RoadRace / canyon carver engine - GS1000's vs GS1100E - 70's Rickman CR chassis

[BadBillyB]

Thanks again for the reinforcement of that opinion, Billy. I would have thought that the 1100G port size would be more than adequate for mid range punch and port velocity if Suzuki designed it for a 1074cc touring bike. Even with a 1085cc 10.25:1 Wiseco kit, you think the 78-79 GS1000 smsll port head ported for CR33's (or would you do CR31's???) & maximum low lift flow would be better than a mild port job on the big port head?

Factory design and port size/shape back then was awful. Dont dwell on it. Look at how inlet port design has progressed over the years. They were not even in the ballpark back in 1980's.....I ran a big port head on my 1260cc GS1000 drag bike back in early 80's but if you look at my sketch/plan for my intake mods you will see I added material on the short side radius to give it a smoother turn, turn it earlier and attempt to keep the short side and long side closer to equal length. This also gave the benefit of not making port bigger (velocity). The roof of the port was raised all the way into the lifter cavity, giving it a better angle to flow past the valve (modern design). The intake floors were raised with "Manley A&B Compound" held up very well in a drag bike motor. My exhaust ports were "D" shaped with a bit of JB Weld which held up not so well. Look at this sketch/design I made up before porting my own cylinder head back in the early 80's......The higher lines drawn in the roof and floor was my intended port shape. The flow numbers on my local speed shops air-flow bench were not so impressive, but the track performance was exceptional. Its all about the shape and the velocity. Notice that the port roof went all the way into the lifter cavity. Thats as high as you can go. This was sealed up with custom aluminum spring bases JB welded in. This was for a 1260cc motor and I did not try to make the port bigger at all, just reshape it.....BillyPicture 001.jpg

[mmattockx]

I'll be first - A long time ago (1986 i guess) I had an 8V 1000 with 1085 kit, lumpy cams and headwork running CR29"s

the thing pulled like a freight train and survived 2 years of serious abuse ....

I'm going to be an unpopular dissenting view....Use a small port head on the 1085 8V motor.
I've built both the D port and several small port head motors around this capacity with various cams, both for roadracing and the street.

Any idea what type of power to expect from a 1085cc 8V motor built as above?


Mark

[BadBillyB]

Hey Chuck78, saw your PM but wanted to reply here as others may want to follow your thread. I do not know how much longer the GS1100 4V rods are as that was long ago. Seem to remember that the copper base gasket was .040" thick. Member NickP now has that base gasket now as he bought everything from me a while back. My bike and all the race parts went to the UK. My crankshafts were built by Falicon and did not hold up well. John Pearson may be able to answer questions about rod length. If I were you, I would source a crankshaft, make sure it turns freely in the cases, put a couple 1100G pistons on the rods and place the 1100G cylinders on it. Measure your deck and come up with a piston configuration to give you the correct deck height. Copper base gaskets suck as they do not seal well. try to avoid this if possible. My race pistons were custom machined by myself from off the shelf Wiseco 1238cc 13.5cr pieces. The distance from the top ring land to the deck of the piston was machined down further raising the CR and pinching the squish band very tightly. My first APE "big block" was damaged by an employee of MRE when he replaced a damaged sleeve from a crank failure. The owner of MRE offered to replace the entire block for free. I called Jay at MRE and had him make the new block tall enough to eliminate the copper base gasket. So basically what I am saying is to assemble crank stock piston and block to determine what to do for piston.....Billy

[Chuck78]

Well it looks as if we have a winner...slight deviation - option #2B... Wiseco K1085's but on 1100G rods and cylinders and modified 1100E crank! Thanks for the heads up Nick.

I still intend to build up a big 750 engine as well, but I think I will opt not to resleeve it (for 73mm which would really demand 18mm pins via custom Carillo rods) and stick with 72mm 920cc's as the MTC version I currently run, but in JE Pistons, & with a Rapid Ray ported head. For now I'll need to sort out the 1000E vs 1100G head. A broad poweband is what I'm aiming for, and hoping these Yoshimura cams I have will deliver that even if it takes adjusting the suggested (by Yoshi & drag race engine builders) 110 degree cam timing a bit. I am amazed at how cam timing makes such noticeable changes in powerband. My semi stock 920cc 750 (i.e. retimed stock cams and no head work beyond a Serdi radiused cut) went from high rpm rocket with so-so bottom end power to a total street menace with endless burnouts, unexpected power wheelies (but slightly down on power 8500-11000), & giving my buddies on late model zx7 ninja and two zrx1200's a serious run for their money with them getting nice views of my taillight...

