CB450 K0 dynojet and why it doesn't need a five speed transI resisted this time....I'm really wanting a scrambler for sentimental reasons. I'm still holding off on my dyno runs till the shop has their "dyno day" special prices......my record for "low HP" is still posted on their board! 66 dream, 78 cb750k, 02fz1, 09 wing
Hi,
Last Sunday I covered 500+ km (300+ miles). the weather was beautiful, not to hot, and not to cold. It was a perfect Sunday. I rode over 100 km high way (65 miles), with an average speed of 120 - 130 km/hr (75 to 80 miles/hr). I also covered 400 km small roads, back lanes, and crossing villages, in the speed range from 20 to 50 miles/hr, including lot's of shifting from first to second to third and back. It seems that the bike runs great, and that the issue with the gap between the first and second gear is less noticeable. Within a few weeks I will hopefully confirm what I feel as the improved torque curves due to setting the needles. Fuel economics on the other hand is not so great, and not what I expected. It does 18 km a liter, and that is very low (if I'm not wrong that is 11.2 miles per liter, and 50 miles per gallon). My CB72 does 25 km a liter (70.6 miles per gallon), and according to the gas analyzer measurements on the dyno of both bikes, the mixture is about the same. Jensen assembly of Japanese motorcycles requires great peace of mind (Pirsig)
Hi Jensen, thanks for this , very interesting. I have recently bought a bomber, I have always liked them.
I had read about the lag between 1st and 2nd gears but knew how to deal with it due to once owning a 1975 GT250 Suzuki, it has the same symptom, and was noted in a period road test. To get around the lag I would keep the revs up some and slip the clutch a bit at the same time. I took the bomber on a first test ride last night and only noted the lag on down shifting so applied my method. Because the 450 has more torque than the old GT250 I probably over did it and I think after a few more rides I will be able to avoid the lag altogether by timing the changes differently, and the timing is only really needed when downshifting into sharp or right angle corners, you just have that bit of free wheeling feel that can be off putting somewhat. Interesting to me was that the feel of the whole bike was very similar to a Notron 650SS Mercury I had some years back, it too had a 4 speed box, no gear lag though and probably due to being a 650 with more torque again, but the whole package of the bike just pulling and pulling thru the gears was pretty much the same. I sure would like to get the bomber to sound the same as that old Norton:-) Here is a pic http://www.netbikes.com.au/cycleauction ... nished.jpg Cheers Chris @ www.netbikes.com.au
Hi Chris,
Welcome to the forum, and it’s good to read that you ride it. For a bike with its roots back in the 60’s its very usable in modern traffic. You’re so right about the sharp angle corners . When approaching a corner in third gear, you shift back into the second gear, but in the corner the speed drops below 20 miles an hour thus below the point that the second gear can “pull it out” the corner. Then, especially when used to two –strokes, you almost automatically grab the clutch and pull out of the corner with a slipping clutch. I don’t know how the clutch will behave after a few 1000 miles using this method, but I think that more modern clutch plates can handle the abuse. Most sharp corners are in or around town, so shifting back into first gear before the corner, and accelerate out the corner in first gear too, will make heads turn, but not from motorcycle noise lovers only, so around town that’s not an option (in the Netherlands). I cannot confirm your experiences with a Norton 650 SS Mercury. Actually I have no experience at all on British bikes ( it’s a shame or a relieve ?) But many people I met while riding the CB450 BBt say that the CB450 BB has the sound and character of a British bike (and the looks). The bike in the pic is a good looker and nice restored . Jensen assembly of Japanese motorcycles requires great peace of mind (Pirsig)
Hi,
some pictures to share :  CB450 engine close up by dream1964, on Flickr and this :  CB450 after a long trip by dream1964, on Flickr Jensen assembly of Japanese motorcycles requires great peace of mind (Pirsig)
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