920 cc Conversion of Iron 850 Cylinders

cliffa said:

Is it possible that they are all like that, and you only realize it once the liners are removed?

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Does a stock barrel/cylinder have a liner ?

(I notice I am starting to call a barrel a cylinder more and followers, lifters)

acotrel said:

When CB750 Hondas were introduced into Victoria, I was still racing my 500cc Triton. I can remember riding down the front straight at Calder Raceway, weaving in and out as I passed them. After they fitted the CB450 pistons, they were marginally better. These days they are 1100cc and methanol fuelled - my Seeley 850 is better. A bit later Z900 and H2 Kawasakis were the go. I once lowered the gearing on my Triton and led them all for a lap at Winton. Their big advantage was their gear box, NOT their larger capacity.

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The difference might be, the Z could finish the race then ride out the gate and do a lap of Australia or the US with tyre and chain replacement along with checking the oil now and again.

The Z goes back to around 1967 as a 750, Honda beat them to the punch so they Kawasaki went back to the drawing board with a 1000 DOHC 4 reduced to 903 cc for late 1972.
Remember 12 years after that came the first 150 mph production bike in the GPZ900 and the only way from there on was up.
Cookie cutter 4 cylinders have been around for 50 years now so it was no flash in the pan ( I have only ever owned one 4, a 1981 Z1000J which was a great bike even on gravel back roads)

The stock barrel does not have a liner. It's just a one piece gray iron casting.
The 920 kits definitely have problems with cylinder distortion and sealing, but they usually work OK for a while.
When I first built my bike I did the 920 bit and had the barrel sleeved by LA sleeve and used pistons from Sunset Motors. It was a disaster with it's first long road trip. Something like a quart of oil every 100 miles and oil blowing out of the oil tank. When I took it apart there was a strip on each cylinder about 1 1/2 inch wide where the rings had not been touching the cylinder wall.
Then I tried what I was told was pretty risky and simply bored a barrel for the 81 mm pistons. It looked good but when I rode it down to LOP I had an oil leak show up. It was coming from between a couple fins on the barrel. If you looked close with the engine running you could see the flashes of light from combustion between two fins. But it did make it home with several stops for oil.
Then I went down to sunsets 880 kit with 79mm pistons. They worked pretty well and I even built a few motors without sleeves. A couple times I found the part of the cylinder that fits inside the case would crack so I started installing sleeves again. But even at the 79mm bore the sleeves are pretty borderline and cooling is questionable.
It's too bad Norton did not cast their barrels of high nickel cast iron like BSA [and Oldsmobile] did. BSA barrels are some tough stuff.

Would that include the later 650 twins? I ask this because price wise a 650 BSA sells for a lot less than a Triumph or Norton.
And at the bitter end BSA punched out the twin to 750. Always wondered how that stood up.

Onder said:

Would that include the later 650 twins? I ask this because price wise a 650 BSA sells for a lot less than a Triumph or Norton.
And at the bitter end BSA punched out the twin to 750. Always wondered how that stood up.

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Yes, that is the barrel I am familiar with.
They are tough to hone. They require heavy pressure and a lot of time to get anywhere.

Time Warp said:

The difference might be, the Z could finish the race then ride out the gate and do a lap of Australia or the US with tyre and chain replacement along with checking the oil now and again.

The Z goes back to around 1967 as a 750, Honda beat them to the punch so they Kawasaki went back to the drawing board with a 1000 DOHC 4 reduced to 903 cc for late 1972.
Remember 12 years after that came the first 150 mph production bike in the GPZ900 and the only way from there on was up.
Cookie cutter 4 cylinders have been around for 50 years now so it was no flash in the pan ( I have only ever owned one 4, a 1981 Z1000J which was a great bike even on gravel back roads)

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If you are riding a Commando and a 1000cc 4-cylinder superbike gets you out in the open, you are usually done for. I tend to stay away from large race circuits which don't suit my bike. A GPZ900 still pulls very good money in Australia. They now get into Period 6 Historic racing. Commandos fit into Period 4. I have ridden Z900s - to me they feel like 350cc British bikes, but ten times as fast.

