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Ben
Honda CB350 Racers Promotion - Moderator
Victoria
288 Posts |
 Posted - 04 Oct 2005 : 11:19:32 AM
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Hi all,
I have a wacky idea to save buying a high lift cam for the saga......
After reading up, I have found out that using a higher ratio rocker arm to increase lift actually works better than increased size on the cam lobes and is less harsh on the valve train. Can anyone confirm this?
Also, how do you measure the rocker arm ratio? (then increase it?)
Cheers!
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acotrel
Advanced Member
Victoria
2147 Posts |
Posted - 04 Oct 2005 : 6:59:48 PM
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| I believe you'll end up changing the location of the rocker spindles, unless you are going to play with valve angles. Better I believe to keep the ratios standard and regrind the cam, you'll have more control over the results. If you vary the rocker ratios, you will also vary the lift rates, and that has a major effect on the result. You could also end up bending pushrods, if the loads are too great. |
Is your machine authentic or merely eligible? |
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acotrel
Advanced Member
Victoria
2147 Posts |
Posted - 05 Oct 2005 : 6:49:09 PM
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| Better way to go is to copy a race cam from a motor which is known to not be a 'valve dropper'. Lift won't give you as much advanage as changing the duration, and overlap. |
Is your machine authentic or merely eligible? |
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Ben
Honda CB350 Racers Promotion - Moderator
Victoria
288 Posts |
Posted - 06 Oct 2005 : 4:31:38 PM
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Thanks Alan, gives me a good start on the decision process!
P.S - The tank and wheels are working out well! |
Try Everything |
Edited by - Ben on 06 Oct 2005 4:32:48 PM |
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acotrel
Advanced Member
Victoria
2147 Posts |
Posted - 06 Oct 2005 : 6:42:19 PM
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| Ben , if the cam is for your honda, you might need to do something to stop the cam chain from clapping out. When Honda brought out the kitted CB750 (CR750), the cam chain couldn't stand the stresses of the race cam. I believe some of the guys use a HyVo chain these days. |
Is your machine authentic or merely eligible? |
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Ben
Honda CB350 Racers Promotion - Moderator
Victoria
288 Posts |
Posted - 07 Oct 2005 : 2:27:47 PM
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Thats one thing I do have covered  I fitted a nice chunky Tsubaki cam chain on the first build.
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acotrel
Advanced Member
Victoria
2147 Posts |
Posted - 07 Oct 2005 : 6:57:18 PM
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The biggest difference you can make to a motor is to fit a 'full race' cam. Most of the quick 70s Jap stuff had yoshimura cams fitted, and they weren't that hot. In the mid 70s I was involved in setting up the timing on a Z1R Kawasaki, which had an Italian Termignoni cam in it. That cam was as hot as a Laverda SFC, or a Triumph 3134 race cam. That year the bike was the quickest in the unlimited at easter Bathurst.
I've looked for Termignoni over the years, but I've only seen exhausts made by them of recent years. They used to supply cams for Ferraris.
It's not hard to make a motor supply a lot more power, however you might need a close box to keep up with it. You could end up with a much narrower power band.
Ben, A person worth talking to about Honda twins, is Bill Horsman in South Australia. He had a 450 going really fast. |
Is your machine authentic or merely eligible? |
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