Topic: cb 750 versus z1 900 any thoughts

[LesterPiglet]

I thought the GS750 was a far better bike than the 1000. The 1000 was a bit of a lump to me.

[Terry in Australia]

The GS750 was a great bike Lester, I've owned one of them too, but personal opinions aside, the GS1000 was an excellent evolution of Suzuki's DOHC Superbike theme. Suzuki purposely redesigned the engine to reduce the physical largess of a bigger engine, and in fact it was no taller or wider than the 750, and actually a couple of inches shorter, by Suzuki's designers removing the kick starter assembly.

A GS1000 engine will fit into a GS750 frame (with longer rear engine mounts) but a GS750 engine won't fit in a GS1000 frame. At 512 pounds, it was only 5 pounds heavier than the GS750. (and 8 pounds lighter than the CB750F2, and a whopping 54 pounds lighter than the CBX) "Motor Cyclist" magazine's "Great Bikes of the 70's" book described the GS1000 as "The best motorcycle ever built". A slight exaggeration perhaps, but a great bike, nonetheless. Cheers, Terry.    

[trueblue]

I've got a discontinued NOS Wiseco 1170cc 15:1 compression ratio big bore kit here for mine.   

Holy Crap, 15:1!!!!! Are you sure that's right?  With that amount of compression you should be able to screw an injector in to replace the spark plug, hang an injector pump off the side and fill the tank with diesel.  With compression that high, you would be struggling to control detonation and it would eat big ends.

[Terry in Australia]

I've got a discontinued NOS Wiseco 1170cc 15:1 compression ratio big bore kit here for mine.   

Holy Crap, 15:1!!!!! Are you sure that's right?  With that amount of compression you should be able to screw an injector in to replace the spark plug, hang an injector pump off the side and fill the tank with diesel.  With compression that high, you would be struggling to control detonation and it would eat big ends.

Yeah mate, that CR is correct, it is a "Drag Bike Only" kit, the pistons are works of art with the domes pretty much filling the combustion chambers with deep reliefs for bigger valves and high lift cams. I've also got a set of Ivan Tighe race cams here with another 2.5mm of lift on the inlets, but I don't want another drag bike, I want something I can ride to the shops, or do some summer touring on.

You can still buy all this stuff for the 16 valve engines though, check out this site and scroll to the bottom of the page, how about a 1640cc kit with 15:1 compression? : http://www.mtceng.com/piston/mtc-products/pistons/suzuki/gs-1100
Cheers, Terry.  

[trueblue]

That is a bloody high CR, it would almost have to be a methanol only engine.  You could ride it to the shops with those pistons, it would be a quick trip, and you would want to hope they aren't too far away about 1320' 

[Jeff.Saunders]

Terry, the Early GS1000's are probably the best value older motorcycles out there.  I have two of them - cheap to buy, fairly fast, reliable, easy to work on, and with good handling.  I don't know why there isn't more of an aftermarket supply of parts for that bike.    Having said that, many companies like Kerker, V&H, Wiseco and others have slowly cut back on their products for all the older bikes.  I had some 1170 turbo pistons in my Z1 - but when I needed replacements, I had to source some old stock 1200cc turbo pistons.  Wiseco will make more of any piston - but the short run pricing is prohibitive.  Interestingly, Wiseco is starting to make more pistons for the older bikes.  They recently launched piston kits for a number of the small Honda twins.  So it's really all down to supply and demand - if there's enough demand, someone will make it. 

The early CB750 SOHC and Z1's have both achieved collector status .  With the GS, because it's a clone of the Z1, it's just never going to become a collector bike - so it's suffered as the collectors and restorers don't give it a second look.  Other than a small niche market for Katana parts, there's really no companies making very much for the early GS's - a shame really. 

Retro Rocket, I don't think you realize just how much Z1 stuff is being made these days....  everything from replica frames, to billet crankcases - with many of the parts, it's not if you can get it, but which version to choose from.  For example: fork assemblies - want stock forks, they are available, or billet triple trees, or upside down fork conversion kits, conversion kits for different calipers - no problem.

Have a look at some of the stuff on these sites - these are just two of the suppliers we buy from.
http://www.win-pmc.com
http://www.doremi-co.com/

[Retro Rocket]

Jeff, i wasn't questioning what is available for the Kawasaki mate, actually, i am well aware, it was your comment about there being a :massive amount more" parts for the Kwaka. As i said, there are literally 1000's of guys making parts for the Honda, and although i am not sure about engine cases {no shortage anyway} everything else is available. I have billet tree's and billet block for my Honda's among piles of other "trick" stuff....

billet triple trees, or upside down fork conversion kits, conversion kits for different calipers

All mentioned on this site and all available for our bikes, maybe you are not aware how much stuff is being made and constantly developed for the Honda's....   Just saying...

