1980 Liquifire engine problems

[hounds84lhs]

Having some problems getting my LF started and running after an engine rebuild. See below for what we have tried so far.

Completely went through engine, disassembled, cleaned, new crank seals, gaskets, Pistons were cleaned, bores were cleaned. Carbs were disassembled and cleaned. All passages were checked, floats were checked. Air bleed screw setting are back to factory (1 ½ turns out from bottomed out), Set slide adjustment to WOT with the bottom of the slide at full opening on the engine side of carb. New fuel pump was installed. Fuel tank was also flushed and a filter was installed before the pump. Timing was set to factory baseline. Stator was put at the split line of the lower end. Compression was checked after assembly. 120+ in both cylinders. Fuel is getting to the carbs. Fighting possibly two issues. Wiring on machine is questionable, and engine fires and run, but not real good/consistent. Engine will fire at times, but not all the time, if it runs, it is not consistent, meaning it will fire at idle, but won’t stay running or accelerate. Will also fire at WOT, but wont run for more than 10-20 sec, and then die. When it does run, acceleration is poor, if throttle is left off, it will not respond to any change in throttle and fade out and then die. Have tried different CDI box, multiple coils, new plugs, went back through carbs and found nothing. Plugs usually come out dry/light wetting after a bunch of pulling (20-30 pulls with only a few pops and an occasional 1-2 cycle run by engine). At this point we are only running on the main engine wiring, complete unit harness is disconnected (see possible 2nd issue below) While pulling can see wetting around the exhaust pipe to muffler connection. Smokes when it is running indicating it could be flooded, but with dry/lightly wetted plugs, or a new set of plugs installed with no change, it doesn’t correlate.

Wiring side. Lots of splicing done in past life. Tried to clean up connections as best as possible. Throttle switch was removed cleaned and in working order. Three way switch for kill was also checked and is working properly. Key was bad, so I jumped with a wire to close circuit (simulating key was in ON position) Wondering if the rev limiter could be a problem. Tried to see if it could be bypassed or if at all possible checked (other than what the service manual stated) The Only way sled will fire or run is with the main harness connector removed. Only powering CDI and Coil.

[JDT]

I am thinking pluged exhaust.

[JDT]

As far as your wiring issue goes if you jumpered the two wires on the key switch you have turned the engine off.
This is an open ignition system. Remove your jumper and you will have spark.

[harleysportster]

To eliminate the rev-limiter, just unplug the wires going to the handle-bar control for it behind the throttle lever.

[hounds84lhs]

Exhaust smoke is coming out of the exhaust.

I was reading some of the other posts on 80-81 Liquifires. Is there an upgrade to the carbs that lead to easier starting?

[That Girl Racing]

Still sounds like a carb issue. Did you get the pilot jet circuit and jets cleaned? Regardless of which variation of factory carb settings you have in it , the motor should start easy and run.

[JoeRainville]

Agree with Peter, but I would also pull the jumper harness that goes to the RPM limiter and plug the chassis harness right into the motor. The only other issued I can think of that has similar issues was having a crank with slipped timing. It's easy to check by marking the clutch and finding TDC on both jugs.

Good luck getting your sled figured out. They can be a little finicky.

-Joe

[flacker36]

I noticed you said you set the carb slides to WOT so that no part of the slide obstructs the throat on the "ENGINE SIDE". The throttle slide should be adjusted so that it is flush with the throat on the "AIR BOX" side not the engine side of carb. The manual shows using a finger to feel for the slide - with the needle installed there is no way to feel the engine side of the slide.

[harleysportster]

I noticed you said you set the carb slides to WOT so that no part of the slide obstructs the throat on the "ENGINE SIDE". The throttle slide should be adjusted so that it is flush with the throat on the "AIR BOX" side not the engine side of carb. The manual shows using a finger to feel for the slide - with the needle installed there is no way to feel the engine side of the slide.

flaker, not to disagree but if you set the throttle slides as you stated at WOT they are not open completely. The best way to confirm that the back-side(engine side) of the throttle slide is flush is with a small mirror and light. Hold the throttle lever against the handle bar with a rubber band. Use a light / mirror and lock inside the carb with the airbox removed. adjust the cable on each carb accordingly. Remove the rubber band.

[hounds84lhs]

Thanks for all the advice.

Have a Merry Christmas.

[hounds84lhs]

Okay, we tried some of the suggestions and still could not get the sled to run. We did a low pressure test by blocking off the intake and exhaust ports on both cylinders. The pressure went from one cylinder and escaped to the other. Does this mean the center seal on the crank is bad? I am guessing if so, the crank will have to be taken apart, center seal replaced and pressed back together? Any other ideas why pressure would be leaking from one cylinder to the other?

[harleysportster]

Okay, we tried some of the suggestions and still could not get the sled to run. We did a low pressure test by blocking off the intake and exhaust ports on both cylinders. The pressure went from one cylinder and escaped to the other. Does this mean the center seal on the crank is bad? I am guessing if so, the crank will have to be taken apart, center seal replaced and pressed back together? Any other ideas why pressure would be leaking from one cylinder to the other?

What you are experiencing is normal for the 80 and up Liquifires. The center seal is a labryth type which seals when the engine is running with the oil injection supplying oil to the seal. Seal both sides at the same time ans see what you get.

[Lake City Machines]

I recently rebuilt a 1983 Sportfire and had similar problems. turned out that I had torn one of the intake manifold gasket on one side. It was sucking air but the plug looked rich and was not firing unless mid to full throttle. It would only idle a short time and then die, and was hard to start. A pressure test of the crankcase and using some liquid soap/water solution on the seals, crankcase and manifolds will tell you a lot, a few latex gloves pulled tight and rubber bands/hose clamps to seal the manifolds work to seal before the test.

[hounds84lhs]

So if I have the correct oil pressure on the injector lines I should have a good seal between the two cylinders, correct?

[harleysportster]

Yes, if the new oil injection is working, the center seal should be fine. Did the engine run before you did all the work to it.