@tjkoyen I have found same issue with KA, engine is troublesome to start at times without choking airbox.
Biggest thing I have found with fouling issues is actually people forgetting to open and clean out their carb between race days / track days. It takes very little time but makes all the difference. Without cleaning the gunk out and every now and then checking pop off and so on, you can lose a lot of time and have some headaches with the engine bogging on throttle application.
@Eric_Gunderson1 We also had issues of throttle lag at my last race weekend. Another point is that the carb settings are very picky. It could be something as simple as that. Just throwing that out there.
Indeed I have found the carb settings to be quite picky. I have found (at least at altitude in CO) that we are often running both needles leaner than the 2.0 TO that they recommend…my engine seems to like 1.25 T.O. on Low, 1.0 Turns on high.
@Eric_Gunderson1 2 T.O. I assume that means 2 turns out, which seems excessive.
Here are the tuning tips from Remo Racing in Australia. 1 tun out for both the High and Low jets with the HW-33A carburetor.
The motors really bog sometimes and have a lag, especially if the low setting is too rich, when the kart isn’t under a load. I notice that a lot on out laps when I’m just warming up tires and not pushing hard, or formation laps as well. Once the motor stays under load the issue seems to go away.
I don’t know why they recommend 2 turns for the carb, I think we run about 1 1/8 low and 1 on the high.
One thing I have also noticed is that the carbs will draw fuel if they just sit around. I didn’t run my kart all week and took a bit of turning over while covering the airbox to get the motor running today, otherwise the cylinder was just too flooded to start. They’re fine if they sit for 6 days, Sunday to Saturday, but Sunday to Sunday was a problem, at least today. I’ll keep an eye on that as the season goes on too
@Billholt thank you for the link! I have read through that a few times as I was getting my new engine set up. The IAME factory manual recommends 2 T.O. , which is what I was referencing.
Seeing as Remo racing is the IAME distributer in Aus, i thought its manuals would actually be the IAME factory manual. Seems odd that there would be such a discepancy.
That sounds like a classic case of a pop off (inlet needle) leak if it’s excessive. Sometimes you’ll have the dab of fuel below the diaphragm in the chamber trickle out the jets, but the amount is tiny…
I must have missed that in the factory manual. I have always gone off what Remo has said, and a set of tuning lights that I run.
When I’m really trying to get to the fine edge of tuning during racing sometimes have the low jet at 50 minutes and the high at 55 minutes, and my tuning lights read that it is still “safe”.
Otherwise I just run them at 1 hour. I had over 30 hrs on the first piston. admittedly I’m not at the pointy end but I was still setting PB’s.
How much are you guys paying per season to run and maintain the engine?
Never mind, retracting.
So I just reached the 8 hour mark on my KA, and that was about the point where the top end just tanked hard. I was losing 2-3 MPH down the front straight at Road America compared to the race I ran 3 weeks before, and I was a tooth lower on gearing too.
It ran fine the previous weekend, very competitive except I was on old tires from last year but that’s not an engine issue imo. It may have been starting to drop off towards the end of the day but it wasn’t noticeable until the next weekend.
Actually I just looked at the data; it was dropping off that raceday, and I just didn’t think anything of it.
Anyways, 8 hours on a motor before needing just a piston to be competitive is pretty good, especially if the bottom end is going to hold up even longer, I’m hoping at least 20 hours but I really have no idea. It’s much better than the 6 hours for a piston and 10 for a whole rebuild we were getting with a Yamaha.
Overall I’m pretty happy with the motor and have had no complaints anywhere regarding it
I’ve been getting about 15,500, but it’s fairly dependent on track too. Shorter tracks are seeing a bit higher sometimes, New Castle wasn’t seeing quite that much at our gearing.
I haven’t had any carb issues, except that when the engine started going I was about 40 degrees cooler in EGT suddenly, so that’s something to look out for
Can you post a screenie of your speed traces with the delta. Curious what that looks like.
I wonder if you could do a ring every six hours and piston at twelve…depending how the bore looks and measures for square.
Please excuse my appalling driving in the 53.001, but the red line was 3 weeks before, the blue line was this past Saturday. Most noticeable for me at the start of the lap. I was on a 10/78 for the red line and a 10/77 for the blue line, and the motor is running 500 RPM higher on the red line and it was still accelerating up until braking, whereas on the 10/77 topped out almost 120 feet before braking. This didn’t happen with another driver’s data that I looked at, where he was on a 10/76 and still pulled out of the turn better than I had, which is why I know something is up.
I ended up starting to get in my own head since I was so off pace that I just drove terrible. I had brand new tires and was sure I should be faster than the previous set that was damn near worn to the cords. Yeah, I could’ve driven better, but I don’t think the motor should be acting like this coming out of the final turn.
Also, my Y-axis units are missing and I don’t know what I did to have that happen, but oh well ¯\(ツ)/¯
Yeah the apex speeds and so on vary a bit, but overall I think it’s fair to say you were possible down on power, especially on the top end…
One other question… any possibility we’re comparing a lap with a draft vs none?
I know I wasn’t drafting, the 52.0 was in a heat where I was 4 seconds clear of second, and the 53.0 was a practice session I was on my own during. I was thinking about that and made sure I’m looking at sessions I was on my own for
What adjustments did you make to the carb?