Popping out exhaust

[tory]

I actually have turned the screw all the way in, and out to 3.5 turns. But the popping persist.

[tory]

If the comp is good I doubt you are off by a tooth but it is a relatively easy check if it would help you get it off the list.

Dos the idle drop work on the # 1 carb?

What do you mean by idle drop

[cfairweather]

What happened to the engine when you turned the screw all the way in? Did it stall a bit or was there any change in the idle?
Is the temperature of the exhaust pipe hotter or cooler than the others?

[Whiskerfish]

If the comp is good I doubt you are off by a tooth but it is a relatively easy check if it would help you get it off the list.

Dos the idle drop work on the # 1 carb?

What do you mean by idle drop

https://ngwclub.com/forum/viewtopic.php?t=43626#p453009

[Whiskerfish]

Idle drop is recommended by the book for the later EC Carbs but is an excellent indicator of carb function for all years. If you do not have a RPM Drop when performing the test odds are very high that the idle circuit in the carb is not functioning.

[gltriker]

Idle drop is recommended by the book for the later EC Carbs but is an excellent indicator of carb function for all years. If you do not have a RPM Drop when performing the test odds are very high that the idle circuit in the carb is not functioning.

Remove that carburetor's air/fuel mixture adjuster screw. Examine its pointed end to determine if it may have been broken off and is now, irretrievably stuck in the carburetor body.

[tory]

What happened to the engine when you turned the screw all the way in? Did it stall a bit or was there any change in the idle?

The pipe on that cylinder is indeed cooler than the others.

[cfairweather]

That probably means less fuel is getting through the idle circuit on that cylinder. I bet when you turn your idle screw all the way in, no change is noticed. The most likely thing that is plugged, is the slow idle jet. They must be perfectly clean or the tiny #35 jet hole gets plugged when some foreign particles go into the idle circuit. The next most likely thing would be the idle discharge tube; the tiny tube that stands up in the venturi next to the butterfly. This may or may not be part of the popping, but it is a good starting point.

[redglbx]

One other suggestion I would add is if you still are using the oe Honda header pipes you should inspect them to ensure that the inner smaller tube has not come loose, probably not your problem but when this does happen it will cause all kinds of weird problems that are hard to trace, from a strange rattle to run issues.

[Whiskerfish]

One other suggestion I would add is if you still are using the oe Honda header pipes you should inspect them to ensure that the inner smaller tube has not come loose, probably not your problem but when this does happen it will cause all kinds of weird problems that are hard to trace, from a strange rattle to run issues.

I have seen 3 of these now on junkers I picked up. Makes me wonder if bikes parked in the past were done so because they could not figure out why they ran poorly.

[BikeMaine]

This thread is proof of the great people on this forum. The suggestions and help offered is just awesome.

[redglbx]

Personally I am not a fan of the OE factory headers because besides the double walled pipes that tend to fail with time , and are a much smaller crossection than the od would make you think. Honda just ran the rear cylinder pipes basically into the side the front cylinder pipes, very bad for flow. But most of the aftermarket headers actually employ some kind of an actual collector which improves the exhaust flow, plus they have a larger single walled pipe diameter than the OE’s.

On my 76 I went with a chromed set of head pipes that were popular way back then (can’t remember the brand name) and there was a noticeable butt dyno improvement, but keep in mind that I had a failed inner pipe so another new oe pipe might have been noticeably better as well. But the replacement head pipes have a very nice collector and being an old hot rodder that has to be much better,,, right ?

I will add that I still am using the much maligned oe muffler which is actually quite good but the consensus has been that it can’t work well because it’s so quiet but my experience is that it is not a liability until you’re in the 80-90 rwhp range, I think the oe head pipes are a much bigger problem, but that’s my .02,,,, gotta have more coffee.

[Sidecar Bob]

I read an article about Lang Hindle years ago that quoted him as saying that the loudest pipes rarely produce more power....

As I understand it loud pipes only give the impression of being faster because nobody wants to be close behind you

[Shadowjack]

I always found I was slower on louder pipes both because they made me think I was attracting unwanted official attention, and the noise offended even me. So I always rolled off.

[redglbx]

In the time I got on my buddies dyno either using it or observing others bikes being ran on it rarely, very rarely did a set of aftermarket pipes/mufflers outperform the factory stuff, most made less power and usually significantly less. They usually only made more noise.

The only exception to this was when the Harley guy’s used Screaming Eagle stuff which always made more power along with a little bit more noise, really good stuff ! One of the worst examples was on my buddies Valkyrie when he put a set of 6 into 6 pipes on it that (can’t remember the brand) that were popular at the time, very cool looking with a lot more noise and lost a minimum of 10% power & torque everywhere, just junk pipes.

I would’ve liked to have been able to dyno the oe double walled head pipes vs the aftermarket header type on my wing but it just wasn’t a possibility at the time. Everything I know about exhaust header type pipes is wrong on the oe’s. But one lesson I learned in my time on the dyno is what you think you know is usually wrong,,, the dyno doesn’t lie!