Author Topic: side valve owners  (Read 1927 times)

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Offline FrAlan

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Re: side valve owners
« Reply #60 on: February 26, 2019, 11:45:46 pm »
On the subject of gas conversions, the yanks run quite a few engines on methane, they are often referred to as pigfart engines, which sort of sums it up quite nicely.

Offline $sidevalve

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Re: side valve owners
« Reply #61 on: March 05, 2019, 08:30:28 pm »
I had a C10 some years ago. It had similar symptoms to yours. It would run hot and was totally gutless and would seize up even on short runs. I spent ages checking out jets, ignition timing.
I was moaning about it to a pal. He said, 2 take the head off and I will come and have a look."
He took one look at the head and said, " Someone has skimmed 2mm off the head."
I fitted a spare head and it ran like a dream.

Offline bangers-c10

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Re: side valve owners
« Reply #62 on: April 19, 2019, 12:17:46 pm »
Thanks $idevalve, carnt remember is mine was shaved, dont think so.  I ended up putting a 120 main jet in, seems pretty good other then a bit of a splutter up around top rev range, but i just change gear before it gets to that stage, its like hitting rev limiter  sound..  doesnt really do it once in 3rd, just pulls it self along ok,     Might need to lift needle a notch maybe, gap plug, or set timing a bit better now it has a 120 jet..???

Offline ianinglis

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Re: side valve owners
« Reply #63 on: April 19, 2019, 01:33:25 pm »
i think mine has a 140 fitted
(375 carb)




ian
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Offline hampshirebiker

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Re: side valve owners
« Reply #64 on: April 19, 2019, 02:45:54 pm »
Certainly top end problems point to main jet. A 140 shouldn't affect the general running.
Postal - Liphook Hants - But just into West Sussex.

Offline bangers-c10

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Re: side valve owners
« Reply #65 on: April 20, 2019, 01:25:42 am »
It has a 120 in it,  I think its on the borderline of to rich, but seems to be starting ok so on,  plug is black/soot.  But see how she goes, if it always starts and i put up with the small splutter now and then, Think id rather leave her running rich,     If i raise the slide needle a notch that might get her spot on,do u think..  I know i should just go and try it, but thought id share here, as its / was raining all morning..




39c10 274 

Online Owen

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Re: side valve owners
« Reply #66 on: April 20, 2019, 07:02:48 am »
So how may miles have you done now.  Seems that increasing the jet helps but with the black plug you risk causing other problems. Ride her slower and get more miles done to free up the engine is my opinion.
1940 C12 (350cc)
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Offline timsdad

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Re: side valve owners
« Reply #67 on: April 20, 2019, 09:29:32 am »
It'll be either the main jet or the needle position, can't be both. Too big a main jet will have little effect until you get right up there close to flat-out and will do no harm - too big is much better than too small. Needle position affects running at around 3/4 throttle and I'll move it two notches to the top if I think it may be too rich or two notches down to the bottom if too weak. Sometimes it's a job to tell, just that it's a bit fuzzy, and doing it two grooves will have a more noticeable effect. When you know which way it has to go then it can be fine-tuned to the groove in between. Neither main jet size or needle position will have any effect on ease of starting.

It's difficult to get a good indication from plug colour with modern fuels, especially on a side valve where the plug is about a yard and a half from the main bang. You have to do a proper plug-chop when it's run in to learn anything at all, bangers.


Ray
Just a motorcyclist.

Offline bangers-c10

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Re: side valve owners
« Reply #68 on: April 22, 2019, 12:03:08 pm »
Done alot more miles now, ,Im thinking a 110 main would be good ,still havent got to have a play around with the needle postion yet, let you,s know when i do. And yes a good plug check is always in order.      it has a nice rumble/ when off the throttle rolling now ,sounds good..

Online camman3

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Re: side valve owners
« Reply #69 on: April 22, 2019, 03:40:18 pm »
As a matter of interest what plug are you using?...maybe a hotter plug would help?
Graham
1957 C12
In sunny (sometimes) Christchurch, Dorset, UK

Offline bangers-c10

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Re: side valve owners
« Reply #70 on: April 26, 2019, 01:15:42 pm »
When i bought a bpr8 guy gave me a bosch one to match, carnt remember the numbers, all thats on the plug is bosch super.    plug isnt so bad now, black only on half the ring,and centre is white ish.    might just leave her the way it is,

Online camman3

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Re: side valve owners
« Reply #71 on: April 26, 2019, 02:08:44 pm »
Only a general indicator, and you need to cut the engine and whip the plug out immediately after a good run, but the attached chart may help.
Sounds like you maybe on the kinda hot side :-\......and I don't mean you personally ;D
Graham
1957 C12
In sunny (sometimes) Christchurch, Dorset, UK

Offline timsdad

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Re: side valve owners
« Reply #72 on: April 26, 2019, 03:42:39 pm »
You don't really need a plug with an 'R' in its number, Bangers, because on an NGK it means it's a Resister plug and old bikes are better off without this extra resistance in their ignition system. The equivalent Bosch would also be a Resister but I can't remember how their numbers and letters go.

A plug check is not a plug chop - a chop is getting the thing pulling hard, slightly uphill is better, in top gear then killing the ignition and pulling the clutch in at the same time. The bike will then coast to a halt with the plug keeping the same colour as it had when running on the main jet. Whip it out for inspection with a glove on or by spitting on your finger and thumb and saying 'Oh' and 'Ah' while passing it quickly from hand to hand. Side valves don't plug chop very well and plug colour can be misleading with modern fuel.


Ray
Just a motorcyclist.

Offline bangers-c10

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Re: side valve owners
« Reply #73 on: May 02, 2019, 01:17:22 am »
Thanks,  11 or 12 is what looks like, so might be right. will go on few more rides.

Offline timsdad

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Re: side valve owners
« Reply #74 on: May 02, 2019, 07:05:18 am »
With a side valve and modern petrol, there are, to my mind, only three plug conditions to look out for :


Wet plug = maybe ignition problem so throw the plug away and try again with a new one

Sooty plug = too rich so check carburation, clean the plug and try again

Anything in between = it's ok but, if you're concerned about anything, do a proper plug chop to check the main jet size is about right.



Ray
Just a motorcyclist.