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Author Topic: Building my own two-stroke "Mongrel" - Inspired by CharlieT & TedT  (Read 19786 times)

Offline BillyGoat4130

  • Posts: 176
    • Live Oak FL Real Estate


Bushed the pivot on the swingarm for the smaller 15mm swing arm bolt. Chain alignment is pretty sweet.  Think I got a game plan to mount shock direct to swing arm.  Wanted to take the spring off the shock to check range of motion easily but couldn't figure out how. Service manual says "Rear shock absorber: do not attempt disassembly. Unit is unserviceable / unrebuildable.  Do not attempt disassembly." then has 2 pages on how to drill it to drain the oil before "recycling". Suzuki logic I guess... Lol

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Offline BillyGoat4130

  • Posts: 176
    • Live Oak FL Real Estate
After sleeping on this thing last night I came up with what should have been my first thought. The problem was i wanted to take the spring off the shock so I could setup the suspension at max compression on the rear, but couldn't get the spring off and the suzuki manual was no help. Decided this morning I'd just measure the over all length,  measure the stroke from the top of the exposed chrome shaft to the bottom of the bump stop (about 3.250in) subtract from the overall fully extended length (about 13.300 in) and wind up with a roughly 10.125 overall fully compressed length of the shock. So I'll just make a mock-up strut with the eyelets that length, and that way I can check my setup under full compression and make sure the arm does not rub inside the frame anywhere, or pivot up too high and knock the back out of the engine cases, etc.

When faced with a conundrum, I've found for me its best to walk away and let things sit a bit. The answer is usually very simple, just have to dream it up!
The question isn't who is going to let me, it's who is going to stop me.
You can't reason with the unreasonable.
Too dumb to quit.

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Offline 540Nova

  • Posts: 91
Good thinking!


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Offline TedT

  • Posts: 2
There you go! Told you the chain would be good to go! Looking forward to seeing the next chapter on this, looks great so far.

On the Mongrel we went without a strut and literally just moved the entire swinger as far up and down as possible.  The design of the stock Honda rear mount makes it almost impossible to hit the engine with the swingarm, unless the shock completely departs from the bike.  With the silencer I figured that if I started running into problems there with tire clearance, that I'd have much bigger issues than the tire hitting the silencer!


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Offline BillyGoat4130

  • Posts: 176
    • Live Oak FL Real Estate
This seemed like the most sensible way to make a shock mount to weld onto the swig arm.



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The question isn't who is going to let me, it's who is going to stop me.
You can't reason with the unreasonable.
Too dumb to quit.

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Real Job: http://landsofnorthflorida.com

Offline BillyGoat4130

  • Posts: 176
    • Live Oak FL Real Estate
There you go! Told you the chain would be good to go! Looking forward to seeing the next chapter on this, looks great so far.

On the Mongrel we went without a strut and literally just moved the entire swinger as far up and down as possible.  The design of the stock Honda rear mount makes it almost impossible to hit the engine with the swingarm, unless the shock completely departs from the bike.  With the silencer I figured that if I started running into problems there with tire clearance, that I'd have much bigger issues than the tire hitting the silencer!


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The SV swingarm is a lot "thicker" up and down than the 250R one, and at full drop (Extension) the arm currently sits on the bottom chain roller guide off the frame, so that is going to have to get whacked off and re-positioned. To help minimize that I re-drilled the bottom mounting fork and moved the bottom shock bolt eyelet about 3/4 of an inch further up.

 If the arm came all the way up in full compression (past where the shock would bottom) it would actually rub on the inside edges of the subframe (Probably getting whacked too) but the front cross member of the swingarm where the pivot area is would also lever into the back motor mount on the engine, and that'd be a really bad scenario, haha. So I just had to account for and check that stuff out.
The question isn't who is going to let me, it's who is going to stop me.
You can't reason with the unreasonable.
Too dumb to quit.

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Offline BillyGoat4130

  • Posts: 176
    • Live Oak FL Real Estate
At a stand still now for a few days.  I'm kind of undecided about doing the mount this way, not too keen on the shock and swingarm angle but looking at yours Ted seems to be fairly close so maybe I'm just looking at things a bit too much :)

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The question isn't who is going to let me, it's who is going to stop me.
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Offline BillyGoat4130

  • Posts: 176
    • Live Oak FL Real Estate
Rough idea of how the new mount is going to be.  Probably do some triangulated gussets off the sides.  Debating on Welding the mount to a piece of 1/4 plate from the bottom and sides, and then Welding the plate as a reinforcement onto the cross member there.  The mount seems a little dinky by itself even if I made several passes around it.  Would probably be good but..

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The question isn't who is going to let me, it's who is going to stop me.
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Too dumb to quit.

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Offline BillyGoat4130

  • Posts: 176
    • Live Oak FL Real Estate
Well I have the rear shock mount welded on. Not super enthusiastic about how it turned out, will probably wind up with some further modification or replacement at sometime in the future. Probably some triangulated gussets off the sides or back, or something.

The front of the swing arm also needed cut out to clear the motor once I had all the motor mount bolts tightened down. I was contemplating just running it without the rear 250R motor mount (It's really 3 mounts, a middle one that the pivot bolt goes through and then a top and bottom that goes to the cases) but after seeing it was rubbing there in that same area ever so slightly once that bolts were tightened down I just band sawed that section out. It also lets me utilize the standard 250R rear motor mount that way (You'll see in the pictures if you look again how it is absent in the previous mock-up). I will need a second set of front pivot needle bearings and turn some new bushing caps, but now its fixed, and I have no worries about full compression of the arm ever tearing into the back of the motor and breaking something serious off. I'd cry if that happened on a built 250r engine, but if that happened on my Rotax, it'd be like having my dog die...

Once the pivot area is completely buttoned up, I'll whack off the steering neck and work on that area. The SV650 has kind of a unique bearing setup where the top and bottom stem bearings are sized significantly different. What I plan to do is get a piece of tubing similar in diameter to the factory 250R neck, and machine it, and then weld on bushings on each end that have been bored ID to fit the appropriate new bearing races. This way I don't have a piece of 2.5in 1/4 wall hunk o' iron welded on for a neck. I've seen some English guys swedge their tubing to fit the different sized bearings at each ends but I am not sure I am brave enough to do that :)



Question: When setting up the HEIGHT of the steering neck where it is positioned on the frame, it makes the most sense to have the centerline of the axle for the front and rear an equal amount from the ground, correct? In other words, I should make it where I can lay a level across the the rear axle to the front axle, and have it be level, right?
The question isn't who is going to let me, it's who is going to stop me.
You can't reason with the unreasonable.
Too dumb to quit.

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Photography: http://wgolightly.smugmug.com

Real Job: http://landsofnorthflorida.com

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Question: When setting up the HEIGHT of the steering neck where it is positioned on the frame, it makes the most sense to have the centerline of the axle for the front and rear an equal amount from the ground, correct? In other words, I should make it where I can lay a level across the the rear axle to the front axle, and have it be level, right?
Rim + tire height will determine level of the axles to the ground not steering neck height. You're talking about radii from centerline of each axle.