Isolastic Centering?

KiwiShane said:
What year is your cb 750 ?
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We're off topic. Apologies. 1976, K6. I'll qualify what I said. The Commando suspension's ability to smooth out bumps is superior to the Honda, but the Honda has a lighter turn in feel and changes direction more easily / quicker. It's possible it may just be Dunlops vs. Avon. However, I think it's weight distribution, the weight is more to the rear on the Norton.
 
Mart UK said:
We're off topic. Apologies. 1976, K6. I'll qualify what I said. The Commando suspension's ability to smooth out bumps is superior to the Honda, but the Honda has a lighter turn in feel and changes direction more easily / quicker. It's possible it may just be Dunlops vs. Avon. However, I think it's weight distribution, the weight is more to the rear on the Norton.
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It's way way off topic but
I had a 1972 K2 and a 1977 f2
The ones I owned did not handle as well as my MK2a at that time in my opinion
 
baz said:
It's way way off topic but
I had a 1972 K2 and a 1977 f2
The ones I owned did not handle as well as my MK2a at that time in my opinion
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I never owned one, I was WAY to stubborn for that!

I personally thought they were fine, no issues, no drama, etc. Dreadfully dull though.

But I would’t say one out handled a Commando. Well, not one with the ISOs adjusted correctly at least.
 
Yes, that's the common view and I wasn't expecting it. My isolastics are fine.
 
Mart UK said:
Yes, that's the common view and I wasn't expecting it. My isolastics are fine.
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I wasn’t saying they aren’t btw.

In reality lot comes down to set up, tyres (as you already pointed out), shock choice and condition, fork condition, wheel alignment, etc, etc.

There’s lots of things that can easily override, or partially overcome, the theoretical affects of frame design.
 
A test you could try is to set the ISOs deliberately wide
Say 20 thou or more then take it for a ride
That should be wide enough to not put any drag on the ISOs form misalignments
Then you will know if it's simply the rubber being too hard
Be careful because it'll handle like it has a hinge in the middle or handle like a "CB 750 "🤣🤣🤣 delete as appropriate
 
baz said:
A test you could try is to set the ISOs deliberately wide
Say 20 thou or more then take it for a ride
That should be wide enough to not put any drag on the ISOs form misalignments
Then you will know if it's simply the rubber being too hard
Be careful because it'll handle like it has a hinge in the middle or handle like a "CB 750 "🤣🤣🤣 delete as appropriate
Click to expand...
The very FIRST Commando I rode was a MK III with totally bagged out iso's, on some winding roads in TN. I was so intoxicated with the prodigious torque & smooth vibration level, I just laughed at the 1/2 degree of random course deviation while railing fast sweepers.😎💨
Knew I had to have one then.
 
Regarding CB 750, I had a 1970 Daytona and my buddy bought a CB 750. He loaned it to me and I nearly crashed in a series of tight corners that were nothing on the Triumph. Sold that to buy first commando not sorry about the commando but missed the Triumph. Later on while turning wrenches in a Volvo dealership a guy came in wanting to trade his CB 750 on a used car. Boss said take the Honda for a ride and tell me what you think. I crashed at around 70 mph on a straight part of freeway and later when I took a look at it which I should’ve done earlier I found worn plastic swingarm bushings, 12 pounds of air in the front tire and a handlebar fairing. Advice here; do not high speed crash wearing cotton coveralls.
 
Don’t be so freakin’ narrow minded y’all.

Those Honda‘s can be made to handle nicely with a bit of tweaking here n there…

Isolastic Centering?
 
Besides the cradle, is the frame bent ? If you stick (straight) 1/2" rods through the front and rear isolastic mounts and the replace the front and rear axles with similar rods, do both sides look the same ? Is one of them in a different plane or the ends closer or farther apart ?
 
Mine handles well. But 4 x carbs are a pig. Very sensitive to float height. They're coming off for the 4th time this morning. It's just a very different ride to the Commando. Not better or worse, just interesting to have two very different bikes that were the best of their kind in the same timeframe (1975/76).
20230315_220517.jpg
 
concours said:
I have a CB500 4, that came as a package deal. It's a gutless lump.
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They can be made to go
I had a 500 four with a full Yoshi kit big bore full race cam and a box swingarm CMA 3 spokes
It was very fast
Screamed like a banshee but it didn't last too long
There was too much flex on the liners
 
gjr said:
Besides the cradle, is the frame bent ? If you stick (straight) 1/2" rods through the front and rear isolastic mounts and the replace the front and rear axles with similar rods, do both sides look the same ? Is one of them in a different plane or the ends closer or farther apart ?
Click to expand...
I can say the frame was stripped down a year and a half ago to correct some down tube distortions (likely had highway bars at some point that damaged the tubes) and repair sidestand bracket. The experienced frame guy used a jig and stated all issues with frame were corrected.
 
baz said:
They can be made to go
I had a 500 four with a full Yoshi kit big bore full race cam and a box swingarm CMA 3 spokes
It was very fast
Screamed like a banshee but it didn't last too long
There was too much flex on the liners
Click to expand...
"Whiz-bang" 🤣
 
concours said:
"Whiz-bang" 🤣
Click to expand...
Tell me about it
I seized one of the pistons I rebuilt it using 750 f2 pistons that were available in the right bore size but I have to machine the valve pockets deeper but that didn't work out
So I decided to fit a cb550 barrel but that needed work
I had to push the liners out and reduce the spigot diameter to fit the 500 cases
It worked out well in the end
No wonder I drink
 
Does anyone know why the MKIII rear iso setup uses two larger diameter bushes while the MKII non-vernier setup uses three bushes? Seems a heavier bike (starter/bigger battery) would want a beefier iso mount, no?
 
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