GS400/500 Gr650 Hybrid engine

[Rensdw]

Thank you guys for all the input, really motivational I'm frigging excited too!

Regarding the bracing, the plan is to design the exhaust and inlet system first, then work around those systems when it comes to bracing.
Most of the work is done to the frame, all the crappy Suzuki welds have been removed and redone properly, you can see most of the bracing in the pictures.
The bracing you talk about chuck will be done, it's not in the pictures yet.

I like the frame for not being symmetrical, it's a nice detail IMHO.

I found a company here in the Netherlands that can handle my crankshaft, they will put it together properly and re-balance it for use without the balancer shaft.
They will also make sure the crankshaft handles more then 80HP to be future proof.

I am still working on my lathe, I need to get the darn thing fixed so I can start working on the clutch.

Will send out the camshafts to Rapidray anytime soon.

Ooh and chuck.....don't forget this was originally a GS450 frame!
In the end only the frame number plate will be originally, lol.

[Chuck78]

I do recall it was a 450 frame...a little extra bracing there in my opinion would be beneficial, to keep headstock twisting to a minimum. Brace A&B in the OSS bracing diagram takes it to another level, may cause tank frontmount fitment issues:


the outer frame rail box tubing bracing that the OSS frame bracing typical layout uses, I would have probably done a bit longer brace using box section tubing as I brace C in photo. This is considered one of the most important ones. I would have tapered a box tube section from the rear under side all the way up to where the center frame top spine lateral termination brace connects to the outer frame rails. you might want to get further consultation on this, as it is definitely always pointed out to be the most critical.

[Chuck78]

Also, the factory brace below bracing "F" I don't believe is present on 750's & smaller, good idea to add a tin wall piece of tubing there, not too thick needed, just need to keep the motor mount plates from flexing as they are the weak link in connecting the engine as a stressed frame member.

[Rensdw]

Thanks for the input chuck, when everything is back together and working I have to take it apart again for painting, I will do some more bracing then because I know where everything goes, to prevent clearance issues.
I forgot about the horizontal brace below the F lines, consider it done

"A" is already done just not in the picture yet, D and F will be done later maybe E too

this is going to be one of the most fun and most radical GS twins that most of us have ever seen, & 559cc 10.5:1 if my calculations and memory serves me right! With a very lumpy cams to boot. I'm sure this thing will be as fast as a 750 2 valve and handle miles better! I would maybe consider that additional frame bracing, and some very expensive rear shocks so that you will want to ride this awesome bike even more than that R6! There's one or maybe two other very awesome gs twin race bikes that I have seen on this forum, one of them was pushing the 600cc from a GS 450 platform! Those two are very impressive as well. I can't wait to see this come together more.

Thank you so much! the rear shocks are gonna be a pair of ohlins, but I want some professional help with seting up the suspension, so many cool looking Cafe Racers that have a miserable geometry.

[Chuck78]

F is not as important, but Suzuki added the brace below F to later frames. Maybe some smaller corner gussets on the GS1100E factory brace shown below F, but probably just on top and not below, as F makes it tougher to get the exhaust on/off and is less critical. C, D, & E are by far the most criyical. If you already did A, then forget about what I was saying about other bracing closer to the ignition coils in that area.

[Chuck78]

The rear shocks are gonna be a pair of ohlins, but I want some professional help with seting up the suspension, so many cool looking Cafe Racers that have a miserable geometry.

Do some serious number crunching to figure out rake and trail, and use the rear shock length to get the rake angle stdepend from the stock 27 degrees more toward 24.5 degrees. More important than rake is the trail #. Get it between 3.9" (more high-speed stability but still quick enough turning) to 3.7" (very quick turning, probably want a steering stabilizer to help with high speed stability when you hit a bump and compress the front suspension which lessens trail momentarily and causes a very twitchy front end).

If you are running 17" wheels, use the offset of whatever fork tripleclamp yokes you decide on as a basis for calculations, as well as fork length and front tire diameter. Spend $99 on the Tony Foale frame geometry calculator software, or you can manipulate the free Web software from a choppers site to show you the effects on rake and trail of changes in tire radius and shock height, but this takes a lot more thinking and allows more chance for human error. See my thread, post #9, halfway down for how to use the "advanced chopper calculator" for more geometry inputs than they give you (using shock length and tire size radius changes imputed in with the "new fork length" input field to determine adjusted rake and trail.

