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The downside is that you have to arrive early and are out on the track all day.  The upside is that you can't get any closer to the action unless you are riding and being there early means you might see riders and bikes way up close.

I acted as a Marshall at the Australian GP years ago and at Superbike events and it is very rewarding. You are part of the action so to speak and right there at trackside. If I lived closer I'd sign up in an instant.

As they said at the end of Shawshank redemption: You have come this far.  Would you go a little further. Or words to that effect.

Top end is off.  The PO used gasket goo on the head gasket?  IS that what I read?  That's not only not necessary, it actually makes it harder to seal. 

Surface rust on the crank is OK but it suggests that perhaps the shafts might be rusty and may have damaged the seals. With the head off, you might as well go the rest of the way and send the crank to Bill Bune, or your favorite rebuilder. You might get away with new rings and if not, pistons are available from Mitaka, or Cruizin or even Wiseco. 

A central plug squish head is a really good upgrade too.  Raise compression and decrease the chance of detonation all in one neat package.  Mr Livengood knows people who can design and machine a head after a short trip to the welder. And at a lower price and better idea than a head from RK-Tek with inserts.

BTW do not use stock or most aftermarket head gaskets.  Get a head gasket from Cometic with say a 71mm finished bore and .043 thickness.  OEM gaskets are about 76mm bore to allow for the fact that casting cores were not always in the same place, so bore to head spacing tends to be shall we say, imprecise.  https://pinkpossum.com/GT750/GT750head.htm  has more details.

It's unusual for an accent ignition to fail but it has happened on a couple. But before you send it back to Uwe to test it, double check the "points" lead to the coils and the 6 pin coil connector.  It's possible one of the pins is loose or pushed out or corroded.

And check voltage at the coils.  I usually fit a relay to feed the coils and that can make a difference. 

I have not run an Accent ignition on the test rig but have run DYNA and Ignitech on our test rig up to 10,000 rpm.  It's set up for Yamaha twins and I use it to check timing on Motoplat and Hitachi CDI systems but have an adapter that allows it to test GT750 systems as well.

Had a couple of sets of DG pipes and they are lighter and better than stock, but mine came on a project bike, so they were the right price.

.....). I have a line on a local set of cases, same year range and everything, including the cylinders AND potentially all the engine covers for around $600.

I don't think I paid that much for a complete bike... Just don't ask how much I sank into those cheap bikes though..

Going back a step, is it possible that the pipes are now full of fuel along with the crankcases?  Pull the SRIS valves or plugs and see how much black oil/fuel mix drains out.

If the airbox is off, apply air flow to the carb inlets and see if the slides all lift at more or less the same rate. Did you do a leakdown test?  It's possible that when it was running that a crank seal tore.

If none of the above work, please wrap it up and send it to me and I promise I won't charge you much to take it off your hands. If you happen to be headed to WI or states west or north anytime, drop the bike off with me and I'll see if I can work out what's wrong before you have to head home.

"  Otherwise, throttle wide open and kick until it starts to pick up and don't close the throttle until it clears its throat and starts to rev.  "

Tried this.
Fired up.   

Why would it lose its fuel prime while just sitting for that week only?

M

That's great news.  As to WHY?  Why do motorcycles do stuff like that? It's in their nature.  Run fine for years with total neglect and one day they just decide that today is the day to fight back. It may be as simple as a spec of dirt in the fuel tap holding it off its seat just enough to allow it to flood. Or the float needle was slightly sticky from ethanol in the fuel and the humidity was high or the ambient temperature or pressure changed enough to allow something to weep.

I normally leave the fuel tap on ON or Run or whatever they label it as except after standing for a while and then I start it on prime just to make sure there's fuel in the bowls.  Flooded motors happen and teh old wide open throttle trick usually works.

To start a flooded motor if it's really bad, remove plugs and kick it over to expel surplus fuel. Otherwise, throttle wide open and kick until it starts to pick up and don't close the throttle until it clears its throat and starts to rev.

Drop the fuel level a little and fit hotter plugs to see if that cleans it up a bit.

BTW, don't ever try to build a budget for rebuilding it.  You may go into shock and never get around to it.  I prefer the opposite approach of buying parts when I have some cash and eventually it gets done.   

With an older motor, it's really important to tweak things to get it to run as well as it can. A healthy motor can be way out of spec and still run OK but a worn motor needs more attention. If the exhausts have much carbon in the baffles, that could contribute to the symptoms.

