Author Topic: The elusive surge  (Read 1938 times)

Offline Nurse Julie

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Re: The elusive surge
« Reply #45 on: January 20, 2022, 05:34:22 PM »
It's a shame I don't need one, due to not having Hettie anymore and she had a lid anyway but, thats just great.
Im a Nurse, trust me, this won't hurt.....much !!!

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Offline K2-K6

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Re: The elusive surge
« Reply #46 on: January 21, 2022, 09:41:00 AM »
Hey K2 (is that your droid name?)

Nah man by all means labour away! Having taken some time off and re read Bryanj's post, I did not in fact follow that procedure to the letter. I will take it back from the top.

Two things I have forgotten to mention: I do not have the spring retainer for the air filter and I haven't got either the air filter cover. I have used duct tape as a makeshift cover but no garantee it is air tight. Do you think these missing elements might leanen the mixture? I say this knowing that at the moment the mixture is rich ( sooty plugs) but if it does leanen the mix it wouldn't  help getting a reliable setup right?
Lastly on that front: The airbox is the original and because of its age, it has warped a bit, the front end is a tad concave. Consequently connecting properly the air intakes for carb 2 and 3 is not feasable. I can get them in and even tighten the collars but not get the connectors all the way in. I guess that doesn't help either? Could not find a lot of info on those issues.

All the best

Nothing profound in my site name, met someone from this site at the Ace cafe that told me about this site, setting up first ever such interaction and just used previous Honda models that I'd owned. Not very inventive I'm afraid  ;D

For the surge problems, as we on here can't be present to see things it makes the process a little more laboured naturally.  The bench synchronisation and then leaving it alone is also an important element in giving continuity of conditions. It is easily good enough to run any of the four cylinder engines at correct parity and importantly vetifies that technically correct status to analyse other components and their effects.
If, gradually, you fix down each variable (the box lid another good move) then the potential problem sites will just be less in number, and possibly more visible to help you find solution.
The significant problem that may arise with gauge carb sync at this point is that if you have an air leak or similar as principle cause, then the synchronisation with guages will direct you to adjust the slides to accommodate it,  making another error included on the bike, then it just keeps you going round in circles.

Something else to check if the carbs are appart is the idle circuits as they are very small and hard to fully clean, but absolutely crucial to how the engine runs.
One way to check with the carbs installed is to try each carb on it's own (not change all four together) and turn the idle airscrew both in and out from it's accepted setting. Each one "should" give you a response in engine running as you move it. If there's no or very little response, that would indicate that one is partially or fully blocked and nor able to meter fuel consistently enough to run smoothly.

Offline Lobo

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Re: The elusive surge
« Reply #47 on: January 21, 2022, 11:17:33 AM »
Last year I had no end of problems with a 15HP outboard that wouldn’t idle consistently. I had the carb apart a couple of times, was CONVINCED it was clean as a whistle and moved on to dismantle the whole bloody engine as thinking internal seals (2 stroke). Not fixed. Bought a whole new ignition system. Not fixed. Tearing my hair out. Carb out a third time… and on this occasion I finally discovered a blocked gallery in the idle circuit … aargh. Totally embarrassed at the time and expense it cost me 🙁.
(the gallery split into two paths - unknown to me. Finally got it clear by successive syringes of isopropyl blasting through. Happy days 🙄)

I’m no mechanic… but surely an air leak on the atmospheric side of the carb would not give the significant problems you’re seeing? Ie is it not more likely within the carb or inlet manifold area?

Offline Alexrayz

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Re: The elusive surge
« Reply #48 on: January 22, 2022, 02:12:45 PM »
Last year I had no end of problems with a 15HP outboard that wouldn’t idle consistently. I had the carb apart a couple of times, was CONVINCED it was clean as a whistle and moved on to dismantle the whole bloody engine as thinking internal seals (2 stroke). Not fixed. Bought a whole new ignition system. Not fixed. Tearing my hair out. Carb out a third time… and on this occasion I finally discovered a blocked gallery in the idle circuit … aargh. Totally embarrassed at the time and expense it cost me 🙁.
(the gallery split into two paths - unknown to me. Finally got it clear by successive syringes of isopropyl blasting through. Happy days 🙄)

I’m no mechanic… but surely an air leak on the atmospheric side of the carb would not give the significant problems you’re seeing? Ie is it not more likely within the carb or inlet manifold area?

Haha yep I know that feeling. It sucks harder than an airplane toilet.

Makes me wonder if there are any resources like schematics showing the innards of a carb.
If it aint broken don't fix it

Offline Alexrayz

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Re: The elusive surge
« Reply #49 on: January 25, 2022, 10:10:08 AM »
Hey everyone, I figured a small update would be in order.

I took the carbs off this week end to go over it once again. Checked all the passages I’m aware of and rechecked the floats height. The mixture air screws were set to 2 turns out as the plugs were sooty and the manual calls for 2 turns as a base setting for the 400F. I then did a bench sync, this time making sure I followed bryanj’s instructions to the letter.

With the carbs back on I made a sudo air filter cover and spring (too impatient to wait for Alan’s care package to arrive hehe). With a BTR wrench I managed to push the air box boots properly onto the carbs.
As a result the bike fired up nicely!. Haven’t done the diagnosis and touch ups while running, just wanted to hear it run. Will investigate more this week end.

Cheers
If it aint broken don't fix it

Offline taysidedragon

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Re: The elusive surge
« Reply #50 on: January 25, 2022, 10:12:55 AM »
Hey everyone, I figured a small update would be in order.

I took the carbs off this week end to go over it once again. Checked all the passages I’m aware of and rechecked the floats height. The mixture air screws were set to 2 turns out as the plugs were sooty and the manual calls for 2 turns as a base setting for the 400F. I then did a bench sync, this time making sure I followed bryanj’s instructions to the letter.

With the carbs back on I made a sudo air filter cover and spring (too impatient to wait for Alan’s care package to arrive hehe). With a BTR wrench I managed to push the air box boots properly onto the carbs.
As a result the bike fired up nicely!. Haven’t done the diagnosis and touch ups while running, just wanted to hear it run. Will investigate more this week end.

Cheers

Sounds promising,  well done. 👍
Gareth

2010 Street TripleR
1977 CB400F
1965 T100SS

Offline K2-K6

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Re: The elusive surge
« Reply #51 on: January 26, 2022, 10:15:36 AM »
Hopefully you've a decent platform to get the finer parts where you want them now.

That's a very neat routine that Bryan put up there as it covers all the elements to reassemble and provide accurate setup in one go.

Once done, they stay remarkably close during use and don't usually need constant retuning as many internet views seem to suggest.

 

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