Really, a set of billet triples with interchangeable offset inserts would be ideal...
With triple clamp offset and tire diameter, use longer rear shocks to get the swingarm angle somewhere in the range of 9-12 degrees from horizontal in order to get the rake and more importantly trail set where you want it. Closer to 11 or 12 degrees swingarm angle and you may need to run larger sprockets to clear the chain on the swingarm pivot tube.

If you don't get satisfactory results with the modern fork stock triple, get a custom billet triple in a different offset or adjustable offset. Trail is the most critical, but a rake of 25.5 down to 24.5 would be quite nice. It may pitch your frame too far forward sloping to achieve that, however, so be cautious, as you don't want it to be uncomfortable to ride. I'm going to settle on 25.5-25.8 degrees rake on my formerly 28 degree rake Rickman CR900, 3.73" trail and steering damper. Take out the YSS +10mm ride height shock adjusters and I'm down to a more stabile long haul road trip rake&trail geometry. Put them back in when I get to the twisties!

[Chuck78]

Good YSS shock options - more for the money than Ohlins

I think these are awesome options for shocks, far better for the money than Ohlins:

http://www.yssusa.com/series-g.html

G series = adjustable piggyback,
30#/36# = piston diameter
##2/##6 = 12mm/16mm shaft diameter

With a bike the weight of yours, the 12mm shafts I would think are plenty sufficient. The billet model G 362 TRWL would be pretty much the ultimate and blow the Ohlins out of the water as far as features for the money. 330mm is the shortest length but will help steepen your rake slightly. Even the G-362 will be an awesome shock, but the billet model is fully adjustable with high speed and low speed compression, as well as rebound and preload. And it is Billet so it is lighter and stronger. I think you're going to get more for the money from these than Ohlins for sure

YSS G-302 TRCL Twin — Gas Twin Shock Absorber
Price: $699.00 per Pair
Available Lengths: 280 mm, 300 mm, 310 mm, 320 mm, 330 mm, 340 mm
Type: Self Adjusting Gas Shock with Piggyback Reservoir
Features: Pre-Load Adjustment, Rebound Adjustment 60 Clicks, Compression Adjustment 20 Clicks — Springrates Model specific or customised — (Included: Ride Height Adjuster (Length Adjuster for +10 mm)
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YSS G-362 TRCL Twin — Gas Twin Shock Absorber

Price: $769.00 per Pair
Optional 20 Click Adjuster— Price: $50.00

Available Lengths: 280 mm, 300 mm, 310 mm, 320 mm, 330 mm, 340 mm, 350 mm, 360 mm, 370 mm, 380 mm, 395 mm, 420 mm
Type: Self Adjusting Gas Shock with Piggyback Reservoir
Features: Pre-Load Adjustment, Rebound Adjustment 60 Clicks, Compression Adjustment — 3 Positions: Soft, Medium, Hard —36 mm 50 Micron Steel Bore and Radial Sinter Piston — 12 mm Hardened Shaft — Low Friction, Long Life Seal Block — Bearing and Bushes or Clevis/ Fork to suit each Model — Damping and Springrates Model specific — (Included: Ride Height Adjuster Length Adjuster for +10 mm)

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YSS G-362 TRWL Billet Twin — Gas Twin Shock Absorber

Price: $1069.00 per Pair
Available Lengths: 330 mm, 340 mm, 350 mm, 360 mm, 370 mm, 380 mm, 395 mm, 420 mm
Type: Self Adjusting Gas Shock with Piggyback Reservoir — Billett milled GP Shock for High End Racing
Features: Pre-Load Adjustment, Rebound Adjustment 60 Clicks, Hi-Low Speed Compression Adjustment (20 Click Low Speed and 20 Click High Speed Compression) — 36 mm 50 Micron Steel Bore and Radial Sinter Piston — 12 mm Hardened Shaft — Low Friction, Long Life Seal Block — Bearing and Bushes or clevis/ fork to suit each Model — Damping and Springrates Model specific — (Included: Ride Height Adjuster (Length Adjuster for +10 mm)

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YSS G-366 TRWL Billet Twin — Gas Twin Shock Absorber

