The Sportster and Buell Motorcycle Forum Zipper's Performance  

Go Back   The Sportster and Buell Motorcycle Forum > SPORTSTER MOTORCYCLE ZONE > Sportster Motorcycle General Discussion and Problems
XLF Gallery XLF Classifieds XLF Blogs XLF Shout XLF Arcade XLF Disclaimer/Privacy Statement/Terms Of Use

Sportster Motorcycle General Discussion and Problems For discussing problems about your Sportster motorcycle that don't fit anywhere else.

Members Birthdays
DK Customs
Lickscycles
Lickscycles
Energy One Clutches

Foxcreek Leather
Reply
 
Share Thread Tools Display Modes
  #1  
Old 22nd August 2010
JBierschwale JBierschwale is offline
Biker
 
Join Date: Oct 2009
Posts: 19
Sportster/Buell Model: XL
Sportster/Buell Year: 1977
Reputation: 10
JBierschwale is an unknown quantity at this point
Default 1977 ironhead not firing on front cylinder

I have a 1977 ironhead chopper that will not fire one the front cylinder all the time. We've replaced plugs, wires, coil with known good parts. Checked for vacuum leak at the intake, new rubber there. Runs all the time on the rear cylinder, but will only fire on the front cylinder when you rev the engine. Adjusted the valves with no change. Points have been adjusted several times. Has new thicker copper head gaskets. Points are advanced almost as far as they will go. Any ideas? I have to have this bike running today. Thanks, guys!
Reply With Quote
  #2  
Old 22nd August 2010
72Iron's Avatar
72Iron 72Iron is offline
Senior Chief Know It All 2nd Class
 
Join Date: Jul 2009
Posts: 1,395
Sportster/Buell Model: XLH
Sportster/Buell Year: 1972
Sportster/Buell Model #2: Harley-Davidson
Sportster/Buell Year #2: 2009
Other Motorcycle Model: FLHTCU (Geezer Glide)
Reputation: 7813
72Iron is just really nice72Iron is just really nice72Iron is just really nice72Iron is just really nice72Iron is just really nice72Iron is just really nice72Iron is just really nice72Iron is just really nice72Iron is just really nice72Iron is just really nice72Iron is just really nice
Default

Condenser?
__________________
I gave up smoking, drinking and sex.
It was the worst fifteen minutes of my life.

RIP: Eli
Reply With Quote
  #3  
Old 22nd August 2010
superwarden's Avatar
superwarden superwarden is offline
Custom Bike Builder
 
Join Date: Dec 2006
Location: I really don't know :)
Posts: 2,477
Sportster/Buell Model: XLH
Sportster/Buell Year: 1968
Sportster/Buell Model #2: XLC
Sportster/Buell Year #2: 2003
Other Motorcycle Model: FXSTD
Other Motorcycle Year: 2003
Reputation: 11505
superwarden is a glorious beacon of lightsuperwarden is a glorious beacon of lightsuperwarden is a glorious beacon of lightsuperwarden is a glorious beacon of lightsuperwarden is a glorious beacon of lightsuperwarden is a glorious beacon of lightsuperwarden is a glorious beacon of lightsuperwarden is a glorious beacon of lightsuperwarden is a glorious beacon of lightsuperwarden is a glorious beacon of lightsuperwarden is a glorious beacon of light
Default

Compression test?
__________________
Any date that is not on your tombstone is considered a lucky day.
Reply With Quote
  #4  
Old 22nd August 2010
ericfreeman's Avatar
ericfreeman ericfreeman is offline
XL FORUM TEAM MEMBER
 
Join Date: May 2007
Posts: 4,466
Sportster/Buell Model: Ironhead XLH Sportster
Sportster/Buell Year: 1978
Sportster/Buell Model #2: Ironhead XLT Sportster
Sportster/Buell Year #2: 1977
Other Motorcycle Model: Honda CBX 1000
Other Motorcycle Year: 1979
Reputation: 22134
ericfreeman is a name known to allericfreeman is a name known to allericfreeman is a name known to allericfreeman is a name known to allericfreeman is a name known to allericfreeman is a name known to allericfreeman is a name known to allericfreeman is a name known to allericfreeman is a name known to allericfreeman is a name known to allericfreeman is a name known to all
Default

JB

You'll likely get more replies if you post your issues on the Ironhead Forum directly. Lots of us tend to skip over the other sub-forums and stay where the posts are more relevant.

