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Problem with carburation? V35

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LechCichon View Drop Down
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    Posted: 07 Apr 2020 at 23:50
Hi, I have been struggling to get my V35II to ride properly, but I am loosing faith.
I was trying myself and two mechanics haven't succeded. It looks like an easy thing but I don't know what else can I try.
Every 30-40km one of the candles is getting black or dies completely. 
Bike looses power, but still rideable on the second cilinder.
Looks easy- adjust carburation, but not the case. 
It was adjusted many times, works perfect with vacum gauge and rides for short time.
What else I have tried:
-adding more air to carburator
-changing to different candle
-new rings on cilinder
-new electric coil
-new valve seals
-adjustment of ignition points

What next? What to test?
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Richard Hyatt View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Richard Hyatt Quote  Post ReplyReply Direct Link To This Post Posted: 08 Apr 2020 at 06:45
Looks like that side cylinder /plug is running rich if it goes black.
Have you checked the float height and the float needle valve ? It may not be cutting off fuel at the right level and flooding that side
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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 08 Apr 2020 at 08:02
Have you checked that the cold start enrichment circuit ( which is usually referred to as the "choke") is sealing properly? The little rubber pad on the bottom of the brass piston can wear or split and should be replaced.
If your chokes are cable operated check for about 4mm free play in the cables.If there is no free play the brass pistons will not seat properly causing rich running and black candles, or "spark plugs" as we usually call them in English.
Best of luck and welcome to the forum.
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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Brian UK View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 08 Apr 2020 at 08:21
Yes, I would check the choke pistons first of all. 
Brian.

Better 5 minutes late in this world than years early in the next.
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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 08 Apr 2020 at 09:38
Another thought Lech. Check the needle jet.If the hole in the jet looks oval rather than round it's time to replace it.Also check for wear of the needle,can you feel a ridge on it at all. If so ,replace.
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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Brian UK View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 08 Apr 2020 at 10:19
All valid, but unless one needle jet has been replaced, I would expect both to wear about the same amount, and this problem seems to be affecting one pot only.

I certainly improved the fuel economy when I renewed the needle jets.
Brian.

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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 08 Apr 2020 at 10:26
Agreed Brian,but I've worked on bikes over the years where I've found miss-matched carb' settings, jets and in one case, an R80RT with two different float weights. Who knows what indignities a bike has been subjected to over forty plus years.
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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Brian UK View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 08 Apr 2020 at 10:31
Mis-matched, yes that's always a possibility.
Brian.

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AdrianW View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AdrianW Quote  Post ReplyReply Direct Link To This Post Posted: 08 Apr 2020 at 13:12
Lech,
I too have a V35II that ran rich on both cylinders and didn't need choke to start..  Attempting to fix this resulted first in it not running at all, then on one cylinder.. !!

Finally after replacing a few things it runs again, starts well. However it still doesn't need the choke and runs a little rich. I'm going to leave it at that !!

So, I have been there with this one !!  I presume you have the stock VHBZ 26 carbs..

As others have suggested first call would be to check the choke cables and plungers. Cables stick and plungers wear - mine had a funny little nipple on the end where it had been forced into the jet hole!
I replaced mine with manual levers because (at the time) they were on special and cheaper than the plungers. The LHS one though is very hard to operate so this is not really recommended. I have new choke cables ready for converting back to cable choke sometime - the lever mounting screw won't budge at present !

I didn't find a way of reliably altering the float level - I just checked they were not leaking.

Check needle position on both carbs - it is possible one is not set correctlly.

I also replaced both float needles , main needles (mine were corroded) & needle jets (atomisers). A thorough clean and new gaskets completed the job.

Thanks to being locked down at present I have not been able to give the bike a proper test run though..

Hope this helps,

Adrian
Bristol UK
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