ADVrider

Go Back   ADVrider > Bikes > Thumpers
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 04-27-2015, 12:26 PM   #1
lunkerjunker OP
Adventurer
 
Joined: Sep 2011
Location: SLC, UT
Oddometer: 21
XR500R Carburation frustration

Hey,

I have an 81 XR500R. End of last year it was running just about perfect. Easy starting, idled great. I didnt ride much after about August as I had some serious back issues and I failed to add stabilizer. The bike sat for about 4 months. I would kick it over throughout the winter and let it run for short amount of time.

Anyway, beginning of March I have the bike out and start it up. She ran for a few seconds and died. I opened the fuel valve on the bottom of the carb to see if I was getting fuel in there and sure enough, nothing.

Pulled the carb. The fuel float needle was stuck in place with some gunk build up so I cleaned it out and went through the rest of the carb as good as I know how. Claened out the air screw, main and pretty much every other orifice I could see. I pull the air cut off diaphram and actually replaced the diaphram and spring.

Put it all back to gether and she starts right up but will not idle for long without staring to miss, run rough and then quit. Sometiomes the idle rpms will increase and then decrease without me doing anything. I have had that carb off 4-5 times and have tried to clean and clear out every passage possible. The carb was professionally serviced last summer and like said the bike was running perfect. I have a new float valve ordered as the old one seems ok but appears to have some corrosion. I dont know if that could be whats causing the problem.

I am at a loss. Any help would be apprecited.
lunkerjunker is offline   Reply With Quote
Old 04-27-2015, 12:53 PM   #2
Gladly
Gnarly Adventurer
 
Gladly's Avatar
 
Joined: Aug 2009
Location: Whitehorse, YT
Oddometer: 158
Quote:
Originally Posted by lunkerjunker View Post
Hey,

I have an 81 XR500R. End of last year it was running just about perfect. Easy starting, idled great. I didnt ride much after about August as I had some serious back issues and I failed to add stabilizer. The bike sat for about 4 months. I would kick it over throughout the winter and let it run for short amount of time.

Anyway, beginning of March I have the bike out and start it up. She ran for a few seconds and died. I opened the fuel valve on the bottom of the carb to see if I was getting fuel in there and sure enough, nothing.

Pulled the carb. The fuel float needle was stuck in place with some gunk build up so I cleaned it out and went through the rest of the carb as good as I know how. Claened out the air screw, main and pretty much every other orifice I could see. I pull the air cut off diaphram and actually replaced the diaphram and spring.

Put it all back to gether and she starts right up but will not idle for long without staring to miss, run rough and then quit. Sometiomes the idle rpms will increase and then decrease without me doing anything. I have had that carb off 4-5 times and have tried to clean and clear out every passage possible. The carb was professionally serviced last summer and like said the bike was running perfect. I have a new float valve ordered as the old one seems ok but appears to have some corrosion. I dont know if that could be whats causing the problem.

I am at a loss. Any help would be apprecited.
did you check the tank vent and petcock?
__________________
'03 XR400R
Gladly is offline   Reply With Quote
Old 04-27-2015, 01:11 PM   #3
lunkerjunker OP
Adventurer
 
Joined: Sep 2011
Location: SLC, UT
Oddometer: 21
I have not checked the tank vent and petcock. I'll give it a look later today.

I am getting fuel and she runs pretty good at higher RPM's from about 1/4 to wide open.

Thanks for the response!
lunkerjunker is offline   Reply With Quote
Old 04-27-2015, 01:21 PM   #4
mcma111
Beastly Adventurer
 
mcma111's Avatar
 
Joined: Jul 2007
Location: San Francisco,Ca.
Oddometer: 12,560
Plugged PILOT jet
__________________
Steve in SF

BMW's
58 R26
79 R100s
91 R100gs

87 Harley FXRS-SP ~ 06 KTM 625 SMC ~ 72 Honda CB750/915cc ~ 92 XR600/654cc ~ 95 XR650l/675cc ~ 03 CRF450r ~ 05 CRF450x ~ 02 XR650l/675cc ~ 86 YZ490 ~ 93 YZ80 ~ 93 XR650l Project
mcma111 is online now   Reply With Quote
Old 04-27-2015, 01:57 PM   #5
lunkerjunker OP
Adventurer
 
Joined: Sep 2011
Location: SLC, UT
Oddometer: 21
The pilot jet is not the same as the pilot air screw, correct?

Showing my ignorance of carburetors here but I'm not exactly sure where that one is. Is it right next to the main jet only not as long? If so that one has a jet that does not appear to be removable. I'll try and go back through that one again.
Thanks
lunkerjunker is offline   Reply With Quote
Old 04-27-2015, 02:55 PM   #6
mcma111
Beastly Adventurer
 
mcma111's Avatar
 
Joined: Jul 2007
Location: San Francisco,Ca.
Oddometer: 12,560
The PILOT jet is next to the Main jet and has a straight slot across it to accept a small straight blade screwdriver.

I snip one strand from a wire brush and put it in the jet and turn it. Works like a charm. You could do so without even removing the jet.
__________________
Steve in SF

BMW's
58 R26
79 R100s
91 R100gs

87 Harley FXRS-SP ~ 06 KTM 625 SMC ~ 72 Honda CB750/915cc ~ 92 XR600/654cc ~ 95 XR650l/675cc ~ 03 CRF450r ~ 05 CRF450x ~ 02 XR650l/675cc ~ 86 YZ490 ~ 93 YZ80 ~ 93 XR650l Project
mcma111 is online now   Reply With Quote
Old 05-09-2015, 10:41 PM   #7
lunkerjunker OP
Adventurer
 
Joined: Sep 2011
Location: SLC, UT
Oddometer: 21
OK, so my woes continue. I've been back through the carb and I have cleaned everything possible. I've blasted carb cleaner down every orifice. I feel like I've done everything I can to clean this thing. The more Ive researched this I think I've gained a pretty good understanding of how it all works. Blasting cleaner down the different openings ive been able to see where it comes out and it looked to be good. I've gone through the pilot jet and all related openings. Now, the bike starts really as easy as it used to, and will start out idleing ok then begins to run rough and will quit. Starts right back up but wont idle smooth. Also seems to hiccup slightly here and there at higher rpms as well.

The fuel is flowing fine as I checked all of that. Replaced the fuel needle and the plug looks good too. I thought it might have been fouled by the poor running before but no.

I dont know. Losing my mind. I want to just take it to the shop but thats not an option right now. I need to fix this!!!!

I'll try to take some video tomorrow to show what its sounding like.

As always I apperecite any advice!
lunkerjunker is offline   Reply With Quote
Old 05-09-2015, 11:06 PM   #8
Off the grid
Chaotic Good
 
Off the grid's Avatar
 
Joined: Jan 2008
Location: That buzzing in your earhole, NorCal.
Oddometer: 11,368
New bike? It's an 81' XR. They never ran good even when new.
__________________
Wedding(s) = $30,000
Divorce(s) = $25,000
2009 Husky TE610 = Priceless
Off the grid is online now   Reply With Quote
Old 05-09-2015, 11:12 PM   #9
lunkerjunker OP
Adventurer
 
Joined: Sep 2011
Location: SLC, UT
Oddometer: 21
Well it's all I got and ran like a F'n top last year. Thanks for your help!
lunkerjunker is offline   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


Times are GMT -7.   It's 12:58 PM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2015, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2015