Author Archives: Zen
Zen Mechanic Exhaust
Over the past period, we have worked hard on what is now known as the Zen Mechanic DH exhaust. There is great interest in this exhaust. On this page you can read what you can do if you want to get one too. Be aware, there are very limited pieces available!
A nice video about this can be found on our YouTube channel.
Hondadag 12 June 2022
ZOn June 12, 2022 the time had come, more than 300 Hondas gathered in Utrecht for a joint ride of 140 km. Old, new, fast, slow, small and large, there was a lot to see. At the USV Hercules in Utrecht there was first a beauty contest for the most beautiful or special Honda. After the prize giving, the ride started. The lunch was organized in ‘t Vitus in Blaricum. The sleepy village was brutally shaken awake by a huge number of Hondas. On return to Utrecht there was a nice drink on the terrace of USV Hercules and the opportunity to discuss the ride in detail while enjoying a nice cold drink
Here’s a video summary of the ride.
Cylinder head swap
For my personal project, the CD90, I’m looking for a bit more performance. Currently the C90 engine (HA02, GB6) has a 52mm bore making 110cc on a standard C90 crankshaft (49.5mm). But the engine still has problems going faster than, say, 80 km/h. There can be 3 reasons for this. First is the cylinder head, Continue reading
First ride HGG&V
Today I joined a local group of Honda motorcyclists called Honda Gangers Gooi & Vecht region for their ride “Holderdebolder through the polder”. Sunday morning at 10:00 AM we gathered in Blaricum for a 150 km long ride through the polder to Lelystad. The weather was absolutely fantastic, nice and sunny, temperature around 25C. The turnout was great with about 44 Hondas! According to the tradition of this group, they gathered after the ride in café D’Ouwe Tak in Blaricum to enjoy a nice cold beer. Thank you for the hospitality and I will join you again on the next ride.
Replacing glass speedometer
A few days ago I decided to replace the glass on my speedometer. The old glass was all cracked. Especially annoying when it rains. A good friend of mine, Martijn, was already doing this job on one of his Honda’s and offered me his experience and tools to help me. Since there are no more parts available for this speedometer, we were forced to make a new glass.
This short video shows how we did it. I am really happy with the result. I don’t think Nippon Seiki would do better on his own…</p>
6-volt CDI ignition
By a video of Josh from YOUR Vintage Honda Mini’s I came across a really nice product: a 6v CDI ignition. When I re-entered the world of Honda last year, there were a lot of people advising me to switch from 6v contact points ignition to 12v CDI ignition. I was a bit reserved for several reasons. First of all: a contact point ignition works fine if the adjustment is correct. Especially if you have an advanced flywheel. Second, if you want to convert to a 12v CDI ignition you will need to modify your left crankcase as there is no room for the pickup. And finally: you have to replace all electrical items that are not suitable for 12v (all lamps, horn, battery, etc.). So it is quite an investment if you want to go from 6v to 12v.
But this 6v CDI ignition from OHTOKC is the best of both worlds. All you need to change is your base plate. The pickup is integrated in the light coil. So no external pick-up required. And perhaps best of all: you don’t have to make any further changes to your electrical installation. It spins with your own flywheel and generates your normal 6v. All you have to look for is a place to place the CDI unit. The CDI unit has advance, so even if you have a non-advanced flywheel, you already have an advantage!
I’ve done a few test drives with this ignition and I’m quite excited! It starts easily and the torque seems more even from low to high rpm.
Watch my video for details on the assembly and of course: subscribe!
Upgrade CD50 50cc to 90cc
In my intention to upgrade a CD50 from 50cc to 90cc, I made a video on what to look out for. The parts you need to upgrade:
– Crankshaft with a longer stroke (52mm);
– Oil pump and oil pump shaft;
– Gear ratio (optional);
– clutch (you need a clutch with more than one plate);
– and of course a bigger cylinder.
Watch my video about the project here:
A small sound sample of the 90cc with the famous Honda DH exhaust :
Assembling a Honda CD50 engine
After 25 years of buying a Honda CD50 again, I immediately started overhauling the engine. This one had a lot of ticks and noises and it didn’t deliver the power it should. I decided I could make a video of putting the bike back together, so in this video I’m assembling a Honda CD50 engine!
Original Honda DH-exhaust
By far the most beautiful “Honda -sound” of the original HM087 exhaust as delivered in the 1970s. A design that seems to come from the 1960s, in the Netherlands we know this exhaust as the “DH” because of the letters D and H stamped on the bottom of the buck attack. They were only delivered in the Netherlands on the CD-50. In the late 1970s, Honda already stopped producing these exhausts and delivered the simpler HM067 (aka “D”) that didn’t sound the same.
The sound actually consists of two parts, a deep dark bass and a kind of ‘woody’ knock. What is striking is that, especially when the engine is idling slowly, almost every power stroke of the piston seems to be heard individually. Driving past a Honda with a DH exhaust at a somewhat greater distance also has a very unique sound. Even between whole groups of Honda’s you can effortlessly pick the DH’s out.
Although many have tried, none have succeeded in reproducing the famous DH sound of the 60s and 70s. A very well hidden Honda secret.