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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: 11 Apr 2018 at 17:15
Yes, cut the engine at the point it loses power then look at the plugs.
 
Sooty or white will tell you which is missing. But if the colour is still that perfect light brown then it must be another cause.
Brian.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote c13pep Quote  Post ReplyReply Direct Link To This Post Posted: 11 Apr 2018 at 19:06
Pretty soon it became apparent that the bike would happily cruise at 50mph, but if I tried to accelerate beyond that, the motor would become "fluffy" and lose power until I closed the throttle a bit, and which point it would resume cruising at 40-50mph./QUOTE]

This fault mirrors exactly what occurred on my V50/3 last year and finally solved by this forum. I removed the air filters (K & N type) and the bike ran fine on a short test run thus when I inspected the Chinese K&N s they were severely restricting the air flow, hence wouldn`t go faster than 50mph, replaced air filters for non restrictive type and bike ran brilliant.
CHRIS
you can`t have any fun in a straight line

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken-Guzzibear Quote  Post ReplyReply Direct Link To This Post Posted: 11 Apr 2018 at 19:13
quick thought stuck choke msybe
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hyline Quote  Post ReplyReply Direct Link To This Post Posted: 11 Apr 2018 at 20:39
The plugs are grey in color.
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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: 11 Apr 2018 at 22:13
At what point did you check the plugs, this is critical. Did you cut the engine and check when you were experiencing the problem or did you wait till you got home?
Brian.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpc Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr 2018 at 10:13
It's a two hour fault-finding job, been going on for a week.

Pet theories don't fix engine troubles, checking systems does.
 
"Just saying".


Edited by jpc - 12 Apr 2018 at 10:21
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Post Options Post Options   Thanks (0) Thanks(0)   Quote iansoady Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr 2018 at 10:49
Plug chops with modern petrol are not very reliable as the additives can give misleading results.
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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: 12 Apr 2018 at 11:25
Originally posted by jpc jpc wrote:

It's a two hour fault-finding job, been going on for a week.

Pet theories don't fix engine troubles, checking systems does.
 
"Just saying".
All depends on the owner's knowledge. While you might think it a short fault finding job, others would have some difficulty with this.
 
 
 
Yes Ian, I know modern fuels can give misleading results, but you can't mask a very rich or very weak mixture. And here we are talking of extremes to cause this problem.
Brian.

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Ken-Guzzibear View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken-Guzzibear Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr 2018 at 11:44
As always if you can't find a fault looking at the obvious get someone else to look .in the past I have known someone spend literally a few hundred quid, tearing their hair out replacing parts to find it was a fairly simple fix done by someone who knew their way around a particular bike

It is real difficult to diagnose an issue when you can't see or hear the bike

If the fuel is flowing well to the carb input then pop the carbs off they are very easy to look at and blow through ....

Save yourself grief after that and get someone to do it for you, often the most economic route!...Not everyone is brill at everything ....
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hyline Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr 2018 at 15:22
Originally posted by Ken-Guzzibear Ken-Guzzibear wrote:

As always if you can't find a fault looking at the obvious get someone else to look .in the past I have known someone spend literally a few hundred quid, tearing their hair out replacing parts to find it was a fairly simple fix done by someone who knew their way around a particular bike

It is real difficult to diagnose an issue when you can't see or hear the bike

If the fuel is flowing well to the carb input then pop the carbs off they are very easy to look at and blow through ....

Save yourself grief after that and get someone to do it for you, often the most economic route!...Not everyone is brill at everything ....

Yep, you are absolutely correct and I have reached that point. Many things are easy when you know how to do it - unfortunately I have very limited knowledge regarding carbs & electrical faults so the bike is going to someone next week who hopefully will resolve the issue quickly.

As a quick update, I realised my bike only had one gasket where the carb attaches to the cylinder instead of two and it was also missing the fibre sealing washers. I fitted the missing parts and now the bike accelerates up to 70mph easily, but when slowing down a misfire is definitely very apparent. On getting home I took the plugs out and both were light grey in colour.

But, as I said above it is now going to go to an expert to sort out.
Thanks again for all the advice which was very helpful.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpc Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr 2018 at 16:52
Originally posted by Brian UK Brian UK wrote:

Originally posted by jpc jpc wrote:

It's a two hour fault-finding job, been going on for a week.

Pet theories don't fix engine troubles, checking systems does.
 
"Just saying".
All depends on the owner's knowledge. While you might think it a short fault finding job, others would have some difficulty with this.

I know, I've been there like everyone else.

Which is why it helps to acquire a method early on as I tried to explain on page 2 of the saga:
1) DIST  2)IGN   3)CARB.

It's at most a couple of hours of simple steps, a more humble attitude than "theorizing" the cause.

This method moves you from prime to secundary causes, for instance avoiding obsessing with carburation when auto advance is stuck, or with ignition when valves don't close.

Or getting fed up after a week of getting nowhere... Confused
 


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr 2018 at 18:48
There is also the old adage that "Most carburation faults are electrical" Just a thought.

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Ken-Guzzibear View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken-Guzzibear Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr 2018 at 19:14
Be interesting to find out what is causing the issue, whilst we can theorise, being with the bike seeing and hearing it makes a World of difference. The 2 inlet gaskets are to stop the vapourising of the fuel when it gets hot, later bikes did away with that by having a rubber inlet, which caused different issues ...banging and popping on over run is often air getting into exhaust ....
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr 2018 at 22:48
Originally posted by Dave P. Dave P. wrote:

There is also the old adage that "Most carburation faults are electrical" Just a thought.
Hadn't heard that one.
Brian.

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