Engine needs a refresh - make that a big bore!

[Syscrush]

no doubt it's gotta feel good to get back in the saddle and ride her...

This morning before the traffic got super bad, I filled the tank with ethanol free gas and did the real break-in ride. It was still pretty cold, and there was a lot going on, with trying to go through the break-in routine that I wanted while keeping from getting a ticket or making too big of an ass of myself in traffic. It was anything but a pleasure ride, but it did definitely feel good to be reunited! The only bike I rode last year was my wife's Monster 620, and this bike is worlds apart from that in terms of riding position - especially with the comfort mods done with the handlebars and the lowered pegs. It felt really dorky at first, but it didn't take long before I remembered why it's set up the way it is.

Here are a few more pics for those who are interested:


Mechanic inspects his work and says goodbye for now.


I got home at almost the same time that my wife and kid got back from the toy store. My little guy is shouting "Motorcycle!" here, which he does any time he sees a bike, but he hasn't yet realized that it's his dad's.


Looks right at home.


I'm very happy with how the exhaust looks for now. We'll see how long it lasts once it's dealing with rain and road debris. That valve cover will be painted when we revisit the valve clearances at about 500 km. I'm also pleased with how the new fasteners worked out.

[steve murdoch icoa #5322]

No doubt the feel and sound of riding your CBX made you quickly forget about the chilly temps.
Looks like your long resto journey is almost finished.

[Syscrush]

No doubt the feel and sound of riding your CBX made you quickly forget about the chilly temps.
Looks like your long resto journey is almost finished.

The ride out to Pickering to drop off for tuning this morning was much more pleasant. My body is remembering how this bike feels and works. The riding position is comfy but does feel really dorky after getting so used to the Monster, but I'm getting over the self-consciousness of being an old man on a bike with old man ergos.

At this point I'm waiting for the other shoe to drop regarding the carbs. They've been gone through a couple of times and are still not working exactly right. Hopefully the dyno + sniffer tune will get them perfect, but if not then I'm looking at another round of non-trivial repairs. Fingers crossed!

[Syscrush]

Another couple of notes:

Since the rebuild the top end of the bike has lost its characteristic pre-rebuild noise. I believe that I have Scott Miller at Fast Company to thank for this - when I called to ask him what he remembers about the state of the engine when it was rebuilt 20 years ago (it seemed like a long shot!) he immediately said "the lifter bores are bad, that's why it makes so much noise when it's cold". If we had just left the head assembly together and only done the bore & pistons, we wouldn't have sorted out that issue.

The idle on this bike was very good before, but it's a bit better now - just perfectly rock steady. I don't know how much that matters, but IMO it's just good news.

UPDATE: I just got a txt from Zaid, the tuner. He's done some more break-in runs on the dyno and says that it's not blasting oil past the rings like it did pre-rebuild.

[wyly]

Another couple of notes:

Since the rebuild the top end of the bike has lost its characteristic pre-rebuild noise. I believe that I have Scott Miller at Fast Company to thank for this - when I called to ask him what he remembers about the state of the engine when it was rebuilt 20 years ago (it seemed like a long shot!) he immediately said "the lifter bores are bad, that's why it makes so much noise when it's cold". If we had just left the head assembly together and only done the bore & pistons, we wouldn't have sorted out that issue.

The idle on this bike was very good before, but it's a bit better now - just perfectly rock steady. I don't know how much that matters, but IMO it's just good news.

astounding that someone can remember rebuilding a single particular engine 20 years ago

from what I can recall from 39 years ago it would idle (and elsewhere) so smoothly the reflection in both mirrors were clear/steady...now I have a vibration in the left mirror while the right remains clear/steady...but that's how I recall it maybe I just think that's the way it was, Dave may recall something different...

[Syscrush]

astounding that someone can remember rebuilding a single particular engine 20 years ago

It is amazing! Let's assume that it's because the CBX is so memorable.

The seller told me that he knows Miller personally, but he bullshitted me on some other stuff, so I didn't know what to expect. Apparently he was telling the truth about that part, and I assume that the personal connection is a big part of why he remembered the bike so clearly. I also assume that he's a perfectionist and was pissed off about reusing a head that was damaged by a Honda tech who should have known better.

