Swap twin engine into single frame?

[56G80S]

This is not a formal help request so posting in General Topics; it's a discussion point.

I've taken quite a tour round the Search but not a straightforward answer to my thoughts.

Forum readers will know that I amn awaiting recovery from Germany of the Matchless after failing to reach the Polish IJR.

I'm pretty sure that the there'll be quite a bit of work to do to get the engine straight. I had planned to strip all down during the winter anyway, refit the Burman box that I'd refurbished with all new bushes and bearings etc and remove the AMC box that I prefer to do a refurb on that.

I also planned to split the crancases for the first time in 25 - 30 years and get a couple of small jobs done as well as replace the timing side bush (have a new one in hand never fitted).

But now think that maybe I could just buy a working 500 / 350 engine, fit it, get the original re-worked and then swap back and sell on the "new" engine. Now here's the question:

Could I drop in an early twin for a change as I've only ever had AMC singles! Setting aside the exhaust question and assuming that I could clamp a head steady onto the front downtube. I'm guessing that the rest should be relatively straightforward? But IKBA about twins and knowq that the 1956 is an interim frame with the different oil tank and battery box and odd seat (although I have a a pattern seat fitted that was on in 1970's I now have a "correct" seat except is haas AJS piping and I don't care).

Johnny B

[Rob Harknett]

A lot of work that could result in a lot of problems. Consider also, old father time may be creeping up on you and the twin may soon prove to be too much to handle. Why not sort out the single engine that you have enjoyed many years of riding. I had always wanted a twin, eventually got one. Nice 650 cc CSR. Great more power. But I soon turned back to favour using my trusty old 350 and prewar 250.

[SPRIDDLER]

Forum readers will know that I am awaiting recovery from Germany of the Matchless after failing to reach the Polish IJR.

Oh, no! Not AGAIN? Condolences.

Can't help with the swap John as I know as much about twins as a pig knows about Sunday, but if you really want a twin (double trouble in my opinion ) I'd be inclined to buy a twin (that you can hear running and test ride) and sell it on after you've sorted the single. Even if you lost a couple of hundred on it it would be far less than the cost of buying a twin engine, carbs, alternator, oil pump etc., etc. of unknown condition, in spite of the seller's glowing assurances; (haven't we heard far too much woe about bikes sold with 'restored'and 'rebuilt' engines, gearboxes etc.?). When I see 'good condition' s/h engines and carbs for sale the cynic in me wonders why anyone would replace perfectly good ones, or 'rebuild' an engine that they don't need. Plus the cost of zorst system(s) and many other bits and pieces. It always costs much more to do this sort of stuff than one imagines and could take the rest of the summer to complete the swap.

Just had a thought:
Roy might lend you one of his 'much sought after, restored and utterly reliable' twins?

[Flash]

Forum readers will know that I amn awaiting recovery from Germany of the Matchless after failing to reach the Polish IJR.

Sorry to hear this, I have just returned from the rally, had I known of your problems, I could have picked up your bike on the way back, I had plenty of room. I left the rally on Sunday morning, just after they all went on the ride out. got home at 9-30pm last night after quite a delay on the ferry.

John

[Rob Harknett]

Forum readers will know that I am awaiting recovery from Germany of the Matchless after failing to reach the Polish IJR.

No! Not AGAIN? Condolences.

Can't help with the swap John as I know as much about twins as a pig knows about Sunday, but if you really want a twin (double trouble in my opinion ) I'd be inclined to buy a twin (that you can hear running and test ride) and sell it on after you've sorted the single. Even if you lost a couple of hundred on it it would be far less than the cost of buying a twin engine, carbs, alternator, oil pump etc., etc. of unknown condition in spite of the seller's glowing assurances; (haven't we heard far too much woe about bikes sold with 'restored'and 'rebuilt' engines, gearboxes etc.?). When I see s/h engines and carbs for sale the cynic in me wonders why anyone would replace perfectly good ones, or 'rebuild' an engine that they don't need. Plus the cost of zorst system(s) and many other bits and pieces. It always costs much more to do this sort of stuff than one believes and could take the rest of the summer to complete the swap.

