's the drain screw. Has nothing to do with tuning the carb. Leave it screwed in.
Check the air cleaner. If it's dirty, that will cause the motor to run rich. Clean it.