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

[tkent02]

RapidRay suggests 108 / 110, I'll start there.

[Chuck78]

Holy smokes, 106/118 is much further out than I could imagine..I had read on here that there was a broad desparity of cam timings on our engines, hence you might find 2 identical models with completely different engine power carachteristics.

Generally people well versed in cam timing say to put the GS at 104/106 for a huge boost in mid range street torque (I'm envisioning 4000-7000rpm), and to set them both at 110 for top end horsepower. Your Ray recommendation falls right in line with that. Ray is an awesome wealth of engine knowledge.

Web actually have a massive writeup on cam timing, and changing lobe seperation angles.
Have you seen this?

http://www.webcamshafts.com/mobile/degreeing.html

[tkent02]

I have seen it, thanks. I think my problem is in the dial indicator mounting. Don't have a long enough extension on the tip, it's hard to get it in line with the valve without hitting the cam lobe as it comes around. Had it at a bit of an angle at first, got funny readings. It reads differently on the way back up than it did on the way down, which skewed everything. After redoing all of the measurements a couple times it's much closer to 106 / 108, but I'll recheck it when I get the extension thing figured out. Also Chef is sending me some carburetor parts I need to put a set together, that's the last big thing I need to finish this up.

[tkent02]

Man this is going slowly. The engine is done, cams are timed as closely as I can, but it's still hard to get a good reading on the dial indicator. Bought a set of dial indicator tips, but none are long enough and skinny enough to get to the shim bucket without rubbing on the cam lobe when it comes around which knocks the tip around. It's difficult to get within three degrees consistently.

I wanted to know how much of the difference in power and torque were due to the increased displacement and the shape of the head and pistons, and how much was due to the 650 cam, so I put another set of 650 cams into the 550 engine. The 550 cams have lobes that are much wider visibly than the 650 cam lobes. Finding out a few things about the cam sprockets too. The 550 sprockets need to be drilled to 7mm, and the timing is different than the 650 sprockets. The numbers and arrows for setting them in the head are indexed differently in relation to the bolt holes. Looked at a bunch of 750, 850, and 1000 cams I have here, there are several different choices in how their sprockets are indexed. Anywhere from 3 1/2 to five teeth between the bot hole and the arrow and number. Some have 6mm holes, some have 7mm. Also found one aftermarket 750 exhaust cam that fell down behind the wall with a slotted sprocket. They are all the same 30 tooth sprocket that the 550 uses so good to go. Trying different combinations of sprockets to get close to the timing of the 550/675 engine. Think I'll end up using the slotted sprocket, but...

Being hampered by the dial indicator tips. Seems worse on the is 550 head than on the 650 head for some reason. I think I need to make one about three inches long to get in there...
And no one in town sells 4-48 taps to make such a tip. Looks like another time suck coming.

[tkent02]

Speaking of time suck, I just picked up a 1982 R80ST. I'll try not to start on it until this 675 project is done.

[tkent02]

Got the 650 cams in the old 550 engine, having a hell of a time measuring the cam timing. I think it's close, but I get different readings each time because the dial indicator tip won't stay where I need it to. Need to make yet another dial indicator tip, the one I made today isn't much better than the old ones. Think I need to make a curved one, to get around the cam lobe. Very annoying.

[tkent02]

OK, the cams in this beater 550 motor are at 107.5 and 110. Was shooting for 108/110 but that's close enough for a temporary beater motor. Time to torque the sprocket bolts, red locktite and... Holy cow the manual says 18 ft. lbs. Hmmm, 216 inch pounds. That seems like a lot for a 7mm bolt, can that be right?

I know Ray posted something about it a few weeks ago, but I can't find it anywhere.

[Buffalo Bill]

Steel in steel ok, not into aluminum.
Those are high carbon steel too.

[tkent02]

Yeah I guess that's right. Nothing broke anyway. It's all back together, going to try it out in the morning if it doesn't snow too much. Our 70 degree riding weather went back east someplace.

[tkent02]

Rode it a little, it pulls a bit harder the first couple thousand RPM... And that is all. The power comes on about like a Honda, no big rise in torque at 6,000 or so, no top end kick starting at 8,000 at all. What a dog. If this was what riding was always like I'd take up knitting.

Also it was really rich, especially at higher RPM, where it was slightly lean before. (tuned that way intentionally so it runs better up in the mountains where I mostly ride.) So rich it made as much power at half throttle as it does wide open. Blubberingly rich even. it almost seemed like riding a bike with sea level jetting here at 6,000'. I didn't think different cams would have much effect on jetting requirements. I guess I have a lot to learn.

Deciding whether to waste the time changing to smaller main jets to try it out some more or just put the 550 cams back in. Or just throw the 650 engine in with the 550 cams and let er rip.

[tkent02]

Interesting, dropped the main jets from 105 to 97.5, it's not perfect but close enough to see how it runs. Still on the rich side, can't believe how much difference the cam timing makes in the jetting.

Stronger down low than with the 550 cams, easier to get going from a stop. You can ride it around at 4,000 or so now instead of needing 6,000 to get out of it's own way. About like the old 650's power band only less powerful all around. The big top end kick starting at 8,000 on up as far as you care to take it is completely gone, might as well shift at the redline like a normal person. Boring.

I think I'm going to use the 550 cams in the 675, it's just more fun. Maybe tweak the timing for a little more midrange if I can do it without losing the top end blast.

[Nessism]

Can't wait for the ride report with the new engine. This thread almost makes me want to built one of those bikes myself.

[tkent02]

Just need to get a pipe figured out and put the carburetors together. Weather is too nice to take it apart again right now, been riding a lot.

But I'm getting ready to do it. Maybe tomorrow. or Friday....

[tkent02]

Heck with it, it's going in today.

[boontonmike]

Man, It's so nice to hear a comparison finally instead of just armchair engineering talk. I am confident in sticking with the 550 cams now. Thanks for the feedback.

Interesting, dropped the main jets from 105 to 97.5, it's not perfect but close enough to see how it runs. Still on the rich side, can't believe how much difference the cam timing makes in the jetting.

Stronger down low than with the 550 cams, easier to get going from a stop. You can ride it around at 4,000 or so now instead of needing 6,000 to get out of it's own way. About like the old 650's power band only less powerful all around. The big top end kick starting at 8,000 on up as far as you care to take it is completely gone, might as well shift at the redline like a normal person. Boring.

I think I'm going to use the 550 cams in the 675, it's just more fun. Maybe tweak the timing for a little more midrange if I can do it without losing the top end blast.