inline or straight 4 cylinder 2 stroke

[dollydog]

after MUCH googling etc, i cannot find an instance of a modern inline 4 cylinder 2 stroke engine - well not for a bike anyway. apart from mr millyard's welded together crankcases to make his multi's, i'm stumped. i'd love to build an engine using the gt250's as my base. the crank would be fairly easy, but the crankcases are such a weird shape, getting 2 of them side by side looks virtually impossible. converting an inline 4 cylinder 4 stroke to 2 stroke looks just as difficult. any thoughts/ideas would be welcome. apart from don't do it
cheers, dd.

[daxman]

I think Millyard is pretty approachable and now has a column in Classic MCM. why not ask him how he'd do it?

[dollydog]

hi dax, i don't think he's ever done the gt250's though, and i can't say i blame him. the only way i worked out how to do it would need 3 lots of gt250 crankcases. or i suppose the easier option would be to start with a gt380 engine? same bore and stroke, but the cranks are smaller. this is the one project i want to achieve before i peg out. determination is there, just stymied at every turn so far. but i'll keep trying and drawing on beer mats etc
cheers, dd.

[Alan H]

Mercury outboards. I think they did a straight 6 as well.
Lots ofsingles, twins, straight 3s, v4s, v6 & v8s too but all expensive - and water cooled for some reason......

A few years ago, Ford did a 3 pot 2 stroke with 'fourstroke' bottom end and (I think) a supercharger and fuel injection. Lots on t'interweb about it, so summat like that should keep you occupied for an hour or 2.

[daxman]

Jet skis and 'skidoos' also feature some highly tuned 2T motors I believe

[titan performance]

Brave man...a project I could only dream of. Could you cut the gear box off, then cut the engine down the middle, and add a cylinder to each end of a second complete motor?....

Didn't Yamaha prototype a 4 cylinder in-line 2 stroke road bike back in the 70s? What about the TZ 700/750, that was an in-line 4.
I bought a Suzuki GT500 from Allen Millyard, which he was going to add a cylinder to, but decided against, as Suzui had already built a 750/3....and back in the late 70s, we had a local sidecar racer who was trying to join a pair of Suzuki 500s, though never was successful.

I think you should graft a couple GT500s together for a 1000cc/4, or maybe a couple of RM500s for a twin with awesome power...good luck with what ever you decide on.

[dollydog]

hi titan, with 20 or so t250/gt250 engines in my shed and one t500 crankcase, what would you use?
the only way i worked it out to anything like fit together was using 3 sets of crankcases. i've got quite a few damaged in different places [never throw owt away] crankcases which i could use to cut up. i'll also need 3 crankshafts to make the 4 cylinder crank. it's how they press together, you couldn't do it with 2 cranks, i've tried. luckily i've got a boxful of knackered cranks, some/all for rebuild. the tz's could welll have been inline 4's, as they were made by doubling up 2 x tz350 engines. all i can think of is the crankcases were 'easy' to join - like the kawasaki triples - not like the gt250 crankcases, which are a nightmare. there's nothing like a square, flat bit on them. they'd have to be laser cut for accuracy and then who could weld them? that would be a mammoth task i presume, without warping/twisting them. unfortunately i should have started this 20 years ago, unfortunately i couldn't afford it then years are running out, i need to get on with it before the morning i wake up dead
cheers, dd.

[busa1300]

TZ700/750 had a regular upper and lower crankcase
Nothing bolting two engines together
They did use a pair of TZ350 barrels initially though.



Yamaha also had an inline 4cyl stroker in snowmobiles.

[Alan H]

i need to get on with it before the morning i wake up dead
cheers, dd.

Try and avoid that bud, it would be very annoying.

[dollydog]

thanks alan, i'll try my best not to do it soon
busa, i'm not much up on yam engines, i just remember reading something about joining 2 tz350 engines together to make the [very rare] tz700. unfortunately the chances of getting a snowmobile engine here in england are approximately nil, but thanks anyway
cheers, dd.

[titan performance]

Well seeing as you have so many 250 cases, I think you best aim for a 500/4....watching with great interest and admiration.