Matchless G15/45

Matchless

Matchless

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Here are a few pictures of a bike I started building twenty odd years ago, & finally got around to finishing this last summer. I have always thought that the G45 was one of the best looking race bikes of all time, so I built a road going version.
The bike was purchased as a very scruffy, bodged up racer, but what I wanted was the frame. Most of the bike including the engine was scrap, so was disgarded. As nothing was available off the shelf I set about making damn near everything, including the engine plates, top yoke, swan neck bars, brake & gear levers, footrests, inlet stubs, belt guard, chain adjusters, the list goes on.
The frame which was out of line when I aquired it, was sent to P&M for Steve the frame builder to sort out.
The engine is the very rare g15/45 750, which came back from the U.S. Nigel at NRP made a very nice exhaust system to my requirements.
I had it running briefly this summer & will drag it out next spring once I get time.
 

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Matchless said:
Here are a few pictures of a bike I started building twenty odd years ago, & finally got around to finishing this last summer. I have always thought that the G45 was one of the best looking race bikes of all time, so I built a road going version.
The bike was purchased as a very scruffy, bodged up racer, but what I wanted was the frame. Most of the bike including the engine was scrap, so was disgarded. As nothing was available off the shelf I set about making damn near everything, including the engine plates, top yoke, swan neck bars, brake & gear levers, footrests, inlet stubs, belt guard, chain adjusters, the list goes on.
The frame which was out of line when I aquired it, was sent to P&M for Steve the frame builder to sort out.
The engine is the very rare g15/45 750, which came back from the U.S. Nigel at NRP made a very nice exhaust system to my requirements.
I had it running briefly this summer & will drag it out next spring once I get time.
Click to expand...
Very very nice
 
Nice, Martin! Have you considered ABSAF G12 big fin alloy barrels? It would make the engine look more like a G45.

Extracting more power off the G12 or G15/45 requires the cylinder heads to be substantially modified. Routing of the oil lines detracts from the overall clean lines, I think.

- Knut
 
Last edited:
mdt-son said:
Nice, Martin! Have you considered ABSAF G12 big fin alloy barrels? It would make the engine look more like a G45.

Extracting more power off the G12 or G15/45 requires the cylinder heads to be substantially modified. Routing of the oil lines detracts from the overall clean lines, I think.

- Knut
Click to expand...
Popular lore says more power should not be inflicted on the 750 Matchless engine.
 
mdt-son said:
Nice, Martin! Have you considered ABSAF G12 big fin alloy barrels? It would make the engine look more like a G45.

Extracting more power off the G12 or G15/45 requires the cylinder heads to be substantially modified. Routing of the oil lines detracts from the overall clean lines, I think.

- Knut
Click to expand...
I have looked at them, but I think they would be a bit spendy. As it is the engine cost me a kings randsom, & still needed a full rebuild. Luckily Russell motors had some +0.020" pistons in stock. Everything else apart from the top end gaskets is the same as the 650 version.
If funds were unlimited I wouldn't have used 750 Honda forks & BSA/Triumph conical hubs.
 
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Triton Thrasher said:
Popular lore says more power should not be inflicted on the 750 Matchless engine.
Click to expand...
I totally agree with that statement. They do seem to have been reasonably reliable though, as they had the SG iron cranks & the larger oil pumps, but the crankcases are simply over bored 650 types & look to be on the very limit. The heads are the same casting with slightly different machining in the squish area. I have a pair of race kit cams but decided not to fit them.
 
Triton Thrasher said:
Popular lore says more power should not be inflicted on the 750 Matchless engine.
Click to expand...
Provided you do the usual upgrades, the only weak point I can think of is the head studs. There appears to be a solution. A Matchless enthusiast in California races them.

- Knut
 
Matchless said:
I have looked at them, but I think they would be a bit spendy. As it is the engine cost me a kings randsom, & still needed a full rebuild. Luckily Russell motors had some +0.020" pistons in stock. Everything else apart from the top end gaskets is the same as the 650 version.
If funds were unlimited I wouldn't have used 750 Honda forks & BSA/Triumph conical hubs.
Click to expand...
Why the preference for honda 750 forks?
Do they work/damp better than other Japanese forks from that ere ? Cheers
 
baz said:
Why the preference for honda 750 forks?
Do they work/damp better than other Japanese forks from that ere ? Cheers
Click to expand...
The reason for using Honda 750 forks is because I had some, & secondly they look similar to the AMC comp. type. Obviously it would be better to have the real thing if money was unlimited.
 
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When I sold my 500 cc Triton back to my mate for $5000 , it had front and back 7R hubs, which cost $5000 each if somebody wanted them. The bike was cannibalised for the hubs - ended up with Commando wheels. The 7R hubs were dangerous - they have strange snail cams and rollers, pushing the brake shoes. I am a bit dubious of anything Matchless.
 
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