Onder said:

Would that include the later 650 twins? I ask this because price wise a 650 BSA sells for a lot less than a Triumph or Norton.
And at the bitter end BSA punched out the twin to 750. Always wondered how that stood up.

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When the BSA Super Rocket came out. it was faster than the Bonneville. BSA motors did more in sidecars than solos. There is one British BSA sidecar in Victoria, which is the real deal. For what it is, it is very good. The latest Classic Racer magazine has an article about Mick Boddice, who worked for BSA and had all the trick bits in his sidecar motor. Triumphs and Nortons have a bigger following and you can get the bits you need to make your motor faster.

I owned a Kawasaki Z900 around 20 years ago, must admit it never felt like any British 350 to me !
It was though a great looking bike, but unfortunately in the end just another boring UJM.
Still ---- looking at the crazy prices they go for in the UK, selling it was not a good move :-(

The early-mid 80s GPz is quite different to 70s Z900. Handling is much crisper and the whole bike does feel much lighter, more modern. Fast. I rode quite a few of them, 550, 750, 1100 in the early 90s and liked them.

To me, my Triton always felt huge. The Seeley feels smaller and lighter. But the z900 surprised me. I expected it to feel like a Harley. The Z900 must be like Dr Who's Tardis. Some guys have different impressions of various bikes. Until I raced my methanol-fuelled T250 Suzuki, I believed two-strokes were peaky. My 500cc short-stroke Triton was much worse for being peaky, than any two-stroke I ever rode. It turned me into an instant dud when I first raced it. I used to be a very competent rider, but when I first started racing I could not understand why all these guys were faster than me. Of course, I was too lousy to buy a more modern bike - one which was not developed by a theoretical genius.

acotrel said:

If you are riding a Commando and a 1000cc 4-cylinder superbike gets you out in the open, you are usually done for. I tend to stay away from large race circuits which don't suit my bike. A GPZ900 still pulls very good money in Australia. They now get into Period 6 Historic racing. Commandos fit into Period 4. I have ridden Z900s - to me they feel like 350cc British bikes, but ten times as fast.

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The point was missed, those big reliable bikes opened up reliable adventure across vast landscapes, racing was a minority.

Sure people had been doing that since the first vehicles in general but the 1970''s opened up whole new playing field's and you did not need to do the 'ton to enjoy it, but you had the option.

I still remember a stock (new) Z1000 with 4 into 1 and a Egli Vincent coming over the hill at Pukekoehe and crossing the finish line side by side, old verses new with little in common but neither was the better.

trident sam said:

I owned a Kawasaki Z900 around 20 years ago, must admit it never felt like any British 350 to me !
It was though a great looking bike, but unfortunately in the end just another boring UJM.
Still ---- looking at the crazy prices they go for in the UK, selling it was not a good move :-(

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A Z1/Z is a toy compared to my 242 kg Africa Twin.

Is it a Kawasaki thread now, my only ever 4 cylinder bike (I have has singles,twins, triples and sixes) and a long way from home back in 1983.
I think those were Pirelli Phantoms same as on my H2.
Oddly back in the 1990's, someone asked me why I was buying basket case H2's (or complete non runners) and beveldrive 750''s and 900's. (2 more of each)
Who would have thought !.

The American and English technology won the war, The Japanese won the peace.

