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Staggering / dieseling #697848
06/08/17 2:42 pm
06/08/17 2:42 pm
Joined: Aug 2001
Posts: 223
Westfield, Indiana, USA
Geoff Offline OP
BritBike Forum member
Geoff  Offline OP
BritBike Forum member
Joined: Aug 2001
Posts: 223
Westfield, Indiana, USA
Hello all - looking for a confirmation / help on my troubleshooting on what I think is my problem. Reassembled my top end after fixing push road tube leaks. Bike started but had hesitation at low throttle openings (test ride ~ 5 miles). Went back, fiddled with the carbs and that seemed to do the trick on low throttle openings, but the hesitation moved (another ~5 mile test). I figured I was chasing a carb setting problem, adjusted the needle up for more fuel, took out the bike and could not get more than a tenth of a mile from my house without the bike trying to throw me like kicking mule due to the stuttering. Ended up in my driveway dieseling as I turned it off via kill switch.

Timing is still set on where its been since I don't know when (probably mid 90's - running a Boyer). Amals are worn out, however that is all I know and am used to it smile - I no longer think there is problem there (plugs are showing black to brown) of this magnitude. Checked tappets last nice, very bad (only right inlet was within spec, the rest had no clearance). The four outside head bolts were barely tight (more than finger, less than requiring effort). Prior problem I had years ago was the pigtail from the EI pickup coils coming loose at the connection to the wiring harness. That was a bit different as the bike would backfire alot.

Obviously I have to retorque the head, and reset the valve clearances. Anything else I am missing or is that it? (Besides getting rid of the composite cylinder head gasket and going back to copper!)

Thanks!
Geoff


'78 T140V
'74 Commando
'71 A65L - Cafe in progress now almost 20 years!
'69 TR6R
'58 Allstate (Puch) 175
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Re: Staggering / dieseling [Re: Geoff] #697852
06/08/17 4:19 pm
06/08/17 4:19 pm
Joined: Oct 2003
Posts: 3,579
Emsworth, sunny south of Engla...
D
dave jones Offline
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dave jones  Offline
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D
Joined: Oct 2003
Posts: 3,579
Emsworth, sunny south of Engla...
When I had a worn out carb on my 650 1967 it suffered similar symptoms. I could either set it to idle well and then have it 8 stroking down the road (miles too rich) or set it for the road and have the idle bad. When set for the road on coming to a standstill the idle would gradually slow down, become more and more erratic, peter right out and the engine would stop. I had the carb repaired rather than buying a new one as it was considerably cheaper. They bored it out and put a sleeve on the slide. After this it was perfect with the old standard settings from the handbook. A lot of riding is done on the idle jet and it is good to set this as weak as possible without spitting back through the carb or you use a lot of fuel.

Running on after switching off the ignition is normally a sign of very over rich running causing carbon build up. When I first got my bike it had a drilled out main jet for running on alcohol for racing. The previous owner had slung the bike together without checking anything. If not carbon, very bad overheating of the spark plugs or some other metal in the combustion chamber causes a similar thing. A lot of carbon can also be caused by retarded ignition. Also, in this case, case the exhaust downpipes will turn blue and in the dark they will glow red hot. Always best to get the ignition right before carb fiddling.

Talking of carb fiddling the Amals (in good condition) are so simple that if the bike doesn't run right on the standard settings there is some fundamental problem elsewhere.

Regarding torquing the head bolts- on mine it was the four large inner bolts that needed resetting due to settling of the rocker gaskets.

Re: Staggering / dieseling [Re: dave jones] #697863
06/08/17 8:33 pm
06/08/17 8:33 pm
Joined: Aug 2001
Posts: 223
Westfield, Indiana, USA
Geoff Offline OP
BritBike Forum member
Geoff  Offline OP
BritBike Forum member
Joined: Aug 2001
Posts: 223
Westfield, Indiana, USA
Ok - Back to AMAL fiddling then (I did refresh the gaskets and such during this process). This might just set me down the path of new Amals smile.


'78 T140V
'74 Commando
'71 A65L - Cafe in progress now almost 20 years!
'69 TR6R
'58 Allstate (Puch) 175
Re: Staggering / dieseling [Re: Geoff] #697882
06/09/17 1:07 am
06/09/17 1:07 am
Joined: Dec 2006
Posts: 3,895
Massachusetts, U.S.A.
B
btour Offline
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btour  Offline
BritBike Forum member
B
Joined: Dec 2006
Posts: 3,895
Massachusetts, U.S.A.
What is it?


Bob, Lifetime bike: '71 T120R, bought in '71 at Ken Heanes, England.
Re: Staggering / dieseling [Re: Geoff] #697894
06/09/17 2:32 am
06/09/17 2:32 am
Joined: Sep 2001
Posts: 405
Great Southern Land
tridentt150v Offline
BritBike Forum member
tridentt150v  Offline
BritBike Forum member
Joined: Sep 2001
Posts: 405
Great Southern Land
Dieseling can mean you are getting fuel into the exhaust stroke. Boyers use wasted spark, so it would be igniting the fuel coming around your worn out carbies.

Re: Staggering / dieseling [Re: Geoff] #697899
06/09/17 3:34 am
06/09/17 3:34 am
Joined: Nov 2008
Posts: 2,767
Bishop, Calif.
D
desco Offline
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desco  Offline
BritBike Forum member
D
Joined: Nov 2008
Posts: 2,767
Bishop, Calif.
New needles and jets might be a worthwhile investment.


