A pad is really the simple solution. First time I drove, MAJOR bruise ('bout hardball size) behind elbow. Now, small pad, maybe 4" X 3" X 1/4" closed cell foam, wrapped in place with ace bandage. Don’t even notice the cylinder head when driving and 0 bruising. Chicken winging-it or tucking your elbow in against your rib protector will prevent bruising but take your focus off driving.
For a while, my daughter used one of these elbow guards. It molds to her elbow size. It’s one of those baseball elbow guards.
1 Like
I use a similar McDavid product, but mine is more of a soft shell padding. It’s basically a basketball shooting sleeve with foam padding over the elbow. Light, breathable, and no bruises since 
I have a question about fuel mixture and starving/bogging.
Had a club race this past weekend at one of our local tracks… this track has a right hand turn with a VERY tight entry but an increasing radius exit that leads onto the main straight. So very low min rpm at apex, but you have the throttle pretty much pinned as you exit.
During practice the day before the race the kart was working quite well. EGTs were in the ballpark, maybe a tick rich… but kart was working well and power was good. On race day, I felt like the kart was bogging exiting the right hander and accelerating onto the straight. Not bogging in a “the kart is a little too bound up” sort of way… but like a noticeable drop in power initially exiting the corner. For instance, I would be on a good lap with 2-3 tenths green on the MyChron. Then after exiting the last right hander, I would lose all the green on the MyChron or even show a tenth red. Looking at the data compared to the day before, there was a noticeable stumble out of that corner… and I was a solid 3-4 tenths slower from exit of that turn to end of straightaway.
My question is, is it possible that the motor was too lean and fuel starving coming out of that corner? The weather was all over the place(both temp, wind, and humidity) throughout the race day, and my EGTs were way hotter than the day before. Definitely leaner than what I usually shoot for(was seeing 1140F max). I didn’t feel like the motor was too lean anywhere else, though. How susceptible are KA100s to fuel starving due to carb settings? Particularly starving on the low end?
My biggest issue with learning to tune the KA was dealing with lean bog. I was soo focused on max EGT that I had it lean enough that it was bogging off the corners exactly how you describe.
I found I was plenty quick only shooting for 1050-1100 for EGT and I’d never have to worry about lean bog when I was in that temp range.
Logic would tell you to leave the high alone and adjust the low for that condition but personally I always felt like it was lazy through the whole RPM range when I made it happy with low vs. just using the high to compensate.
2 Likes
I agree with Andy’s sentiment regarding a “lean bog”. I was used to other carbs and engines that would really feel like they were bogging if the carb was too rich. For the KA it definitely feels like it’s too rich on the low-end sometimes, and it can be caused by being too lean. It doesn’t feel like your usual fuel-starvation situation that you get with the carb being too lean, it definitely feels rich.
Seems much easier to go too lean on the low rather than too rich.
Look at your EGT! Is very fast at giving readings! Any drop, on the low-speed, coming out of a corner, can most definitely mean a lean condition. 2 cycles get hot, when they do, they can get lean. What’s it going to hurt to open the low-speed?
Will your instrument give you a recap. Of what? Any chance of an EGT read out?
Yes, it felt exactly like the motor was super rich on the bottom. Not at all like a typical “too lean fuel starve”, where the motor just kind of cuts out. But the EGTs definitely indicated that I was running too lean.
For reference, when the kart was working well during the practice day, the max EGTs were around 1040-1050F. During the race day when it was stumbling, I was seeing ~1140F. Unfortunately, I was wrenching for myself and it had rained in the morning(the track was drying over the course of the day)… so I had my hands full making changes to the chassis, etc, and I didn’t really revisit the carb tuning after morning practice. At the time I didn’t really think the carb settings were off enough to cause the stumble, because the motor felt good pretty much everywhere else… but looking back at the data and what the kart was actually doing, I think it was likely a lean condition causing the issue.
Really good info, though. Thanks guys.
Two other things you should be considering, air density and air temperature. Air density includes air temperature and barometric pressure. Still, on a hot day, cooling the engine can be a factor.
1 Like
As Al said, the air density probably changed due to the weather, and made the carb go lean because of that. It’s always tough here when the humidity starts jumping around, I can be right on one day, and then way off the next without touching anything, just the weather changed. I tend to run the low needle a little richer just to avoid this situation if I can.
I have someone charging me 287 for parts and they are asking 1000 for labor and blueprinting on a mini swift engine. And this with no dyno or break in. Thougts…?
Unfortunately, Al is no longer with us.
In your situation, we would need to know more…Is this for a rebuild and blueprint or just a blueprint? If this is some degree of a rebuild that rate seems high but not totally out of line.
That is pretty close to what I paid for a rebuild on my last one. Maybe a bit high, but I paid 1200 for a rebuild with one builder. And I have paid as low as 950 for a build (included dyno break in) with another.
Seems kind of high for labor without dyno or break-in, especially on a Mini Swift. I have had a Mini Swift rebuilt, blue printed, and dyno 3 times. Here is what I spent each time.
2017 - Builder A - $852.29 ($500 was labor, dyno and shipping)
2018 - Builder A - $1,004.06 ($500 was labor, dyno and shipping) cost difference from first rebuild was new clutch
2019 - Builder B - $886.74 ($400 was labor, dyno and shipping)
Of course, labor and dyno prices could have changed, but that’s what I’ve spent in the past.
1 Like
Was the labor for just a rebuild or a blueprint as well? I’m not sure how much a mini blueprint specifically is, but $400-$500 is pretty standard for a KA blueprint.
Most rebuilds the labor includes the “blueprinting” since there isn’t much they can do. Both of these builders are top level nationally recognized builders.
And yes, i use builder B for my KA rebuilds and the labor is the same.
Rebuild and blue print
Curious to hear what you guys are running in terms of fulcrum height and pop-off pressure. Importantly, which fuel are you using those settings with? I haven’t played around with either of these much, but I’m trying to learn when to adjust what. My understanding is that lower pop-off pressure will be richer, but not really sure on fulcrum height.
David,
I assume you are making reference to the KA. I run the fulcrum flush with the carb body. As for pop-off, this had been reviewed in another post but I find my pop-off is between 9 and 10 and hold between 6 and 7. I have used the stock spring but they do make different springs as well. Christian Fox recommended a lighter spring…
Christian Fox
pop at 8, hold at 6, needle settings the same. Try a 31 gram spring, stock is 37
I tried this in my sons kart this past weekend and it seemed to run well with the 31 gram spring but I was getting 9psi.
With all that said I am still skeptical 1 or 2 psi matters when you consider how much the diaphragm pulses.
1 Like
For mini swift i just got a new motor blueprinted by a reputable place.
1099 including dyno/shipping