Price: $1239.00 per Pair
Available Lengths: 330 mm, 340 mm, 350 mm, 360 mm, 370 mm, 380 mm, 395 mm, 420 mm
Type: Self Adjusting Gas Shock with Piggyback Reservoir — Billett milled GP Shock for High End Racing
Features: Pre-Load Adjustment, Rebound Adjustment 60 Clicks, Hi-Low Speed Compression with Adjustment 20 Clicks, 20 Click Low Speed and 20 Click High Speed Compression — 36 mm 50 Micron Steel Bore and Radial Sinter Piston — 16 mm Hardened Shaft — Low Friction, Long Life Seal Block — Bearing and Bushes to suit each Model — Damping and Springrates Model specific — (Included: Ride Height Adjuster (Length Adjuster for +10 mm)

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[Rensdw]

Thank you for all the information chuck, really helpful, I did not know about YSS and I'm really going to consider them!

A small update, I have the frame back in the my shed, I am going to concentrate on the front end first so I can determine the geometry early on and maybe be able to make changes along the way.
Also I have decided to use a rotary steering dampener under the lower triple plate, you wont even see it!

Don't mind the mess


The engine now fits in the frame perfectly, but the valve cover hits the fuel tank, not a real problem I will solve that quickly







I am very happy about how it looks so far!!!

The oil cooler I bought is too big, and it is hard to hide it on a minimalistic bike like this, to keep it visually minimalistic I am thinking about hiding it UNDER the engine.
I will have to make sure it gets enough airflow and the whole idea depends on how much ground clearance I'll have but I like the idea.
The cooler is probably overkill, so less airflow shouldn't be a real problem, And it would be hard to actually see it, how cool is that.
I could also buy a smaller oil cooler and mount it in front of the engine, but I very much dislike blocking the view to the engine, on some bikes it's cool, not on this one.

What do you think?

[Chuck78]

I would not be putting an oil cooler underneath the bike! Stone impacts, speed bumps and steep approaches that would scrape/dent the exhaust, the heat from the exhaust... A lot of reasons not to mount there, don't want any failure/damage to dump all your oil out because of the oil cooler location! Sell the thing and get a smaller one and mount it in a different place.


Suzuki performance spares has some small runs of oil cooler take off adapters that fit many GS models, a few different options, one with an oil pressure sending unit thread, one without. They are the nicest that I have seen, on ebay or their website for about 100 something dollars US.



I will chime in later on suspension setup. Knowing your tire sizes and overall tire diameter is critical, and then you can adjust the frame as it sits on your bench to simulate the locations of the axles off of level ground based on tire radius and fork height, and shock length. Then you can measure the rake angle of the head tube manually getting it somewhere in the range of 26 down to 24 degrees, I would probably stay at 24.5 or 25.5, but with a steering damper & very stiffened frame, 24 might be a safe bet, especially running Radial tires. 24 degrees will have the gs frame leaning forward quite a bit, so 25 or 25.5 is good as long as you get the trail dialed in perfectly. Trail is a much bigger factor than rake angle, much more critical, whereas rectangle can be in the ballpark, trail is immediately noticeable when changed. try to do most of the steepening of rake with the rear shock height but make sure the chain is not going to rub the swing arm at the pivot tube Ashley arm angle increases. Don't take the swing arm above 13.5 degrees incline no matter what, with no wait on the bike. 12.5 is more than enough fully topped out. Somewhere in the range of 10 or 11.5 degrees swing arm angle would be great. 12 if you can get it.

once you get the rake set where you want it and evaluate how much the frame slopes downward to the front as far as comfort in riding position, find a happy medium between a steering angle and a seat that is close to horizontal so you don't slide into the tank or put all of your weight on your hands. Then you can calculate the amount of offset needed for the triples. Billet bike bits in the UK have really cool custom billet triple on their website, definitely look into that.


refresh my memory, what forks are you using? upside down or conventional right side up? where you doing that crazy Buell style brake rotor?

[Rensdw]

Chuck, all that info is really gonna help, like you said it's not very important right now, thats why I'm concentration on the front end, I want to have a rolling chassis asap to get the geometry set up.

