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Messages - john11668

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1
British Bikes / Triumph model P info needed
« on: April 17, 2023, 10:59:16 AM »
Hi  Folks !
Its a long time since I have been here  so please excuse my absence
Looking for help with a Triumph model P

Was trying to set the timing after my mate had fitted a refurbished Mag dyno ( He  was turning the engine while I looked for TDC on compression stroke)
Book we have does not have much detail so was going for 7mm before TDC on compression stroke with full advance . (points gap set at  .012)
Was surprised to see that  engine appears to run backwards ( clockwise as viewed from the contact breaker side )   Is this Correct??

The reason for the mag upgrade was due to its history .  Almost impossible to start.  When delivered the  seller started it with some difficulty,  and my mate has not managed to start it since.

We have exhausted all the usual possibilities  Carb. plug , mag, before delving deeper,   ie before  stripping the head and Cylinder so next step would be to test compression. Can anyone advise what figure is reasonable for such a longstroke sidevalve??
And then of course if   problem was lack of compression  are spares available  and where to search.

Many thanks     John



2
British Bikes / Re: B31 spluttering and flashing back through carb
« on: December 21, 2019, 04:42:28 PM »
Interesting

3
British Bikes / Re: B31 spluttering and flashing back through carb
« on: December 20, 2019, 11:46:22 PM »
The problem fuel came from a  local station , one of a chain , run by a local cumbrian family and all of their stations sell BP product.
I believe the original problem stuff was their BP "ultimate " whereas the bike is now running fine on 95 Ron regular fuel .

My last runabout was a BMW K100  but I was told by the guy who sold it to me that he found it did not run well on ultimate fuel, and to ensure I used regular .

4
British Bikes / Re: B31 spluttering and flashing back through carb
« on: December 20, 2019, 09:23:46 PM »
Juice was no more than three months old yet apparently clean  ,   New stuff sorted the bike (and made us look like a pair of Idiots) . 
Old juice was  yellowish .   New stuff  virtually clear .

5
British Bikes / Re: B31 spluttering and flashing back through carb
« on: December 20, 2019, 12:51:33 AM »
We dont have those options at our pumps . The troublesome fuel was just bought at a local station shortly before this thread started . BP ultimate.

6
British Bikes / Re: B31 spluttering and flashing back through carb
« on: December 19, 2019, 09:47:16 PM »
So I am now back after having tried what we considered was everything . Cleaned carbs , prodded carbs , blew carbs out with air ( and carb cleaner ). No trace of even a spec of dust in the fuel filters.  Spoke to Amal technical  (who suggested Mag) .
Checked timing again and again,  tried  a bit less advance ,  a bit more advance , simple when you have made a proper tool.
Checked  full timing gear train (all fine ).
Tested mags on the bench but then swopped anyway ,
Swopped carbs,
Spoke to couple of local experts.  One said the only other thing left to check is the valves . The other said it would definitely be the valves  so off off with its  head .  All fine  but ground valves  in anyway and reassembled it all . 
And all still the same . Starts at first push of the button or kick but  wont run without spluttering and flashing  back unless on full choke.

So!  What have we missed?  we ask ourselves.
Could it be fuel ????
Went and got five litres of fresh 95 ron  and put it in the tank
Tried again  and Voila!  Runs like a dream,  after a couple of minutes warming we could ease the choke back to wide open and it still ran sweet and revved freely. No flashing back.

So after an hour or two of self flagellation, we came to the conclusion that in future clean new petrol will be step one .
But we have learned quite a lot in the meantime,  both from you guys and from  practical experience.  So thanks to you all  :D
Not quite sure how to sum this up really.

Gonna change the carb  anyway cos a 928 is not the correct throat for the machine and there is significant wear .  Amal say 626 /300 with 210 main jet , .106 needle jet , and 3 1/2" slide .
Any comments please?????   

7
British Bikes / Re: B31 spluttering and flashing back through carb
« on: November 21, 2019, 09:15:42 PM »
Carburettor is  spotlessly clean, and all the filters including the banjo.. But will go through it all again to satisfy ourselves. 
Were there models of this carb specified with no pilot jet at all .  And in such a case am I correct in presuming that the mixture screw is the only regulaion for pilot fuel
When the bike started to play up there was no doubt  that the timing was seriously over-advanced. (points breaking 1.5 " btdc ) . What if anything might be damaged by this.  It is now spot on at 7/16" and can be seen to be with a timing light and we can see the effect of retarding to fire at TDC,  but none of these adjustments seem to produce better running. 

