Not a good shakedown...

Took my bike out for a good shakedown after some of the niggling problems I've been having.

About an hour into the ride and 45 miles from home, the bike seemed to be missing occasionally under power (about 60 mph in 3rd). Still responded well with a good handful of throttle, but I decided to turn around and head back home. When I pulled the clutch in the engine died. I put it in second and attempted to roll start it, thinking the plugs had fouled. It backfired as the bike slowed to a halt on the side of the road and would not restart.

The guy who lived across the street was pretty cool and gave me a few beers while I waited for my pickup. Got the bike home, still thinking the plugs were fouled.

Pulled the left plug and it was pretty sooty. I had a valve guide seal come loose on that side awhile ago and I wonder if it isn't loose again. The right side was nice and tan though, which I thought was strange as I've started and idled the bike on one cylinder plenty of times while carb balancing.

Checked the battery voltage and that was good, with minimal drop when loading it with the lights and ignition.

Tried another kickstart in my garage just for kicks before hitting the sack for the night. Bike backfired (it almost *never* does that). Gave it one more kick for good measure and same result but slightly more violent with smoke coming out the air filter. Sparx Ignition FWIW.

So where do I go from here? I have done quite a bit of fiddling with the carbs since the last good run, and though I have had several short trips, this has been the last serious run (over 30 mins) since then. Seems weird that the ignition/timing would have gummed up all of the sudden in close sequence after that, making me wonder if a needle hasn't dropped or something...

Cheers,

- HJ

Check at night tugging and tapping on wires and connections. If Sprax ignition fires on make/break leave it on with a plug or two out on head. Check wire to tail-brake light too. Coil can do this but still run on the good side. Kill button always a suspect.

May have to change sooty plug now too if too fouled to spark.

Check carb for air leaks, bolts/gasket, balance tube.

I have many shakedown runs in my future and I expect problems, mostly wiring, which is why over the winter I'll redo as many of the connections as I can.

I found a really old thread from you, but never much followup on the build. I was going to try to see what all you had done.

It may be carb-related but so many carb problems turn out to be ignition-related, so start there — apart from checking the obvious things like if a needle has dropped out of its circlip groove. Check if it misbehaves with brand new plugs and kick it over with the plugs out to check if there's a good spark. Your battery voltage may be adequate, but the earth ('ground' in your money) connections for your ignition system may be poor / intermittent. You don't mention the ignition system you're running. If it's the old Boyer, the wires from the little stator coils inside the points cover tend to fracture inside their insulation due to vibration and should be checked for continuity with an ohm meter. Check also while wiggling these wires.

Ahhh, don't I love my points. Do you have a set around just to replace and see if that's the problem? Does sound like a carby problem though. So many issues, could be anything, just have to go through them one at a time unless you like the scattergun approach, but then you never know what it was.

Dave
69S

Start by cleaning up your ground point(s) to frame. Work back to battery. yes check wires at pickup plate too. Had a fuseholder give me this grief once. Use oxyguard paste to cleaned up connections . Good luck.

Had a glass fuse go bad internal connections but looked fine otherwise. Ugh.

Boyer factory trigger wires must be replaced even if still intact right now, they for sure will not be too soon enough. Greg Faulth has the upgrade kit and follow its nut instructions not what looks more secure or spend a day and night like me getting nothing but backfires and super advanced timing because double back nuts clipped the pick up posts, just.

Had one event bike would only run with good-too much throttle. Took days of crazy making till noticed a carb bolt gone and gasket hanging out. Hi throttle sucked it tight = till let off stalls.

Had another heading out of shed across grass, misfiring on and off till died. Hunted and hunted till noticed brake light dim and wire hot, shorted V's to Boyer. Fault was in the tail light ground connection once and pinched from brake peddle area another time.

For best ease of throttle response and starting w/o trying to total max out riding I prefer points and dual Amals now. Condensors can be a show stopper out the blue here too.

