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Messages - cbxman
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61
« on: June 14, 2022, 04:48:12 PM »
There are two lengths of springs fitted to the 750. Early ones were short with a thicker dia coil. Later springs are longer with smaller coil 
Trigger, Thank you. Being an American import, this bike could have anything in it! I have measured the springs that are in it. They are 35.5 mm long, with 8 turns of 2.6 mm of wire. Extremely hard to compress by hand. There's a company called Barnett (sp?) and they produce performance parts. Their take on the 750 is springs 36 mm long with 2.6 mm wire. I think those springs are the hopped up ones. Apparently stock Honda springs are supposed to be 31.75mm with 2.54mm wire.. A lot shorter with thinner wire. Also....Studying the release mechanism a bit more, I noticed that the release bearing was not seated in the release plate. About a 1mm short of seated. The release cup which fits into it was not seated either. They were solid I had to press them out. I cleaned the faces, greased them and pressed them back in to seated. How did that happen? They must have been like that from factory. I have been trying to figure out what that might mean in terms of clutch performance....maybe nothing other than the adjuster screw might be set further out than normal. The interaction between the face of the release cup and the release mechanism is unclear. The adjuster screw seems to just push the release bearing away, which means the face of the release mechanism isn't running against the flat portion of the mechanism...may be that's how it is.. with the nose of the adjuster screw running in the bottom of the cup rather than the flat faces of the two Baffled, and apologies for the waffling.... Jerry
62
« on: June 13, 2022, 08:47:32 PM »
Nigel
Thank you for the info. I don’t need drag bike clutch performance, so I’ll try to find some standard springs. They are incredibly stiff.
I have checked the steels for flatness and they all have warps exceeding the 0.03mm limit. The friction discs too exceeds the 0.03mm
So looks like new springs and discs. Ouch!
Cheers,
Jerry
63
« on: June 13, 2022, 05:34:39 PM »
Hi Guys,
The clutch on my 750 K1 was not too good. It would drag. Not nice changing gears. So searching on this site revealed some interesting stuff.
Based on some of those threads, I bought a K6 clutch on eBay which had a very nice looking lifter plate on spec......just in case.
I have pulled the clutch today an hey-ho the lifter plate is broken with three of the spring posts having fractures. I guess this would be a major contributor to my problems.
The steels are quite badly stained. Maybe not to the point of serious corrosion, so I think I will buy new.
Now having got this K6 clutch assembly, I don't want to break it. I have read that they can be broken if the pack is not assembled correctly, so care is required here.
I thought I would check the spring lengths and found that all four of them were around 35.5 mm, which would be much too long if the 30.5mm WSM spec is to believed. I'm wondering if that extra length may have caused the lifter failure.
Any idea what the correct length should be?
The lifter mechanism looks good though
And the friction plates are barely worn.
Photos attached
Cheers,
Jerry
64
« on: May 28, 2022, 05:07:24 PM »
Nigel,
Interesting.
I think I might try a 100:1 mix with two stroke oil in the tank and have ride before I put her away in the autumn for the long winter snooze. Same with the CBX. I have a Suzuki GT550, so I have 2T oil handy.
Cheers,
Jerry
65
« on: May 26, 2022, 04:39:37 PM »
For interest, the clip statement a couple of post back about ethanol is from here https://extension.psu.edu/fuel-ethanol-hero-or-villain which appears to offer reasonable balance in topline discussion of that fuel supply.
Nigel, Interesting article. It is light on the downsides, like for "older machinery". We all know how corrosive the use of ethanol can be and this must be our main worry. However, I don't see that we have a great deal of choice. Mark is suggesting a way of compensating for the "Leanness", but of course if you end up using variable E numbers, or none, then you may run rich. I think in the states they are stuck with E10, so it makes sense to re-tune the engine somehow. I have read that some people make a weak two stroke mix in their tanks, which is claimed to reduce the corrosive element of ethanol fuel. Not sure of this as I am not a chemist. Cheers, Jerry
66
« on: May 26, 2022, 01:23:56 PM »
Nigel,
Just had another look at an emulsifier. The small holes are at the bottom, not the top as mentioned in my last post
Sorry,
Jerry
67
« on: May 26, 2022, 10:14:04 AM »
Nigel,
Interesting stuff, so why open the emulsifier holes. That would make sense of Mark's explanation of adding extra air with the airscrew which enriches the idle mixture. However, we know that adding extra air via the airscrew to the idle jet actually leans it out.
Maybe the difference between how an idle jet works and how a main/needle jet works is the answer.
Somewhere, the emulsion tube function is explained, maybe in that same thread. The lower holes are under the fuel height in the bowl, the upper (smaller ones to be opened up) are above the fuel height. This would imply weakening the mixture if we are observe the equivalent in the idle circuit. Marks explanation of making the fuel bubble up faster would make sense in making it richer.....
