360 ??

[YUMASTEPSIDE]

Just picked up an oval case square barrel motor at a swap meet for $200. I think its a 360 but I cant find any serial numbers on it anywhere, it has a 78 mm bore..........any ideas ?? It came with a full gasket set.......bit of a bonus

                   Roger

[YUMASTEPSIDE]

.......from what I've just found on the net....I'm thinking its a '69 360 X4 mx.......'68 was oval barrel (X3)......'70 was 400 with different cases....360 had 77mm bore.........anyone confirm??

                    Roger

[Mick D]

Hello Roger, both the 360 and the 400 started with 77mm bores as standard.

The easiest way to tell without measuring the stroke is to look where the Decompression valve is situated?
The 360 is located at the front, above the exhaust port.
the 400 is located at the rear of the cylinder, above and slightly to the left side.

[Mick D]

Here you go Rodger, this is a 360 with the Valve above the exhaust port.


The 360 vibrated allot due to an unrefined crankshaft balance factor.
The easiest fix is to fit a 400 crankshaft.

Then you will have the beginning of a great out come.

[Mick D]

Hey Rodger, how much profit would you like to make on it

[firko]

The easiest fix is to fit a 400 crankshaft.

Or even better a 74mm stroke 350 crank....smoooooth.

[Mick D]

The easiest fix is to fit a 400 crankshaft.

Or even better a 74mm stroke 350 crank....smoooooth.

Sooooo,,,,, how many 400 crankshafts would you like for one of your spare 350 cranks Firko? 

PS; your lattest purchase caught this evenings post

[YUMASTEPSIDE]

.....360 it is then, decompressor, front and centre ! 

                        Roger

[YUMASTEPSIDE]

.....now that we've established capacity,a few probing questions......Will this motor fit my '71 square barrel frame ??.......As I would like to keep this motor as a 360 ( or even a 350 ), whats the best option for a better crank, where do I get one and whats it going to cost me ??......and the last question that I can think of at the moment......what oversizes can I go to ??
   This bike is to be used for Vinduro's,as most of my bikes are ! 

                                               Roger

[firko]

Sooooo,,,,, how many 400 crankshafts would you like for one of your spare 350 cranks Firko

If I had a spare you'd be the bloke to get it Mick but unfortunately I've only got one spare and it's going into my 360 oval engine.
 

now that we've established capacity,a few probing questions......Will this motor fit my '71 square barrel frame ??.......As I would like to keep this motor as a 360 ( or even a 350 ), whats the best option for a better crank, where do I get one and whats it going to cost me ??......
   This bike is to be used for Vinduro's,as most of my bikes are ! 

Roger, the 360 motor will bolt straight into your frame, all of the sqaurie and radial 4 speeds have the same mountings. As Mick and I said, the 350 and 400 stroke cranks are better options but I don't think the 360 should be disregarded off hand. While I agree that 360's and to a slightly lesser extent 440's are terrible vibrators, I reckon a crank balance by somebody who knows his shit would vastly improve the engine. Considering that you're intending to use it for Vinduro's you'd want the bike to be as smooth as possible, with less chance of things vibrating off in the middle of the mulga, a bottom end balance is money really well spent. If you're thinking that it might be a good idea, PM me and I'll put you in touch with the crank guru.

and the last question that I can think of at the moment......what oversizes can I go to ??

The bores go up in .25 increments with Mahle pistons to 1mm over or even more if you can find the right Tarabusi or Wiseco piston. 

[paul]

my 360 is a 400

[firko]

 My 350 is still a 350 It's a good thing you don't race the squarie Paul as you'd be getting the tap on the shoulder from the scrutineers over your front wheel like I have .
                                                                 

[YUMASTEPSIDE]

Thanks, now the fun begins !!

                      Roger

[YUMASTEPSIDE]

0K, next set of questions.............'73 on pistons are also 77mm with 18mm pins, can they be used in the earlier square barrels???..........also I was told that it was possible to use RM400 pistons in the squaries............anyone know anything of this ??

                             Roger

[firko]

Roger, The radial fin Maico pistons are fully interchangable with the square barrel items, they're the same item. The RM400 conversion is popular with our American friends but I don't know a lot about what's involved. I'd stick to Maico Mahle pistons myself or if the dollars are short, perhaps Tarabusi or Wiseco.