Hk1 yellow fever
- Thread starter Tweakin
- Start date
Tweakin
Active Member
Changing the swingarm to increase stability, the flex on the stock swingarm is significant. I am anxious to see if the Gcraft swing arm will tighten up the rear end or if the flex actually comes from the frame where the swingarm mounts.
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Tweakin
Active Member
The Takegawa rear shocks and new swingarm finally came in so I can pretty much call this build "complete". I am really happy with the performance shock/swingarm combo. I was also able to get the carb pretty close, it is still a little rich at idle but I will fine tune everything once I get it on the dyno. Using the auto style timing light is the way to go IMO, the bike runs much smoother not that timing is dead on.
Just in time for the Tiddle Tour group ride around Vashon Island tomorrow.
Had to take a few more photos:
Just in time for the Tiddle Tour group ride around Vashon Island tomorrow.
Had to take a few more photos:
I'm interested in your impression of the difference the G`Craft swingarm makes. IDK, maybe the K0 swingarm is more flexible than the K1-later; Honda wouldn't have gone to fully-boxed construction for shits-n-giggles. I've run across a few tweaked K0 arms (never a later version) and they are shockingly flexible, as a loose part. That said, once the wheel assembly is torqued into place, it's a whole different thing. Axle, swingarm pivot and motor mount bolts are structural components, thus torque is important. Personally, I've never felt any difference from a swingarm change. IMHO, the swingarm isn't being stressed very much by riding. The main deflection point is at the pivot and virtually all of the undesirable lateral motions comes from the combination of the swingarm bushings and frame...that is its weakest point. Biggest improvements I've noticed, in descending order: road tires, real shocks, swingarm pivot bearings (needle instead of rubber), frame bracing, swingarm itself.
Squeeze the chain, top & bottom, and you'll see how the wheel is moved, toward the LH side of the bike...as well as where the motion is centered. FYI, one hand can generate far more force than the machine will ever "see" while riding. IMO, it's an extreme test but good for a visual demo, as well as finding anything that is seriously loose. (Not applicable here, with all-new parts.) I have used this swingarm and done the test described. Didn't see a bit of change in the amount of wheel deflection. That said, I still like this piece. Why?...it's a classic - typical G`Craft quality, honest/functional bike jewelry. And, my biggest motivation, it'll stay looking like new for a very long time. There's no paint to damage. Instead, the manufacturer placed Delrin plastic rub strips...a most welcome ounce of prevention, that works.
To that end, that swingarm looks like it belongs on this build...really rounds-out the visuals, imho:thumb:
As for dialing-in the timing, quite right. If only point gap would hold steady. That's why I'm a fan of CDI. Having access to a dyno is a huge advantage. Being able to monitor output and air:fuel ratios in real time not only eliminates guesswork, it speeds the process as nothing else can. You should be able to do about a day's worth of road tuning in more like an hour...and without pissing-off the neighbors in the process:19:
Tweakin
Active Member
I immediately did the "chain squeeze" test on the new to compare to the same test on the stock swingarm and the difference was significant to say the least. The new swingarm has zero flex or movement at all. After riding the bike hard today the swingarm and shocks are the biggest improvement on this build to date. The roller bearings over the bushings are a big plus as well. I think it is a bigger improvement than when adding upgraded boxed swingarms to my hopped up cb750 builds.
Yes, the timing light was also a major plus for this engine. I am used to using optical advance on my bigger cc bikes and the timing never felt right on this bike until now.
Yes, the timing light was also a major plus for this engine. I am used to using optical advance on my bigger cc bikes and the timing never felt right on this bike until now.
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kirrbby
Well-Known Member
DANG that bike is NICE!!
You didn't pull any punches on this build...it's all you.
The swingarm and shocks look like they belong for sure. I don't miss the stock parts at all. Of course it helps when they say Takagawa and Gcraft on the side
I would love to have that one in my garage. I'm sure you're proud of it too.
You didn't pull any punches on this build...it's all you.
The swingarm and shocks look like they belong for sure. I don't miss the stock parts at all. Of course it helps when they say Takagawa and Gcraft on the side
I would love to have that one in my garage. I'm sure you're proud of it too.