I'm using GSXR-750 USD forks, and yes I'm doing the crazy brake rotor

About the oil cooler, I have thought about all the issues you talk about and I agree it is not a wise place to put it, but I think I'm still gonna do it....call me hard headed
I will use a dense row of "scoops" to direct air into the cooler and protect it from stones and a manual shut off valve to block it off in case of a leak.
Not really afraid of hitting a bumb though, never had that happen to me, on any of my bikes, we have very good roads here.
As long as I have a fair amount of ground clearance I will be fine, the exhaust is a bigger issue when it comes to hitting bumbs

When it turns out to be a completely stupid idea, not practically and just plain dangerous then what the heck....it's just a couple of lines and a bracket
I just don't see me putting the oil cooler in plain sight and not be very irritated by it lol, this bike is all about how I want it to be.

Or what about just sticking the oil cooler in the fuel tank and have a fuel/oil heat exchanger lol

[Chuck78]

I'm sure you probably have the triple clamp yoke set for the GSXR Forks already, correct? you are probably running a 17 inch front wheel with a 120/70-17 I would imagine. I would also guess that the GSXR 750 those forks came off of had around a 24 or 24.5 degree rake. if your tire size is identical to the bike the forks came off of, then in order to get sportbike steering response out of the vintage bike frame, you would need to install longer rear shocks to raise the rear end up until either the chain rubs on the swing arm pivot tube, or until you reach the same rake angle of the steering stem as the donor bike specification.

Since our bikes came from the factory at around 27 degrees, and the donor bike somewhere around 23.5 up to 25.5 degrees, raising the rear would require 38 to 48mm of additional ride height ( so probably 43-35mm longer shocks since they are angled forward and not vertical), probably not possible.

If the front end is shorter than the original (29.5" on my gs425), the amount of difference from the stock fork length could be taken away from that approximate 3 inch increase in the rear, but you don't want to go lowering the front end much more or you will have cornering clearance problems on your foot pegs, exhaust, etc you will also end up with a seat that is sloped forward quite a lot and handle bars that are much lower than the seat. For this reason it is not practical to copy exact caster or rake angles of the modern bikes, but rather change to triple clamps with more offset to help decrease the excessive amount of trail compared to the bike geometry that the front end came off of. Trail is much more noticeable than steering angle (rake or caster).

95mm of trail is a good twisties and track bike geometry that turns in quick but still maintains decent stability. 100 mm of trail is still agile in turns, but more high-speed stability. 90mm turns in very fast but is very ywitchy and not great at high speeds.
our GS's came with close to 120mm of trail I believe, 117 or 121mm. very stable, but slow turning. 1 inch longer rear shocks on most bikes always helps reduce trail steepen/lessen the rake to make them turn in much much better, making them much more fun to ride in the twisties. 100mm is a great neutral quick steering number. perhaps you could look up one of the companies that makes billet triples with adjustable offset insert that you can interchange. This might be the best setup for you in order to maximize the bikes steering response once you have it completed and on the road, still being able to make changes to the geometry without spending major money on new triples. I have seen at least four or five different companies websites that make billet triples with adjustable interchangeable offset stem insert pieces.

so the moral of all this is try to get the rake down around 25.5 degrees at least, if you can get 24.5 easily, that is great. A braced frame and radial 17 inch tires should do quite well with that angle. then get your trail set up around 100 or 95 mm. use adjustable offset triples to be on the safe side. Calculate the trail both with math equations or web-based trail calculators, and also do it manually to check for margin of error.

unfortunately the way my Rickman frame was built, for the shortest possible forks, and with a 28 degree rake, I doubt that I can get the rake much below 26 degrees, so I'm going to shoot for 95 or 96 mm of trail to make up for it. No more than that. This will mean smallest diameter front tire possible in a wide enough width (110/80-18) 18 inch, as well as a lot more offset in the triples than what I had planned for.

in order to keep the seat fairly horizontal, it is possible to have a set of custom bearing race adapters made to effectively change the rake of the frame by running smaller bearings that are then offset from the angle of the head tube in the frame by use of complicated to machine eccentric angled adapters. most of the time that these are used are for chopper guys who want the raked out chopper appearance and the poor & slow steering that comes with it (which is manageable if they pay attention to proper trail figures and offsets), but for our intentions, we will install them the opposite direction with these eccentric offsets, to steepen the caster, giving the bike less rake. I have only seen one place so far that advertises these, a flat track racing supplier in the United States.

[Chuck78]

thats why I'm concentration on the front end, I want to have a rolling chassis asap to get the geometry set up.

