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Discussion Starter · #21 ·
Alrighty, disassembled the carberators, remeasured the float height, and set them both to 23mm. One was a little high and that may have been the source of my weird issue of stalling on some, but not all right turns.

But there is no progress without struggle, and the float bowl gasket on one carb had been streched somehow and would not go back in. I tried to jam it in but that only led to a leaky float bowl, which we knew would happen. What to do, what to do?

Then I realized if I cut the gasket and took out the extra material, I could use a small length of heat shrink insulation for wires and make the gasket complete again. It worked, but I had to carefully trim the edges of the new joint to make it narrow enough to fit into the channel. Reinstalled carb and it does not leak and engine idles very well.

Once it stops raining in a few days I'll be able to get back out and report if I fixed my problem.
 

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Discussion Starter · #22 ·
Rain stopped for while and I got out for a couple of brief rides. Everything seems fine. Bike runs well. We shall see.
 

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23mm float height? What carbs are you running? Stock for a 71 are 3D carbs and they are the same as the later 722A carbs with a factory float setting of 26mm. I set mine to 27mm due to the changes in fuel density from the 70's to now.
 

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Discussion Starter · #24 ·
23mm float height? What carbs are you running? Stock for a 71 are 3D carbs and they are the same as the later 722A carbs with a factory float setting of 26mm. I set mine to 27mm due to the changes in fuel density from the 70's to now.
Hi, I went with 23mm at the suggestion of the team at Common Motors in their videos. I lowered to that height to see if more fuel in the bowl might solve my strange problem. I agree that 26mm float height is usually standard.
Interesting point about fuel density.
 

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Sorry, Common Motors is in my opinion a very poor source of information. You are going to be running rich and if you are using aftermarket jets/emulsion tubes replacements my experience is they also run richer than stock.

Sounds more like a wire is beginning to break and separate internally so that when you move the handle bars the voltage to the coils drops.
 

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Discussion Starter · #26 · (Edited)
I truly appreciate the input about the aftermarket jets. I just rebuilt the carbs with a rebuild kit and maybe that's the source of my rich problem. The main replacement jet was a 105 while the stock was a 110 as I recall. I will look into maybe going back to the original jets.

I also think you're right about maybe I'm facing an electrical problem, as I have reflected on my situation. I will go down that road and see what I can find. It's just such a strange situation happening in a way that I can't quite pin down, that I admit my float theory was shaky at best. Maybe the throttle on/off switch has a loose connection.

I do wonder why Common Motors gets no love on this forum. I agree that they do charge a premium. Until someone else puts up a bunch of videos to show how to do things, then they should at least get some love for that. I have found every video to be solid advice that has helped me understand a lot. Without those videos to get me started, the service manual would be almost indecipherable. In the absence of having a relative/neighbor to share his moto knowledge, we're forced to rely on help wherever we can find it. And so I salute you, Boomer343 for your input, sir.
 

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If you look at the percentage change from 26mm to 23mm you are close to 12% change.
My suggestion to go from 26 to 27 is roughly 4%.
If you take the 27mm that some of us have experimented with and found to work and compare it to your 23mm setting you are at 16% difference in the two settings.
When you do large percentage changes you are usually masking problems temporarily or compensating for something else that was changed dramatically.
 

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Discussion Starter · #28 ·
I have now been out on 4-5 short rides and I seem to have fixed the problem. It has not stalled once since I changed the float height.
I'm also going to stop worring over the carbon on the plugs and just ride the bike for while and see what develops.
 

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A sooty plug is the least of the issues ..... excess fuel washes down the cylinder walls and dilutes the oil. Excess carbon builds up ....
 

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That engine sounds terrible. There's definitely something wrong.
 

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Discussion Starter · #32 ·
The main thing wrong with it is that I did the work. Remember that was the very first start after the rebuild. More of a Dr Frankenstein moment of shouting “It lives!!!” than any tutorial on a good sounding engine.

Here is the engine now. Actually sounds the same to me. Chased down the electrical gremlin with a close inspection of the headlight bucket and I solved my rich running problem on the right cylinder by adjusting the mixture screw.

Thank you everyone for your input.

 

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Discussion Starter · #35 ·
I rebuilt both carborators and set the float level to 23mm which is a higher fuel level than in the service manual, but it is working for me. Then I did A bench sync on them to set the idle baseline, and finally set the idle mixture screws to 1 full turn.

Once the carbs were on and the throttle properly adjusted, I adjusted each of the idle mixture screws using the method of running each cylinder alone, and then dialed in the idle using the tach.

I monitored the spark plugs and found the right side running rich. I slowly leaned it out and compensated with small tweaks to the idle screw to keep the carbs synced.

Hope that helps.
 

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Discussion Starter · #37 ·
Too bad yours doesn't sound as cool as mine. Maybe if you chopped a few inches off of the mufflers? Seriously, thank you for sharing this video. I hear a louder ticking on my running engine and perhaps the different exhausts makes a difference in the volume? I know that the CL exhaust is the source of the 3hp reduction between the two models, so maybe it affects the exhaust note as well.

It would be cool to hear some running engines from other folks on here. I've scoured youtube for running videos, trying to learn something from the differences..
 

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That is how the engine is supposed to sound, you should not have a loud ticking sound. That sound is metal hitting on metal.
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