Eric
__________________
1978 Anniversary Edition XLH. Wiseco 10:1 forged pistons, Andrews R5 cams, dual plugged heads with Super Port Flow, single fire ignition, Mikuni Solex 36 PHH carb, Jagg oil cooler, '73 gauges, kickstart, Barnett kevlar clutch, Progressive front springs, Hagon Nitro shocks, all-Andrews tranny. 1977 XLT, Mikuni Solex 36 PHH carb, tapered dual exhausts, Andrews Y cams, Progressive front springs, Hagon Nitro shocks.
Reply With Quote
  #5  
Old 22nd August 2010
ericfreeman's Avatar
ericfreeman ericfreeman is offline
XL FORUM TEAM MEMBER
 
Join Date: May 2007
Posts: 4,466
Sportster/Buell Model: Ironhead XLH Sportster
Sportster/Buell Year: 1978
Sportster/Buell Model #2: Ironhead XLT Sportster
Sportster/Buell Year #2: 1977
Other Motorcycle Model: Honda CBX 1000
Other Motorcycle Year: 1979
Reputation: 22134
ericfreeman is a name known to allericfreeman is a name known to allericfreeman is a name known to allericfreeman is a name known to allericfreeman is a name known to allericfreeman is a name known to allericfreeman is a name known to allericfreeman is a name known to allericfreeman is a name known to allericfreeman is a name known to allericfreeman is a name known to all
Default

Check your points gap on both of the lobes of the timing cam. These cams are notorious for being off and you may find a gap of say .018" on one side and .025" on the other. Some of us have had success by loosening the cam lockscrew slightly and shifting the cam over to the tighter side, thereby averaging out the 2 gap readings. May take some fiddling to get the two point gaps within .004" of each other, the factory spec.

Eric
Reply With Quote
Know Thy Hog

  #6  
Old 22nd August 2010
wedge's Avatar
wedge wedge is offline
Whitworth Products
 
Join Date: Jun 2010
Posts: 9,404
Sportster/Buell Model: 1200R
Sportster/Buell Year: 2005
Other Motorcycle Model: 5 bikes and 1 quad
Reputation: 716429
wedge has a reputation beyond reputewedge has a reputation beyond reputewedge has a reputation beyond reputewedge has a reputation beyond reputewedge has a reputation beyond reputewedge has a reputation beyond reputewedge has a reputation beyond reputewedge has a reputation beyond reputewedge has a reputation beyond reputewedge has a reputation beyond reputewedge has a reputation beyond repute
Default

Quote:
Originally Posted by JBierschwale View Post
I have a 1977 ironhead chopper that will not fire one the front cylinder all the time. We've replaced plugs, wires, coil with known good parts. Checked for vacuum leak at the intake, new rubber there. Runs all the time on the rear cylinder, but will only fire on the front cylinder when you rev the engine. Adjusted the valves with no change. Points have been adjusted several times. Has new thicker copper head gaskets. Points are advanced almost as far as they will go. Any ideas? I have to have this bike running today. Thanks, guys!
What's the compression? Is the front backfiring through the carb when it trys to run?
__________________
A Biker is not just any guy who rides... that's a motorist.
A guy that gets up and rides again after every crash... that's a Biker.