[Terry in Australia]

Thanks Jeff, and you're right, the GS will never achieve the same collector status as the CB750 or Z1 for the reasons you've mentioned, but that's a good thing for "cash poor collectors" like me, I can't afford a mint 1973 Z1, but I can pick up GS1000's for cheap. It's sad in one way, but brilliant in another, I just wish there was more stuff around for them, not that much ever goes wrong with them. You don't have a pair of wire wheels for one do you? Cheers, Terry.

[Stev-o]

I would guess there were far fewer GS1000's made.

I've seen the numbers on annual CB750 manufactured, but what about the Z1's? (I would say less)

[Jeff.Saunders]

about 85,000 Z1's over the first 3 years.  KZ900's about 50,000

GS1000's I'm not 100% sure - the Suzuki frame numbering has some serious gaps in the range - so it's not as easy to figure out.

From what I see available in the used marketplace, there were a good number of 2-valve GS1000's - but less than the corresponding year KZ1000's.

RR - last year we spend considerable time and money having our agent in Japan visit all the CB750 specialist places we could find - to put it mildly, it was a disappointment.  There are a handful of very good suppliers - one in particular we will be doing business with - that gentleman has excellent contacts with old OEM suppliers - and he provides Honda with parts for their museum bikes.  What's frustrating is when we discussed ordering with most of the places, few of them had product in stock.  We tried to get some of the replica 300 pipes - and while there's still a few unsold sets in circulation, they have not been making them - but they would if we ordered a staggering number of them.  Similar story on the CB750 tanks - we were not impressed with the replica wrinkle tanks, and couldn't buy any regular CB750 tanks without ordering 50+ at a time (and prepaying 50% for the priviledge of waiting 4-6 months for them).  So while there are places that had or might have parts again, not all the places stock parts like the PMC or Doremi.

What has made matters much worse, the earthquake/tsunami has crippled a few suppliers - we see it with many of our other parts.  Several manufacturers have ceased to exist.  Keihin lost their slide manufacturer, Vesrah lost their head gasket manufacturer.  Many of the old parts you could routinely find will be gone once current stock is exhausted.

[MRieck]

Very interesting info Jeff...thanks for sharing.

[Jeff.Saunders]

In regards to the earthquake and tsunami, the Japanese motorcycle industry made out fairly well.  Most of the bike manufacturers and their suppliers are centered around Osaka, no major impact other than rolling blackouts and minor building damage.  But many companies supporting both the automotive and motorcycle industries were in the northen part of Japan.  These took severe damage and in some cases the companies ceased to exist overnight.  Vesrah had a factory in the area just south of the badly hit area - their factory was damaged with cracks in the walls and floor.  That facility was out of actions for many, many weeks. 

While some companies survived the damage, they have not survived the massive downturn that followed.  None of the OEM's have been building many motorcycles - and as a consequence the OEM suppliers have struggled - with many of these just shuttering their doors - possibly for ever.  The slide manufacturer Keihin used was the same one Mikuni used - both companies have been scrambling to get slides made - and sadly, all the older slides and less popular carbs have been discontinued.  While the CR29's are now back in production several of the larger CR carbs are permanently discontinued now as Keihin doesn't want to invest in getting the slides made again.

[Retro Rocket]

about 85,000 Z1's over the first 3 years.  KZ900's about 50,000

GS1000's I'm not 100% sure - the Suzuki frame numbering has some serious gaps in the range - so it's not as easy to figure out.

From what I see available in the used marketplace, there were a good number of 2-valve GS1000's - but less than the corresponding year KZ1000's.

RR - last year we spend considerable time and money having our agent in Japan visit all the CB750 specialist places we could find - to put it mildly, it was a disappointment.  There are a handful of very good suppliers - one in particular we will be doing business with - that gentleman has excellent contacts with old OEM suppliers - and he provides Honda with parts for their museum bikes.  What's frustrating is when we discussed ordering with most of the places, few of them had product in stock.  We tried to get some of the replica 300 pipes - and while there's still a few unsold sets in circulation, they have not been making them - but they would if we ordered a staggering number of them.  Similar story on the CB750 tanks - we were not impressed with the replica wrinkle tanks, and couldn't buy any regular CB750 tanks without ordering 50+ at a time (and prepaying 50% for the priviledge of waiting 4-6 months for them).  So while there are places that had or might have parts again, not all the places stock parts like the PMC or Doremi.

What has made matters much worse, the earthquake/tsunami has crippled a few suppliers - we see it with many of our other parts.  Several manufacturers have ceased to exist.  Keihin lost their slide manufacturer, Vesrah lost their head gasket manufacturer.  Many of the old parts you could routinely find will be gone once current stock is exhausted.

Not to mention the exchange rate went south after the GFC, i have been buying guitars out of Japan for about 10 years, everything went up around 25-30% after the GFC due to the poor exchange rate... I can understand the problem you have as a shop trying to buy parts from suppliers in Japan, i've had no problems as a consumer though, helps having friends in Japan....