The carb as far as we can see is as it was when it was running well, yet it is running like a chip machine and no adjustments  seem to improve on that.
Tappet clearances are ok and there is no visible damage seen using an endoscope in the cylinder ( although we cant see all corners )

8
British Bikes / Re: B31 spluttering and flashing back through carb
« on: November 20, 2019, 09:46:56 PM »
Just taken the screw out this evening and there is no  Brass pilot bush behind it.   The paths are all clear to the tiny holes in the the body and also to the hole  below the intake aperture . so no crud or obstructions and this carb would seem to be as it was when the bike was bought  and bearing in mind it has run perfectly well on this carb for well over a year.

9
British Bikes / Re: B31 spluttering and flashing back through carb
« on: November 17, 2019, 12:35:47 AM »
Lot of usefull stuff there L.A.B.
Will have a good read tomorrow night

10
British Bikes / Re: B31 spluttering and flashing back through carb
« on: November 16, 2019, 09:38:31 PM »
We  have been confused too! By the information in the parts books
See  https://www.hitchcocksmotorcycles.com/partsbook-pages/3375
Item 20 is clearly a screw fitted into the underside of the carburettor body hence a threaded tapping  in the underside .
Carb has been ultasonically cleaned , washed in brake cleaner , blown through with Hi  pressure air so no reason to suspect it not clean.
It is not a premier carb.
The wassel carb however does have the premier type adjustable pilot jet  but fares no better (worse in fact)  hence it was taken off again and the original refitted.
And remember from the start of this thread that the problems started  when Dynamo worked loose  and we found that the contacts were  breaking at about 1.5" Btdc.  Is that in itself  not sufficient reason to suspect timing over carburation.

And we have studied a number of manuals , none of which tell us that the pilot jet is hidden away behind the pilot air screw.
You guys  may well have lots of experience with big old singles which is why we come here for help. We on the other hand are learning  still.

11
British Bikes / Re: B31 spluttering and flashing back through carb
« on: November 16, 2019, 04:44:17 PM »
Quote from: chaterlea25 on October 26, 2019, 09:33:42 PM
Hi All,
Quote
Can valve timing be known to move on these.

Not unless something jammed the timing gears and sheared the key in the crank pinion
Remove the tappet cover, wind the engine to TDC, if both tappets are free (the pushrods should be free to rotate at TDC on compression stroke) then turn the crank one more complete turn
As the piston rocks over TDC you should be able to see the exhaust tappet dropping and inlet rising this should happen equal amounts either side of TDC

I now see you have a a concentric, The pilot passage bush within the body gets blocked,  a 16 thou guitar string or a no. 78 drill can be used to poke through the pressed in pilot bush
It has happened that new concentrics are not set up properly or have swarf and so on inside

John
Hi all ,
Sorry i have not been back on this  but other things (and  the weather) have kept us tied up elsewhere and it is not really biking weather anyway.
So runs best on old carb , timing spot on as far as we know ,  yet still spluttering a bit .
I am trying to understand the pilot jet  function in this .  As we look at the Amal catalogue  it shows a pilot jet which can be varied yet looks to be a screw in item. We dont have that! just a threaded hole in the underside of the body corresponding with a gallery which seems to draw from the bottom of the float chamber. Where do we find the so called pilot bush?

12
British Bikes / Re: B31 spluttering and flashing back through carb
« on: November 06, 2019, 10:11:30 AM »
Not Amal but Wassel .    Supplied by Draganfly as direct replacement .
I can see your point about the quality control , but it is out if the reckoning now as she is back on her original proven carb.

Had just topped up with fuel  when the problem started  but at  our usual regular station,  and have  changed fuel a couple of times since.

13
British Bikes / Re: B31 spluttering and flashing back through carb
« on: November 04, 2019, 08:41:26 PM »
Fitted  spare mag with no suppressor and  gave it a whirl.
With new carb in place it fired but would not  run.  Tickled some fuel up and try again , and same , a short burst then petered out.
Switched back to the original carb (albeit with new float) and we got her to keep running and warm up,   not bad  but not brilliant  still pops back in the exhaust when you reduce the throttle  ,  odd  spit back  at the carb. Takes quite a  time before it is hot enough to reduce the choke, and on a short run up the road it seemed to produce a fair  bit of blue smoke.

Will try to upload some videos
Not sure where to go next,   Just feel we need someone  with an experienced ear to have a look at it .
None of you guys anywhere near Cumbria are You??? :)

14
British Bikes / Re: B31 spluttering and flashing back through carb
« on: November 03, 2019, 05:55:42 PM »
It is but the spare from the shelf has a fatter spark. so  worth a try changingthat.
If it comes down to just a bad suppressor cap, we will sure be kicking ourselves .




15
British Bikes / Re: B31 spluttering and flashing back through carb
« on: November 03, 2019, 11:40:05 AM »
Hopefully will get a chance to test the replacement (on the bike ) on Monday afternoon.
Have to say though that I approach each each "test" with increasing trepidation  :-[

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