carb woes

[tomale]

I just bought my son a 81 honda XL 100. I bought it for such a good price I could not go wrong. It runs fine but when I take it off of choke it dies. I did take the carb off and found varnish in the bowl and I cleaned it up. I pulled off the main jet and cleaned it out. I sprayed carb cleaner in everything that looked like it could be plugged. I am use to my bing on my KTM. I could not find a pilot jet. Any ideas.

Thom Green,I bought and raced my 76 250 MC5 in 76'and 77' but I am just now getting back into riding again.

[Mike Lenz]

Im looking for jets for the same reason for my xr 75. If I find any Ill let you know.

 

[scooterdude]

Hi guys, my '78 xr75 was doing the same thing so I bought a brand new in the box NOS carb( bolt on and go)and it still does the same thing. That was my last resort. The only thing left is holy water to chase the demon out.

 

[john durrill]

Check for an air leak.
 Intake manifold , burn't valve , head gasket , etc.
its sounds like they are running lean at idle
Might not be the carb.
john


 

[Dwight Rudder]

Remove pilot jet , and needle jet and main jet, soak in carb cleaner. DO NOT USE WIRE TO CLEAN JETS.   The pilot jet is stopped up.
Dwight

Dwight Rudder
7 time ISDT / E medalist
7 time National Enduro Class Champion.

[tomale]

I am not sure about the pilot jet on the xr75's but on my Xl the pilot jet is pressed into place, so removing it is not such a good idea. The O ring on the front of the carb that seals the carb to the maninfold is looking old and flat. I think this should be replace so I will try to find a replacement. Any ideas to clean this pilot jet without using a wire.... varnish can be very stubborn, as I have found out. I have thought of soaking the carg in laquer thinner but if there are small rubber seals in the carb this could cause a problem.
this bike only has 900 miles on it I doubt that it has a burnt valve. I have known the previous owner for alot of years and he is trust worthy. thanks for the input.

Thom Green,I bought and raced my 76 250 MC5 in 76'and 77' but I am just now getting back into riding again.

[Frenfroe]

Having owned a TL125 (same carb as the XR75) I know it's a pluged pilot jet. I have a air chuck w/a rubber plug on the end. I use it to blow the thing clear. Unlike Dwight, I regularly use a fine wire to clear the jets......but i use a single thin wire clipped out of a copper 14GA electrical wire. Copper is much softer than brass and won't hurt anything. Blow out all the passages too.
Frank

 

[Dwight Rudder]

I have never seen one with a pressed in pilot jet. I have seen plugged low speed fuel screws.
I have a XL / XR100 but I couldn't tell you what the carb came off of. I put it together from several bikes.
Dwight

Dwight Rudder
7 time ISDT / E medalist
7 time National Enduro Class Champion.

[leoheyman]

hey man
on xr75*s there is a longish brass tube that
you need to carefully pull out with needle
nose pliers...then clean out the hole(jet) with a small wire.  then press back in the
longish brass tube and use a little jbweld
if you need to make it stay. very little jbweld will be needed....

lee-lee

[tomale]

Thanks leo,
As it turned out I did do that. On christmas day me and one of the other guys took that carb apart and we or I pulled off that brass pressed in pilot jet. A single wire from a wire brush is just the size. It took several try's, it was really plugged. I discovered that the jet is so small that anything will plug that jet. I spent another 30 minutes going over everything to make sure that it was spotless. I have learned alot from this ordeal. I was given an old truck that I am fixing up for my teenage son. And it was easy to tell what was causing it to run like it did. Carbs are carbs they just are not all plumbed the same way. The truck had sit for two years with gas in the carb. Hmmmmm I wonder what could be wrong? Thanks again to everyone for their help.

Thom Green,I bought and raced my 76 250 MC5 in 76'and 77' but I am just now getting back into riding again.