Hi,
just to let you know I had a sparx ignition and not just 1. Same symptoms as you describe. Because my bike was still under warranty from a rebuild I had done the trigger was replaced 2 times same defect and not only that it failed the 3rd time and I said to the builder no way I can't do it a 3rd time. I mean this was at no cost to me the builder was great however the sparx unit wasn't working I wanted of course something that would work I had a rita for 15 years prior to rebuild I was going to go back to that but I went with pazon instead and thats about 3-4 years ago and no problems since. That sparx unit was a nightmare and just gave out no warning. I had each unit about a week to 10 days of driving maybe 500 miles then it would fail. I even took the bike back to the builder after the 2nd failure and had him install the unit just incase I did something wrong during my install but as I stated the unit failed a 3rd time the exact same cause the trigger{Heat} so the builder said ok and paid for a pazon I installed it and no problems. I have a 69 750 my ign is on the left side of bike not right side, not knowing if your familar with that model but maybe that had something to do with the failures the trigger couldn't handle the heat. However I did notice shortly there after that the builder no longer used the sparx ign on his rebuilds. The builders name Matt Rambow and don't get me wrong he was great for service replaced the unit each time no problems with any of that we just both agreed I said I can get a pazon local and thats what I did no complaints. I guess this is a long story to let you know I think the sparx unit is unreliable and I had 3 fail.. hope you sort it out soon
Doxford

swooshdave said:

I found a really old thread from you, but never much followup on the build. I was going to try to see what all you had done.

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Alot of messing around with the Amals (been apart several times and installed chrome slides), as well as replacing a broken spring and valve seal on an intake valve. Everything else has been pretty minor overall, just regular shakedown stuff like tightening up things that vibrate loose and using up several tubes of loctite in the process. It's mainly annoying because everytime I *finally* think things are dialed in something like this strikes 60 miles down the road. But for those 60 miles to that point she is so sweet that everything is forgiven...

Anyways I'm really hoping it is something like a dropped needle as I'm thoroughly proficient at stripping apart the Amals by now. I was just in there this past weekend so it wouldn't surprise me.

I don't want to start a thread war, but is there a good iridium plug that I can use to mask my fouling cylinder while I fix this issue? Right now running NGK BPR7ES and having a hard time figuring out the iridium equivalent.

Cheers,

- HJ

Yes the fine point iridium or similar solved my 1st week of Combat ownership from fouling plugs to stall in 20 miles. Run like bat out of hell after wards as avatar attests. Don't have the numbers at hand right now.

And the fouling is due to unburnt petrol and not oil?

A few spare 7s or even 6s might be cheaper than one iridium till you get to the bottom of this. I have 5s in my Johnson 20 horse 2-stroke that runs on a 20:1 petroil mix and they will fire when the plugs are cold and oily. Old bevel Ducatis with those accelerator pump Dell' Ortos run 6s to prevent fouling in town due to the gobs of petrol injected into the inlet tracts on acceleration.

Checked your plug leads and plug caps?

daveh said:

And the fouling is due to unburnt petrol and not oil?

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I suspect oil...

Took a gander tonight. Note: I know nothing about how timing is set or how to properly set it... (although I suspect my ignorance may not last long)

Accessing the throttles from the throats, the slides are in good shape. I can just barely squeeze the needles with two fingers and they seem firmly affixed. In any case they both move up and down as normal with the slides. I suppose I'll have to taken them out to be sure they are still properly set in the clips though. Everything else on carbs looks good from external inspection (no visibly loose bolts, etc.).

No signs of loose wires on the plugs or coils. Looking at the Sparx under the inspection cap everything seems normal.

Took off the primary cover because my garage floor needed oiling. Nothing seems abnormal there to my (rather untrained) eye. Shot of battery charge lead is the wire in the foreground.

Photos of the plugs below so you can judge for yourself. Right one is a little sooty, but not too bad. Left one very sooty and wet looking, making me think it is getting oil in the cylinder. Note the left one is actually a BPR6ES that I had swapped in when I originally had the slipped valve seal and hadn't gotten around to swapping back. Hobot: if you get a chance please post numbers for Iridium plugs.

All the lights and electrical work just fine. Battery is 12.10V with no load. With just ignition 12.09V. With all lights 11.75V. Ground to frame electrically good with no voltage drop. Note this is a rather small gel battery that sits in a rubber mount ontop the cradle so is subject to lots of vibration and heat. Put on a charge tonight.

Wondering where to go from here. I did not kick the bike tonight or test for spark.