If you are not running it hard, you go to a B7 or even a B6 plug which will tend to burn off excess fuel. I ran B8 or B9 in mine at the drag strip and dyno testing and they were fine.

The fact that it runs at higher loads and fouls at idle strongly suggests excessively rich mixture.  Check the pilot jets, but also check the chokes.  The plungers or whatever the correct Mikuni nomenclature is go hard over time and no longer seal properly allowing the "choke" to be active even when you have closed it.  MikesXS has a plunger for a BS38 that is the same part at a reasonable price.

With the cracked cases, it's not hard to build that area up with weld but heat the cases before welding and obviuosly that has to wait until the motor is stripped. I have had a couple of cases done.  For sure it's a lot of messing around to dress the case back so it looks perfect but worth the work.

And just a heads up.  Check that the points and alternator leads are well clear of the exhausts.  If the leads droop and melt on the pipes, the trail of destruction can be interesting to say the least.

Sounds like it's flooding on that cylinder.  So much fuel it can't fire at idle. Increasing the gap means the coil voltage has to build higher before it jumps the gap.  Stronger spark helps it run.

Are all 3 as low compression as that one? It should be north of 120 and possibly closer to 135-140. I like to run at least 140 on mine with a few tweaks.

test compression and do a leakdown to see if the seals are also shot and pull the carbs again.  Fortunately you have to remove them to do a leakdown test.  And fortunately you can test one cylinder at a time without having to blank off the other cylinders - No lab seals on this high tech beauty.

How about changing the mechanical tacho arrangement to a modern Single Speedo/tacho etc to free up the space.  Does that ignition have a tacho output.  If not  I imported a few CDI tacho adapters that might work.  I tested them with a Motoplat and stock Hitachi CDI IIRC and they do the job.

But back to the point, a single unit would mount off the top triple with a little work and could eliminate that mounting plate and open up the space.  Or perhaps drop the speedo/tacho head unit down below the clipon risers down where a stock tacho goes.

Excellent video.  he makes it look easy.  I guess that skill and experience do that. :-)

All relevant comments.  Irk mentioned that there are a couple of nice bikes and that's the way it works.  You sell off the best stuff ie highest dollar items and as you move down the list you end up with more and more parts that no one needs or wants.

A pile of RD parts and parts bikes are potentially of use to someone restoring or building RDs.  A trove of GT parts is useful up to a point for someone building GTs but you quickly run out of stuff that anyone wants and as John from Economy pointed out, that's a lot of stuff to work through and potentially to clean and list and try to sell.  It's a lot of hard work for very low return.

To those of us that love farting around with old bikes, it looks like a pile of hidden gems, but only for those that are young enough to make it all work out and with enough spare time and cash.

I picked up a truck load of GT750 parts a few years ago and have used some of those parts for sure, and piles of it went to recycling - like about a ton of it - literally.  And I could build a bike from what's left BUT i still would have to buy a lot of parts that are not in that pile and it's not cost effective.

Good Question.  My interpretation of that chart was that with the billet heads there's a steady 1-2HP gain across the rev range compared to the stock 41HP. 

I would speculate that the difference would be larger on a modified motor, but maybe not.  I haven't tested different heads on an RD.  Does anyone know what difference say a DG head made on a stock motor for comparison?

They do look beautiful though and the machining is amazing.

Rings are not there to reduce piston slap.  Their sole purpose is to create a seal between piston and bore.

A bottom (skirt) ring is not uncommon on some older diesel motors because they have "ridiculously" high compression.  The only practical way to reduce piston slap is to reduce piston to bore clearance.  There are other ways to reduce it by design such as changing bore and stroke and rod length, moving the piston pin higher in the piston, making the skirt longer so it rocks less and YES, some of those are headed in different directions as solutions.

BTW, Pistons are neither round not parallel. They are cam shaped and tapered so that the parts that get hottest, start off smaller so that at operating temperatures tjhe psiton is more or less the same diameter top to bottom.  They are cammed to created more clearance on the sides to reduce drag (friction) and that's why many 4 stroke pistons are of the so called slipper design, ie the sides are cut away from the pin down.

And as a prior poster mentioned, there's not enough metal in a stock piston to machine a piston ring groove.

No.  you should not do it.  That would be self indulgent and not at all responsible. PM me your address and I will relieve you of that sinful temptation..

I figure that was worth a shot.  No?  Ah well.  Have fun.