If you are racing 500cc single cylinder four strokes. It takes a very good bike to beat a Manx Norton. A 500cc Ducati Silver Shotgun does not get there. The problem lies in the race classes. If we are racing 1000cc twin cylinder air-cooled four strokes, Commandos are good. But an air-cooled Ducati is usually marginally better, depending on the circuit. I have not seen many Japanese air-cooled V-twins going fast in races.. That might be due to the lack of appropriate race classes.
When I was racing years ago, Z900s and H2s were the go. My bike was a 1950s Triton. I led the field on some occasions, by outriding them on a tight circuit.. Trying to out-drag them down a long straight, was not smart. All you can do is be much faster in the corners, so be quicker as you come onto the straights. I think a Paul Smart Replica Ducati would be faster on most circuits than a Z900. They take a similar race line coming out of corners.
In the 1970s I fitted a race cam into a Z1000 which was raced at Bathurst by Craig Hemsworth, the father of those actors. It had the fastest speed down Conrod straight that year.

In about 1973, Mick Hone, Alan Decker and several other fast guys were all riding Z900s at Phillip Island in an Allpowers race. Vic Vasella absolutely creamed them with a 750SFC Laverda twin. It was straight out of the crate, but Jim Eade had put it on methanol. That did the trick. Of course, if you do all the stuff to a Z900, that is a different story. Top end power was never a problem with big Japanese bikes. All you have to do then is be able to ride them. Rex Wolfenden's 110Occ methanol-fuelled CB750 Hondas are NOT RC750s. They are much more tractable. And that is what Seeley Commando 850s compete against in Period 4 Historic. He also runs them in Period 5 against the Z900s. But I know where they are bad and work on that.

comnoz said:

Yes, that is the barrel I am familiar with.
They are tough to hone. They require heavy pressure and a lot of time to get anywhere.

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I wonder if the new Andover barrels are made of better stuff? Have you tried working one of them yet? One can only hope they thickened up the walls a bit. We’ve all seen too many overbores with ventilation.

swooshdave said:

I wonder if the new Andover barrels are made of better stuff? Have you tried working one of them yet? One can only hope they thickened up the walls a bit. We’ve all seen too many overbores with ventilation.

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I don’t see why they should.

The OEM did not produce parts intended to the over-bored beyond their design criteria.

Adding metal to facilitate this would add cost and weight to a component and these are two factors that a designer is always trying to minimise.

If they didn’t, all bikes would be overweight and overpriced.

Actually, writing this makes me want to edit the above to “all designers, apart from Harley Davidson designers”...

Andover has made changes to the new product they have offered, especially with known flaws. So your assumption needs to be validated.

swooshdave said:

Andover has made changes to the new product they have offered, especially with known flaws. So your assumption needs to be validated.

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Yes they have. But ‘known flaws’ doesn’t include boring out to 880 / 920 etc. At least not by my reckoning.

A ‘known flaw’ would be the likelihood of the component to fail during normal use / within normal design parameters.

For example, they made the 750 barrels a through bolt design. That eradicates a known flaw to crack at the base flange.

Actually, I think it would be fantastic if someone did do what you’re suggesting and actually add metal in order to allow a barrel that could be taken out to bigger sizes without recourse to use of a liner. An iron linerless 920 barrel would be very strong and ideal on a road bike.

But it would definitely fall under the heading of ‘after market / tuning parts’ rather than ‘replacement OEM parts’ which is predominantly what AN are in the business of.

Fast Eddie said:

Yes they have. But ‘known flaws’ doesn’t include boring out to 880 / 920 etc. At least not by my reckoning.

A ‘known flaw’ would be the likelihood of the component to fail during normal use / within normal design parameters.

For example, they made the 750 barrels a through bolt design. That eradicates a known flaw to crack at the base flange.

Actually, I think it would be fantastic if someone did do what you’re suggesting and actually add metal in order to allow a barrel that could be taken out to bigger sizes without recourse to use of a liner. An iron linerless 920 barrel would be very strong and ideal on a road bike.

But it would definitely fall under the heading of ‘after market / tuning parts’ rather than ‘replacement OEM parts’ which is predominantly what AN are in the business of.

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So the short answer is that we don't actually know if AN beefed up this area of the cylinder.