Harris magnum 2 engine position.

[clivegto]

What are peoples opinions on mounting a oil cooled 1127 motor in a magnum 2 frame, is it best to have the weight forward or as far back as possible. Have seen it do e both ways. Any advantages or disadvantages with either method?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Edited November 10, 2018 by clivegto

[dupersunc]

Sprocket to swing arm pivot position is the key.   Sorted everything else out after that.

[clivegto]

26 minutes ago, dupersunc said:

Sprocket to swing arm pivot position is the key.   Sorted everything else out after that.

So in theory the closer & level the front sprocket is to the arm spindle the better.

[nlovien]

few yrs back I stuck a gsxr1100L into a mag3 originally for a gpz1100  - i.e. plenty room - I did bias towards fwd weight versus getting the sprocket as near to swingarm pivot - maybe  by 10 to 15mm  after much suspension tweaking I just loved how this bike could be pinned on the front end ( ok also had 16" 130 section front wheel) - -  the only bit I would say was noticeable was when  driving hard out of a corner whilst still cranked over it needed a fair bit of counter steer input to hold the line - wrecked the bike before I sorted this - could have been rear squat effect related - could have been something else - noting only observed when pushing hard 

since then my solution would be - as per dupersunc's good advice - then, if you want to play with fwd weight bias ( usually a good thing with these older chassis ) then fit eccentric head bearings - i.e. pull the rake back by maybe 1 deg. - - not for the trail - you need to work this via the yoke offset afterwards - - but to pull the front wheel back and hence get some more fwd weight bias - can also be improved by a longer swing arm

[dupersunc]

41 minutes ago, nlovien said:

few yrs back I stuck a gsxr1100L into a mag3 originally for a gpz1100  - i.e. plenty room - I did bias towards fwd weight versus getting the sprocket as near to swingarm pivot - maybe  by 10 to 15mm  after much suspension tweaking I just loved how this bike could be pinned on the front end ( ok also had 16" 130 section front wheel) - -  the only bit I would say was noticeable was when  driving hard out of a corner whilst still cranked over it needed a fair bit of counter steer input to hold the line - wrecked the bike before I sorted this - could have been rear squat effect related - could have been something else - noting only observed when pushing hard 

since then my solution would be - as per dupersunc's good advice - then, if you want to play with fwd weight bias ( usually a good thing with these older chassis ) then fit eccentric head bearings - i.e. pull the rake back by maybe 1 deg. - - not for the trail - you need to work this via the yoke offset afterwards - - but to pull the front wheel back and hence get some more fwd weight bias - can also be improved by a longer swing arm

This.

[dupersunc]

42 minutes ago, clivegto said:

So in theory the closer & level the front sprocket is to the arm spindle the better.

That's a good start.

Ideally if you project a line through the rear wheel spindle and swing arm pivot it should run 10mm above the front sprocket centre line at ride height.

[Dezza]

On 11/11/2018 at 12:12 AM, clivegto said:

What are peoples opinions on mounting a oil cooled 1127 motor in a magnum 2 frame, is it best to have the weight forward or as far back as possible. Have seen it do e both ways. Any advantages or disadvantages with either method?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Aren't you constrained to some extent by the rear upper engine mount? Unless you go in for major frame surgery to move the rear mount, if these mounts are aligned as shown in the picture with the yellow frame, doesn't this largely determine where the engine is going to sit other than being able to rotate it slightly around this point a little bit either up or down?

[nlovien]

one thing I found with the gsxr motor was the loose fit of mi bolts through the cases so I reemed out the mounts and machined up inserts to get a nice snug fit - ok a bit pedantic but mi take is - where you can - these little tweaks can all add up - my learning example is a P&M frame - when you see the level of detail they go to to achieving a really snug engine to frame fit 

plenty scope to playing with that rear top mount via doglegging the spacers - i'd think of - the short LH side a solid bush with x 2 off centre threads and the longer RH side = weld the bolt off centre and thread the otherside - you assembly these spacers to the engine 1st then align with the frame -  just an example

[SiBag]

My frame had a gs1000 in when I first got it. To put the B12 motor I used the front engine mount and plated over the rear. A left the original mounting holes as can be seen.