1968 T120R
1972 T120RV
Any advice given is without a warranty expressed or implied.
Re: Staggering / dieseling [Re: Geoff] #697907
06/09/17 7:59 am
06/09/17 7:59 am
Joined: Oct 2003
Posts: 3,579
Emsworth, sunny south of Engla...
D
dave jones Offline
BritBike Forum member
dave jones  Offline
BritBike Forum member
D
Joined: Oct 2003
Posts: 3,579
Emsworth, sunny south of Engla...
Just to clarify a point in my post. I mentioned my bike had a massive main jet when I first got it. This was just to say that you should check that the parts in the carb are correct. My idle and road running woes were still there when I had fitted the correct jet. The main jet doesn't really have much to do with low speed running although there must be some crossover because with the giant main jet if I blipped the throttle black smoke came out the exhaust. Mind you the hole in this jet was literally double the size of a 330.

Re: Staggering / dieseling [Re: btour] #697972
06/09/17 6:42 pm
06/09/17 6:42 pm
Joined: Aug 2001
Posts: 223
Westfield, Indiana, USA
Geoff Offline OP
BritBike Forum member
Geoff  Offline OP
BritBike Forum member
Joined: Aug 2001
Posts: 223
Westfield, Indiana, USA
Early 78 Bonneville


'78 T140V
'74 Commando
'71 A65L - Cafe in progress now almost 20 years!
'69 TR6R
'58 Allstate (Puch) 175
Re: Staggering / dieseling [Re: Geoff] #699022
06/19/17 1:28 pm
06/19/17 1:28 pm
Joined: Aug 2001
Posts: 223
Westfield, Indiana, USA
Geoff Offline OP
BritBike Forum member
Geoff  Offline OP
BritBike Forum member
Joined: Aug 2001
Posts: 223
Westfield, Indiana, USA
Just dropping a line to give an update. I retorqued the head (amazing how loose it had become after a heat cycle) and readjusted the valves (for some reason they became really tight) yesterday. Took it out for a quick high speed test - and it sort of passed. I still have this annoying cutout that happens at high speed (around 60 - 70 mph). The cutout made me return to the stable a little early.

Ugh.


'78 T140V
'74 Commando
'71 A65L - Cafe in progress now almost 20 years!
'69 TR6R
'58 Allstate (Puch) 175
Re: Staggering / dieseling [Re: Geoff] #699024
06/19/17 1:36 pm
06/19/17 1:36 pm
Joined: Aug 2005
Posts: 1,318
melbourne florida
B
bodine031 Offline
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bodine031  Offline
BritBike Forum member
B
Joined: Aug 2005
Posts: 1,318
melbourne florida
Retorque = head sucked down pushrods loose clearance = tite valves
Other sounds like fuel jetting issue good luck

Re: Staggering / dieseling [Re: Geoff] #699475
06/24/17 1:50 am
06/24/17 1:50 am
Joined: Aug 2001
Posts: 76
Central Ohio
P
PFribley Offline
BritBike Forum member
PFribley  Offline
BritBike Forum member
P
Joined: Aug 2001
Posts: 76
Central Ohio
Air leak!!

Re: Staggering / dieseling [Re: Geoff] #699479
06/24/17 4:03 am
06/24/17 4:03 am
Joined: May 2007
Posts: 1,944
Christchurch NZ
R Moulding Offline
BritBike Forum member
R Moulding  Offline
BritBike Forum member
Joined: May 2007
Posts: 1,944
Christchurch NZ

You need to confirm the throttle position at which this cutting out takes place, so mark the throttle. If it occurs after 3/4 throttle then try going for a ride without the main jets fitted. If the cutting out remains the same chances are what you are experiencing is eight stroking. Try fitting main jets 2 sizes smaller.

Rod


So remember, when you're feeling very small and insecure,
How amazingly unlikely is your birth;
And pray that there's intelligent life somewhere out in space,
'Cause there's bugger all down here on Earth!
Re: Staggering / dieseling [Re: Geoff] #699496
06/24/17 1:31 pm
06/24/17 1:31 pm
Joined: Oct 2003
Posts: 11,180
North Georgia, USA
RF Whatley Online content
BritBike Forum member
RF Whatley  Online Content
BritBike Forum member
Joined: Oct 2003
Posts: 11,180
North Georgia, USA
► First of all you haven't told us if this problem existed before your work began.

► Secondly, you haven't told us very important information like: Were the carbs removed from the head during your work ? Was ALL your work completed going by the Parts Manual ? Did you pull the carb slides out of the carb bodies to do this work ? And if so, did you experience any hesitation for the slide to go back into the carb body on re-assembly ? Did you replace the intake manifold balance tube ? Do you have Concentric or Mark II carbs ? Did you replace the spark plugs or reuse ? What spark plug are you using ? Did you pull the cylinder or just the cyl head ?

► You can't do any carb testing or jetting until you verify that you have everything else spot on. That means proper spark plugs, plug wires in good condition, timing set with a strobe lamp at 5000 RPM, Boyer properly installed, valve clearances adjusted, etc, etc.

bigt


Don't hide 'em, Ride 'em !!

RF Whatley
Cornelia, GA

"Shop Boy" at Rodi British Bikes

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