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T8's 750 Cafe Racer Project
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Guest repliedOriginally posted by T8erbug View Post
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If you are interested in frame bracing, which I did to my 1000 then this is a good read. You will find out that the only, or recommended , bracing is C, D(in red) and E.
Last edited by Fjbj40; 10-05-2013, 07:41 AM.
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Guest repliedOriginally posted by Chuck78 View PostLookin' good T8! I hope you get to ride that thing this season! That's why I've been doing mine one project at a time and trying to keep it on the road. Finally getting pretty darn close on the carb settings. I LOVE the way my bike rides, and the power it has with the GS850 pistons. I highly recommend you tear yours down and bore it out for Wiseco 10.25:1 844cc pistons, it will be a real blast... Do all the brake/suspension/wheel/frame stuff first by all means, and ride the thing a good bit!
I'm not sure how far along you are with the frame and having the engine mounted in it, but when I pull my engine to swap in GS850 cylinders bored to 920cc and do a valve job etc, I plan to do some bracing and welding on the frame with this info that I got from the defunct oldskoolsuzuki.info website.
A. these tubes support the headstock against torsional movement. The plates B. support the frame tubes to prevent them from bending due to the load created by tubes A. The cross-bars D. stiffen the area above the swingarm pivots. The tube connecting both sided is placed at the same height as the engine mounts to keep the engine in place under acceleration. If we replace the cross-bars with a pyramid D1. we add even more stiffness to that area and prevent the swingarm pivots from moving back and forth in addition to up and down. It may look a bit awkward and I question if it adds anything as you must not underestimate the strength and function of the rear subframe.
The connecting rectangular tubes E. help to distribute loads from the swingarm pivots to the rear of the frame, as well as providing a mounting point for the rear brake amongst other things. F. There's very little room to triangulate the space in front of the cylinders because of the exhaust pipes but it is possible. You may need to dent the tubes a little to make them clear the exhaust pipes but this is better than making the V smaller. Tightening the two center exhaust clamps will prove difficult too.
Now that the headstock and swingarm pivot areas are beefed up the connecting tubes are supported by plates C.
You should also consider making B. and C. box sections, so placing a plate on both sides of the tube with a strip in between to close the box. Or use rectangular box-sextion like I did (60x20)
Tubes only need to be around 16mm in diameter with a 1mm wall thickness. Box sections need to have 1mm wall thickness and single gussets 3mm.
By all means take note when removing the engine as to how much clearance you need to the frame overhead to remove it, and don't make those box tube braces hang too low! A good place to start is tack weld in the front F braces with the header and engine in place, and then fit up the top C braces and make sure when you pull the engine that you have them sized good enough for engine removal. Sorry to dump more work on you! Just do it my way, ride the thing with the mods in the works now, and then pull the engine later for a big bore kit and freshening and weld in some cromoly tubing to stiffen the thing in the proper areas!
I might as well start a new thread on here with the entire article from the oldskoolsuzuki.info site. I saved that whole webpage when I realized no one had posted on those forums for a year. site owner lost interest after too much spam infiltrating the board.
I'm kind of partial to the modifying of a frame's rigidity. . I'll be honest, I'm just not smart enough at this point to even say whether it's a good idea or bad idea. I sell fasteners for a living at the moment and can honestly say even while being in an engineering program at school I did not know a bolt was designed to stretch or in other words have elasticity until going through training at work (I'm sure I'll learn this at some point in school haha). I had no idea how over-torquing a bolt could completely ruin it's strength properties and how easily over tightening one can actually be (90% of us do it every time we wrench on something).. Once a fastener is improperly tightened it reaches a point of no return where it is no longer the same. In a critical application it's as good as trash. That being said, I just have no idea all the work motorcycle engineers put into designing a motorcycle frame. They are made to flex under load in certain areas and transfer loads to others. I'd just be worried to over strengthen an area even by a little bit. The load has to go somewhere and it WILL find a weak spot. Who really knows? Shoot, I just need to hurry up and get my degree so I actually know stuff! I do know one thing though and that is that a motorcycle is a fine machine that is designed entirely upon the concept of balance. You can't change anything on a motorcycle without having it affect something else. The intricacies of a motorcycle never cease to amaze me. I guess that's why I love it. Always a challengeLast edited by Guest; 10-04-2013, 11:59 AM.
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Guest repliedOriginally posted by AX2007 View PostWill those Supermoto wheels hold up under the weight of the 750? The GS has to be 250lbs heavier than any dirtbike....Last edited by Guest; 10-03-2013, 11:51 PM.
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Lookin' good T8! I hope you get to ride that thing this season! That's why I've been doing mine one project at a time and trying to keep it on the road. Finally getting pretty darn close on the carb settings. I LOVE the way my bike rides, and the power it has with the GS850 pistons. I highly recommend you tear yours down and bore it out for Wiseco 10.25:1 844cc pistons, it will be a real blast... Do all the brake/suspension/wheel/frame stuff first by all means, and ride the thing a good bit!
I'm not sure how far along you are with the frame and having the engine mounted in it, but when I pull my engine to swap in GS850 cylinders bored to 920cc and do a valve job etc, I plan to do some bracing and welding on the frame with this info that I got from the defunct oldskoolsuzuki.info website.