And on that note... The tuner first reported that the bike was not smoking, but after a few more break in runs, he says it smokes on decel from high revs. Maybe, maybe, MAYBE (please please) the rings need to seat a bit still and there's enough hone texture left in the cylinder walls for that to still happen - but my guess is valve guides or seals. Time will tell.

[Syscrush]

Another little update from the tuner today. The baseline showed that "the jetting is spot on up top however very lean at idle and cruising throttle, and quite rich in the midrange." Carbs are coming off for tweaks informed by that baseline testing.

Peak horsepower was measured as 101 hp at the wheel. At first I kind of balked at that number, but given that displacement was bumped ~10% (and I assume some compression increase despite being "standard compression" pistons), and the light mods to intake and exhaust, an increase in power of ~15% does not seem too much of a stretch. Of course there's always some variation from dyno to dyno, and I'm not certain what correction factors (if any) were applied. Still, I admit that there's some satisfaction in breaking 100 hp.

The bike should be ready next week sometime. I'm getting a bit antsy about getting it back and seeing how good (or not good) the tuner was able to get the jetting...

[wyly]

Another little update from the tuner today. The baseline showed that "the jetting is spot on up top however very lean at idle and cruising throttle, and quite rich in the midrange." Carbs are coming off for tweaks informed by that baseline testing.

Peak horsepower was measured as 101 hp at the wheel. At first I kind of balked at that number, but given that displacement was bumped ~10% (and I assume some compression increase despite being "standard compression" pistons), and the light mods to intake and exhaust, an increase in power of ~15% does not seem too much of a stretch. Of course there's always some variation from dyno to dyno, and I'm not certain what correction factors (if any) were applied. Still, I admit that there's some satisfaction in breaking 100 hp.

The bike should be ready next week sometime. I'm getting a bit antsy about getting it back and seeing how good (or not good) the tuner was able to get the jetting...

100hp at the rear does seems logical, if in original spec it produced about 90hp for 1050cc at the rear an increase of at least 100cc and other mods should result in another 10 or a bit more hp...

in discussions with a mechanic in regards similar upgrades(100cc/compression increase and others) on my Z his estimate was 112-116hp at the crank, so at the wheel probably I expect similar result as to what you have...

[Rick Pope]

Do you have a "before" chart to overlay with a current dyno chart? You might have more power in the lower and mid-range now. Everyone talks about the peak numbers, but it's the power in the lower range that you feel in the seat.

[Syscrush]

Do you have a "before" chart to overlay with a current dyno chart? You might have more power in the lower and mid-range now. Everyone talks about the peak numbers, but it's the power in the lower range that you feel in the seat.

No, there's no "before" chart. It's been a year and a half, and the tuner has moved to another shop with a different dyno, and it's a different time of year. Even if I had both charts, I wouldn't base anything on a comparison where there are so many variables.

I am pleased to hear about 101hp at the wheel, but that's really just childishness. :) The bike had enough power before to do everything I need it to do - what I really care about is getting the carbs dialed in, getting it as rideable as possible, and having it last. I'll add that if I cared about low and mid-range power, I wouldn't have bought an I6.

My dream is to one day convert it to closed-loop EFI with a catalytic converter, but that's (many) years off. The immediate goal is to tune out all of the light-throttle popping and burbling and eliminate the potentially dangerous lean running at certain rev/throttle values.

[Syscrush]

I got curious about how much the ceramic coatings I chose could have contributed to that 101 number. According to this seemingly well-researched article, it would not be surprising if the coatings were making the difference between high 90's and 101:

http://www.hotrod.com/articles/hrdp-061 ... -coatings/

[Syscrush]

Here's the baseline dyno before the jetting was changed:



The main jet looks great, and so does peak power. When the tuner told me that it made over 100 whp, I was assuming that there was some excessive correction factor applied, but no. Uncorrected was 103-104. It was a cool day (65°F, 29% humidity) so the SAE correction factor was 0.98 - the corrected number he gave me had been corrected DOWN.

Obviously there's some crazy crap going on below 5000 RPM, the bike feels a lot better now with the changes made to the jetting.

