7-11 swap, 8v 750 vs 16v vs gs1100e - Rickman CR900

[dorkburger]

[QUOTE Chuck78;2244816]"Bronze Welding" is much more common in Europe, by the drag bike link from a GSR member that Glen pointed out, numerous UK welding forums, Rickmans, Harris, Egli frames, etc... in the US it is held very skeptical in most people's minds aside from the custom high end bicycle frame market.

Glen, I'm sure you can vouch for this.. in my extensive BMX days from 14 years old into my 20's, I brutalized a lot of heavy duty dirt jumping frames, race frames, etc, all 4130 cromoly TIG welded steel. They ALWAYS broke on the metal immediately adjacent to the weld... frames, handlebars, etc... even my 6061 t6 aluminum PK Ripper racing frames, broke 3 of those on the metal directly adjacent to the weld.

Boy, you're bringing me back now... Yes, I had a couple of GT frames crack at the top tube just behind the headtube weld. A friends did also.

The other night, I was considering the oddity of how bent cranks came to feel normal. My goofy footed friend and me would ocassionaly swap bikes and bend them back....

 

[Chuck78]

I had to get some more advanced suspension and braking up front, although I will never go with a modern looking and improper height upside down fork, I had to pick something that was a big upgrade over cartridge emulators in GS1000 37mm or GS1100GK 41mm forks (still a very excellent option, but this is a RICKMAN CR900, it's simply THE BEST road handling vintage styled twin shock chassis!), was proper height, and easily allowed use of GS wire spoke wheels still (with minor machine work of all new axle spacers, and larger 20mm axle bearing and speedometer drive swap), so I picked 6 bolt GS pattern 296mm Honda rotors and Honda Superhawk vtr1000f forks, same as pictured on this Dunstall GS1000. Also, the most clearance to wire spoke wheels using opposed piston modern calipers was to be had with the 01-02 GSXR1000 6 piston calipers, the VTR's calipers, even with the smallest diameter pistons of any Tokico or Nissin 62mm mounting 4 pot calipers in this category, are very close to the wire spokes...




These are the ones, they will get stripped and polished. $100 ebay score, wow...

But with these blingin' calipers... I would prefer something a little more low key looking but they stop really well and will give me the most clearance to my spokes. The stock calipers are crap on those forks even though they look just like a dozen other calipers of this spec that all stop very well, they all have larger pistons than the Superhawk calipers, which puts them even closer to the spokes since the wire spokes are angled from the widest point at the hub. These are a direct bolt on to the Superhawk forks as in photo. the other 4 piston calipers that stopped as well as these would need minor clearancing at the lower bolt hole on the outside of the piston bores, and also would likely need angle milled to shave a little extra clearance in next to the spokes, on the inside lower edge nearest the wheel hub.

And these CB1 rotors, since they have the most offset of all of the Honda 296mm 6 bolt rotors that fit our GS hubs:

Any other feedback on the engines? I'm leaning towards the big bore 894cc GS750, or if I could ever find one, GS1150E. the convenience (local, w/all ignition& oil cooler parts on it) and power and advanced technology in the katana gixxer mill is still appealing, and maybe pulling the rotors off the bike and being right next to it might sway me... but the classic films on the other engines definitely give the look for the bike. A modern fork and possibly YSS rear shocks will be plenty of modern enhancements. I am really looking for another vintage pair of Fox or Ohlins or Works rear shocks...eventually, rear shocks are a quick&simple bolt-on and always are at the end of my priority ($$budget) list.

 

[T8erbug]

Chuck, I'd say go with the GS750 engine. The Rickman frame is saweeet but it's still old tech compared to a modern GSXR frame. While I'm sure the Rickman will hold up to a high HP GSXR engine I think a built GS750 engine will more finely compliment the Rickman frame and make a better overall package. Plus, you KNOW your GS750's inside and out. Use your expertise to your benefit.

 

[Chuck78]

Yeah, I'm leaning that way now... with a 920cc 10:1 & stock cams retimed to 105/106 lobe centers, this is a very potent engine on my primary street bike/long hauler. I think the 894cc build with either the basic hot street grind or the step up to the street/race .380"(Megacycle)/.395"(Web) lift cams on 106-108 lobe centers will give blistering mid and high rpm performance.

