I am an addict. There, I said it. H2

I have thoroughly enjoyed this thread from the initial find and start up to the exponentially expanding discovery process and subsequent tear down. I have a question about the three cylinders that has bugged me for a long time. I have built many old piston port two-strokes for mostly Ossa and Penton engines. All of them have been singles and the pressed together cranks seem like child's play next to a pressed together three cylinder crank. How do you disassemble, reassemble an true such a complex crank? Is this a job for a specialist? I have shied away from three cylinder, two strokes, as project bikes, because I figured that the crank seals would need to be replaced.

Big_Jim59 said:

I have thoroughly enjoyed this thread from the initial find and start up to the exponentially expanding discovery process and subsequent tear down. I have a question about the three cylinders that has bugged me for a long time. I have built many old piston port two-strokes for mostly Ossa and Penton engines. All of them have been singles and the pressed together cranks seem like child's play next to a pressed together three cylinder crank. How do you disassemble, reassemble an true such a complex crank? Is this a job for a specialist? I have shied away from three cylinder, two strokes, as project bikes, because I figured that the crank seals would need to be replaced.

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I chose to have the crank rebuild done by a shop highly recommended in the triple Kwacker community.
I COULD have used my skills to design, fabricate fixturing, etc. and press it apart, together and indicate it in.
BUT, I was very happy to purchase the experience, already set up fixturing, tooling, etc. of an accomplished craftsman.
Same as the Commando crankshaft, inasmuch as I chose a shop well recommended here, to have the BEST chance at a good job, the first time, with no "dog-ate-my-homework" excuses.

The Kaw triple uses lip seals between the sections, many two-stroke multis rely on labyrinth seals.

concours said:

The Kaw triple uses lip seals between the sections, many two-stroke multis rely on labyrinth seals.

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Makes perfect sense to use a reputable crank builder for the set up. Can you elaborate on the difference between lip seals and labyrinth seals? I assume that these seals can be installed without splitting the crank?

Big_Jim59 said:

Makes perfect sense to use a reputable crank builder for the set up. Can you elaborate on the difference between lip seals and labyrinth seals? I assume that these seals can be installed without splitting the crank?

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Lip seal is like every other seal you're familiar with. Rubber lip in contact with the crank. Cannot be changed without pressing the crank apart.

SOME, not all labyrinth seals are split, can be removed without seperating the crank.

Big_Jim59 said:

I have thoroughly enjoyed this thread from the initial find and start up to the exponentially expanding discovery process and subsequent tear down. I have a question about the three cylinders that has bugged me for a long time. I have built many old piston port two-strokes for mostly Ossa and Penton engines. All of them have been singles and the pressed together cranks seem like child's play next to a pressed together three cylinder crank. How do you disassemble, reassemble an true such a complex crank? Is this a job for a specialist? I have shied away from three cylinder, two strokes, as project bikes, because I figured that the crank seals would need to be replaced.

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When the crank is rebuilt, the inner seals can be replaced with labyrinth seals - as in a TZ Yamaha. They can easily be made. I have them in my H1 motor. It also has Yamaha connecting rods.

I never get into pulling two-stroke cranks apart. Learning how to build something which can become very expensive on your own bike can be false economy. Everything in a two-stroke motor is usually much closer to the limit. When H2R Kawasakis were raced in Australia Ron Toombs used to race them. He used to come from New South Wales to Phillip Island via Sale in Eastern Victoria. Kevin Doyle lives there - he reshapes cylinder heads to factory race spec. and rebuilds cranks, and he is still there. He also knows the port timings and chamber specs.

concours said:

Lip seal is like every other seal you're familiar with. Rubber lip in contact with the crank. Cannot be changed without pressing the crank apart.

SOME, not all labyrinth seals are split, can be removed without seperating the crank.

Labyrinth seal - Wikipedia

en.m.wikipedia.org

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Thanks for the explanation. It has been a question that has bugged me for some time and has actually kept me from purchasing a Suzuki GT750. Somewhere in the back of my mind is that voice that says "it's a two-stroke. How hard do you think those seals are?"