Tweakin
Active Member
Thanks Kirrbby! I absolutely love ripping around on this bike, I think my other bikes are getting a bit jeleous. It's almost like riding a miniature super moto bike around the neighborhood. Tomorrow should be fun on the Island. Our local vintage motorcycle chapter is putting on a Tiddler Tour ride. A meet up and ride of vintage bikes 250cc and smaller.
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See what I was talking about? Once you get the motor, chassis & suspension upgraded and balanced, for the road, rides all feel shorter than they used to. The basic CT70 design has a lot of potential which, once tapped, delivers more than seems possible. I've learned to measure the success of this type of build...with the odometer. Sounds like you're headed in that same direction
Tweakin
Active Member
First time on real open road today and this thing pulls like a train. I need to get the gps out to document the true speed but it was burying the stock 50mph speedo on a long uphill with plenty to give. Never thought I could get one of these to feel so stable at 50+ speeds. I think I am in love.
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Tweakin
Active Member
Braking was one of my biggest concerns with the stroker engine and higher speeds. I rebuilt both drum break systems and honestly they work great, even at high speeds. I thought about adding one of the Chinese upside town forks with a disc break because of my concern but don't like the look of them. After talking to a few people who have them decided it wasn't worth it and am happy with my decision. Even though the bike breaks well I am always aware of the performance of drum breaks.
kirrbby
Well-Known Member
I've only had to hit my brakes hard a couple few times...because I nearly ran a stop sign or light while taking in my surrounding sights. lol
Certainly the most important part of braking is not putting yourself into a hard braking situation in the first place. I think the second most important thing is to condition yourself to use both front and rear brakes simultaneously and with the same amount of force. In a panic situation you want to use both to their full potential. Typically, I will hit one hard, then it takes a split second before I think about how hard I'm hitting the other. But if you use both, just right, you can stop really fast.
I have one bike with a disc brake on the front, it IS a much better brake, and really smooth. In a panic situation I'd be a little worried about locking up the wheel.
Certainly the most important part of braking is not putting yourself into a hard braking situation in the first place. I think the second most important thing is to condition yourself to use both front and rear brakes simultaneously and with the same amount of force. In a panic situation you want to use both to their full potential. Typically, I will hit one hard, then it takes a split second before I think about how hard I'm hitting the other. But if you use both, just right, you can stop really fast.
I have one bike with a disc brake on the front, it IS a much better brake, and really smooth. In a panic situation I'd be a little worried about locking up the wheel.
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This is about as far as one can take suspension, chassis & braking without making huge changes that go beyond the stated scope of the project. Between the front ends mentioned in #152, it's a choice between better braking or suspension. I'd have made the same choice; a well-tuned K1 front end is surprisingly competent, the low-buck inverted fork is too soft. Unless you really like the aesthetics, or just want an inexpensive disc brake, it's more of a tradeoff than an outright gain.
This chassis setup should be pretty good to about 60mph, over decent pavement. The front drum brake is competent, IMHO, to about 55mph. Above those speeds, I'd want more fork travel...or very smooth pavement. And with a little rider skill, engine braking will yank the bike down below 55mph pretty fast. Then you can just grab a handful of brake, as needed, drama-free.
There are better front ends out there and kirrbby's twin-piston-caliper/large-diameter disc brake can deliver at least double the braking power of the stock drum. It's also effective to at least 80mph. I've had to execute a few real-life panic stops, some while riding two-up. That hydraulic front disc is in a another league. It doesn't mean that it's the only setup worth having. I ran stock drums front & rear, until 2004...about 4,000 road miles...and lived to post this.:3: Not everyone wants, or needs, the same things from a bike. Thus, there is more than one "right" answer.
FWIW, speeds above ~65mph are only good for short bursts, on these little bikes. And one can get away with a lot for the occasional short banzai blast. 80mph sounds like more fun than it really is, with a machine of this size & mass.
This chassis setup should be pretty good to about 60mph, over decent pavement. The front drum brake is competent, IMHO, to about 55mph. Above those speeds, I'd want more fork travel...or very smooth pavement. And with a little rider skill, engine braking will yank the bike down below 55mph pretty fast. Then you can just grab a handful of brake, as needed, drama-free.
