Best pre 75 Four stroke motor ?

[Rosco400]

Have a complete 73 250 maico which wouldnt mind setting up as a dirt tracker, would like a 250 fourstroke to make competetive but looking for opinions/reason to which motor would be beneficial to compliment the bike. Open to British or Jap but want motor sitting in bike to look aesthetically correct i.e, as if it was meant to be.
Cheers

[Noel]

If its complete whats wrong with the Maico motor,
If you want to go four stroke look at what # 52 was doing to the pre75 over 50's at Barleigh ranch.
250 Honda motorsport engine tweeked

[clutchslip]

Hey Rosco,

Brit motors are going to be very thin on the ground in that capacity size...things start to get interesting at around the 400cc level, but even then, many are pre-unit and as such might need more space than you have. You could forget conventional wisdom and try and do something with the Matchless semi-unit/unit 250 found in amongst other things the G2CS. This is a link to the 'model' you're after:

http://www.flickr.com/photos/kernowcopia/3921048132/

Bikeboneyard have a cheap one for sale here:

http://www.bikeboneyard.com/matchless.html

Make no mistake though, this is still a big unit for its size, especially across the cases. Its a bit of a shame it was never developed by the factory. Interestingly they did make a scrambles version (as in the picture maybe), so hotter cams must have been available at one time. Maybe not enough to persuade you not to go Jap, but I would personally like to see what could be done with these motors..

[Noel]

As if Rosco would even see the bike on flickr
noel

[Rosco400]

As if Rosco would even see the bike on flickr
noel

I kinda checked out some kinda motor

[firko]

Don't do it Rossco. To cut up a complete Maico to undertake a less than satisfactory engine swap is a bit sad. The stock Honda XL Motorsports frame is fine once you grind all the crapola off it . To answer your question though, the Honda 250 with a 305 kit is my favourite. Gearboxes last much longer than in the big strokers.

[DR]

what about a C15? I hear they go alright

[Rosco400]

If its complete whats wrong with the Maico motor,
If you want to go four stroke look at what # 52 was doing to the pre75 over 50's at Barleigh ranch.
250 Honda motorsport engine tweeked

Motors Good, just looking what may be achieved,

#52 was inspirational and it sounded sweet running around, think ive hear louder posty bikes, that 250 motored like ive not seen, it seemed to have so much more than anything else in the class

Hey Rosco,

Brit motors are going to be very thin on the ground in that capacity size...things start to get interesting at around the 400cc level, but even then, many are pre-unit and as such might need more space than you have. You could forget conventional wisdom and try and do something with the Matchless semi-unit/unit 250 found in amongst other things the G2CS. This is a link to the 'model' you're after:

http://www.flickr.com/photos/kernowcopia/3921048132/

Bikeboneyard have a cheap one for sale here:

http://www.bikeboneyard.com/matchless.html

Make no mistake though, this is still a big unit for its size, especially across the cases. Its a bit of a shame it was never developed by the factory. Interestingly they did make a scrambles version (as in the picture maybe), so hotter cams must have been available at one time. Maybe not enough to persuade you not to go Jap, but I would personally like to see what could be done with these motors..

I would think stock motor would be a bit of a slug, dont know much about them

Don't do it Rossco. To cut up a complete Maico to undertake a less than satisfactory engine swap is a bit sad. The stock Honda XL Motorsports frame is fine once you grind all the crapola off it . To answer your question though, the Honda 250 with a 305 kit is my favourite. Gearboxes last much longer than in the big strokers.

That has been my thoughts for a while with it as well, just weighing up the options, would like good set up pre 75 dirt tracker tho and have this spare sitting away doing nothing

[Grasy 6]

Don't waste a good bike,With the result on at the Ranch on the weekend in the over 50 yrs 250 cc race the modifications Pete #52  has made to his Motosport 250 (to be precise 262 cc legal engine for the class).Pete would have liked the engine stripped down to confirm the fact. This is a cheap ticket using modern bits only top end stuff(you will have to do the rest of the thinking from here on as we are a fairly secretive bunch here in the Godfather capital) & easier to ride then the two strokes.  

[Rosco400]

Pete would have liked the engine stripped down to confirm the fact. This is a cheap ticket using modern bits only top end stuff(you will have to do the rest of the thinking from here on as we are a fairly secretive bunch here in the Godfather capital) & easier to ride then the two strokes.  

C'mon stripping it down was the last thing it needs, running to sweet for that, sounded close to a 250 to worry about that stuff, now bit of expansion on the secretative stuff is what we need to know, ive heard bunnings 750 watt generators revving harder

[Lozza]

That 250 of your sounded like a hairy goat Rossco plus good 4T engines are in the same league santa claus and the tooth fairy. I've seen a 250 Maico and they would be a doddle to get some serious torque out of.

[Grasy 6]

Firko shame you left before lunch break on Sunday as Pete & I went for a wander around the track then for a yarn with you, but you had disappeared.
Regarging the XL 250 gearboxes they are fairly tough as that is what we run in our big bore 350 engines close ratio compared to the stock 350 box . The engine I use is on it's second 250 gear train after 14 yrs & about 6 big ends (until I went to the Carillo option)when assembled carefully they are near bullet proof.

[Rosco400]

doddle

  whats a doddle Lozza

The motorsport is an option and suspect spares would be plentiful.

 Maico produce its first 4t engine in what year Firko, just another brainwave

[firko]

Yeah mate, sorry to have to leave early but this shit happens a lot lately.
I ran a stock bore 350 with Carillo rod, Venolia 12:1 piston, Megacycle roller cam, welded up rockers, some nice portwork and 36mm Amal concentric in my Champion frame back in the 90s and had a hard time keeping 3rd gear in it. I also ran a 420 engine, stock other than a mild cam and the Henry Abe big bore kit and had the same 3rd gear hassles. I was using a Mk8 Bultaco rear hub with no cush drive so I decided to change over to a Yamaha DT250 wheel with cush drive and the gear problem disappeared. The third engine I had was the 305 Yoshimura stage 3 engine and it hooted. I've been offered my old 350 engine back from the current owner and I'm tempted. That thing dug trenches.
I may be taking a drive down to visit friends in Yenda later in the year so I'll look you guys up for a beer or two and talk about some upcoming "things".

Maico produce its first 4t engine in what year Firko, just another brainwave

Maico never released a production 4 stroker Ross.

[Rosco400]

Maico produce its first 4t engine in what year Firko, just another brainwave

Maico never released a production 4 stroker Ross.

Ok, thinking of the grafts I saw in another thread, too technical for me