Author Topic: Nasty Cough...  (Read 321 times)

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Columbia13

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on: June 22, 2022, 02:33:38 pm
Hi
Can any of you kind people out there help me, my 2008 350 CI bullet frequently coughs through the carb when I shut the rev's off.
Amal 626 carb
Hitchcocks pancake filter
Standard exhaust
I have assumed the cause is a weak mixture, but there is no air getting in anywhere that I can see.
I have turned in the air screw on the carb.
Is there something else obvious I should try?
The bike runs fine on the throttle otherwise.
Thanks a lot
Michael
 
 


Carl Fenn

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Reply #1 on: June 22, 2022, 04:23:17 pm
Well you could try stripping the carb inspect it and check valves and carb connection.


Adrian II

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Reply #2 on: June 22, 2022, 10:04:10 pm
Maybe it needs a richer carb slide, e.g. a 3 instead of a 3½?

A.
Grumpy Brit still seeking 500 AVL Bullet perfection! Will let you know if I get anywhere near...


Carl Fenn

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Reply #3 on: June 23, 2022, 09:41:39 am
Could be a hard to trace air leak but in saying that l have run plenty of brits with bellmouth with no issue at all, l would strip the carb and clean inspect and readjust check jets look at valves l have had bikes spit back it was always normally a valve issue. Another thing you could look at is the throttle slide and bore leaking to much air l have had them wear out in as little as 8,000 miles on a triumph one of their symptoms.
« Last Edit: June 23, 2022, 09:49:36 am by Carl Fenn »


Adrian II

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Reply #4 on: June 23, 2022, 08:33:48 pm
You can get heavy brass slides, possibly some hard chromed, these will last a lot longer.

A.
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Carl Fenn

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Reply #5 on: June 23, 2022, 09:06:51 pm
Yes l know but back in those days l had money so l just bought brand new carbs, l know they were repairable but as l remember not that cheap.


Columbia13

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Reply #6 on: June 24, 2022, 11:34:59 am
Thanks for your replies lads.
I have checked and cleaned the carb so I don't think that is the cause. It was fitted (badly) by the previous owner and is virtually new. When I got the bike the carb had been over tightened and the flange was a bit bent, but I have had this straightened and I am pretty sure the seal on the inlet is good.
The bike has done less than 2K kilometers from new so I'm hoping the valves are ok.
I had thought myself that a richer slide might be the answer, does anyone else have to use a no 3 on theirs?
Cheers


Carl Fenn

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Reply #7 on: June 24, 2022, 12:32:06 pm
Might be worth checking the flangers again with a straight edge one of mine on head side was once warped on triumph.


Columbia13

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Reply #8 on: August 08, 2022, 09:01:46 pm
Well I've tried a no 3 slide (it was 3.5 before). I've stripped the carb again and I've checked the timing, checked the points gap and adjusted the push rods, but the problem still persists. Carl, if i investigate the valves, what should I be looking for?
Thanks in advance, Michael