There are better front ends out there and kirrbby's twin-piston-caliper/large-diameter disc brake can deliver at least double the braking power of the stock drum. It's also effective to at least 80mph. I've had to execute a few real-life panic stops, some while riding two-up. That hydraulic front disc is in a another league. It doesn't mean that it's the only setup worth having. I ran stock drums front & rear, until 2004...about 4,000 road miles...and lived to post this.:3: Not everyone wants, or needs, the same things from a bike. Thus, there is more than one "right" answer.
FWIW, speeds above ~65mph are only good for short bursts, on these little bikes. And one can get away with a lot for the occasional short banzai blast. 80mph sounds like more fun than it really is, with a machine of this size & mass.
IDK exactly how hard you ran the motor, or for how long, and that could make a difference. If it's lean, it's probably just a bit toward the lean side. I see some color on most of the side electrode and a bit on the center insulator 180-degrees away. How's it running? What kind of peak oil temps are you getting? Ambient air temp? How many miles of riding, how many above 50mph?
If the engine feels strong and throttle response is crisp, you've gotta be very close...if not spot-on. The most accurate answer will come on dyno day, if you have access to an EGA that uses a wideband O2 sensor. It doesn't have to make educated guesses, like someone sitting behind a desk, hundreds of miles away.
If the engine feels strong and throttle response is crisp, you've gotta be very close...if not spot-on. The most accurate answer will come on dyno day, if you have access to an EGA that uses a wideband O2 sensor. It doesn't have to make educated guesses, like someone sitting behind a desk, hundreds of miles away.
Tweakin
Active Member
I put around 50 miles on it with the majority of time and 40 mph and over on up and down terrain. The main jet was a 87.5 so I decided to try out the 92.5 main and do some similar riding. I do have access to a dyno with wideband but with my work schedule and daughters soccer schedule making the time to get the bike on the dyno is challenging. Just want to get it close until then.
Not enough time, mileage and sustained high-speed cruising to get any kind of handle on what it'll do under heavy load. Things change rapidly as speed increases. Power requirements increase dramatically above 50mph and that's where peak temps will spike. It's unlikely that you could run lean enough at 40mph to do damage, unless it's ascending long, steep, grades. However, increasing speed from 50mph to 60mph (for example) requires 60% more hp...that's where combustion chamber temps can run amok :flame:
At moderate speeds, under light load, you can easily get by with A:F ratios as lean as ~15:1. Under closed-throttle deceleration, ~16.1. At other end of the spectrum, WOT, ideal numbers are in the mid-to-high 12s. They'll go into rich misfire anywhere between 12.4-12.7:1, depending upon the fuel, and specific engine combo. That's rich enough to foul plugs, at low speed. Under full power, that extra fuel keeps temps under control. It also strengthens throttle response, on the way up.
Get out on the road, where 55mph can be sustained for miles at a shot, and then you'll find out how well the setup is balanced. IMO, this motor needs a lot more break-in mileage before being pushed that hard. This includes a full-on dyno workout. You're still dealing with frictional heating and a flood of metallic particles being shed from new parts.
At moderate speeds, under light load, you can easily get by with A:F ratios as lean as ~15:1. Under closed-throttle deceleration, ~16.1. At other end of the spectrum, WOT, ideal numbers are in the mid-to-high 12s. They'll go into rich misfire anywhere between 12.4-12.7:1, depending upon the fuel, and specific engine combo. That's rich enough to foul plugs, at low speed. Under full power, that extra fuel keeps temps under control. It also strengthens throttle response, on the way up.
Get out on the road, where 55mph can be sustained for miles at a shot, and then you'll find out how well the setup is balanced. IMO, this motor needs a lot more break-in mileage before being pushed that hard. This includes a full-on dyno workout. You're still dealing with frictional heating and a flood of metallic particles being shed from new parts.
Tweakin
Active Member
Bike "was" running better with one size larger main jet, only problem is the coil shit the bed on me. The one part I didn't replace new when completing the build. I guess the law of averages got me. In my haste to complete the engine instal I reused the old coil that was in pretty bad shape. New Honda coil installed and back to running strong. Pretty excited about this engine, carb and exhaust set up. 67 on a flat road with slight uphill grade at the end clocked by my gps.
Felt like it had more but didn't want to push it anymore until it is properly broken in. Also picked up a Gcraft auxiliary fuel tank to help my fear of running out.
Felt like it had more but didn't want to push it anymore until it is properly broken in. Also picked up a Gcraft auxiliary fuel tank to help my fear of running out.