Finally getting around to the 550/699 project....

[boris.h]

I had condenser issues, sometimes a big spark appeard on the ignition plate. I bought new condenser.... and new ones failed quickly... bought new ones again.. the issue did not appeard anymore...

[tkent02]

Interesting, opening the throttle, a snap, it felt like soothing broke and the throttle stayed open. Like the return spring broke or fell off or something, there's about an inch of play when you twist the throttle. Pulled the throttles down on the carbs open and closed a few times, something snapped inside, now it works normally again. I think I should probably fix this.

Probably something to do with the fact that I'm using one of the throttle cables for the VM carbs on the CVs. Didn't fit perfectly, but it seemed to work fine. Until now.

[boris.h]

Getting close for me on the same project.... i think the first start will occur before end of may. Did you manage to drive it more?

[tkent02]

No I need to fix the petcock first so I can put the gas tank on right and see why the throttle got stuck. Couple other little things.

[tkent02]

Switched petcocks to one with the outlet and vacuum nipple facing aft to clear the CV carbs. This petcock is too fat, it hits the frame. Waste of effort.

[tkent02]

OK, swapped ignitions back, so that should be good. Went down to the local moto wrecking yard and looked through their petcocks for the pre 1980 style with the pipes on the aft side. The only one I found had a bad oring on the vacuum valve, so it wouldn't shut off. Remembered how to give it a manual off position from several years ago and put it all together. Petcock works, no leaks, went for a short ride, it's still misfiring. Kind of an annoyance, I just want to ride it.

[tkent02]

OK, progress. After checking and setting the points twice, checking the condensers twice, reseting the timing twice and not improving the misfiring at all, I sat back, drank a beer, looked at the bike and listened to what it was saying. Definitely ignition it says, the mixture is close enough. Ignition huh? OK I got this. So instead of thinking about what I might have screwed up the last time I worked on to cause this misfiring, I looked at it as I would a new to me bike that was running that way. I'd check the points and condenser once, if that didn't fix it I'd check the spark plug caps. So that's what I did. All fubar. Too much resistance, took them apart, missing one the little connector springs, corrosion in a couple of them, one had been "fixed" by some PO. How it's been running perfectly the whole time it was a 550 I have no idea.

So new caps went on, new spark plugs too, just fired it up this morning. Idles nice, no missfiring. Got my jacket and helmet on, went for a little ride. Smooth as silk. Mixture seems pretty close to being right. Couple miles down the road, it's warmed up enough, open the throttle, this thing is fast now. Raining, roads are wet and there's a few rush hour stragglers around so nothing too crazy, but this ****er goes! Hell of a lot better than it did with the 550 engine!
Finally, get to an open space on the road, no cars, no cops in sight, let er rip!! Woo HOooo what an improvement, up through two or three gears, maybe four..... and the throttle sticks again. Wide open, and of course I didn't notice it until I got to the end of my open space, woo hoo indeed.

I totally forgot about that part. I need the proper CV carb throttle cable.

[boris.h]

Yeah, so good!
While listening to you, I can not wait to try mine. Just need to finish mine. I need again the 650 head which is slmost finished, and the exhaust (modified bandit exhaust). I think the diffferences between mine and yours will be: ported head, velocity stacks, and the bandit open exhaust. That's why I will start with bigger jets.... I'll see....But happy to see it functionnal

[boris.h]

which spark plugs do you use?

[tkent02]

Just picked up NGK D8EA, which is stock for the 650. Picking a head from the local Moto wrecker tomorrow to send off to get ported, will use that one with the 699 pistons if that group buy ever happens... Just using an old 550 Vance and Hines until I find a nice 650 4-1.

[Chuck78]

Sounding great Tom. I can't wait to get ours together here. I really think of the GS650E (& GS550 77-82 + 650 top) as the ultimate all-around GS... GS1000 2nd place, as it's a big beast but probably the best 70's Superbike platform. GS1100E 3rd, heavier, lost the classic styling, but wow what an advanced engine.

The 650 head and piston design is basically a 2 valve shim & bucket version of the 4 valve rocker arm head chamber / dome / port design. So no wonder the 673 makes nearly identical power numbers to the heavier 750 8v...

[tkent02]

Mine is way faster than my 750. No comparison. But the 750 is still jetted for sea level.

[tkent02]

OK, after being gone a month, finally fixed all the stupid stuff and went for a real ride. Up in the hills, around town, I like it. Good torque, pulls hard, but the main jet isn't quite right, it's OK at full throttle and half RPM, but at 8,000 or 9,000 is isn't. Misses a bit, power drops off, if you close the throttle a 1/4 turn it goes like it should... Went to look at the plugs but the tool bag on the bike still contained the plug wrench for the B8ES on the 550 head, the 650 head uses the smaller spark plugs. I think the main jet is too big, but I haven't tuned CVs in a while...
I know you have to get the main jet right first.

Out for a ride... with the correct wrench this time.

[roeme]

(...) it's OK at full throttle and half RPM, but at 8,000 or 9,000 is isn't.(...)

Huh, that's interesting, that sounds like my stock 550?

Begins to pull at 4-5k, dropping off around eight, and hitting a wall at nine (though that might be more because a) in my country you'll get shot on sight at these speeds and b) I have to concentrate so much on the road unless I want to kill myself, and hence do not open further).

Though IIIRC I can't open the throttle fully @5k, engine gets flooded.

Where's the redline after the 699 conversion anyway? (I presume it's dictated by how fast the valves can close/open)

[boris.h]

About your jetting, you said it's pretty close...could you tell us more about your jetting configuration? I know you are not at sea level but it's just to get a referenice. Thanks!