Just had a thought:
Roy might lend you one of his 'much sought after, restored and utterly reliable' twins?

I brought a twin that had a rebuilt engine by reputable dealer. It cost me about £1,000 to rebuild it again.

[leswaller]

John
We had a brief chat at the ferry terminal at Harwich, it is a shame that you didn't make it Poland after all your efforts. I hope everything is recovered back to England OK.
It is an easy job putting a twin into the frame, my machine is a G80 frame with a G9 engine in it. It is easy to handle and a very nice ride, regarding Rob Harknet's comments, remember that a 500cc twin is easier to kick over than a 500cc single, as effectively you are only kicking over 250cc, i.e. one cylinder. My G9 starts 1st or second kick every time

[56G80S]

Thanks for the comments.

I forgot that not everyone will have read the thread about the IJR. I did get to just short of Berlin and the morning of that day was a glorious ride but then it all went sour.

I had a chat with Steve Surbey, always a worthwhile experience in my view, and he basically said tha same as most of you; best advice is fix the engine I have and the condition of engines not in motorcycles is a risk. It's just that there are other jobs to do but I guess (hope) it's going to be as simple as barrel off, check it, the piston and the head then source some +40 rings.

Linda's getting grumpy about my trips and even grumpier with my suggestion that I only use the Matchless in the UK and get a Deauville or touring Trumpet for the trips abroad.

Rob's right, I'm finding the 270 - 300 mile in a day runs harder work and wondered if a twin and higher cruising speed might help reduce time in the saddle.

Maybe just buy a Matchless twin and she won't know the difference.

Johnny B

[Rob Harknett]

John
We had a brief chat at the ferry terminal at Harwich, it is a shame that you didn't make it Poland after all your efforts. I hope everything is recovered back to England OK.
It is an easy job putting a twin into the frame, my machine is a G80 frame with a G9 engine in it. It is easy to handle and a very nice ride, regarding Rob Harknet's comments, remember that a 500cc twin is easier to kick over than a 500cc single, as effectively you are only kicking over 250cc, i.e. one cylinder. My G9 starts 1st or second kick every time

I did say the twin may prove too much to handle Les. Perhaps I should have said too heavy to handle. Due to this, " down sizing " now seems to be going on. Starting a twin may be easier, they don't even need a decompression facility. It is the weight that is becoming too hard to handle.

[G15 Roy]

Forum readers will know that I am awaiting recovery from Germany of the Matchless after failing to reach the Polish IJR.

Oh, no! Not AGAIN? Condolences.

Can't help with the swap John as I know as much about twins as a pig knows about Sunday, but if you really want a twin (double trouble in my opinion ) I'd be inclined to buy a twin (that you can hear running and test ride) and sell it on after you've sorted the single. Even if you lost a couple of hundred on it it would be far less than the cost of buying a twin engine, carbs, alternator, oil pump etc., etc. of unknown condition, in spite of the seller's glowing assurances; (haven't we heard far too much woe about bikes sold with 'restored'and 'rebuilt' engines, gearboxes etc.?). When I see 'good condition' s/h engines and carbs for sale the cynic in me wonders why anyone would replace perfectly good ones, or 'rebuild' an engine that they don't need. Plus the cost of zorst system(s) and many other bits and pieces. It always costs much more to do this sort of stuff than one imagines and could take the rest of the summer to complete the swap.

Just had a thought:
Roy might lend you one of his 'much sought after, restored and utterly reliable' twins?

It could be arranged arranged.

[bigwol]

My first AMC purchase was a M16, later to discover it is in fact a '56 G9 frame with a '56 M16 engine installed. I doubt it would be too difficult to fit a twin engine in your single frame however finding a decent twin engine to just bolt in might be! If anyone knows of a '56 G9 (or M20)engine for sale please let me know as I'd like to replace the 350 single lump. I do have a single frame to take that when the swap is done.
Please place a wanted ad not use the general forum. The adverts police are on duty even when returning from the IJR!