Two Stroke Motocross

Two Stroke Motocross Forum => Vintage Two Strokes => Topic started by: citabjockey on June 21, 2012, 09:22:56 PM

Title: Vintage Yamaha 360, Woods Riding!
Post by: citabjockey on June 21, 2012, 09:22:56 PM: Took a dual sport ride yesterday in the CA Sierra Nevada foothills at Pipi Valley outiside Pioneer.

For some reason I have a hard time keeping up with my buddies!
Title: Vintage Yamaha 360, Woods Riding!
Post by: TMKIWI on June 21, 2012, 10:46:00 PM: I think the main thing slowing your bike down compared to the modern bikes is the Mirror.
Title: Vintage Yamaha 360, Woods Riding!
Post by: SachsGS on June 22, 2012, 03:21:45 PM: You have to convince your buddies to get vintage bikes and then you can all go on a retro trail ride.The very first Can Am 250 TnT's were sure ahead of their time and they are road legal.
Title: Vintage Yamaha 360, Woods Riding!
Post by: citabjockey on June 22, 2012, 04:25:03 PM: I had a (I think) '77 vintage CanAm 175 qualifier (the rusty red one with the lay down shocks in the back) with a street plate on it back in the early 80s. That thing was a blast (until it ate 4th gear). Great power, quiet, easy to ride, oil injection, cushy legs. Yet ANOTHER bike I should have kept.... *sigh*

The guy on the YZ in that video restores bikes for fun and it very good at it. But he seems to have no interest in riding vintage on dirt himeslf. He just sold a Bultaco 360 Alpina. On the street he rides a daytona 400. The other guy rides a '76 honda 750 hondamatic (!) on the street for fun. But again, no go for vintage on dirt.

Quote from: SachsGS on June 22, 2012, 10:21:45 PM
You have to convince your buddies to get vintage bikes and then you can all go on a retro trail ride.The very first Can Am 250 TnT's were sure ahead of their time and they are road legal.
Title: Vintage Yamaha 360, Woods Riding!
Post by: SachsGS on June 25, 2012, 04:33:49 AM: I have a vintage Ossa Super Pioneer 250 enduro and it is a beautiful bike,as light as a 125,smooth,torquey power and nice handling.It takes about half a kick to start the bike as well.
Title: Vintage Yamaha 360, Woods Riding!
Post by: citabjockey on June 25, 2012, 06:44:09 AM: sounds very cool!

but -- maybe you want to check compression on that thing? ;-)

Quote from: SachsGS on June 25, 2012, 11:33:49 AM
I have a vintage Ossa Super Pioneer 250 enduro and it is a beautiful bike,as light as a 125,smooth,torquey power and nice handling.It takes about half a kick to start the bike as well.
Title: Vintage Yamaha 360, Woods Riding!
Post by: SachsGS on June 25, 2012, 03:56:41 PM: The old Ossa's had a long kickstart that spins the motor over a "kazillion" times hence the half kick starting.
Title: Vintage Yamaha 360, Woods Riding!
Post by: Coop on July 01, 2012, 01:38:34 AM: Good stuff.
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 07, 2012, 06:24:23 AM: Don't you fall off and wreak that thing! Good on you for ridding it in the real world. I trail ride my 350 Bighorn here in NZ, hard work but a lot of fun.
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 07, 2012, 09:01:51 AM
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 07, 2012, 09:08:59 AM
Title: Vintage Yamaha 360, Woods Riding!
Post by: citabjockey on September 07, 2012, 02:04:14 PM: Is that a bighorn? With a 2nd air intake for the rotary valves cut into the right side case?
Interesting bike
Title: Vintage Yamaha 360, Woods Riding!
Post by: SachsGS on September 07, 2012, 04:03:19 PM: Is that a hand fabricated exhaust?
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 07, 2012, 07:54:25 PM: Yes it's a bit wide and awkward for trail rides but it's used mostly for VMX, pre 75 open class. Hole in the side gives more power, cool air. Air cleaner has a sock over it replaced every race. Pipe is a reworked ( rewelded ) FMF unit. Rotary valve engines can still deliver startling performance with a bit of "modern" stuff inside. There is not a lot of original Kawasaki inside.
Title: Vintage Yamaha 360, Woods Riding!
Post by: Logan Dewey on September 07, 2012, 11:30:12 PM: The old smokers sound like crf50's in a way.
Title: Vintage Yamaha 360, Woods Riding!
Post by: gpnewhouse7 on September 08, 2012, 11:44:34 AM: Uniflow have you got any close up pics of that engine, Iv never seen a rotary valve smoker before, how does it work? I love the older bikes for reasons like this, they just used to have so many cool, totally different ideas on them but now you can take a look at any of the big motocross brands adult bikes and they're all the same (pretty much).

I read a book about John Britain a few years ago and that guy built some amazing bikes, anyone who is even slightly into the design of bikes should look at the bikes he made.

I don't see where the engineers of today get all this following the crowd behaviour from, if any of them raced the bikes that they make they'd know that you can't pass someone by following them. TM shouldn't be making updated blue Honda cr`s, a company of that size should be instead just going out and finding new ways of doing things.

