Box Stock

hh

Keep in mind those results are not only because of tweaks to the motor , the Gearing used had a big role in those results as well.
 
racing promotor said:
Keep in mind those results are not only because of tweaks to the motor , the Gearing used had a big role in those results as well.
Click to expand...
I'm not sure what you're getting at.

The problem I have is that at WOT this engine will only go 57-58 mph. But after 1/2 mile or approx 60 seconds of WOT it suddenly runs at 64 mph and will stay there until I let off. Nothing is slipping, nothing is bogging. It almost sounds like the engine 'cleans up' and sounds better.

From what I've experienced usually an engine will run worse at extended WOT.
 
05 Prowler said:
I mean I drive it and it tops out at 64 mph. It should go from 0 to 64 mph, right?
Not 0 to 58, then AS I'M DRIVING AS IN NEVER STOPPED, it goes to 64 MPH.

Heres a video, it has no sound because I put the speed on the screen.
Here is the same video with sound.

As you can see I didn't stop and change the gearing, didn't stop and modify the engine, didn't stop and seal an air leak, etc.
Click to expand...

He is not saying you stopped and sealed an airleak but rather an airleak sealed due to heatsoak and expansion of materials (block, rings, intake, etc.)
 
How steep is the downgrade a half mile down the road. Lol. From the looks of the combustion chamber, that is the point the oil burned off and leaned out to fuel. Did you break it in before this WOT test?
 
Not really sure who you think is being "spiteful" but you may not be getting the answers you are looking for or expecting because this is a kart racing forum and not an off road (off track) karting forum and not something many people here have experience with. We typically don't measure engine performance in a half mile straight line or MPH but usually by tenths of seconds per lap on oval tracks. Just my 2 cents though.
 
All that , do you have a theory you want confirmation of ?
At 52 years old you should know better then tear off down a public highway at 50+ in a go kart .
U-tube might Be the answer.
You don't know if its down hill at the end , unless you used a transit or a new fangled gps/ theolite system .
Either the temp comes up enough to optimize the afr or it leans out gaining speed .
Possibly an unexplained phenomenon.
 
Last edited:
05 Prowler said:
Please don't take this the wrong way.
You clearly didn't read or didn't understand my first post. Or look at the videos.

What are you basing this comment of off?

I said I built it in 2013 and provided 3 pictures titled "old pics" and two titled "as of today"

When it was built it had been run and broken in while stock, that's the carbon stain on the head I didn't wipe off. So yes it was broken in and had 8 hours on it in 2013. As I said.

The video shows me driving it down the road both ways and if you pay close enough attention you can see the road is flat. Dead flat. Certainly not enough to cause a 6 mph increase.

I also said it has the original spark plug in it and it looks brand new. I did say I changed the jets a few times.

I cut the original spark plug and there's only a hardly visible gray spot on one side. So that will answer another question, yes I changed the spark plug a few times recently. This spark plug came with it out of the hf box and ran the 8 hours 10 years ago. In short its not burning oil.

I've been working on small engines my whole life, as a hobby, my family ran the largest rental equipment/small engine repair shop in my area from the early 70s to the early 90s.

This doesn't mean I'm anything. I have built a ton of flatheads though because that's mostly all I had access to back then.

I've been around this all my life but it's not what I do for a living. I saw this site and thought the people here have a lot of experience and this is a problem I've never had. Maybe someone can help.

Why can't anyone say anything educational?
Ted did and Kartracing LA. I don't understand why the simplicity of the replies. Like why was I told it goes faster because of the gearing and modifications I made? No crap.

I'm almost 52 years old, I can be talked to like I'm 52 years old, I'll probably understand. But I won't have to because everyone is going to be spiteful for me simply explaining myself better.
Click to expand...

Am I reading this right that your spark plug looks brand new or even a tint of grey color after a run? This could be an indicator of lean conditions. Your spark plug should have a mild brown tint at minimum similar to the buildup on the head. I'd rather it be black than clean. Do you have another carb you can try on it? There are multiple reputable and even one, disclaimer: in my opinion best, 390 builders for us guys who race karts and most, if not all, will not build a 390 for gas on a small block due to tuning/driveability issues. They will only build them for methanol on small blocks
 
It seems to me that it is most likely a build of heat. All tolerances change with heat, air fuel ratio, ring piston cylinder sealing, valve lash, valve opening and closing events. Even the clearances of the karts friction components, bearings, chain, tire pressures.
 
You must log in or register to reply here.
Back
Top