Sandblasted the rusty spots on the tins after stripping

A little alcohol rinse to remove residue

acotrel said:

When the crank is rebuilt, the inner seals can be replaced with labyrinth seals - as in a TZ Yamaha. They can easily be made. I have them in my H1 motor. It also has Yamaha connecting rods.

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Neville Lush built the crankshaft for my H2B (Bought in 1980 and have two H2A's also) which got labyrinth seals along with his billet connecting rods.

Time Warp said:

Neville Lush built the crankshaft for my H2B (Bought in 1980 and have two H2A's also) which got labyrinth seals along with his billet connecting rods.

View attachment 110931

View attachment 110933

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I've not heard of billet rods. Everything 2-stroke that I am aware of is forged, OEM & hotrod too. Tell more please...

concours said:

I've not heard of billet rods. Everything 2-stroke that I am aware of is forged, OEM & hotrod too. Tell more please...

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I don't recall the details being long ago. Neville does (or did do) a single box ignition also but do recall around $1600 for both at the time.

There is a lot of fable around H2's in general but the 1974 H2B and 1975 H2C were a little more refined with the crankcase check valves and other oiling revisions along with the longer swing arm. They are still a usable bike once gone through but will vibrate if over revved. (They make decent power and torque without going over 6500rpm, 6200 being more than ample, beyond that stock its all noise)

Time Warp said:

I don't recall the details being long ago. Neville does (or did do) a single box ignition also but do recall around $1600 for both at the time.

There is a lot of fable around H2's in general but the 1974 H2B and 1975 H2C were a little more refined with the crankcase check valves and other oiling revisions along with the longer swing arm. They are still a usable bike once gone through but will vibrate if over revved. (They make decent power and torque without going over 6500rpm, 6200 being more than ample, beyond that stock its all noise)

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Compared to the 800cc Rotax snowmobile engines (143 horsepower on pump gas with a factory warranty) I ride, the H2 is a lawnmower engine. Nostalgic, yes, but, piston port limitations

concours said:

Compared to the 800cc Rotax snowmobile engines (143 horsepower on pump gas with a factory warranty) I ride, the H2 is a lawnmower engine. Nostalgic, yes, but, piston port limitations

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I was thinking of the death trap and widow maker stories. As far as HP I recall back in the 1980's Brit bikes etc doing random wheelies and routine carrying the front wheel from every set of lights.
With some porting, chambers (nor Wirges) and a set of 34mm VM's 90 rwhp was easy, add some longer decent rear shocks and the handling improved.
My own H2B had a factory twin disc front end very early as it was production raced (but seemed quite quick for a stock even compared to the Z1000J I also had at the time)
That brake set up was more than capable of lifting the rear wheel off the ground, maybe Pirelli Phantoms helped.

I used to post many decades ago on the Kawasaki Triples Worldwide website (maybe from late 1990's onward and long gone iirc) Mraxl etc were posters back then, Rick Brett etc, Tom Loftus being the owner of the site (I sent him an RGV250 banana swing arm for one of his H2 projects) Even back then the dudes in the Netherlands were starting on billet cases, reed block modified cyinders etc so getting the bikes to go quicker was no problem.
I seem to remember H2's still hold all the normally aspirated drag racing records, the likes of the Redline/USA single H2 engine bike running 7.7/177
The Denco Triple Triple something else......
Let the good times roll and they did starting with a 250 triple in 1977.



Looking forward to the next instalment.

I got to visit Santa's workshop

I'm in for plan "B" Bourbon restaurant. And I like the green! My favorite green, Kawasaki lime green!

I was still racing my Triton 500, when H2 Kawasakis arrived. Ken Colvin had one. He rode around turn two on Winton Raceway and gassed it hard. The back of the bike came out, and the bike shot him up the road. It was very spectacular. I also saw one guy on an H2R replica get chucked up the road as he crossed the start-finish line, halfway up the main straight on Calder Raceway. He was really flying. Those crashes were usually pretty harmless. You would never gas an H2 unless the road was clear in front of you

This is an interesting video;



Some people here will recognise the roads Harry is riding....

He also does a very good video documentary series on farming.

To be clear, my bike will be RIDDEN.
Ridden HARD.
And my buddies can ride it too.
No trailer queen.
Mechanical function. Some cosmetics