Cheers,

- HJ

DOXFORD said:

Hi,
just to let you know I had a sparx ignition and not just 1. Same symptoms as you describe. Because my bike was still under warranty from a rebuild I had done the trigger was replaced 2 times same defect and not only that it failed the 3rd time and I said to the builder no way I can't do it a 3rd time. I mean this was at no cost to me the builder was great however the sparx unit wasn't working I wanted of course something that would work I had a rita for 15 years prior to rebuild I was going to go back to that but I went with pazon instead and thats about 3-4 years ago and no problems since. That sparx unit was a nightmare and just gave out no warning. I had each unit about a week to 10 days of driving maybe 500 miles then it would fail. I even took the bike back to the builder after the 2nd failure and had him install the unit just incase I did something wrong during my install but as I stated the unit failed a 3rd time the exact same cause the trigger{Heat} so the builder said ok and paid for a pazon I installed it and no problems. I have a 69 750 my ign is on the left side of bike not right side, not knowing if your familar with that model but maybe that had something to do with the failures the trigger couldn't handle the heat. However I did notice shortly there after that the builder no longer used the sparx ign on his rebuilds. The builders name Matt Rambow and don't get me wrong he was great for service replaced the unit each time no problems with any of that we just both agreed I said I can get a pazon local and thats what I did no complaints. I guess this is a long story to let you know I think the sparx unit is unreliable and I had 3 fail.. hope you sort it out soon
Doxford

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Thanks for the info! Sparx seems to be a fairly popular alternative to Boyer, but good to know there could be issues with the unit.

Cheers,

- HJ

Joe, Not wishing to be over-critical, but shouldn't you check for basics such as spark, fuel supply, etc. before posting and asking advise? Without these and other basic checks anything in the way of advise that anyone can give is mere speculation. If you haven't actually looked it could be anything from a broken fuse to a rod through the case.

dave M said:

Joe, Not wishing to be over-critical, but shouldn't you check for basics such as spark, fuel supply, etc. before posting and asking advise? Without these and other basic checks anything in the way of advise that anyone can give is mere speculation. If you haven't actually looked it could be anything from a broken fuse to a rod through the case.

Click to expand...

It sounds like he may have. Or at least most of the basics. Sometimes it's helps to post because you forget the basics amongst the frustration. Don't ask me how I know. :mrgreen:

Swooshdave, to quote from Joe's second to last post: "I did not kick the bike or test for spark". I'm sure we have all had instances where we missed the obvious, I certainly have in the past. Therefore I am encouraging Joe to check these basics so that we can be more helpful. If he has spark there will be a different diagnostic route than if he does not, likewise with fuel.

I've had a similar thing happen and I was able to narrow it down to timing and ignition. My Boyer overheated. I switched to a sparx digital ignition which has worked really well since. The issue forced me to rewire the whole bike, from scratch, by hand - took forever but it was worth it and I learned a lot....

I suggest looking at the wiring to the Sparx and more importantly check the timing both static and the timing curve. If the timing checks out fine then you can rule out electrical.

Joe — If you suspect this is oil fouling, and I can't quite see from the photo, then you have a separate mechanical problem, and you need to see how much oil it is burning. Even engines that burn oil will run if the ignition system is healthy, unless you are being followed by a huge cloud of blue smoke!

But it still seems likely you have an ignition problem or less likely, carb-related. No matter how frustrating this is, you gotta start from the basics and solve your problem by a process of elimination. Kick the engine over with a fresh set of plugs resting on the cyl head — with the battery fully charged and showing over 12 volts. It should produce a decent, blue spark, not a puny, yellow spark. If the spark is still poor on the left, swap the plug leads. Is it then sparking poorly on the rght? So now you can narrow it down to a coil or coil connection. If the spark is healthy with fresh plugs, starts well but then fouls when you give it some gas, you might have a dodgy earth/ground to your left coil or the left carb is flooding the cylinder.

Disclosure Statement: I am a Sparx reseller. I am also the one who overhauled Will's (Hungry Joe) bike.

Matt used Sparx way back when they were new in the marketplace; they've long since solved teething issues. That said, we went through a rotor AND stator issue with Will's bike early on. Those are the only two issues I've ever had with over 50 Sparx units installed and/or sold to clients. Maybe they were from an old batch? Who knows.

Sparx is far more forgiving on battery voltage than Boyer, so I'd rule out the slightly low battery voltage.

I suspect bad electrical connections somewhere, most probably at the coils.