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dozerash

SWM Modifications

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  I got into vintage trials a few years ago, I always wanted a SWM! When I was a kid SWM trials where the bike to have! I didn't have one then but almost 40 years later I finally bought one! I really like them! They handle great and the brakes even work! I enjoy them as much as the modern trials bikes I had! I actually ended up with four over the summer, (sold the 240 to a friend of mine). I have a 1980 TL320 that's my main bike, I bought from the top rider from our club, he also won the AMA National twin shock series in 2013 on the same bike! I also have a 1982 TL 320 practice bike that runs good but needs work and a 1980/81 TL 320 that needs rebuilding. 

 I'm wondering what everyone is doing for modifications? I really like my bike and just curious of improvements.

I already used a different clutch lever with different leverage, new clutch cable, installed electronic ignition (works awesome! See Martin at MotoSWM)! Betor gas shocks. I have a newer Can Am clutch cover with the 12mm balls for the clutch actuator that I might install this winter. 

Thanks, Ash

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Being up in new york, Chris Arnold used to i think still does ride a swm. He would be a good guy to pair up with about these. Good rider to might be the guy your talking about. He rode the D4 events. if you want to find him go to a d4 event someone if not half the club can help you out. 

Edited by briangg

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As you know, they are pretty good as standard. Really they just need everything working 100% . Depending how tall you are, moving the footrests down and back is a worthwhile mod. Easy and can be done neatly by adding to originally flat plate, bit of strengthening also required behind. A lot of people go for a bolt on plate, but looks horrendous imo, and makes frame wider. 

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The clutch cover off an aprilia climber improves the clutch action no end but they are thin on the ground nowadays. The middle box and the silencer weigh a ton. The middle can be cut open and everything inside junked and there are plenty of after market alloy silencers available. Some play with the timing of the induction rotary valve disc to try and soften the power, but I liked to put a spacer under the barrel to achieve the same.

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As B40RT posted, try to get everything really sound, from engine, to exhaust, also airbox and air filter as these tend to be restrictive,

A rebuild of the middel and end silencer is a good idea improve engine Response a lot and quite expensive if you can't do it by yourself.

If the engines does rattle a bit and got a bit tired, a new conrod a rebore with a custom made next size piston is also an improvement for riding in general and an investment which emty the wallet easy.

Too smooth running cables with teflon inliner, good brake pads with soft paddings, good rear shocks that suits your weight.

Fork stanchions are they really straight or a bit off, if a bit off for better action you can let them straightened and rechromed and Special polished improves Action and you will have less stiction too, then you might too mount HFS air cartridges to the Forks to improve dampning and Rebound.

Last not least an electronic ignition.

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8 hours ago, briangg said:

Being up in new york, Chris Arnold used to i think still does ride a swm. He would be a good guy to pair up with about these. Good rider to might be the guy your talking about. He rode the D4 events. if you want to find him go to a d4 event someone if not half the club can help you out. 

  I bought Chris’s SWM last fall! He is riding a Yamaha now. Like I said the bike is in great shape and works awesome just as it is! He has it set up well. The clutch is a little stiff but not bad and I might need higher bars or bar risers, I’m 5’11”.

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Other than making sure everything is in good working order;

Use the Marzocchi 35mm yokes with your Betor forks, this is what the works riders used to do back in the day. It tightens up the fork angle and handlebar mounts much better position.

Lose some weight, axles and swinging arm spindle can all be aluminium alloy, rear silencer and front pipe !

Electronic ignition with advance along with a lighter flywheel will pep things up.

Fantic 300 front brake plate.

Lowering footrests and moving back is essential.

Speak to Martin Matthews.

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I’ll probably won’t do a lot to the 1980 TL320, it’s working pretty good as it is. The 1982 TL320, needs fork work, engine needs to be looked over, it needs some odds and ends. I would like to find the 82 style headlight for it, Martin is out of stock. 

 When you guys lower the foot pegs do you use after market ones?

whats the procedure to repack the mid and end muffler? I have use of a plasma cutter and I own a mig welder.

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38 minutes ago, dozerash said:

I’ll probably won’t do a lot to the 1980 TL320, it’s working pretty good as it is. The 1982 TL320, needs fork work, engine needs to be looked over, it needs some odds and ends. I would like to find the 82 style headlight for it, Martin is out of stock. 

 When you guys lower the foot pegs do you use after market ones?

whats the procedure to repack the mid and end muffler? I have use of a plasma cutter and I own a mig welder.

Something thing like these  https://www.ebay.co.uk/itm/TRIALS-UNIVERSAL-FOOT-PEGS-RESTS-TWINSHOCK-PRE-65-FANTIC-BULTACO-MONTESA-WELD-ON/183462194054?hash=item2ab732eb86:g:VswAAMXQTghRTKm4

I would move footrests 50mm down and back at your height, any more and you run into issues with side stand etc. 