Confused
Jerry
68
« on: May 25, 2022, 02:48:47 PM »
Nigel, It seems that the air entering the throat by way of the twist grip is the air that sets the 14.7, demand from the needle jet. I guess the emulsion tube makes the petrol flow out of the needle jet in smoother and, as you say, homogeneous way. However enlarging the emulsion tube holes even ever so slightly must add air to the mix, which I guess means leaning the overall mixture. Mark suggests that ethanol in the fuel makes the combustion burn cooler. So maybe the extra leanness is compensating for the coolness and makes the combustion run hotter, maybe  ? Perhaps a reduction in main jet size is too crude for such subtlety? Jerry
69
« on: May 24, 2022, 04:41:58 PM »
Not being an expert at all. See my bumbling earlier in this thread.
The theory may be fine if you are familiar with fluid dynamics and can understand it, but simple test surely is to check plug condition against an airscrew setting. that should settle it....
Jerry
70
« on: May 24, 2022, 09:48:32 AM »
Nigel, http://forums.sohc4.net/index.php/topic,164119.0.htmlThis is a long thread. Checkout reply #27, then go on to #55, then #60. All very interesting, particularly the arguments over the what the airscrew does! Also mods to Emulsifier. Cheers, Jerry
71
« on: May 23, 2022, 04:15:22 PM »
Steve,
I'm very near Needham Market.
Jerry,
72
« on: May 23, 2022, 11:24:06 AM »
Nigel,
Thank you for your in-depth analysis of what is going here.
Yes, the procedure should make allowances for varying qualities of fuel, bearing in mind these bikes were sold all over the world.
Interestingly, Hondaman on .net has written about how the ethanol content, that Mr Honda was probably not planning for, has affected the way ethanol alters the burn rate and temperature. He suggests that the main jet emulsifier holes which have two different diameters, the smaller ones should be drilled to the size of the upper ones....I think. Opening the holes up allows more air to the mixture without reducing the fuel rate through the main jet....I think.....
As I am lucky enough to live in an area where the premium fuels are slated as having no ethanol in them, I will reserve judgement.
Anybody seeing this information should check very carefully before altering their emulsion tubes. They seem to be quite scarce items.
Cheers,
Jerry
73
« on: May 18, 2022, 11:48:39 AM »
Hello Phil,
I scrapped a 550 a few years ago. It had a cam meltdown. I scrapped the frame, but I kept all the parts....I think. I have just had a rummage and found nearly all the bits for a T reg 550. I have looked at the CMS for a 550F 1976 and the parts pretty much match what is in the parts book.
Have loads of engine parts and a solid tank, etc....PM me if you are interested
Cheers,
Jerry
74
« on: May 17, 2022, 10:00:16 AM »
Hi,
Just an update on my struggle with this 750.
After fooling around with jets, settings, advancers, camshafts, needle heights etc………
I did install some new brass floats. I set them at 26mm (some say 24mm). The clear tube method indicate about 4-5mm below gasket. I barely had to adjust the float tangs at all. I don’t think this has any bearing on the problem though as the fuel height was no different. It could be an issue with the angle the tang presents to the float needle, just a guess.
I believe that I may have sorted the problem….
Although there were some camshaft issues, I don’t believe that it was bad enough to cause the fuelling problems I was having. I always felt it was a mostly a carb issue.
Along the way, I have found that the condition of the tappet ends were bad enough to give erroneous cam timing results. I refaced the tappet screws and it made the cam timing results much closer to the spec. The main thing is that it was so much easier to adjust the clearances. However all the minor improvements I have done may have influenced the final result a little, but to me, It was something that Nigel (K2-K6) mentioned to me in a PM…. He pointed me to the Honda carburation setting section of the WSM, which loosely described the set up procedure. It was not very specific on the exact process. Nigel suggested in Reply #25
“The manual has routine for starting with airscrew at a baseline then running it and shifting the airscrew further outward to make it leaner, this until it's heard that the cylinder you are working on starts to falter as it goes too lean. Then bringing the idle speed back downward by 100 rpm when turning the airscrew inwards to make it run slightly richer than that peak rpm just as it falters.
Then you reset the main idle speed control (master adjust for carb rack) to bring rpm in reasonable range overall. Repeated for each cylinder, you'll then have set the mixture for those idle jets in use.”
It made me think that I may have been starting the procedure with too much idle set, rather than starting low and adjusting the airscrews to improve the rpm. I went round the carbs with this in mind and ended up with airscrews out further that I had managed before. I knew that with the airscrews set out would allow the throttle response to good. So with a good idle with a hot engine, I took it out for a ride……really good throttle response on-off the gas and when I stopped it would idle nicely….Result.
So it seems to have the been the mental approach to adjusting the carbs rather assuming only one way to do it.
Could say that the 750 WSM is geared for qualified Honda Service guys, rather than amateurs like me. Maybe if I had the Haynes manual.it might have helped.
I would not say I had any real experience with carbs, in spite of quite happily stripping and refurbishing a six-pack of carbs from the CBX and getting it to run perfectly with just following the set up procedure…
The CBX1000 WSM is very specific regarding tolerances and torque settings, etc making it really useful to the enthusiast….
Big thank you to Nigel for his guidance.
Cheers,
Jerry
75
« on: May 12, 2022, 08:39:46 AM »
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