Going mad trying to get this bike working.

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
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spookefoote1956
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Re: Going mad trying to get this bike working.

Post by spookefoote1956 »

Hussah
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jackstringer
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Re: Going mad trying to get this bike working.

Post by jackstringer »

Well, it's gone back to the orignal issue we had after it was rebuilt with new pistons etc.

Runs and rides ok. But if you do a few hills it will slow down and eventually stop. Almost like it has seized. I did 10 miles to work this morning all good. On the way back though Hell....sorry Wells I filled up with 99octane super unleaded....its the E5 stuff. Rode out and it was a rather steep but steady climb and on the gentle hill it did feel a little hard to get going. I avoided full throttle and giving it too many revs it still only 100 miles into a new piston. But going along a flat bit I did seem a little flat. The next hill it got 75% of the way up and then it rapidly slowed and I grabbed the clutch and coated to a halt.

Now the issue I have is after getting it into neutral I was able to kick it over and start it, first kick. Then I gently rode it the last 2 miles home with no issue.

At the weekend I rode it to a local farm shop for a show and it was ace there and back. Even cleaned the crap out of the tank and there was hardly any there.
IMG-20230521-WA0000.jpg
We kept it green.
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SPRIDDLER
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Re: Going mad trying to get this bike working.

Post by SPRIDDLER »

jackstringer wrote: Fri May 26, 2023 1:52 pm Well, it's gone back to the original issue we had after it was rebuilt with new pistons etc.
Was it rebored as well as having a new piston?
It conked out on a hill when your Dad was riding it so I assume that was before you fitted the new piston. :?
Runs and rides ok. But if you do a few hills it will slow down and eventually stop.
Hills seem to feature often in your various posts so are you sure it isn't nipping up?
At the weekend I rode it to a local farm shop for a show and it was ace there and back.
How far and were any hills involved in those trips?
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jackstringer
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Re: Going mad trying to get this bike working.

Post by jackstringer »

Twas rebore and new piston.

Done a few small trips, trying not to use too much throttle. Maybe 100 or so miles.

Well the idea we have is its nipping up. We swapped out for a new carb as we were concerned the worn out carb might be letting it run lean under faster riding speeds.

The ride I did last week had hills but enough downhill to rest.
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jackstringer
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Re: Going mad trying to get this bike working.

Post by jackstringer »

Screenshot 2023-05-26 at 17-14-23 Cycling route planner UK - see cycle map and elevation profile.png
or
Screenshot 2023-05-26 at 17-14-37 Cycling route planner UK - see cycle map and elevation profile.png
86ft to 964ft but 800 of that is in the last 5 miles of uphill. Well, it is the Mendips.

This morning was much easier on the engine, not the brakes.
Screenshot 2023-05-26 at 17-25-38 Cycling route planner UK - see cycle map and elevation profile.png
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MatthewC
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Re: Going mad trying to get this bike working.

Post by MatthewC »

It does sound an awful lot like it's nipping up. Mine nipped up while running in after something like 800 miles IIRC, also going uphill. Very similar symptoms, it felt almost like the HT lead had dropped off, and after coasting to a halt and letting it cool for a couple of minutes it fired right up again. I bet if you take the barrel off you'll see the evidence on the piston. The high spots can be very carefully filed down (I used needle files as they're the finest ones I've got), but don't use abrasives as they embed into the aluminium and will cause problems later. Ideally measure the high spots and the undamaged surfaces as closely to the sides of each high spot as you can with a micrometer, so you can blend the high spots in. When mine part seized the aluminium picked up and smeared a bit, causing them to become even higher spots, hence the need for this.
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Re: Going mad trying to get this bike working.

Post by SPRIDDLER »

It has also ocurred to me that your original issue of a partially obstructed petrol flow would weaken the mixture and when opening the throttle going uphill the level in the float chamber would drop causing the spitting back and lack of power. The weakened mixture could also have caused overheating which would have increased the risk of nipping up.

Or maybe I'm merely creating a scenario to fit the symptoms :?
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jackstringer
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Re: Going mad trying to get this bike working.

Post by jackstringer »

Last weekend I emptied the fuel out and removed the taps and flushed the tank and removed a small amount of rust but not enough to cause a blockage.
20230521_150528.jpg
Will tweak take the plug out to see if its running lean. Thanks for your thoughts.
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SPRIDDLER
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Re: Going mad trying to get this bike working.

Post by SPRIDDLER »

jackstringer wrote: Sun May 28, 2023 3:30 pm Last weekend I emptied the fuel out and removed the taps and flushed the tank and removed a small amount of rust but not enough to cause a blockage.
Yebbut, that was after you had already found and cured the weak flow ............
jackstringer wrote: Wed May 10, 2023 8:58 pm Turns out you are all wrong, and so was I :-)

It was the damned fuel taps, they were dribbling like Spriddler going for a pee. So gave them a quick reverse blow and there was a little more flow. Took it up the road and woop the thing flies again. Thoughts are that when we opened the throttle they were preventing even the fuel in the carb from flowing as there was a blockage at the tank.
My thinking was along the same line as MatthewC. The earlier weak flow had caused a weakened mixture and the piston had nipped up leaving scarring on the piston and/or the bore, or a ring stuck in its groove by smeared piston material.

(Or It may be just my wild guess.
:? )
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1608
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Re: Going mad trying to get this bike working.

Post by 1608 »

I always remove the filter on the taps, because if/when they block its a messy road-side fix. Fit an extra filter on the fuel line if necessary.
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