1105cc 1100E/Wiseco K1085 it is for this one. I hope the 1100E crank doesn't add too much weight to the bike, but if it does, it will be In the name of reliability. May have to have Pearson look into knife edging it if weight is substantially more.

[srsupertrap]

I ran the Gs1000 Wiseco K1085, Mikuni 29s, Andrews S1, Supertrapp on the street for 25 years. I then replaced the 1000 head & cylinders with 1100G head & cylinders bored for Wiseco K1100, 73.5mm pistons with Mikuni RS34s everything else carried over. From a street stand point, my GS1000 with the 1100G head, cylinders, K1100 with Mikuni RS34s pulls significantly harder down low.

On the flipside the 1100G head & cylinder are heavier than the corresponding Gs1000 components specifically the 1000 cylinder bored to 1085. IIRC according to Cycle first GS1000 test report from Feb 1978 the GS1000 engine is lighter than the GS750 too.

That being said I voted for GS1085

[Chuck78]

The modified "GS1000 66mm stroker crank" (modified 1100E crank with machining to swap primary gear and besring positions + MTC straight cut gear, w/later i.e. stronger GS1100G rods) is looking to be a done deal. Wiseco K1085's will yield 1105cc and a slight bit more compression ratio with this setup.
I'll need to send the 1000 transmission to APE or similar to have it back cut. And of course H.D. clutch backing plate upgrade and welded rivets.

What all is involved in the H.D. clutch basket backing plate upgrade? Just swapping in a straight cut gear and a different backing plate? Then weld together with existing factory rivets that were ground off? Or do the plates come with new rivets or weld-in fasteners? New clutch hub springs included? Or is this something to buy seperately?

[Nessism]

The clutch backplate upgrade is simple in comparison to most other things you are doing. I think Rustybronco (Dale) has some photos in his Skunk rebuild thread.

Question: what is your intention for this engine/bike? Are you going to be racing it at the track on a regular basis and spinning the crap out of it? Reason for asking is that you are going down this very expensive road that is completely unnecessary for a normal road going bike.

[Chuck78]

Question: what is your intention for this engine/bike? Are you going to be racing it at the track on a regular basis and spinning the crap out of it? Reason for asking is that you are going down this very expensive road that is completely unnecessary for a normal road going bike.

My intention is to build a bulletproof bottom end capable of handling racing abuse (WERA & maybe AHRMA road racing, possibly ECTA top speed racing, and street riding excursions into the hills and mountains on occasion) and capable of handling whatever top end work I may upgrade to in the future. Initially, it's looking like the 66mm stroke crank (on its way) & 1085 pistons, with my 1100G D-port head or possibly a 79 1000 head. Either route will be sending the head to Rapid Ray for porting work to improve low lift flow in particular. Yoshimura isle of man spec race cams. Yoshimura Series 1 exhaust. CR31 or possibly VM33 smoothbores.

In all reality, my Formula 500 GS425-489cc project will see the majority of the track time, as it is more forgiving and less of a heartache if I crash it. Rickman parts are much more difficult to come by than GS400/425/450 parts...
The Rickman I am building up to WERA spec but I don't see it getting as much racing use for the above reasons. If I do end up getting very immersed into vintage heavyweight racing, I may transfer the engine into a Harris or other (XR69 replica) frame.
I realize this is a pricey route to go, but with the bottom end, I wanted to build it the absolute strongest within reason in anticipation of any future upgrades and of course to handle any abuse dished out...

I do a lot of riding in the hills and mountains of the Appalachian region, more sane than on the track, but still get healthy doses of throttle twisting regularly on any bike I ride.

the back cut trans gear dogs I was on the fence about, but I don't really want to have to tear down the lower end again any time soon. I keep hearing that 2nd and 3rd gears on most bikes are the most critical ones in need of back cutting for racing power loads, but am unsure if I should go for just that or do an up-down back cut on all 5 sets.

if it makes it live substantially longer, then it is worth it. After all, 1 of the 2 prospective engines I'm looking to pick up is a GS1000 with a bad trans, jumps out of gear...

