How To Install An External Gas Filter On A 1985 Honda Cb650cs Nighthawk

16MAR2020 Update

Summary: I ran her till she was warmed up, fine tuned the carb sync, and she runs like crap.

Bike - It's a 1983 CB650 nighthawk with 14k miles. She was in storage for many years (probably viii-10 years) before I bought her final summertime. She had a kerker 4-i exhaust on her but I replaced information technology (very rusty) with a MAC 4-1 frazzle. I will say, based on the sound, I don't think this exhaust provides much in the way of back-pressure, then information technology's possible my jetting does need to come up. The air filter is new, simply a stock paper one, so shouldn't impact jetting. The merely good thing that happened this weekend was I got a pic of her (although not a slap-up angle) with all her wearing apparel on.

Carbs? As you probably know I recently removed the carbs and cleaned them. I ran "loftier-Due east" guitar strings through the idle circuit. I held my finger on various holes and fabricated certain there was a steady flow of carb cleaner coming from every pigsty. I separated the carbs and everything has new o-rings. The carbs looked groovy when I got into them so I recall they were recently gone through (just not separated). I put new jets in rather than cleaning the old ones. I went with stock jets for both the low and high speed jets. The only thing non stock is I put a single washer under the needle.

Symptoms:
---Note: All testing was done on sunny, high 40's degree F, so yet pretty cold---

1. Difficult to start: I put the asphyxiate on and I notwithstanding have to give information technology a wee scrap of throttle while spinning the starter. I hear her trying to first but information technology takes longer than it should, probably about xxx seconds. Subsequently that I have to run her around 3k RPMs just to go her warm enough to stay running with the asphyxiate on. After that the choke does it'due south matter and the idle does increase as she warms upwards.

two. Slight Erratic Idle: After she warms up in the driveway I tin take the choke off her and she'll idle around 1100 or 1200 RPMs. But every 3-5 seconds the RPMs seem to jump up 100 RPMs. Information technology isn't a huge amount, it isn't surging 500 RPMs or anything, merely it is noticeably more than a well running bike should.

3. Stumbles off-idle without load: If I twist her to WOT (even so in the driveway) she does not shoot upward the tach like she should. It takes a second to go from idle to 3k, then moves much quicker up the tach. This part might exist my imagination, only I think she actually shoots up the RPMs better, without load in the driveway, while on the cold side? After I took her for a ride this off-idle stumble seemed to exist more than noticable? I'm non 100% certain on that i though as I may have inverse something else before making the post-ride observation.

4. Runs like domestic dog poop under load: So I took her for a  15 infinitesimal ride later running her in the driveway for ten minutes. She didn't stall a unmarried time. Simply she stumbles hard. It is very consistent and noticeable from idle to 3-6k RPMs, but it happened at higher RPMs equally well a few times, just a little less (or at least less noticeable). It's like she runs/bogs/runs/bogs/runs as the RPMs climb.

5. Frazzle: The exhaust looks white (rich) when she first starts but once she is warmed upwardly, in that location is no smoke at all.

WHAT THE HELL???

A. Anyways, I got home, took the tank off, and fine-tuned the carb synchronization. I switched gauges effectually as I did it so my one gauge that is reading a niggling low is not role of the equation. They are spot on. I don't call back I can get them any closer.

B. I thought I might be dealing with a vacuum leak so I sprayed starting spray effectually the carb boots... NO change in RPMs noticed. I did this several times and no modify was ever noticed.

C. I wanted to come across if she is running really lean or actually rich (assuming it is a fuel issue) so I took the air filter out. If she was running really rich this should take brought it back into the skillful/lean realm, right? But she stalled very quickly and didn't want to kickoff like that. And then maybe she's running actually lean? Or volition these bikes not run with an air cleaner in? My V4 Magna wouldn't beginning unless the air filter was in and the airbox was completely assembled, but every V-Twin I've had would at least run without an air cleaner.

D. I took two of the spark plugs out. They wait original, significant 37 years old, just not broken electrodes or anything.

So am I dealing with a fuel outcome or an ignition effect? The nigh common event would be the carbs, only I can't effigy out how the carbs would match my observations.
 - Specifically, if the idle circuit is dirty, I shouldn't see whatever stumble higher up 2k RPMs, should I? I wouldn't recollect I would come across any stumble at all upwards around 6k, but I do.
 - If the main jet is too small (significant she'due south running really lean), would I come across such an erratic stumble with power on/power off surges going upwardly the RPMs? I would recollect she would run consistent, merely not optimal, if the chief jet was too small.
- Vacuum leak? I call up the only other location would be the diaphragms within the carbs... what if I didn't seat one of them perfectly and the diaphragm is not sealing well in 1 carb. Would this cause the symptoms I'm describing?

The other possibility is that this is an ignition issue. I think I read a few months back that someone was having an issue with their ignition coil whereby they would ride for 20 minutes (warming everything up) and and then would have a heck of a time restarting their bike until she cooled back down. I'm going to but throw money at this one. I ordered two coils, wires and boots, and spark plugs. Total price is $ninety and it will be easier/faster to replace what is on there at present rather than diagnose the 37 year old components. Also, the new wires are red and then they'll look 'faster'.

I approximate at that place is i other possibility... I guess this could be a compression effect (gulp!). I didn't think of that possibility.

So whatsoever guesses? Is it a fuel, spark, or compression issue? What did I miss???

How To Install An External Gas Filter On A 1985 Honda Cb650cs Nighthawk,

Source: https://nighthawk-forums.com/index.php?topic=4646.0

Posted by: byerssuman1965.blogspot.com

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