Repacking mid box, cut a hole in the back, make a plate to fit over it, use rivenuts or similar and silicon. Repack with exhaust packing. It will be quiter and run much better. I have never done anything to the back box other than rivet any baffles that come loose.

 

Edited by b40rt
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I agree with b40rt on most issues, specially regarding the footrests. Use CrMo plate of the same thickness as the side plates and TIG the bits in place, pre-warm the plates and keep them warm, making the plates and welds cool down slowly (check for any sign of cracks after every ride during the first couple of weeks).

However, regarding the midbox and rear silencer, a bit more work than b40rt suggest is well worth the effort. Cut them both up longitudinally with a thin disc and start removing whats inside. Repack the midbox with good hi temp insulation and reweld. Then, cut out everything inside the rear silencer and cut off the rear part as shown. Get a bit of perforated pipe or make one up, to fit between the inlet and a new wall in the rear part. Weld the front part longitudinally and do the same with the rear part. Then, weld the new wall in place in the rear part, as shown. Finally, fit the perforated tube into the front part and fill up with insulation before riveting the two parts together, then paint.

I have kept the original twin outlet pipes on this one, but you can also try a bigger single pipe if you like (louder and less back pressure). The silencer shown here is almost as quiet as the original, but is a much better starting point when tuning for better power delivery all through the rev range (porting, ignition timing, carb set up and so on). Of course, you could use any modern mx type silencer instead, but a little visual cheating can be nice, or....?

2016-08-14 18.38.10.jpg

2016-12-10 15.13.44.jpg

2016-12-10 15.17.19.jpg

2016-12-10 15.16.15.jpg

2016-12-11 17.07.46.jpg

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If you find an Aprilia TXR or Climber clutch cover, make sure you get hold of the clutch pressure plate and the centre hub, makes it feel about 20% lighter over the standard SWM parts

20181006_130021.jpg

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19 hours ago, turbohead said:

I agree with b40rt on most issues, specially regarding the footrests. Use CrMo plate of the same thickness as the side plates and TIG the bits in place, pre-warm the plates and keep them warm, making the plates and welds cool down slowly (check for any sign of cracks after every ride during the first couple of weeks).

However, regarding the midbox and rear silencer, a bit more work than b40rt suggest is well worth the effort. Cut them both up longitudinally with a thin disc and start removing whats inside. Repack the midbox with good hi temp insulation and reweld. Then, cut out everything inside the rear silencer and cut off the rear part as shown. Get a bit of perforated pipe or make one up, to fit between the inlet and a new wall in the rear part. Weld the front part longitudinally and do the same with the rear part. Then, weld the new wall in place in the rear part, as shown. Finally, fit the perforated tube into the front part and fill up with insulation before riveting the two parts together, then paint.

I have kept the original twin outlet pipes on this one, but you can also try a bigger single pipe if you like (louder and less back pressure). The silencer shown here is almost as quiet as the original, but is a much better starting point when tuning for better power delivery all through the rev range (porting, ignition timing, carb set up and so on). Of course, you could use any modern mx type silencer instead, but a little visual cheating can be nice, or....?

2016-08-14 18.38.10.jpg

2016-12-10 15.13.44.jpg

2016-12-10 15.17.19.jpg

2016-12-10 15.16.15.jpg

2016-12-11 17.07.46.jpg

 Thanks for the info and pictures! This is awesome information! I’ll have a few projects this winter!

 How does the bike sound compared to stock?

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19 hours ago, turbohead said:

I agree with b40rt on most issues, specially regarding the footrests. Use CrMo plate of the same thickness as the side plates and TIG the bits in place, pre-warm the plates and keep them warm, making the plates and welds cool down slowly (check for any sign of cracks after every ride during the first couple of weeks).

However, regarding the midbox and rear silencer, a bit more work than b40rt suggest is well worth the effort. Cut them both up longitudinally with a thin disc and start removing whats inside. Repack the midbox with good hi temp insulation and reweld. Then, cut out everything inside the rear silencer and cut off the rear part as shown. Get a bit of perforated pipe or make one up, to fit between the inlet and a new wall in the rear part. Weld the front part longitudinally and do the same with the rear part. Then, weld the new wall in place in the rear part, as shown. Finally, fit the perforated tube into the front part and fill up with insulation before riveting the two parts together, then paint.

I have kept the original twin outlet pipes on this one, but you can also try a bigger single pipe if you like (louder and less back pressure). The silencer shown here is almost as quiet as the original, but is a much better starting point when tuning for better power delivery all through the rev range (porting, ignition timing, carb set up and so on). Of course, you could use any modern mx type silencer instead, but a little visual cheating can be nice, or....?

2016-08-14 18.38.10.jpg

2016-12-10 15.13.44.jpg

2016-12-10 15.17.19.jpg

2016-12-10 15.16.15.jpg

2016-12-11 17.07.46.jpg

I didn’t realize the frame was chrome moly, I don’t have a tig welder. I guess I better have the shop weld it.

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