Trouble starting new engine

[Augie]

I purchased a 277 rephased long rod 650 engine that is freshly built. Running a PMA, Pamco, mechanical advance, green monster coils, kick start. Trying to get it fired up for the first time and am having trouble. I have the pamco wired to a good battery, fresh gas in clean carbs fed by an auxliary fuel tank, no vaccume petcocks. I have my timing set correctly (ball park anyway) to the best of my knowledge, according to Hughs guide on installing the Pamco. The bike will fire on both cylinders only when I have the throttle about half way opened, but not consistently. Usually I get one or two bangs but nothing more than that. Any ideas? Thanks

 

[retiredgentleman]

Your carb fuel/air mixture must be way off for starting. You don't say what carbs you have. If you have Mikuni carbs, have you checked to be sure the small jet, in the bottom of the float bowl, is totally clear. That is the source of fuel, that the choke system uses to enrich the fuel/air ratio. The throttle should be left closed, so that the mixture is very rich, maybe 3/1.

 

[Augie]

Sorry I left that out, I have BS 38's. Just pulled the carbs off for a look and one of the jets was plugged up. Both are cleared out now. Also reset the mixture screws and still no luck. Thought I'd mention that the exhaust pipes have no mufflers on them and I have the Uni filters off the carbs while doing all this. No change in the bikes behavior.

 

[retiredgentleman]

It does not matter , if you have open exhausts and no carb filters, as far as the initial start of the engine. That will become a big factor when you want to drive down the road at the higher rpms.
I'd say your timing for the rephased engine is not correct. Need to re-check the timing very carefully.

 

[gggGary]

Compression tested? Plugs wet or dry? Heresy maybe; but I'd give it a shot of ether or raw gas in both sides, that will pretty well nail down whether the issue is carbs or ignition...... If ignition is right It'll run a second or 2 even with the carbs sitting on the bench.

 

[Augie]

Thanks for the replies guys. Checked out the Pamco tonight and discovered I had the rotor set to the wrong notch on the back side. The magnets line up with the pick ups when the according cylinder is right at or near TDC. The engine definitely gave good feedback to that. Didn't gain any number of fires, but they sound as they should now. The ones before sounded non rhythmic and random.

Timing is good. Spark is good. I definitely have compression.. Tried pouring some gas into the cylinders, not sure if I over did it or what, but it didn't fire for about 6 or 7 kicks after that, more than enough I'd think to clear it out. Tried starting fluid with the carbs off straight into the intake runners, left my ears ringing but I definitely heard two loud bangs. Pulled the carbs to check out the small jet again, they are definitely clear. Soaking the bowls in carb cleaner tonight just to be sure. I'm beginning to wonder if it's just too cold for it to start, by the time I get home and to messing with the bike its just below 40 degrees F.

 

[retiredgentleman]

40 degrees F is no problem at all to start an engine. Perhaps you need to remove the plugs and dry them out (propane torch). Are the plugs in good condition and gapped correctly?

 

[Augie]

Plugs are brand new Autolite 63's. Will pull and dry them tomorrow, also will check on the gap, what's recommended?

 

[650Skull]

AHHHH manual.

 

[fredintoon]

Plugs are brand new Autolite 63's. Will pull and dry them tomorrow, also will check on the gap, what's recommended?

Hi Augie,
Like they say, look it up. But it ain't critical. A plug gap you can shove your thumbnail in will work good enough to start and run.
And your first post said "clean carbs" Did YOU clean them or did someone tell you they were clean?

 

[Augie]

AHHHH manual.

I should've known that was coming lol. Will do.

Did YOU clean them or did someone tell you they were clean?

I cleaned them myself, but am no prefessional. When I've cleaned them I always make sure that carb cleaner comes through every orfice.

 

[gggGary]

Sure sounds like you aren't there on timing yet. If you can snag a buddy, with the plugs out you should be able to kick and run a timing light long enough to get the timing right. One of those times where an electric leg would be useful. Like above a reasonably healthy engine will fire and run smoothly for a second or two on raw gas OR starter fluid, no carbs needed. Bet I'm not the only one here that's kept a V8 runnning for a while by nursing gas from an oil bottle into the throat. I seem to recall an adventure where we moved a truck a few blocks, one guy with his head out the window the other sitting in the engine bay dribbling in gas. I for SURE remember yelling: Crank it NOW, suck the fire in! more than once.

 

[fredintoon]

I should've known that was coming lol. Will do.
I cleaned them myself, but am no prefessional. When I've cleaned them I always make sure that carb cleaner comes through every orfice.

Hi Augie,
it seems you are building the bike from a pile of parts? If so, what carbs are they?
Is it possible that the carbs were fitted with EPA-mandated seals over their slow running needles and that those seals are still in place?
If so, the slow-running & enrichment passages that are essential to starting will have never been cleaned since the carbs were first assembled.

 

[mrtwowheel]

I've gotten more than a few small engines to fire and run by removing a sparkplug, dripping in about 3 drops of gas, replace the spark plug quickly and start the engine, works better for me than starting fluid.

Scott

 

[Augie]

Got the engine to start, it runs great. Thank you all for your suggestions. It ended up being an issue with the ignition system. But now thats sorted out, theres one weird thing though. When the bike is running, the tdc Mark is way off from tdc. When I adjust the timing on the ignition (pamco Pete digital) it can't rotate far enough to bring the timing mark to where it should be. Or at least close to it. I have no 15 degree mark yet, need to get a degree wheel. I think a part of the problem might be that on the mechanical advance side my alignment mark for the rod and backing plate are 180 degrees off. The reason they are is that when they are the way they're supposed to be (aligned) the bike WILL NOT start even after trying to adjust timing a tiny bit at a time in both directions. I flipped the rod 180, the bike fired right up. I'm almost wondering if the mechanical timing is off, but then again when the bike is at tdc on the left cylinder, the timing mark is spot on at tdc on the cover. Thoughts?