I'm using GSXR-750 USD forks, and yes I'm doing the crazy brake rotor

I should correct you and remind you that you need to have the geometry figured out pretty well before you have a rolling chassis that requires purchasing custom length shocks and custom offset billet triple clamp yokes!
Concentrate on getting the wheels on it even if it means buying $40 USD worth of conversion bearings that may not be used on the billet triple that you may have made. then you can mock up the rear shock length by putting a jack under rear of the engine, or strapping up the rear of the bike from the ceiling of the shed (adjust the rear ride height with either method), or just using some small lengths of steel angle iron as strut bars to simulate shock length.

From there you can determine how long your shocks need to be (remember YSS gives you +10mm rear shock ride height adjusters that will reduce rake & trail and make it steer quicker, or increase rake and trail by removing them when you want to just cruise or commute without the quick and twitchy racer geometry. Someone also makes and sells 15-30mm ride height adjusters on ebay for Ohlins shocks. Some size around that dimension.


Another tip - a slightly taller rear tire will help increase the rake without putting your chain closer to rubbing the swingarm pivot. Bigger front sprocket (highway gearing) will also allow more shock length without chain rub. Put a nylon or delrin chain slap protector on your beautiful swingarm while you're at it, by the way...

whatever gearing you end up at, make sure that the rear sprocket is not so big that the chain is level on top. Dave Moss just taught me to always watch for this and make sure the gearing selection allows the chain to slope upwards toward the engine. The chain always needs to be sloping upwards towards the engine. The closer the chain gets to horizontal, the more leverage it has against the swing arm under acceleration. too big of a rear sprocket or too flat of swing arm angle will cause problems exiting turns under power, twisting the throttle more will cause you to go wide and possibly crash if you are rapidly accelerating out of turns. Also to steep of swing arm angle will do the same. getting the swingarm angle and sprocket size set up properly will give you a good balance of anti squat and pro squat. Accelerating ship the way towards the rear, which causes the rear to squat. Proper swing arm angle and sprocket size selection will cause the swingarm to pull in more towards the back at a steeper angle, which will steepen the steering. getting just the right swing arm angle and not putting too large of a rear sprocket on will balance out the tendency of the rear to squat under acceleration weight transfer, balanced out with the opposite tendency of the swing arm to pull in closer to the bIke under acceleration.
because of this, powering out of turns, I would expect you to notice with a good balance of the two, that the rear suspension seems much more rigid and bumps more harsh when exiting turns rapidly accelerating.

[Rensdw]

I should correct you and remind you that you need to have the geometry figured out pretty well before you have a rolling chassis that requires purchasing custom length shocks and custom offset billet triple clamp yokes!
Concentrate on getting the wheels on it even if it means buying $40 USD worth of conversion bearings that may not be used on the billet triple that you may have made. then you can mock up the rear shock length by putting a jack under rear of the engine, or strapping up the rear of the bike from the ceiling of the shed (adjust the rear ride height with either method), or just using some small lengths of steel angle iron as strut bars to simulate shock length.

I was planning on doing exactly that , I need to put the fork in with the wheel, swapping the fork with a different model early on is easy enough.
The rear wheel will be done shortly, need to figure out the sprocket off-set and then have the spokes and rim done and then I need to choose a nice set of tires, and go from there.

This week i will focus on fixing my lathe, that will speed things up on both the frame and the clutch project.

[Rensdw]

Guys, just wanted to let you know that I'm moving my workshop and I am very busy with all kinds off stuff except this project
Als I am going to study again so a lot has changed when it comes to the future of this project, I am going to focus on using "modern" performance parts because that will be cheaper then my original plans.
For instance I will not mkae the cool looking front wheel brake hub with internal discs but I will use a dual disc GSXR 750 front wheel, I'm using an SV650 rear wheel.

Here is a picture of my new work shop, It's an ongoing project, I'm moving stuff everyday.
It a 50 square meter garage with a 25 square meter attic, I share this with my grandad (cheap!! )




Anyway, I will probably start working on the project again in a couple of wheeks, I first have to finish the Cagiva mito and a friends R6.
Also I have to sell my Ducati 748S to finance the project since I am going to use most of my budget to finance my study.

Just to keep you update if you're interested

[GregT]

Granddad's side looks interesting. G80 ? Another AMC possibly behind it, then something Norton based - a triton ?