Can I Make a Cheaper 2 Stroke V4?
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- Опубликовано: 27 сен 2023
- This video is a much needed update showing you how far along the design phase I am for the YZ85 based V4. The engine will use all off the shelf parts including a Triumph XC800 gearbox.
The aim is to make something like the Suter MMX500 but for a fraction of the price and with a more manageable amount of power for the average rider.
Depending on how all this goes I will possibly have a limited run manufactured.
Make sure to share this video with anyone you know who might be interested and subscribe so as not to miss any updates. 
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Wow you are good at fusion 360! And a kiwi as well ? I’m going to have to watch all your videos now and subscribe 👍
Thanks you, Fusion 360 is pretty easy to learn, although I’m probably using it at least 2-3+ hours a week. I am self taught in regards to using CAD and CAM programming.
Yep, from NZ living in Palmerston North.
I looked up PWK28 carbs, came up with 82mm long.
Awesome project mate! I'm just about to kick off building a V4 too, my plan is to use KTM 125SX parts and fit it into a BMW S1000RR chassis. I'll be watching closely!
Thanks, it’s a small world. I remember running my RGV up on your dyno years ago.
Have you started the design yet?
The disc valves on an RG500 made for easy packaging of the carbs on the sides of the motor. Performance is better than reed valves too.
Whit the carb placement you have getting filtered air to them is going to be interesting.
You’ve got some good points. My thinking is:
Reeds means I can use off the shelf Yamaha parts (less custom parts = faster build).
Frontal area will be smaller with the reeds, possibly negating the hp advantage at speed.
I’ll likely fibreglass a ducted air box for the carbs.
Also it shouldn’t wipe out the carbs in a crash.
The Aprilia GP bikes also ran disc valves and side mount carbs.
So well sir
Been having the same idea lately. This project is so cool. Keep at it! Subscribed.
definitely would like to see more detail on the conception part, keep up the good work👍
Mate, can't wait to see your next video! Been thinking of doing a Vee twin version of the NSR 500 for a while and you are now inspiring me to move forward. Built and raced a RD500 for a few years, so I dig the layout
The video is almost done. A 500 twin would be cool.
Super sir
Mikuni tm34 carbs are 83mm long.
Four of them beside each other with 90 mm cc they are 375 mm at there widest point.
Maesured from the idle adjustment screw on one side and fuel inlet on the other side.
With just enough room for the petrol hose to go between them.
I have four of them so i just laid them beside each other and measured.
They are for my rg400 engine.
I hope it will help you with the layout on the reed placement.
Thanks for that. Very useful information.
Have you had a look at that RG500 somewhere in nz with the special V4 upper case half on it?
I saw it at one of the Burt Munro rallies that I went to in the paddock at Teretonga.
It was a work in progress and had been for some time...
I’ve seen pictures of it. It’s a neat idea, but donor engines are rather pricey. Rather than find a donor RG engine, I’d rather make the entire thing.
Tillotson HL 324A carbs would be way more compact and they cost no more than $15
Thanks, I’ve never looked into the differences between motorcycle and chainsaw carbs, it will be worth investigating.
yeah¡
Also have you looked at the RZV500 Yamaha
I’ve look at everything I could find. This design is loosely based on that.
Considering you are driving the cranks through a set of gears why not just build a square four? Rotate the cylinders 90 degrees so the 4 cylinders are vertical. That would make a much more compact design. Also, you aren't showing the gear box. You may find it helpful to elaborate on that before a final design decision. I really admire your skills, keep up the great work.
Thank you, I’ll show you the gearbox next time. I did consider a square 4 but the main reason I don’t want to make a square 4 is because of the need for disc valves and that will make for a very wide engine where the carbs will be wiped out in a crash. And how much cooler is a v4 vs a square 4?
Also a 90° V engine has perfect primary balance where the square runs a balance shaft... so I've been told.
You might want to look for Neville Doyle Kawasaki 750 engine and look at the trapezoid layout of his 1970’s engine for competing with the TZ 750, was supposed to be the replacement for the KR750.
Maybe some good ideas there.
This is going to be a fun project and ride.
It’s all there you just have to find it in the metal.
Take care.
I am familiar with the engine you’re talking about I’ve got a few pictures of it floating around on my PC.
Hopefully it’ll ride like a 600cc but much lighter.
@@OddsandEndsMachining I had some info and photos, long lost, from either REVS or Two Wheels, the Horror was still on green paper then, which went into a lot of technical details. Greg Hansford and Nev were very excited by the possibilities of the engine and bike.
Wonder what it would have been like as a big banger.
Looking forward to the progress reports in the future.
Any reason you went with 4 separate cranks instead of two parallel twins? A lot of aftermarket support for the Yamaha 350’s (rd/yfz) and even more for the 701 superjet engine.
Ease of servicing and cost. Yz85 cranks are still being made in large volumes and they are cheap.
I do have a banshee engine in my RGV and if I was making V twin I would’ve use a stroker Yamaha banshee crank for simplicity. Although they aren’t as cheap as the yz units and aren’t as easy to rebuild and true.
I feel the engine is not working for the frame geo. Would it not be better to slop the pistons to the rear then using direct injection to each cylinder. The crank needs to be low down giving a better center of gravity flow to the bike and more metal to encase the bearings. NZ had a famous bike builder who scratched a V twin this design would be better for greater power to the back wheel. Anyway just a thought.
The main concern is having the right exhaust length to make good power, if the cylinder was rearward the exhaust would be very short and would mean the bike would need to rev impossibly high to make any power.
It would make for very easy throttle body/carb placement though.
Maybe open the bank angle up? Assuming you’re going to fire two cylinders at once like the RSA/RSW 250’s
Both will be fired at once, top and bottom 90 degrees apart. Well that’s the plan for now.
Idk single carb with a throttle body? Maybe using planet gears could reduce clutch size
I’ve definitely considered sharing a carb between cylinders, although that will be a last resort.
Any reason you’ve gone for 80 degrees layout ? Packaging r u not concerned about primary vibrations