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Spark-check...Compression-check...Fuel-oh Yes...no ignition on #3/4

Fire in all four pots!

Fire in all four pots!

...and the drum roll please.

Exhaust back on, but not fully sealed against the head (darn you broken bolts; not by me been that way for at least a couple of POs) at the moment. It will be a winter project to get those bolts out.

I have combustion on all four cylinders again, and pretty decent readings on the vacuum synch to start. I'm going to assume that raising the float height has helped the situation, because nothing else I have done specifically targets the #3/4 cylinders. They are still running colder than 1/2, but for now I'm just going to revel in their mysterious reappearance.

Maybe I have a :twistedevil: in the garage. After all...

HAPPY HALLOWEEN! :eek:
 
Hooray for progress! Maybe it just craved your attention- or was intimidated by your carb removal threats.
 
Did replacement of the float needle or careful inspection of the seat on 3 & 4 happen? Just a random thought.
 
Carter Turk said:
Did replacement of the float needle or careful inspection of the seat on 3 & 4 happen? Just a random thought.
Click to expand...
I had a quick look at the seats when I was in there and blew a bit of compressed air around them but I didn't see anything fly out. I had a really close look at the needles and seats when I cleaned the carbs in the summer and nothing looked awry compared to the ones in #s 1 and 2. If I do have to pull the carbs yet again, I'll take some good high resolution photographs to see if I've missed anything.

Tom...don't let my girlfriend hear you say that. I've spent far too much time with the motorcycle this past week, and she's the one craving attention (..as he veers into Off-Topic Forum)
 
BigD_83 said:
Tom...don't let my girlfriend hear you say that. I've spent far too much time with the motorcycle this past week, and she's the one craving attention (..as he veers into Off-Topic Forum)
Click to expand...
Get her involved! maybe she could remove those broken exhaust bolts for you. Remember, no EZ outs, no screw extractors- get some quality left hand drill bits and a decent penetrant, along with patience.
 
EZ outs and header bolts

EZ outs and header bolts

She, um...doesn't like getting greasy, and HER bike is pretty much all taken care of for the moment. I'm probably going the welding route to build up a bead and get a nut on the end to help turn those out. It looks like someone may have already snapped an ez out off in one of the bolts :mad:
 
NEW info regarding idle jets...

NEW info regarding idle jets...

Carter Turk...

in a fit of frustration at the bike firing up but then flooding #s 3/4, I pulled the carbs off the bike yet again, and had a real close look at the differences between the setup of 1/2 and 3/4.

Summary:

Float levels were all the same but my gauge was off, reading closer to 19.4 mm rather than 22.4mm. I reset them all to 22.4mm

The needles and seats all looked fine with no apparent damage to #3/4 and no debris at the seats

All passages were free to air movement

The slides lifted with air pressure

Here's the NEW INFORMATION

While blowing air through the carb, I managed to blow out the rubber plugs over the pilot jets, and along with them the pilot jets from #3/4 carbs. Do you think this might have contributed to too much fuel being dumped into the cylinders? :o

They either backed themselves off, or more likely, I never tightened them down properly. I checked #1/2 and they were tight, so as far as I could tell that was the only difference.

Got them all back together, resynched, in the bike, and fired it up again. Couldn't run it for long as I was getting a racing throttle due to (I think) binding throttle cable; I definitely have all four cylinders firing, and the plugs are staying dry. A little popping and backfiring from #s 3/4, but I'll take that at this point as I still have a bit of an exhaust leak at the joint where #3 header goes into the muffler receiver. At least I have a better starting point

Time for highest idle and another vacuum synch...:pray:


 
now it stumbles off idle...

now it stumbles off idle...

Fixed binding throttle and set highest idle done and settling in around 2 turns. No time for plug chops but the plugs were fairly sooty running at idle. Tightened up the joints so there was less leaking at the receivers.

Vacuum synch not perfect, but all within 1 of each other (Morgan Carbtune). Note that the pipes are 4 into 2 with no cross-over/collector.

Here's the strange part:

it was running well with the tank off the bike (on PRIME, inline fuel filter installed), with no hesitations anywhere, but as soon as I started running the engine with the tank in place (petcock ON, inline fuel filter removed), it would stumble and die as the rpms hit about 2000-2500rpm. I thought it was due to the vacuum line being disconnected starving the engine of fuel, but hooking it back up hasn't fully rectified the situation. It will go through that rpm, but I really have to goose it. Feathering the throttle kills the engine.

FYI: I have previously tested for it, and the petcock does not leak in the ON position

I am going to switch it over to PRIME to see if it helps, and I think that is the next logical step.

Any thoughts?
 