Unfortunately I just missed out on a set of $199 Web cams in the .365" lift here&ebay for $199... bummer. $450-550 new...

 

[Spyder]

Welp, you all know my vote. And I didn't use either bottom mount, and rip the squeal out of mine. She doesn't move at all. With the newly aquired info that I can get pre made mount brackets for 35.00 I might just add them in... I mounted mine 4 years ago and haven't had any issues with it so far... Good luck, anticipating the out come of this project...

 

[Chuck78]

actually, I am even giving thought to possibly downsizing. I have been really curious about building a GS 550 crankcase with GS 650 cylinders bored to their absolute maximum (+3mm to 65mm) to fit stock gs750 pistons. This would require using a 1980 through 1982 GS 550 head with larger bs32 intake ports, as the first generation VM 22 heads would likely be too restrictive unless I did a lot of porting work and made it possible to fit CR 26 carbs or possibly CR 29 smooth bores onto it. Not sure if this is possible with the early head with the small ports.

I can get some NOS 798cc GS750 11:1 pistons, so if resleeving a 650 block were possible, this could yield a 789cc 10.9:1 GS550 that is a good bit lighter than a 750, & could run high lift camshafts... the standard cylinder wall thickness on most GS's is about 3.8-3.9mm, but the 650 being based on the 550's narrow width & tight bore spacing is a squeeze as-is, & I just measured the wall thickness to be only 2.9mm, a 67.8mm o.d. & 65mm bore on the portion of the sleeve protruding below the block.


Only option looks to be a custom made sleeve with no more than 1mm larger o.d. on the step at the top

 

[GregT]

Pull the sleeves from a spare 750 block and bore the 650 one to suit the 750 sleeves...Then bore to suit your big 750 pistons and deck the block.
You may be surprised how easy the sleeves pop out. Propane torch or similar heating sleeve and block, aluminium plug made up to fit the sleeve end and some gentle tapping with a big hammer on the alloy plug....

 

[Chuck78]

Looking at the 650 block I have here, the outside diameter of the sleeves where it is stepped at the top is basically already at near the absolute max, as the sleeves are less than 1mm apart between 1&2 and again 3&4. The bore spacing is darn near maxed out. Also less than 1mm to the head stud holes by the cam chain tunnel. The 750 looks the same to the studs, so the 850 sleeves must be the same o.d. on the step...

I wonder if the o.d. of the steps in the sleeves could be machined down? How could you chuck up a sleeve in a lathe? That's basically what would be needed to run the 750 sleeves in the 650 block.
Can you have custom cylinder sleeves manufactured?


with the stud spacing proximity at the cam chain tunnel to the cylinder sleeve on the 750 being so tight, same as the 650, that makes me wonder if the 850 sleeves are thinner than the 750, as seems the case comparing the 650 to the 550 sleeves and blocks. If the 850 sleeves would fit, or even the 750 sleeves, you could possibly even run 844cc wiseco's...but I suspect that combination would likely run very hot. And we are still not sure if the 550 6speed transmission is up to the task of handling all this power unless a 650 5 speed would fit in.
.

 

[Chuck78]

Seriously, if this resleeving were possible, I would without a doubt build a 67mm 789cc GS550 for the Rickman... I may also still build up an 894cc GS750 as well, but the narrow & very potent 10.9:1 789cc GS550 with megacycle cams would pack one heck of a punch, be substantially lighter, narrower for more cornering clearance, & would be one of the best handling classic japanese 4cyl twin shock 70's superbikes I could possibly build!

I do have one spare 550 engine here, but both the 550's we have are experiencing shifting issues. I have an almost brand new 2000 mile transmission to swap into the one for the wife's bike when I build it up to 673 cc. I have 3 spare gs750 engines however.

For reference below, I'd have to have a sleeve no more than 1mm o.d. larger on the top step portion to fit anything bigger in the 650 block. Forgot to measure the material thickness on the outside of the block between fins to see if I'd be through the aluminum even...