Whitworth Fork Brace: http://xlforum.net/vbportal/forums/m...outme&simple=1

Reply With Quote
  #7  
Old 22nd August 2010
JBierschwale JBierschwale is offline
Biker
 
Join Date: Oct 2009
Posts: 19
Sportster/Buell Model: XL
Sportster/Buell Year: 1977
Reputation: 10
JBierschwale is an unknown quantity at this point
Default

Compression is good on both cylinders.
Reply With Quote
  #8  
Old 22nd August 2010
JBierschwale JBierschwale is offline
Biker
 
Join Date: Oct 2009
Posts: 19
Sportster/Buell Model: XL
Sportster/Buell Year: 1977
Reputation: 10
JBierschwale is an unknown quantity at this point
Default

Just checked points gaps - .018 on both lobes.
Reply With Quote
  #9  
Old 23rd August 2010
JBierschwale JBierschwale is offline
Biker
 
Join Date: Oct 2009
Posts: 19
Sportster/Buell Model: XL
Sportster/Buell Year: 1977
Reputation: 10
JBierschwale is an unknown quantity at this point
Default

Compression is right at 90 on both cylinders. My compression gauge could be wrong, though. We just rebuilt this engine. It has spacers under each cylinder at the base, and thicker copper head gaskets (.030 or better). It has pop up pistons (not sure if they all do). It seems like it's hard to crank, as it kind of stalls while using the electric starter while trying to start it, especially after you twist the throttle to give it a shot of gas. As soon as you twist the throttle, it pauses while cranking, like it's trying to fire the charge before TDC. It has an S&S Super E. Correct o-ring intake with the bands and o-rings, and updated intake clamps. It will sneeze through the carb occasionally, especially if you blip the throttle. Not sure which cylinder that is coming from. It backfires pretty bad through the front pipe (has drag pipes) about every 10th revolution. It's not firing all the time on the front cylinder, so it pumps intake charge through the cylinder into the pipe and then ignites it when it does fire. We turned the points cam 180 out and couldn't get it to start, even adjusting the points from one end to the other. The only way it will run is if the points are adjusted all the way counter clockwise while looking at the points side of the bike. We did not do anything with the cams when we had the motor apart to do a top end. Only base gaskets up.

Forgot to mention - we had to replace the front head with a used one. The exhaust flange broke off of the original head. I did replace it with the correct numbered head. The seats looked perfect, so I installed the valves/springs/keepers in the replacement head. We did bore the cylinders. Replaced rings, pistons, all gaskets.
Reply With Quote
  #10  
Old 23rd August 2010
ezmerf's Avatar
ezmerf ezmerf is offline
Master Custom Bike Builder
 
Join Date: Jul 2010
Location: Booneville,Ms.
Posts: 3,391
Sportster/Buell Model: XLCH
Sportster/Buell Year: 1974
Sportster/Buell Model #2: XLS
Sportster/Buell Year #2: 1980
Blog Entries: 1
Reputation: 41259
ezmerf is a splendid one to beholdezmerf is a splendid one to beholdezmerf is a splendid one to beholdezmerf is a splendid one to beholdezmerf is a splendid one to beholdezmerf is a splendid one to beholdezmerf is a splendid one to beholdezmerf is a splendid one to beholdezmerf is a splendid one to beholdezmerf is a splendid one to beholdezmerf is a splendid one to behold
Default

Give this a try on a cold start up pull front plug wire to where just the boot is holding it on,it isn't snapped in the metal the snap on plug wire is sitting on top of plug.Start bike as your riding down road and it's warmed up pretty good reach down and snap frn plug wire back down.Hope this wks for you I had a rear cyl this wkd on as the rear cyl heated up push plug wire down it didn't miss a lick but everytime on a cold start I had to do this as you say everything ckd good.By the way if your plug wires are good and you push from top you won't get shocked.
__________________
Murphy's Law
Reply With Quote
Know Thy Hog

Reply

Bookmarks


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
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 Off

Forum Jump


Custom Search

All times are GMT +1. The time now is 23:40.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
XL Forum - Linson Media LLC