There's a itty bitty vent hole in the filler neck of the tank, make sure it isn't plugged as it will create vacuum inside the tank and not allow fuel to flow as easily as it should.
 
sedelen said:
There's a itty bitty vent hole in the filler neck of the tank, make sure it isn't plugged as it will create vacuum inside the tank and not allow fuel to flow as easily as it should.
Click to expand...
Thanks, wouldn't that also affect the fuel flow on PRIME?
 
BigD_83 said:
Thanks, wouldn't that also affect the fuel flow on PRIME?
Click to expand...

That's a definite maybe! I certainly believe it would, don't really know to what degree that vent hole relieves pressure and vacuum to the tank.
A tight fitting gas cap with a good seal and plugged vent (within the gas cap) will also create problems.
I guess you could disconnect your gas line to the petcock, place another hose on it to a gas can and put it in prime and see it it flows steadily for awhile with the gas cap on.
You don't have any in-line filters in your gas line do you? Those can be restrictive.
 
Hey Steve,

I get what you are saying, but the reason I was asking about flow and venting in PRIME is that the bike was running just fine with the tank off the bike and set on PRIME.

To clarify, I was using the tank like an auxiliary, with it set on the bench and the petcock on PRIME, with an inline filter just before the carbs, and the vacuum line plugged. Now that the tank is back on the frame, I've removed the inline filter, reconnected the vacuum line and set the petcock to ON.

Then the stumbling began.

I'll have to have a go at it tonight, but the bike will continue to run at idle indefinitely (well, as long as I had patience to run it) so it's not acting like it is fuel starved at idle. Maybe I should put a temporary clear line on to see if there is something funny happening as I roll the throttle on? It could be that I don't have ADEQUATE flow for that initial acceleration.

First things first. I'll try it on PRIME when I get home tonight to see if that helps.

Oh yeah, and more reading about off-idle stumbling during breaks in my day.
 
What type of petcock do you have a 3 position vacuum operated one, or the other?
You do have adequate fuel in the tank?
Have you seen your petcock filter? outside of filter element could be coated with something that might be restricting fuel.
I know I'm grasping at straws here, but you just never know.
 
Yeah, try running it in Prime and see it flounders, then switch it to on and see if there's any difference.
 
petcock issues causing stumble?

petcock issues causing stumble?

sedelen said:
What type of petcock do you have a 3 position vacuum operated one, or the other?
You do have adequate fuel in the tank?
Have you seen your petcock filter? outside of filter element could be coated with something that might be restricting fuel.
I know I'm grasping at straws here, but you just never know.
Click to expand...
Three position; OEM from the looks of it.

I've had it apart once b/c turning it was like pulling Excalibur out of that rock, and it was clean, but there was definitely bits and pieces of fuel varnish scraping around the bottom of the tank. The petcock opens and closes under vacuum, at least with the amount of suction I could create manually.

The filter element is picking up a little bit of rust. I cleaned the tank b/c there was some rust on the fuel gauge float arm and up around the top inside of the tank, and I didn't do the best job of mitigating new rust as I didn't have fresh gas on hand to fill it.

This latest round of testing started with a full tank, and the gauge says I'm around 1/4 (it was dumping raw fuel through to the muffler earlier). The dip test (I'm the dip :o) says that it is a little more than 1/4 full.

Question about that filter element: When I cleaned the tank I was able to remove it and put it back. The petcock froze up on me again and when I pulled it out, I wasn't able to remove the filter element. Should I have been able to do it the first time around or are they supposed to be epoxied in place?

Don't worry about throwing out desperate suggestions...I never would have thought something was amiss with those pilot jets b/c i was POSITIVE I had tightened them down. It's easy to overlook something simple.
 
It doesn't take much suction power to get fuel to flow nicely in on or res spot- less than sipping a drink up a straw- you might have a problem petcock, so just try it in prime spot. I bet the petcock filter was meant to stay fixed, since you wouldn't want it to wander off after a fillup. A liitle rust in tank shouldn't be a problem- mine is not perfect.
How does this thing cold start? mine needs full " choke", starts instantly, but rpms fluctuate wildly for 15 seconds or so, till it calms down and I back off choke to 1/4 spot.
 
Tank sound pretty good.
Petcock fuel filters coming off? not a big deal in my book as there's a piece
of the gasket (at least on my rubber O ring gasket, some don't have this flat piece which joins the two sides of the O ring) that keeps the pluggable (easily detaching) filter in place.
Also I have a petcock that I'be been unable to remove the filter.
If my petcock lever sticks I just spray around the lever with WD-40, there's a rubber seal behind that selector lever that will dry out on you and make it harder to turn.
 
Tom...

Startup is beautiful. After priming, with full choke it just takes a whisper on the starter button and it fires right up.

At the moment it revs up a little too high, I shut it down before it hits 5000rpm and I have to modulate the rpm with the choke. After about 15-30sec I can shut it off and it'll idle happily around 1200-1500 rpm
 
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