 

[Chuck78]

Rapid Ray???? Got any feedback on resleeving here, or custom sleeves? Greg?
A 789cc lightweight 550/650 based four would sure make a nice light corner carver Rickman...

 

[GregT]

I'm sure custom sleeves are available. Until you pop a sleeve out of the 650 block you won't know what you're looking at in terms of how much meat is around the sleeves.
Close flanges...I've just swapped a couple of sleeves in a ZXR400 Kawasaki, they are so close std that they have flats on the sleeve flanges to fit alongside each other...
It's all do-able, but until you pop a 650 sleeve out, you won't know really how involved it is. Oh, and the OD of the protruding piece of sleeve is usually less than the portion in the casting.

 

[Chuck78]

When I get some down time in January, I'm going to have to pull the head off the 550 on the shelf (673cc candidate for wife's ) & compare the combustion chambers side by side to my collection of 750 heads... if slightly smaller, maybe a stock 750 piston with deeper valve recesses machined would be sufficient... but at 741cc, it wouldn't have much of an edge over a 673cc gs650 top end with its more advanced closed chamber raised port head and piston design. A CP custom piston set for 789cc on the gs650 head would be by far the ultimate... but $1000+

 

[Chuck78]

I may pry at Wiseco this winter and see if they still have any records or CAD drawings of their old 741cc GS650 65mm big bore pistons, as the closed chamber 650 head would be the most efficient and highest horsepower for sure, although similar horsepower and more torque could definitely be achieved with the 789cc hemi head and 798cc GS750 NOS aftermarket pistons, but not the combustion efficiency/fuel economy that the 741cc GS650 Wiseco pistons could give.

The Rickman tank has a fuel tap on each side. I need to see if one is a reserve, or if it is truly a dual feed setup (considering the performance nature of the Rickman's). The Keihin CR31 smoothbores on my buddy's 1132cc KZ1000 has dual fuel inlets between carbs 1&2 and the 2nd between carbs 3&4, so the CR setup definitely hits a home run there. The only doubts I have are the application vs venturi size. The Mikuni BS32cv carb heads have much larger intake ports than the tiny vm22 gs550 heads. the GS750 VM26 engine has smaller intake ports than the 550 BS32 head (80+). Am I okay running a CR31 on the BS32 GS550 head, or will this only be good for higher rpm's and potentially kill my crisp low end response?
If running a CR26 or CR29, will the adapter stepping down from a 26mm/29mm carb venturi and adapter have negative impacts on the performance and throttle response when it dumps into a larger intake port made for BS32's?????? Will either scenario (or both), be it CR31's or the smaller CR's, make it so that I would have to roll the throttle on more gently than I would a VM22 GS550 or a VM26 GS750???

 

[Chuck78]

Wiseco GS550-650 740cc pistons - FYI

Wiseco GS550-650 740cc pistons - FYI

I may pry at Wiseco this winter and see if they still have any records or CAD drawings of their old 741cc GS650 65mm big bore pistons, as the closed chamber 650 head would be the most efficient and highest horsepower for sure, although similar horsepower and more torque could definitely be achieved with the 789cc hemi head and 798cc GS750 NOS aftermarket pistons, but not the combustion efficiency/fuel economy that the 741cc GS650 Wiseco pistons could give.

FYI Wiseco said will gladly make a new run of GS650-740cc pistons based on their old designs from the 1980's Wiseco K740 kit they offered, but they have a minimum run of 12 pistons at $125/each piston w/pin/clips/rings. 25+ pistons manufactured and they can be had for as low as $95/each piston. There is a group purchase thread going on elsewhere in this forum stated by Ace07 I believe his username is. This is quite possibly the best combination of GS's to build for best all around good handling corner burning twisties machine with a great amount of power in a rigid lightweight chassis with a 2" narrower and 35lb lighter engine than the GS750/1000/1100.
The exhaust ports didn't really align well with the Rickman frame like the GS750/1000 ports did, so this was unfortunately not the likely candidate to swap into the Rickman for me, but I hope to be building one of these for my wife's GS550 with 650 cylinders and head this year soon.