[bobgroger]

My intention is to build a bulletproof bottom end capable of handling racing abuse (WERA & maybe AHRMA road racing, possibly ECTA top speed racing, and street riding excursions into the hills and mountains on occasion) and capable of handling whatever top end work I may upgrade to in the future. Initially, it's looking like the 66mm stroke crank (on its way) & 1085 pistons, with my 1100G D-port head or possibly a 79 1000 head. Either route will be sending the head to Rapid Ray for porting work to improve low lift flow in particular. Yoshimura isle of man spec race cams. Yoshimura Series 1 exhaust. CR31 or possibly VM33 smoothbores.

In all reality, my Formula 500 GS425-489cc project will see the majority of the track time, as it is more forgiving and less of a heartache if I crash it. Rickman parts are much more difficult to come by than GS400/425/450 parts...
The Rickman I am building up to WERA spec but I don't see it getting as much racing use for the above reasons. If I do end up getting very immersed into vintage heavyweight racing, I may transfer the engine into a Harris or other (XR69 replica) frame.
I realize this is a pricey route to go, but with the bottom end, I wanted to build it the absolute strongest within reason in anticipation of any future upgrades and of course to handle any abuse dished out...

I do a lot of riding in the hills and mountains of the Appalachian region, more sane than on the track, but still get healthy doses of throttle twisting regularly on any bike I ride.

the back cut trans gear dogs I was on the fence about, but I don't really want to have to tear down the lower end again any time soon. I keep hearing that 2nd and 3rd gears on most bikes are the most critical ones in need of back cutting for racing power loads, but am unsure if I should go for just that or do an up-down back cut on all 5 sets.

if it makes it live substantially longer, then it is worth it. After all, 1 of the 2 prospective engines I'm looking to pick up is a GS1000 with a bad trans, jumps out of gear...

Might be totally different with a Zook, but my KZ would pop out of first. It was drag raced a lot though.

[GregT]

Might be totally different with a Zook, but my KZ would pop out of first. It was drag raced a lot though.

Haven't had a problem with the roadrace GS1000. Didn't have to backcut anything as we started with a couple of good gearboxes.
The 1100 box is supposed to be identical but made to closer tolerances.

The GS1000 jumping out of gear is probably a bent selector fork - and possibly the selector fork shaft is bent too. Once it's got that history, yes, have a look at that gear pair and possibly recut the dogs.

I've recently gone through two Hayabusa boxes used for roadrace sidecar racing...Started at one end and cut my way across, LOL. Bent selector forks and rails in both. New forks and solid rails went in. $$$

[Chuck78]

Okay....well here is what I've got now!

$30 '82 GS1100G engine to donate the 1100G cylinders and D-port head
$150 78 GS1000 engine with 79 GS1000 head, bad 2nd gear and one other with dogs hammered pretty bad - all gears back cut. WELDED CRANK!!! (Had no idea!!), stock clutch basket.
$$$$ 66mm welded stroker crank from NickP w/straight cut primary gear
$375 (+ 4 racks of bs/bst carbs trade) almost new Keihin CR31 smooth bores
$200 Yoshimura Isle of Man .365" lift cams
$birthday Yoshimura GS1000 Series-1 4-into-1 exhaust
$30 ebay transmission
APE back cut job on transmission????

All I'm needing now is to call up Rapid Ray & talk about D-port head vs the 79 GS1000 small port head, & have him do some porting for me.
Then Wiseco 1085cc pistons & bore (maybe see about JE Pistons? None in their catalog so custom order)
Full gasket and seal set
Carb boots and filters
New H.D. DID Cam chain
H.D. clutch backing plate upgrade and gear to match the stroker crank


If I would have gotten the $150 engine sooner and had it torn down to find a welded crank, I probably would have just done the budget route with the standard welded crank, 1085 wiseco, & D-port head with a Serdi valve job.

With this 66mm stroker crank and MTC straight cut gear, I feel the need to definitely send Ray the head to work his magic on it.

I plan to do most of the racing on the Formula 500 prepped 489cc GS425, as it will be a better bike for an amateur racer to learn on, & less lost if/when I crash it vs a Rickman... racing the Rickman will be more of a for fun venture and less competitive, as I don't want to crash it up, but since the Rickman is the ultimate in twin shock 70's racing chassis, I also wanted to build up an ultimate engine to power it...
If I really get addicted to racing on the 1105cc Rickman GS1000, I may have to race prep a GS1000 frame and swap the engine into it, or else get a Harris XR69 replica frame or Magnum/F1 frame to road race on. Something more easily replaceable than a Rickman.


Thanks for the advice and support GSR Members... much appreciated.