Carb won't stay seated

Are ya having a problem with your rig? We'll try to help. Share your tech tips and experiences here. Dr. Billy Glaser, author of the "Unofficial 750 Ural Service Manual" site myural.com, is moderating this section.
Forum rules
Here is the place for you to ask questions about or share your experiences about servicing or repairing your Ural or Dnepr. Please post topics concering modifications or accesories in the "Modifications and Acessories" section. Please post oil related questions in the "Oil Threads" section.
User avatar
0ganos
New Member
New Member
Posts: 15
Joined: Fri Aug 07, 2015 4:50 pm
Location: Muskegon, MI

Carb won't stay seated

Postby 0ganos » Mon Mar 14, 2016 7:42 pm

Last Friday as I was cruising down the back roads my right carb came unseated from the flange and it has not stayed in place since.

I have checked for leaks in the air delivery system and did not find anything obvious. replaced the stock air filter with a K&N. I pulled the plugs and the right one was fouled pretty well so I replaced those with NGK BP7HS the ones in there were BP7ES with the longer shaft (which I'm hoping did not cause any damage).

After cleaning out the carbs and changing oil because it was nearly due for the 2500K maintenace it will idle smoothly but as soon as I hit the throttle the right carb pops out of the flange.

The flange itself looks OK and I've taken care not to over tighten. Would that indicate that there are some "micro-cracks" in the flange and it needs to be replaced.

Thanks in advance,
0ganos
Dave O.
2010 Gear Up

User avatar
Albuquralque
Hero of the Soviet Union - 2017
Hero of the Soviet Union - 2017
Posts: 18653
Joined: Thu Jul 19, 2007 2:46 pm
Location: Albuquerque, NM

Re: Carb won't stay seated

Postby Albuquralque » Mon Mar 14, 2016 7:44 pm

When you say flange, what exactly do you mean?

Is the carb coming out of the compliance fitting (rubber piece between the carb and cylinder head)?

Or is the carb coming out of the branch tube (the rubber tube from the airbox down to the carb)?
"Put a little gravel in your travel"

Darrell - Albuquralque
2014 Patrol - Babe the Blue Ox
EFI Map OR 1.02
Throttle Body Vacuum Ports
K&N Air Filter
Raceway 2-into-1 Header (Right Side)
Previous Urals Owned: 2004 Wolf, 2006 Tourist, 2006 Patrol (TOW), 2006 Patrol (TOM)

User avatar
0ganos
New Member
New Member
Posts: 15
Joined: Fri Aug 07, 2015 4:50 pm
Location: Muskegon, MI

Re: Carb won't stay seated

Postby 0ganos » Mon Mar 14, 2016 10:20 pm

The compliance fitting going to the cylinder head.

Although the branch tube can be a pita too
Dave O.
2010 Gear Up

User avatar
wooden nickel
Hero of the Soviet Union - 2017
Hero of the Soviet Union - 2017
Posts: 1635
Joined: Thu Mar 20, 2008 6:55 pm
Location: Louisville, KY 40216

Re: Carb won't stay seated

Postby wooden nickel » Mon Mar 14, 2016 10:33 pm

Did you clean both the carb and the compliance fitting? Any oil or residue on either will make them ornery.
When my compliance fittings cracked they still held together, but they leaked air.
I may not be good, but I'm slow.
Nick
2014 M70 Retros, the sports car of Urals.

eastbloc
Order of Lenin
Order of Lenin
Posts: 1074
Joined: Thu Oct 04, 2007 8:46 am
Location: Brooklyn, NY
Contact:

Re: Carb won't stay seated

Postby eastbloc » Mon Mar 14, 2016 10:35 pm

There should never be significant outward pressure building up in the intake tract.

Is it easy to pull the carb off without undoing the clamp on the flange? If not, check your valves. Maybe the left intake isn't closing all the way?
'14 Gear Up
'00 Bavarian Classic

User avatar
TerryG
Hero of the Soviet Union - 2017
Hero of the Soviet Union - 2017
Posts: 1431
Joined: Wed Jun 03, 2009 4:09 pm
Location: NPR, FL

Re: Carb won't stay seated

Postby TerryG » Mon Mar 14, 2016 11:06 pm

The PO of my BC had to rebuild a head because he used a 3/4" reach plug instead of a 1/2". It bent a valve when it hit the plug.
Terry

2011 Retro
2000 Bavarian Classic (Gone but never forgotten)

User avatar
ichbinbier
Comrade Colonel
Comrade Colonel
Posts: 250
Joined: Thu Nov 13, 2014 1:08 pm
Location: Toronto, ON

Re: Carb won't stay seated

Postby ichbinbier » Tue Mar 15, 2016 2:56 am

I had this happen to me last year on the left side. The branch tube has to be installed first with a bit of a twist towards the cylinder head, then the carb (or in my case throttle body) gets installed on the branch tube and then into the head. The slight twist towards the head pushes the carb/thottle body into the head.
2016 CCM GP450
2015 Kawasaki Ninja 300
2014 Ural Gear Up
1994 Harley-Davidson FXSTS Springer Softtail
1991 Harley-Davidson XLH Hugger 883

User avatar
GHGoodwin
Hero of the Soviet Union - 2017
Hero of the Soviet Union - 2017
Posts: 4288
Joined: Sun Jul 15, 2012 5:43 pm
Location: Cleve, Ohio

Re: Carb won't stay seated

Postby GHGoodwin » Tue Mar 15, 2016 7:41 am

Loosen all the clamps. Put the tube in place. Seat the carb end first and make sure its fully on by feeling along the underside. Make sure the carb clamp is on square after tightening. Too much pressure can cause it to squeeze off. Do the air box side last.

