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I have a 1976 GL1000, which runs very badly below 4000 rpm, I have found that the two front cylinders do not fire and be effective until the engine reaches approx 4000 rpm. I have changed both head gaskets, ground in all valves, checked all clearences, fitted new plugs, points, and condensors, checked all wiring including swapping the coils around. fitted new cambelts, cheked the valve timing both by alingement marks, and with a dti gauge. removed and cleaned the carbs,ballanced the carbs. my best guess is that its a fuel problem. any advice would be much appreciated its beat me!
 

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The 76 models were supposed to be the worst of the bunck, carb wise anyway. Do the front spark plugs look any different than the back ones?
 

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All the posts I've read on the gl1000 suggest that carb problems are particularly bad on the 1976 models. That's why many guys fit either bigger jets or just replace the carbs with ones from the gl1100.
 

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The first questions that I would ask are: 1) Are you using the Honda Point sets? If they do not have the copper (brass) grounding strap on the spring, they may not be allowing good enough continuity to saturate the coils.

2) How many miles on the clock? After 30 to 40 k miles the cam shafts may have a little to much play in the journals. Not much that you can do about this but it does lead us to Q3.

3) Are the points arranged and gapped at a position whereby the 180 degree crankshaft dwell(90 degrees cam rotation) may be resulting in "Dwell overlap" This is to say that both coils are beingsaturated with current (less than the normal 9 volts through the ballast resister) at the same time. This is pretty easy to check in that you locate the two wires leading from the points (blue - yellow) and connected behind the battery cover and dissconnect them both. Then connect a VOM meter to the blue wire (left points set) and to the engine ground. If you are sure that the timing and points gap are correct, rotate the engine until the left set is ready to open at the F-1 mark but not there yet, say 1 or 2 degrees previous to the mark. Un-hook the VOM from the left points wire and connect it to the right points wire. If both have continuity (points closed) then both coils are receiving current at the same time and the voltage to each will drop to around 5 volts. If this is occuring it can cause the mis firing that you are experiencing up to 3000 to 4000 rpm.

Let me know if this is happening.

Pistol Pete
 

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Pistol Pete knows his stuff. I knowa few gl1000people that had terrible problems simply due to not using Honda points. Honda points off another bike (CB450 I think) are suposed to be better than the stock gl1000 points. Not saying that's your problem, but it should be on your checklist.
 

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With two cylinders acting up and four separate carbs, it tends to support the probability of iginition problems. If the excellent trouble shooting outlined by PistolePete doesn't solve it consider the possibility of a bad condenser. Normally ignition problems get worse with increasing rpm. One thing that comes to mind is the possibility of a bad condenser. Failing condensers may have too little capacity left to reduce arcing of the points at low speed while at higher speeds the increasing frequency of the pulses from the points can still be damped by the remaining capacitance. Capacitive reactance decreases with frequency so the arc suppression increases with rpm. The ignition coil depends on a sudden collapse of current in the primary coil to generate high voltage in the coil secondary coil which is fed to the plugs. At low speeds any arcing of the points allows the primary coil current to decrease more slowly over time preventing a sharp collapse of the primary current resulting in much lower secondary voltage. Ergo weaker spark.

I know this is old stuff to most of you but sometimes the electrical workings of the iginition system aren't too clear.
 

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My GL1000 from the dump was assumed to have had a blown engine before I picked it up. It also wouldn't run on all cylinders below a considerable rpm was reached. It runs now... This is what was wrong with it:
All 4 plugs changed- made a world of difference, but still nothing between idle and 4000 or 5000 rpm-
Points were badly gapped-
Ignition bably timed- still nothing between idle and 4000 or 5000 rpm-
Then I pulled the 4 carbs out and quickly (I had a one day temporary operator's permit I didn't want to waste!) cleaned the cv sliders up so that they even slide up and down...imagine!
Voilla- that did the trick-
Things weren't perfect, but the back firing and non-existant middle range came to life (later, as it turns out the primary and secondary jet o-rings were spewing gas so it was really rich).
Hope this helps, Jim
 

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Hi Vic, Creston, BC.

No snow here yet and I had the bike out on the deck running it after finally putting in the second 1200 belt tensioner (messy mod but it is good to go) and retiming the 1000 one more time... Here is a pic with my daughter letting the clutch out- less the point cover and timing belt covers. Man it sure is good to hit the starter button after a big job like this and just have the thing purr! :waving:

Now, I have some PPG Trucks TV show "Copperhead" paint color ready to spray on the colored parts and one front Bridgestone to mount...
 

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the front plugs tend to be wetter than the back ones, the rear plugs clearly show that they have been working, slightly sooted around the edge, with the centre insulator alight brown colour. Ihave fitted new plugs several times trying different makes,the engine runs the same whatever plugs are fitted. compression testshowed 9.5 bar on all cylinders.
 

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Hi Pete, I guess we have pretty much hi-jacked this post...:gunhead:

Oh well... um... The only reason I have changed anything from stock was to save money. Honda belt tensioners were too expensive, and I didn't like the after market exhaust options . So the biggie was deciding to install 1100 exhaust on the 1000. It was very easy and very affordable. I purchased a perfect 1100 set of exhaust for 163 us dollars. The troubles fitting the cross-over balance pipe the 1100 has a 1.5 inch longer swing arm) was solved by using oxy-acetylene and carefully heating/bending dog-legs into them to clear the tire. They still bolted together in the middle.

The other thing that I have done is become a good eBay purchaser. Practically every component that could have been removed from the bike has been replaced by eBay purchases and I haven't spent more than 500 bucks. I have purchased a nice clean and smooth pair of 1200 belt tensioners and modified them to fit the 1000. I had to open up the top of the adjusting bolt groove and will weld in a cap to extend the groove a bit farther for future adjustments when the time comes.

Like darn near every other old wing, the front blinker mounting ears were cut off to allow clearance inside the front fairing. I cut off some old generic blinker posts and welded them in place, then attched the generic rectangular blinkers onto them. The welds are small and covered over with a bead of black RTV. Only real Wing-Nuts will know the difference!

I would prefer to have it totally stock- seat, paint color, blinkers, grips etc, but this would be too expensive to do. This is a good compromise for me.

Oh - I have also made my own votage reducer for the two tank gauges using initially, plans off of internet. They have 1 hour on them now and are still reading correctly. :D


Your bike is awesome looking. Merry XMas, Jim
 
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Dave, thanks for your reply, when I got the machine it was fitted with the later GL1100 carbs, which I removed and cleaned. I was fortunate enough to find another used set of carbs at an auto jumble, which I took apart and cleaned, and fitted but it made no difference to theway the engine ran.
 
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Hi Pete, many Thanks for your assistance with my troublesome wing.

I have fitted pattern points and condensors, which do not have an earth wire, however the set that I removed was the same. I will buy another genuine set from David Silver, and try them.



The machine has done just over 28,000 miles as shown on the clock. but I have no way of knowing if this is the correct mileage of this machine.

I have read through your technical advice on dwell overlap etc. several times. I willfollow these the test procedures/adjustmentsand let you know the result.
 

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Jim,

Been thinking about building a custom GL myself but with my job, hobby and "Honey do's" I can never find the time.
 

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Smit,

If you are wanting the ignition problem solved, buy a Dyna S ignition and you will enjoy one of the best E-ignitions on the market.
 
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