Xing CA77

[conbs]

Teazer, thanks so much for that post. It is very helpful.

This is all theoretical to me. I have never been on a race track, but I think I understand the idea that it pushes everything to the limit. That is, it will amplify the effects of the way everything works.

I also understand that the race track is way different than me riding an old, slower bike out on a pleasure cruise. But, even in my style of riding, I expect two things. 1. A lot of stop and go driving where less space between 1st and 2nd would seem to be a good thing. 2. Revving the motor farther into the power band for passing with an x-ed 3rd gear will help my slow, old bike get around the few vehicles I will be fast enough to pass.

I am not trying to debate this and I have not made up my mind yet. I am just getting ready to button up the cases and am trying to get it right so that I won't be splittting the case again, just to rearrange gears in the transmission.

Teazer, I want to make sure I understand your comment "I have tried 2 seconds, two thirds, Dream top gear, X'd on the race track "

First I assume you were not racing a Dream so the ratios were different. Was it a CL/CB that was sub optimal for racing when X-ed? Second, I am not sure I understnad what you mean by "2 seconds and two thirds". Does that mean you tried 2 different gear sets with different ratios for each? Is that something I should consider?

Thanks again for taking the time to post. Perhaps I am being thick skulled. I am just trying to understand this better and I simply don't have the experience that a lot of you guys have. And, the CPU in my noggin' is old and getting slower.

I have considered a 5-speed, but not the rare and expensive aftermarket offerings. There has been some discussion on this site about transmissions from other bikes (CB350?) that would drop right in. I even bought a couple of tranny's on ebay because they were cheap. Obviously, the chain being on the right side is an automatic issue, but, I thought I might be able to find gear sets to slide on the Dream shafts. The problem is the main and counter shafts of the 305 are closer than any other transmission I have found so other gear sets won't "drop in".

Thanks to all who post and I hope this discussion will help others.

[brewsky]

I just remembered this thread....

http://www.honda305.com/forums/cb-vs-cl ... t=crossing

It appears that crossing the CB/CL gears gives about the same top three ratios as the CA un-crossed

The biggest difference seems to be that the Dream 1st gear is so much lower than the others, causing such a big gap between 1 & 2.

I agree with Teazer, if you are going to be spending a lot of time at lower speeds, maybe it would be better to do the swap, but if more time is spent at 55-60 in traffic or in hilly terrain, probably better of to leave it alone.

Maybe the "problem" with the CB/CL ratios was "fixed" in the Dream.....except for the "granny" low?

[teazer]

2 seconds means that I used a stock second gear in second and I used another pair turned around in place of third gear (same as a crossed set). I had several sets of gears to play with.

IIRC the dream had a 31 tooth sleeve gear and the CB was 3oT or maybe that was the other way round. I'd have to check my notes. That also changes the ratios slightly.

Bottom line is that it's a fairly wide ratio transmission so it's a matter of juggling gaps to best suit the way you ride - or leave it stock.

5 speed is better but race gears have a much closer set of ratios and very high first gear. The optimal answer is what Jerry does and that is to splice in a more recent 6 speed with better spaced gears. 5 can fit in the available space but a sixth requires some serious welding and machining to basically move the bearing saddles and move one crankcase wall out to create more space.

I'm surprised someone hasn't come up with a set of CNC machined cases with 6 speed trans, decent oil pump, gear drive cams etc but it would no longer be a CB77 at all.

[conbs]

Been gone on business for a couple of days, but back at it now.

Brewsky and Teazer, thanks for clearing up the 1st gear questions for me. I now see that the 1st to 2nd gear long-jump is created not because 2nd is too high, but because 1st gear on a Dream is so low. Hence, the Dream is pretty quick off the line. From there getting to highway speed is necessarily a series of long-jumps. It is compounded by lower HP of a Dream motor and itty bitty 16 inch tires.

So, I guess I just need to make a decision and get 'er done. I was a little surprised that there have been no posts from others who have tried X-ing a Dream. Am I really the first guy who may actually do this?

But, then there is that 5-speed thing.......

[G-Man]

I have a ton of gearbox parts but no complete Hawk transmission that I know of. I did a spreadsheet of the gears in the parts manuals to see what I could build up for my CB77.

Here is a little graph of Hawk and Dream ratios (from the gear teeth numbers) and the comparison with X'ing them....

That Dream first gear is rather low but the others, whether X'd or not are much of a muchness. Has anyone mixed and matched Hawk and Dream transmission gears (as pairs) ?



G

[conbs]

G, Now I am starting to get a little confused. In my first post I noted the ratios for the Dream from the Shop Manual are:

Low 3.39
2nd 1.88
3rd 1.38
Top 1.00

The chart you posted shows ratios that look like they range from around 2 to .5. How do I interpret the difference? The chart would also appear to show "much of muchness" for Dream and Hawk gears whether X-ed or not. Do I have that correct?

I realize that there is also difference in 16 vs 18 inch tires as well as different sprocket ratios on the Dream vs Superhawk, which will translate into different RPM/MPH.

The one thing I think I do discern from your graph is that an X-ed Superhawk gives a much more even "line" across the top of the plotted gears, i.e. more even spacing between gears. The Dream - X-ed or not - seems to be much of muchness. Does your final question regard putting Superhawk 2nd/3rd, X-ed in a Dream? That would appear to get at what I have been suggesting, i.e. more even space between gears.

Is there something I am missing in what I think I am seeing in G's chart? I would really appreciate any help anyone is willing to give on this.

[G-Man]

Conbs

I assume that the ratios in the manual include the primary reduction and the final drive reduction. i.e. the total ration between crank revs and rear wheel revs. My graph is just the ration between input and output shaft of the gearbox determined from the teeth on the gears.

It's interesting (but not shown in the graph) that the Hawk and Dream have different pitch gears. The sum of the teeth on Hawk gear pairs is 52 while the sum on a Dream is 51. I have not checked but wonder if you can transfer gear pairs from bike to bike. i.e. could you use a Hawk first gear (pair) in a Dream.

Your observations are correct on the graph but the chart won't tell you what the result actually feels like on the road.

It looks like there might be some fun to be had with building up a gear set from the two different bikes. I'll have a look at the weekend.

G