Look at what Yamaha did when they introduced the monoshock, or look at how John Britain`s bikes did with their crazy suspension setup.
Title: Vintage Yamaha 360, Woods Riding!
Post by: SachsGS on September 08, 2012, 03:28:19 PM: Right here in North America Bombardier built disc (rotary) valve Can Am motorcycles in the 70's and early 80's.

Innovation follows money and in these modern times offroad motorcycles are not very profitable so manufacturers don't stray too far from the beaten path.
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 09, 2012, 08:03:18 AM
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 09, 2012, 08:26:30 AM
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 09, 2012, 08:30:55 AM: Out riding on Sunday, Taupo Berm Buster trail ride. A bit of tuning. Runs on E90, 90% ethanol and 10% petrol.
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 09, 2012, 10:14:47 AM
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 09, 2012, 10:24:07 AM: This what's housed behind the air cleaner. Throttle body is from when it was mechanical fuel injection.
Title: Vintage Yamaha 360, Woods Riding!
Post by: gpnewhouse7 on September 09, 2012, 10:41:51 AM: Did most of this come standard on the bike or have you modified it? That old kawi of yours seems to have more modern tech than most modern bikes have.
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 09, 2012, 09:06:27 PM
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 09, 2012, 09:09:10 PM
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 09, 2012, 09:21:10 PM: Yes modified a bit. I'm using it as a test hack to learn about EFI on twostrokes. I have a spare standard ish engine for offical racing. I'm injecting into the crankcase at the back transfer port. The Kawasaki has an air cavity, suitable for fitting two Bosch injectors and a pressure regulator. Pump is under the engine, you can just see it with mud all over it from the weekend just gone. Link controller is under the seat with a Ignitec ignition beside it. Ignitec runs the servo that powers the vairable rotary valve housing, you can see the drive cables behind the throttle body. This gives a rotary valve timing from 55 to 80 degrees ATDC. More top end power than a reed engine with the flexability of the reed engine. But more complicated! The engine is way too much for the frame and shocks, but it's just a test hack.
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 09, 2012, 09:34:45 PM: The problem is because it's an old bike no one takes the technology in it that seriously and is hard to use the engine and ride fast, even in a straight line. I've just purchased a YZF 250 to take the engine out and replace it with a rotary valve EFI water cooled twostroke. Should handle a bit better.
Title: Vintage Yamaha 360, Woods Riding!
Post by: citabjockey on September 09, 2012, 09:53:46 PM: Uniflow:

Comment 1: this is just so cool! Great to see such a testbed under real development now! Thanks!

Comment 2: you need to start a dedicated thread on this bike (and maybe another on the YZ250 as you dig into it).

Now for the specifics -- :-)

How is it running? does it start easy? idle? give good plug color for mixture at most (all?) rpms and throttle settings? Do the injectors pump based on thottle position or on manifold (i.e. crankcase) pressure?

You have a servo to rotate the rotary valve's "stationary" plate according to a rpm curve?

do you run O2 sensors? Engine and ambient temps?

Can you keep the front end down on this thing at all? ;-)

have you put this frankenstein on a dyno? Do you have access to one?

What is this rotary valve water cooled EFI engine you mention for your YZ250?

Thanks again for posting.
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 09, 2012, 10:56:51 PM: Sorry for taking over the thread, after all it was about the RT2 360 trail riding. It's just good to see there are still twostroke people out there. Seems to have gone all fourstroke here in NZ. Just a few old fools like me still flying the twostroke flage. With the new computers available now it's possible to make the twostroke something it never was. It's got nothing to do with technology, if I can do it to this old 350 any manufacturer could, it just seems the big guy's aren't interested.
Title: Vintage Yamaha 360, Woods Riding!
Post by: gpnewhouse7 on September 09, 2012, 11:23:57 PM: I should of known you were from New Zealand when you did all that modifying to such an old bike. You NEED to start a thread on that thing.
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 10, 2012, 01:06:09 AM: Yes I'll start a new thread. Some quick answers. Yes runs well now. idles smooth, starts well when the day is hot or engine is hot. Ethanol won't vaporize well when cold so I use a little petrol squirt bottle to start from cold, first kick usually. Injection timing is critical around transfer opening. Injection can be staged to minimize fuel loss out the exhaust, at least a lower engine speeds. Throttle uses a TPS. Crankcase pressure is sampled by a small valve connected to the crankcase, is only reads pressure ( or vacume ) when the injectors are on. So far only "seat of the pants" tuning. Yes rotary valve case moves with RPM ( this is a very good feature for a rotary valve engine). The "new" engine will be a made up unit ( for the YZF ) . I'm also doing a "converstion" for a YZ250 T for the local Yamaha shop. I think it will be too dear to sell as a kit, but lets just see if it works first. Yes I have access to a dyno but they cost so I've decided to get it tuned as close as I can first.
Title: Vintage Yamaha 360, Woods Riding!
Post by: SachsGS on September 10, 2012, 02:41:43 AM: Fascinating!