You might consider some perch rings. Raceway sells them. I made my set.
Hal

2011/12 Tourist - "The Russian"
It's a long list.
2014 Patrol - "Blackbird"

User avatar
0ganos
New Member
New Member
Posts: 15
Joined: Fri Aug 07, 2015 4:50 pm
Location: Muskegon, MI

Re: Carb won't stay seated

Postby 0ganos » Tue Mar 15, 2016 8:02 am

Wooden Nickel:
I did not clean the compliance fitting but it seems to be seated firmly when I attach them. I will give it a going over though.

Eastbloc and Terry:
I'm concerned that it is the valves because of those spark plugs. Damn PO's! I'm also concerned about getting in over my head. If the valves are bent would a gear-head friend and the "Unofficial Manual" be sufficient? Besides the valves would there be any other parts that would possibly need to be replaced?
Dave O.
2010 Gear Up

eastbloc
Order of Lenin
Order of Lenin
Posts: 1074
Joined: Thu Oct 04, 2007 8:46 am
Location: Brooklyn, NY
Contact:

Re: Carb won't stay seated

Postby eastbloc » Tue Mar 15, 2016 8:22 am

There's nothing to worry about. The valves are easy to service, but let's not get ahead of ourselves. The first thing is to determine root cause.

The valves are easy to check. Pull off the valve cover and watch what happens as you operate the kickstarter with the ignition off. It's easier to do this if you remove the plugs. Your problem may become immediately obvious, but if it isn't, use the standard procedure to check the valve lash.

Take the plug off the flywheel inspection hole and find the TDC mark. Each revolution of the flywheel will put the opposite cylinder at TDC. A valve that is fully seated at TDC will enable you to "twirl" the corresponding pushrod. If the pushrod does not allow you to freely rotate it with your finger, that valve is not fully seated at TDC.

Let us know what you find.
'14 Gear Up
'00 Bavarian Classic

User avatar
LRP
Hero of the Soviet Union - 2017
Hero of the Soviet Union - 2017
Posts: 2284
Joined: Sun Sep 28, 2008 8:25 pm
Location: Deltona, FL

Re: Carb won't stay seated

Postby LRP » Tue Mar 15, 2016 8:57 am

When mounting the carb or installing the intake tubes going to the air cleaner, you need to totally clean the mating surfaces of the
carb flange and rubber elbows with brake clean or alcohol. An oil mist from the crankcase breather system makes the parts slippery
and near impossible to clamp down.
Army Bird Dog Pilot, Nam.
'08 Green Patrol "Green Hornet"
130/42 jets. JC Whitney mufflers with 4" added baffles=5mph+

19 previous motos

Brian Crean
Hero of the Soviet Union - 2017
Hero of the Soviet Union - 2017
Posts: 1680
Joined: Tue Oct 07, 2008 2:13 pm
Location: East Centeral Florida

Re: Carb won't stay seated

Postby Brian Crean » Tue Mar 15, 2016 9:59 am

Loosen up all the hose clamps, center everything up, then one by one, tighten the hose clamps till they start to snug down. THEN STOP TIGHTENING. Do this to all the clamps, one after the other. Just snugged, not tightened. Then, go over all the clamps again, tightening each 1/4 to I/2 of a turn. Go down the road a few miles till it's warmed up, pull over and do a carb wiggle test. If loose, go another 1/4 turn. If you tighten too much, it's like squeezing an oily ball bearing, it's going to pop out. Make sure your surfaces are clean, and let the natural friction of the rubber fittings work for you.

User avatar
0ganos
New Member
New Member
Posts: 15
Joined: Fri Aug 07, 2015 4:50 pm
Location: Muskegon, MI

Re: Carb won't stay seated

Postby 0ganos » Tue Mar 15, 2016 10:22 am

eastbloc wrote:There's nothing to worry about. The valves are easy to service, but let's not get ahead of ourselves.


That completely goes against my basic nature! I will take a few breathes when I get home and start diagnosing.

Thank you for all the replies everyone!
Dave O.
2010 Gear Up

User avatar
Snakeoil
Hero of the Soviet Union - 2017
Hero of the Soviet Union - 2017
Posts: 3151
Joined: Sat Nov 29, 2014 9:45 pm
Location: Upstate NY

Re: Carb won't stay seated

Postby Snakeoil » Tue Mar 15, 2016 10:27 am

Take the carb off, put your hand over the compliance fitting and have someone hit the starter button. If you have a valve leaking compression you will feel it trying to push your hand off the compliance fitting.

Easy-peasy.
Regards,
Rob
2000 Ural Tourist
Before you say something stupid, always ask yourself, "What would Harpo say?".

User avatar
Lokiboy
Order of Suvarov
Order of Suvarov
Posts: 2921
Joined: Fri Apr 29, 2011 9:58 pm

Re: Carb won't stay seated

Postby Lokiboy » Tue Mar 15, 2016 10:39 am

Raceway sells a "perch ring" I think it's called - extends the ring on the carb to allow the compliance fitting more area to snug against. I bought one and it does the job beautifully
2011 Gear Up - "Erika"
Yorktown, VA

Mains: 127, Idle: 40, Needle: 1 shim
MKIII air filter
70,000 km and counting


Return to “General Hammerin' and Wrenchin' (all model years)”

Who is online

Users browsing this forum: No registered users and 9 guests