A. these tubes support the headstock against torsional movement. The plates B. support the frame tubes to prevent them from bending due to the load created by tubes A. The cross-bars D. stiffen the area above the swingarm pivots. The tube connecting both sided is placed at the same height as the engine mounts to keep the engine in place under acceleration. If we replace the cross-bars with a pyramid D1. we add even more stiffness to that area and prevent the swingarm pivots from moving back and forth in addition to up and down. It may look a bit awkward and I question if it adds anything as you must not underestimate the strength and function of the rear subframe.
The connecting rectangular tubes E. help to distribute loads from the swingarm pivots to the rear of the frame, as well as providing a mounting point for the rear brake amongst other things. F. There's very little room to triangulate the space in front of the cylinders because of the exhaust pipes but it is possible. You may need to dent the tubes a little to make them clear the exhaust pipes but this is better than making the V smaller. Tightening the two center exhaust clamps will prove difficult too.
Now that the headstock and swingarm pivot areas are beefed up the connecting tubes are supported by plates C.
You should also consider making B. and C. box sections, so placing a plate on both sides of the tube with a strip in between to close the box. Or use rectangular box-sextion like I did (60x20)
Tubes only need to be around 16mm in diameter with a 1mm wall thickness. Box sections need to have 1mm wall thickness and single gussets 3mm.
By all means take note when removing the engine as to how much clearance you need to the frame overhead to remove it, and don't make those box tube braces hang too low! A good place to start is tack weld in the front F braces with the header and engine in place, and then fit up the top C braces and make sure when you pull the engine that you have them sized good enough for engine removal. Sorry to dump more work on you! Just do it my way, ride the thing with the mods in the works now, and then pull the engine later for a big bore kit and freshening and weld in some cromoly tubing to stiffen the thing in the proper areas!
I might as well start a new thread on here with the entire article from the oldskoolsuzuki.info site. I saved that whole webpage when I realized no one had posted on those forums for a year. site owner lost interest after too much spam infiltrating the board.Last edited by Chuck78; 10-03-2013, 08:23 PM.
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Guest repliedWill those Supermoto wheels hold up under the weight of the 750? The GS has to be 250lbs heavier than any dirtbike....
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Guest repliedOriginally posted by mlymanz71 View PostLookin good man, somewhat jealous of those shocks. I was hoping you would not put any gussets in between the bottom of the seat and the bottom portion of the hoop but still looks slick either way.
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Guest repliedGrips, chain, hand controls, and more work on the seat
Things are looking up. I ordered 120 links of chain thinking I'd buy more than I needed and just take a few links out as needed. Turns out 120 was just what I needed! Lucked out there. The seat is getting closer to being done but I don't want to go any farther than where I'm at now until I get the rear tank bracket fabbed up. Nothin worse than a crooked tank and tail and it happens all the time. I've seen quite a few high quality builds by people like Classified Moto and Lossa Engineering that just are never quite right because either the tank isn't straight, the tail isn't straight, or a mixture of both.. I don't know.. I figured I put this much time into the bike I might as well not take any short cuts.
Last edited by Guest; 09-13-2018, 02:51 PM.
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Guest repliedLookin good man, somewhat jealous of those shocks. I was hoping you would not put any gussets in between the bottom of the seat and the bottom portion of the hoop but still looks slick either way.
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Guest repliedI was gone all week to Minnesota for work but when I got home there was a surprise for me. My shocks came!! So not a lot has happened to the bike but I'll bring you up to speed for the most part. These pics aren't current to the day but you'll get the idea. I had to make a front brake spacer for the rotor to reach my caliper so I could leave it's mounting locations alone. I drew the part pretty quickly and we were able to make it relatively quick as well. The dimensions were just about spot on (I won't even bore you with the details of getting the dimensions). So the front brake is all set up and bled and will keep it that way until my steel braided lines come. The rear wheel is still not spaced but not for long. I'm picking up the welder tonight and will be building the upper shock mounts here pretty soon. I'm making a HUGE push to have it rolling by the weekend but you all know how real life is and . . well there's the possibility that might not happen but for now it will haha. Here are some pics of the machining and the body shaping to get the plug closer to how I want it.
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Guest repliedHere's the picture that Klaus over at YSS sent me of my shock. It looks like with my setup I'll also have more room between the bottom mount and the lower spring retainer. I'll take all the space I can get!
Last edited by Guest; 09-13-2018, 02:52 PM.
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Guest repliedOriginally posted by wegs426 View PostAfter seeing how mine sits with the ~350mm shocks you will be on the upper limit with your 380's. I think 365mm would be ideal.
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Guest repliedOriginally posted by T8erbug View PostI actually have the same swinger on my bike and have had the joys of doing almost the same things to my bike as well (grinding the brackets off gs1100 swingarm etc). I also am purchasing YSS shocks and am having mine built a little longer than yours (380mm). My biggest concern is that my chain will rub my shock with a centered clevis mount like yours. How is your clearance? Are you running a stock chain? I'm running a 520 non o-ring chain so it's quite narrow but it is offest 1/4" so that takes up most of the difference and puts it once again closer to where the shock will mount.. I should be good but you know what they say, measure twice and cut once.
After seeing how mine sits with the ~350mm shocks you will be on the upper limit with your 380's. I think 365mm would be ideal.
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Guest repliedOriginally posted by tkent02 View PostLooks good, but a question, can't tell from the pics, will the kickstarter work with the rearsets in place?Thanks for the kind words fellas
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Looks good, but a question, can't tell from the pics, will the kickstarter work with the rearsets in place?
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