bike running issue with gas/front cylinder
04-17-2009, 07:22 PM
#1
Senior Member
Superstock
Thread Starter
Join Date: Oct 2008
Location: Muskego,WI
Posts: 388
bike running issue with gas/front cylinder
been doing some work on the bike to eliminate the carb fart... So I raised both factory pro needles to the highest settings on both the front and rear carb.
bike runs great on the rear cylinder. pulled each cylinder plug and runs on the rear, but not the front. the bike seems like it is not getting fuel at idle on the front carb. the bike will run on the rear and then the front will kick in at higher rpm's.
any ideas... pulled the carbs and will be cleaning them out to see if that is the issue. the bike has a aftermarket WileyCo exhaust with stock jetting. I started with the needles as the bike seems to be running lean at different rpm's.
any ideas as to what to try next? It almost seems like the pilot is not supplying fuel at lower revs to the front cylinder.
some additional info i neglected the first time...
carbs were synced today.
getting spark to the front cylinder
i am thinking the slide is sticking
bike runs great on the rear cylinder. pulled each cylinder plug and runs on the rear, but not the front. the bike seems like it is not getting fuel at idle on the front carb. the bike will run on the rear and then the front will kick in at higher rpm's.
any ideas... pulled the carbs and will be cleaning them out to see if that is the issue. the bike has a aftermarket WileyCo exhaust with stock jetting. I started with the needles as the bike seems to be running lean at different rpm's.
any ideas as to what to try next? It almost seems like the pilot is not supplying fuel at lower revs to the front cylinder.
some additional info i neglected the first time...
carbs were synced today.
getting spark to the front cylinder
i am thinking the slide is sticking
Last edited by skoshere; 04-17-2009 at 07:37 PM.
04-18-2009, 01:05 AM
#2
jet wrench
Back Marker
Join Date: Jun 2007
Location: cowtown, CA
Posts: 175
you can clearly watch if the slides move(lift the front of your tank and run with the airbox lid off), anything at idle, will not be affected with the needles, or likely the slides(I cannot remember but believe the slides are FULL closed at idle). Adjust your FWD cyl mixture and re-sync, you'll likely be happy.
04-18-2009, 12:43 PM
#3
guru of things sparky
SuperSport
Join Date: Oct 2008
Location: Grand Prairie , Texas
Posts: 599
With carbs ( in case you havent dealt with small jets on japanese engines before )
make sure you break them all the way down before cleaining, and make double sure you clean out the pilot jet ( the smallest one ) with a jet cleaner or a tiny wire
(guitar strings make good jet cleaners)
In my past, I learned that skipping any steps or taking shortcuts only made me have to repeat the whole cleaning job over. Even with a single carb. And dont forget to dip that carb body in some real carb cleaner ( berryman B-9 ) or similar. Those passages linking the pilot jet to its fuel flow get plugged, and you cant open them without dipping the body for 20-30 minutes . Dont dip for more than that though, or you can create a whole different set of problems.
rinse body out with tap water, and blow dry with compressed air. Replace any rubber or gaskets with new ones if any damage or wear is detected.
This is my timeless fail-proof carb guide.
Yea you can get away with shortcuts and half-*** work sometimes ...
But when you do this for a living, every day, you learn , you just learn not to skip steps...because by the time youve had to re-do a 4 cylinder carb job for the 5th time, you learn these things. ( pilot jets hate you, and they are out to get you )
make sure you break them all the way down before cleaining, and make double sure you clean out the pilot jet ( the smallest one ) with a jet cleaner or a tiny wire
(guitar strings make good jet cleaners)
In my past, I learned that skipping any steps or taking shortcuts only made me have to repeat the whole cleaning job over. Even with a single carb. And dont forget to dip that carb body in some real carb cleaner ( berryman B-9 ) or similar. Those passages linking the pilot jet to its fuel flow get plugged, and you cant open them without dipping the body for 20-30 minutes . Dont dip for more than that though, or you can create a whole different set of problems.
rinse body out with tap water, and blow dry with compressed air. Replace any rubber or gaskets with new ones if any damage or wear is detected.
This is my timeless fail-proof carb guide.
Yea you can get away with shortcuts and half-*** work sometimes ...
But when you do this for a living, every day, you learn , you just learn not to skip steps...because by the time youve had to re-do a 4 cylinder carb job for the 5th time, you learn these things. ( pilot jets hate you, and they are out to get you )
04-19-2009, 06:51 AM
#4
Junior Member
Squid
Join Date: Apr 2009
Posts: 7
When I installed Dynojet stage 1 jet kit I had a hell of a time getting the rubber gasket/diaphragm to seat properly when I put the carbs back together. I suspected the slide on the carb for the front cylinder wasn't moving so after taking it apart and putting it back together about 3 times I finally got it right. Not sure if it was a dirty jet or an error on the part of the installer (me) but it runs great now.
05-05-2009, 07:00 PM
#5
Senior Member
Superstock
Thread Starter
Join Date: Oct 2008
Location: Muskego,WI
Posts: 388
as an update on the bike....
got the carbs apart and gave them a good cleaning, put everything back together. synced the carbs. bike still wont run on front cylinder. the bike will run on the front cylinder at higher RPM's but at idle, it wont fire on the front. It is getting gas for sure because then it will back fire like a shot gun.
I pulled the plug and ground it the front cylinder head bolt. It was sparking on and off. I think I may have a bad coil. I will be testing tomorrow by switching the front and rear ( which the rear runs great).
any other ideas?????? I am getting to be at a loss.
got the carbs apart and gave them a good cleaning, put everything back together. synced the carbs. bike still wont run on front cylinder. the bike will run on the front cylinder at higher RPM's but at idle, it wont fire on the front. It is getting gas for sure because then it will back fire like a shot gun.
I pulled the plug and ground it the front cylinder head bolt. It was sparking on and off. I think I may have a bad coil. I will be testing tomorrow by switching the front and rear ( which the rear runs great).
any other ideas?????? I am getting to be at a loss.
05-06-2009, 05:55 AM
#6
Junior Member
Squid
Join Date: May 2009
Posts: 2
Maybe someone can verify this for me. What I think may be going on (I'm working with skoshere on his bike) is:
The front cylinder isn't always sparking. Maybe bad coil.
The bike runs on the rear cylinder alone (so the rear cylinder works great.
While the rear cylinder is keeping the bike running, the front cylinder isn't always sparking so it's loading up on gas. Randomly the fron cylinder sparks and ignites WAY too much gas and causes a massive ignition of gas and a flame out of the exhaust.
Does this sound like it's a plausable problem? If we have an intermittent spark, would this be the result?
The front cylinder isn't always sparking. Maybe bad coil.
The bike runs on the rear cylinder alone (so the rear cylinder works great.
While the rear cylinder is keeping the bike running, the front cylinder isn't always sparking so it's loading up on gas. Randomly the fron cylinder sparks and ignites WAY too much gas and causes a massive ignition of gas and a flame out of the exhaust.
Does this sound like it's a plausable problem? If we have an intermittent spark, would this be the result?
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