The Dynojet kit now has the needles raised to the second-last position, and the pilot jets were bumped from 65 to 80 after these runs. Mains were left at 96. It's still not perfect, but it starts MUCH better and the part-throttle cruising is a lot nicer. For reference, the bike has stock airbox (with lid), K&N filter, Wolf 6-2-1 header, and Hindle 16" stealth core muffler with dB killer insert.

In terms of rideability, the main thing left to tune out is that the engine can't be held easily anywhere between 1500-2000 in neutral. It idles very nicely at 1000 RPM, and gentle throttle raises the revs smoothly up to 1500, but then it's like an insensitive lightswitch. Give it just a bit more, nothing happens. More, still nothing. More, ZOOM - 2500 RPM. It makes it difficult to do a graceful launch. I'm using too much revs and riding the clutch more than I'd like, and it's still not very smooth. My mechanic seems to think that an adjustment to the air bleed screws will help with that, but we'll see.

[Syscrush]

Because carb tuning is turning into a black/lost art, and both dyno time and a carb re&re are so expensive, I'm leaning pretty heavily towards getting a datalogging wideband O2 sensor (with inputs for RPM and throttle position), and collect data while I just go riding. Buying and installing the necessary sensors would have a cost comparable to another round of dyno tuning, but allow me to collect a lot more data, and analyze it myself. Whether or not that analysis would allow me to get the carbs perfectly dialed in or not is another matter. In any case, this is the data logging sensor I'm considering:
http://www.zeitronix.com/Products/zt2/zt2.shtml

It can log to a Windows computer running their software, or to this dedicated black box logger:
http://www.zeitronix.com/Products/Black ... gger.shtml

[Syscrush]

During the rebuild, the valves were adjusted just to make sure that all 24 were within spec, with the intention of doing a final tune after break-in.

Immediately after the rebuild, the jetting was changed as a result of the dyno/sniffer results. After about 500 km of riding, the idle mixture screws were backed out a bit more, and part-throttle rideability improved a lot. After another 500 km of riding, it was time for the post-break-in valve adjustment.

Wow, what a difference! The bike is still not perfect, but it's a joy to ride now.

The biggest outstanding issue is fuel consumption. I haven't ridden any real distance since the valve adjustment, but immediately before, I'd hit reserve after ~120 km (that's km, not miles!) of easy steady-state highway cruising at 110-130 kph. I had to go back and check my old posts to verify that I used to complain about hitting reserve at only 200 km. I have the latter half of October off work, I'm hoping to do more riding and get more data about fuel consumption. Wish me luck!

[Gearheadgregg]

Here's the baseline dyno before the jetting was changed:



The main jet looks great, and so does peak power. When the tuner told me that it made over 100 whp, I was assuming that there was some excessive correction factor applied, but no. Uncorrected was 103-104. It was a cool day (65°F, 29% humidity) so the SAE correction factor was 0.98 - the corrected number he gave me had been corrected DOWN.

Obviously there's some crazy crap going on below 5000 RPM, the bike feels a lot better now with the changes made to the jetting.

The Dynojet kit now has the needles raised to the second-last position, and the pilot jets were bumped from 65 to 80 after these runs. Mains were left at 96. It's still not perfect, but it starts MUCH better and the part-throttle cruising is a lot nicer. For reference, the bike has stock airbox (with lid), K&N filter, Wolf 6-2-1 header, and Hindle 16" stealth core muffler with dB killer insert.

In terms of rideability, the main thing left to tune out is that the engine can't be held easily anywhere between 1500-2000 in neutral. It idles very nicely at 1000 RPM, and gentle throttle raises the revs smoothly up to 1500, but then it's like an insensitive lightswitch. Give it just a bit more, nothing happens. More, still nothing. More, ZOOM - 2500 RPM. It makes it difficult to do a graceful launch. I'm using too much revs and riding the clutch more than I'd like, and it's still not very smooth. My mechanic seems to think that an adjustment to the air bleed screws will help with that, but we'll see.

Been through this many times , Not sure what slow Jet your using , These should clear up your part throttle cruising , 1 3/4 turns out on screws easy starting and snappy throttle, 90 percent of riding is in the Idle circuit. https://www.siriusconinc.com/pro-detail ... ct_id=7599