Edited November 12, 2018 by SiBag

[clivegto]

6 hours ago, SiBag said:

My frame had a gs1000 in when I first got it. To put the B12 motor I used the front engine mount and plated over the rear. A left the original mounting holes as can be seen.

Green frame is the one I am fitting the 1127 motor to. Interestingly the green frame is different to your blue one but very simlar to the red one I have.

[Swirl]

The green one had a Kwak motor in at some point, when I got it it had a slabby 750 in, that rear mount could of been changed at some point, what's it look like on the yellow frame and what motor was in the yellow frame originally

[clivegto]

17 minutes ago, Swirl said:

what's it look like on the yellow frame and what motor was in the yellow frame originally

Will ask him.

[baldrick]

mine is mounted back in the frame, but it involved lots of work, including re-making the front downtubes and replacing the side horizontal frame rails.

its got a real neat front engine mount arrangement, if I say so myself., and has no big gaps.

I will try and get some pics tomorrow. its in bits and frame is buried in the shed

[clivegto]

@baldrickYes please I like pictures.

[fatblokeonbandit]

When I did mine, which originally had a gsx1100 engine,  I used the front mount as it fitted really well. and made the rears to suit, I tried using the rear but that would have involved extending the exhaust to clear the frame. mine seemed to work really well, handled a treat, only problem was the cahin hitting the lower frame rail, so I made a plastics chain buffer that went round the rail

 

 

 

 

 

 

[baldrick]

here u go, can you see it, its in here somewhere

Pics aren't the best, but you get the idea, the front tubes have been bent back  with new ends and the spindle, which I couldn't find, but tis there somewhere has thread on each end which threads into a turned alloy "nut, but its not a nut it sits inside the open ended tube at the front , its circular and has like got an allen key machined into the end, for tightening it onto the spindle. When its all tightened all you see is the circular end of the "nut".

 

This probably doesn't make sense, but if you seen it you would know what I'm talking about.

As you can see most of the frame has been altered.

if you look at the rear engine mounts, you can see how much further back it is compared to the other posters ones.

Edited November 13, 2018 by baldrick

[fatblokeonbandit]

Seeing all the pictures again I cant believe I was so stupid to sell mine!!!!!!

 

better keep my eyes open for another one

[clivegto]

Thanks for all the replies fellas. @nlovienwas thinking that might be the way to alter it if I go down that road.@Swirlthe owner thinks the yellow framed one is for the gsxr1100 motor origanly. Have seen other early mag 2 frames with what look to be the same back top engine mount for Z' s. @fatblokeonbanditvery Intresting pics already fitted my engine just about like that but am waying the options up befor the final build. @baldrickI can see the thinking in that but don't really want to alter the frame that much even though the seat unit has been changed.

Edited November 13, 2018 by clivegto

[spondonturbo]

Have you managed to get the engine in the frame as yet? I am trying to decide whether to put an aircooled motor in my mag 2 frame or a B12 motor so ws wondering how easy or not it is / was?

[baldrick]

I would say "if the frame was built for a gsx motor, I would just put that in, its much less work and hassle, to be totally  honest, and that's the "era" of these frames isn't it?

[Gixer1460]

4 hours ago, baldrick said:

I would say "if the frame was built for a gsx motor, I would just put that in, its much less work and hassle, to be totally  honest, and that's the "era" of these frames isn't it?

Yes - but they do go extremely well with a younger generation  engine in the hole!

[clivegto]

On 1/2/2019 at 9:59 PM, spondonturbo said:

Have you managed to get the engine in the frame as yet? I am trying to decide whether to put an aircooled motor in my mag 2 frame or a B12 motor so ws wondering how easy or not it is / was?

Yes, not to trickery use front engine mount on engine & frame make the back ones up to suit.

[spondonturbo]

5 hours ago, clivegto said:

Yes, not to trickery use front engine mount on engine & frame make the back ones up to suit.

@clivegtowould it go any further back if needed? or would it foul something?

[clivegto]

Yes did it like that for room for a plenum.