Truenotch

Nah bol, I’m away for my grandmas birthday.

I CBF and told Nathan we were giving it a miss this month, but go for your lives.

Wow, that looks really good!

More like 8hp between all 4 motors? . Please build a bike with 2 engines.

I've bought a couple of small bottles of CC recently... They're about the size of a large hip flask and are made of plastic. I'm going to have a few and fill them with my poison of choice before the ride. Having a 40oz in my backpack was hard work last year!

My new radiator turned up on friday from @nick_m at Motorsport Fabrication Services in Christchurch. He made this to custom measurements with custom mount bosses, tags to attach ducting, angled inlet/outlets and a 12" fan mounted in place (not pictured). It's a really nice bit of kit! I highly recommend MFS if you're in need of a radiator or intercooler. We got to work mounting it this weekend. This is what we came up with: And with the radiator in place: The angle of the outlets worked out almost perfect: I think it's starting to look pretty good: .... Hmm, looks like it has angry eyes? Again, huge thanks to @Rhyscar for the fab work and extra brain. I wouldn't have achieved much without him. Next up for fab work is to figure out how to mount the oil cooler and to start thinking about ducting.... But for now it's back to sanding .

Wow! That looks great.

I've seen this style used with some success in the past: https://www.trademe.co.nz/business-farming-industry/industrial/manufacturing-metalwork/drills-accessories/listing-2231751981.htm?rsqid=ba82531e18eb4aab987ce06015cfbfa8-001 I'm pretty sure the arbour is upside down in all of those pictures...

Good meet . Well done to @Archetype for winning 4 FREE BURGERS in the Jalapeno eating competition!! It's amazing what a man will do for free burgers. Well done to @Zeubin for a respectable third place. And cars:

Better make sure you're there with him when he lights it up!

This is tomorrow night. A couple of us will be taking small bikes. See you there!

Good progress! Venturi collectors look like a cool idea. I've never seen inside one before.

I might bring my FA50 as a backup bike. It'll do 80kph on the flat, but is geared pretty high so could be punishing up hills. It's got a 2 litre fuel tank, terrible lights and the brakes almost work.

Sheeit, this is next week. This month is going fast! Next meet is Thursday July 18th at 7pm. See you at Burgerfuel! Here's the facebook event: https://www.facebook.com/events/348168292782181/

Hopefully the MX100... Will get started in September once the Racecar is back on its feet.

I’ve made good progress on the right hand tub now. Got most of the finishing and a coat of primer onto it. Then @Rhyscar came around with his tube bender and we started on the new radiator support: This bolts in place on the sides and will have a couple of vertical stays for the radiator and ducting mounts. Popped the guards and bumper back on for a visual inspection: And the new radiator will mount like this: With ducting to take the flow out the bonnet. Woohoo! Now back to body work in the engine bay.

Do it anyway! Bring the ragtop.

Haha, cheers man. I’ve never been much good at bogging, so half the fun was learning how to mix and lay it again... The stuff I’m using doesn’t change colour when you add hardener, so I doubled down on hardener the first time and ended up with a streaky mess to deal with. Recent applications have been much nicer! Plus the sanding is basically cardio . Its getting there now - bit of filler primer and seam sealer done. Now it’s time to start applying filler to the other side and get the rest of the bay cleaned, sanded and primed for paint.

September will be two years since I've driven this car... So I've decided that I should get it going and try to race it at the final round of the Manfeild winter series. I've not done a whole lot since 2017 due to general slackness, but have cleaned up a bunch of welds around the tubs. This was about a year ago: Fast forward to this week and I've started doing things again. More weld removal, a few holes welded up, paint removal etc. A bit of filler and the first coat of etch this evening to see how it looks: The underside is still a bit wrinkly, but it's good enough for an inner arch. Now to get the other side. to this level.. I always forget how long it takes to sand filler! It's a pretty painful job . Once both sides are in primer I can give the rest of the bay a good clean up, sand and start thinking about paint.

16 Valve club for lyfe. @Stu

Yep. And the speed of sound changes with temperature, so it's important to know the rough temperature of your pipes too.

Haha, yep, I read that last night. We need a dyno...

Hmm I don't know. The scavenging isn't necessarily done by sonic waves. As I understand it, when a the gas pressure runs down a the pipe and out the megaphone (diffusion cone) it creates an expansion wave and the gas behind it accelerates. This creates a vacuum that heads up the pipe (negative pressure wave). I starts from the small end of the diffusion cone and works its way back up towards the exhaust port. So the positive gas pressure wave effectively "falls away" as the gas in the diffusion cone expands, which creates a draw in the exhaust port. In two stroke tuning, the sonic wave(s) play a key part in creating resonance, but it only works because there is no exhaust valve in the way and you can get an almost direct connection between the inlet and exhaust sides of the engine. Sonic waves can build up into multiples which is what 2 stroke tuners are trying to achieve (true resonance). Here's quick video that might help: And a not-so-quick one that explains the sonic vs gas pressure waves and resonance in more detail: There's another video somewhere that has good high-speed photos of the gas pressure wave entering a chamber that makes it slightly easier to understand, but I'll have to search around again to find the video.

I’m curious about whether reversion/reflection cone would ever be beneficial on a 4 stroke. The diversion cone makes sense to me - the taper creates expansion waves heading out and at the same time creates a negative pressure wave that heads back up the pipe to aid scavenging IF the wave is timed correctly. I don’t see why adding reversion would work on a 4 stroke because there’s minimal fresh fuel/air in the pipes to shove back into the cylinder.

Have you done any reading about anti reversion chambers on headers / after headers? I know you tested an expansion chamber at one point, but I'm not sure if you've given these puppies a go. It sounds like the theory around stepped headers could serve a similar purpose to these anti-reversion chambers. They look like they could be fiddly to make though... There's quite a few open wheeler headers with these bits in them (high level like F2 and old F3 cars) and lots of chat in the big block speedway world too.