P.S. Are you related to Herbert Schek by any chance? You make that old Bighorn look like an 80.
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 11, 2012, 04:29:03 AM: I have to stand on the foot pegs to start it, buggered hip. citabjockey, have you had any trouble with that RT2 gearbox? Have you a picture of the RT parked?
Title: Vintage Yamaha 360, Woods Riding!
Post by: citabjockey on September 11, 2012, 04:52:56 AM: The bike is an RT3 (1973 model, RT2 was 72 with a 19" front, mine has the 21). Absolutely no issue with the gear box. Shifts like the proverbial hot knife... The whole bike is built like a Sherman tank -- very tough and over engineered. Puts a huge grin on my face every time I ride it.
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 11, 2012, 06:59:33 AM: Very nice. I had one ( 2, one in a box for parts) years ago but in a fit of shortsightedness scraped it! ( them ). I always thought mine was an RT2, it had reeds. I think the RT1 was piston port? The gearbox on mine was not too good. I ended up changing the gear clusters out of a DT 400. The 400's had undercut drive dogs where as the RT's and DT360's did not. Fromm memory I had to change the clutch as well?
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 11, 2012, 07:00:50 AM: This is a DT360 I used to race in VMX a while ago.
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 11, 2012, 07:04:37 AM: This also had 400 gear clusters, clutch and the DT400 head. Because it had a central plug.
Title: Vintage Yamaha 360, Woods Riding!
Post by: citabjockey on September 11, 2012, 07:13:16 AM: Interesting point regarding the undercut dogs on the 400. Is this the case for both the DT and MX400 models?

So can you wrangle up some video of that bighorn? I for one would love to see and hear that monster running.
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 11, 2012, 08:55:11 AM: This is montage of racing at Wakatane two years ago. Somewhere in the middle is the bighorn running. This was with the lower comp head and the mechanical fuel injection ( similar to a Hilborn system) , never the less it did win one race and second in an other. You can see that the old guy riding it needs to try a little harder!
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 11, 2012, 09:10:58 AM: This video is pre the vairable rotary housing. The bighorn is coming to pieces this weekend, as I was taking the photos for you with the throttle body off I noticed the rotary valve is lose. There is a pin that drives the valve and it's had some damage in the past, it seems I didn't do a very good job of fixing it, I'll need to pull the crank out and remachine the drive pin hole out to a larger size. Make a stepped pin to suit. Next time I'm out with the old girl I'll get some video. Our racing starts in a month so it has to be running good for that. I'm going to run in the pre 75 open class with this EFI engine first, untill someone complains. I might have to go back to the old mechanical injection engine you see in the video.
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 11, 2012, 09:17:53 AM: This is typical of a VMX racing in New Zealand, mostly natural terrain. Right up to 1985 bikes.
Title: Vintage Yamaha 360, Woods Riding!
Post by: 2T Institute on September 11, 2012, 02:56:26 PM: Quote from: Uniflow on September 11, 2012, 04:10:58 PM
This video is pre the vairable rotary housing. The bighorn is coming to pieces this weekend, as I was taking the photos for you with the throttle body off I noticed the rotary valve is lose. There is a pin that drives the valve and it's had some damage in the past, it seems I didn't do a very good job of fixing it, I'll need to pull the crank out and remachine the drive pin hole out to a larger size. Make a stepped pin to suit. Next time I'm out with the old girl I'll get some video. Our racing starts in a month so it has to be running good for that. I'm going to run in the pre 75 open class with this EFI engine first, untill someone complains. I might have to go back to the old mechanical injection engine you see in the video.

I can see the engine has spent some at Kaitemako Rd Tauranga I have a Big Horn motor myself a Skidoo cylinder could easily fit onto the Big Horn cases.
Title: Vintage Yamaha 360, Woods Riding!
Post by: SachsGS on September 11, 2012, 03:55:30 PM: How do you pressurize and time the fuel with the mechanical system? Also, why are there so few Euro bikes in the vintage and evo classes in NZ? I think I saw one CZ in your video and that was it for non Japanese bikes. Here in NA it would be a sea of Maicos.

You got it right those old RTs and DTs were built like tanks, 300 lbs of over engineering.
Title: Vintage Yamaha 360, Woods Riding!
Post by: Uniflow on September 11, 2012, 09:45:00 PM: Well well, who do we have here? Yes Wobbly and I talk and there has certainly been some input from him. We build some stuff for him and his RZ based engines.
Fuel in the MFI system was pressurized by a small pump run off the flywheel side of the crankshaft. Based on a Honda 50 oil pump. Continuous flow to a tapered needle in the throttle body with a vairable flow back to the tank. When it worked well, it worked very well but when it didn't ( most of last season ) it was a disaster. That's why I started playing with EFI. From what I know now I think I could go back to MFI with a little better results, still not as accurite as EFI.
We didn't see many Euro bikes in NZ, not sure why? Cost maybe? USA sucking up all the stock?
The ones we did see usually ended up broken and were expensive to fix.