Jump to content
flyingfleasteve

1940 Triumph 3SW Restoration

Recommended Posts

Double check the ignition timing! If it's getting that hot, it might be too retarded. 

Here is my (SV) painted exhaust after 400 miles. I'm using this spray paint which I'm sure I recommended before.

https://www.firwood.co.uk/categories/heat-resistant-paints/product/firwood-75-high-temperature-resisting-paint/75

Unfortunately you can only buy it in '6 packs' which I've  shared with a mate.  Ron

 

DSCF1475.jpg

Share this post


Link to post
Share on other sites

Will double check the timing before it’s first proper outing, good shout, might account for some of the popping/ banging....

Out of curiosity what have you used between the silencer and exhaust, where they join?

Share this post


Link to post
Share on other sites
18 hours ago, Ron said:

Steve one thing I've noticed before you ride it. Your saddle looks awfully close to the mudguard?? It could be just camera angle?Any bump in the road could mean a coming together otherwise. Ron

Scan-150802-0001.jpg

Count the coils on the seat springs, this photo has two more than Steve’s by the looks of it 🤔

Share this post


Link to post
Share on other sites

Yes Graham. Both mine have 9 or 10 coils. But the saddles on mine have a bar under the saddle where the spring tops mount which is lower than Steve's mounting points, which effectively raises the height. Ron

 

3SW 146.jpg

DSCF1266.jpg

Share this post


Link to post
Share on other sites

So after a short ride down our lane it appears the bike runs best with a 1/3 choke open....maybe a weak mixture.....timing out as Ron suggested?

Share this post


Link to post
Share on other sites

Ron, I have check the ignition timing and it’s appears the contacts are breaking prematurely (in the pistons down stroke) and not 5/16” before top dead centre. Silly  question, how do I adjust the timing to where it should be? The manual is really unclear.

I assume this is why it’s not running quite right?

Strangely it does start well however?

F.Y.I the plug is really sooted up and not white (from possibly running hot) any ideas all?

Steve

Share this post


Link to post
Share on other sites
Posted (edited)

Steve if your ignition is happening on the down stroke ATDC then your timing is seriously retarded and no wonder it's running hot. DO NOT run it like that again. 

I can easily talk you through it, but can you first post a picture of the points side of your mag.

  Ron

Edited by Ron

Share this post


Link to post
Share on other sites
Posted (edited)

OK it was just to confirm that you have a tight wire advance cable.

Fortunately with these Triumph's you don't need to remove the timing cover or need a special puller to release the mag pinion.

First thing to do (if you haven't already) is make a gauge. Use a thin rod/spoke/Allen key/ drinking straw through the timing hole on top of the head. Sight it exactly against one of the fins and mark it exactly at TDC. Now mark it again at 5/16" (8mm) above your first mark. 

Set the engine so you know it's at roughly TDC on compression stroke (both valves closed) With a 1/4 Whit socket on a short extension bar through the hole in the timing cover, undo the pinion nut which will also act as the puller. Leave the pinion and socket hanging there once it's released. 

Now turn the engine backwards a bit to BTDC and then bring it forward again until the top mark on your gauge is sighted against your datum fin (5/16" BTDC) 

Make sure your handlebar lever is fully towards you (tight wire, fully advanced) and that you have a 12 thou gap when the points are fully open. Now turn your points block in a clockwise direction until the points just break which will be at around the 10 o'clock position. I use a 1 1/2  thou feeler gauge but traditionally it's a fag paper. Turn the points gently until the paper is just released and that is where you gently nip up the pinion.

Now turn the engine over 2 revolutions and double check it. If you get it spot on first time, you are a better man than me Gunga Pooch!   I've taken 6-12 times to get it spot on on various bikes. Finely nip the pinion nut tight.

With modern petrol and the ability to retard it at the handlebar if necessary, I think it's acceptable to be a bit advanced, so if the piston arrived at 9mm BTDC when the points break, I'd be happy.

Good luck. Ron

 

 

Edited by Ron

Share this post


Link to post
Share on other sites

Thanks Ron.

Perfect  instructions!

I have time it up again, checking and double checking.

the symptoms/ running still appear the same.

It starts easy hot or cold, the plug is extremely carboned up, the electrode is white on the very tip.

bike rides best with half choke, adjusting the carburettor mixture screw doesn't really make a difference under load.

advancing the timing leaver worsens the running......

The bike still appears very hot after light riding...

I am a little stumped at this moment in time, any suggestions would be most welcomed!

Steve

 

Share this post


Link to post
Share on other sites

Firstly if the engine is timed correctly, it should be run at full advance for normal running.

The mixture screw is just for adjusting the idling mixture. 1 1/2 turns out is usually good enough. The running mixture is controlled by the slide, the needle position and the main jet. You should have a 120 main jet, a 5/4 slide, a 107 needle jet, the needle No6 should be in the second groove from the top. The plug should be something like a Champion L86C with an 18 thou gap. 

I think I've said before, A retarded ignition or a weak mixture will cause it to run hot.

If the carb is worn so that the slide is wobbling about like a dick in a bucket will never give a good result. Maybe inspect the carb and remove the jet block as there is a tiny drilling in the throat of the carb (see pic) and a corresponding drilling in the jet block which might require poking out with a wire bristle.  A little bit of verdigris in these drillings can cause running problems. Ron

M20 295.JPG

Share this post


Link to post
Share on other sites

Invaluable advice Ron, thank you!

I have done the timing again, a little too advanced, as it kicks back at me when I try and start it but easily rectified with a very small amount of retard on the hand control.

I have also....

Added a new plug and gapped it.

Stripped and cleaned the carb, all components, apart from the slide are new.

Set the needle.

The plug is still sooting, so as you have suggested Ron the slide maybe warn, it appears to run pretty well, as for getting hot it’s hard to tell if that’s sorted, I guess really only a gentle ride will tell now.

The good news is it appears I don’t need to ride it around now with the air slide half open 🤗

Maybe I just didn’t paint the exhaust properly and that’s why the paint come off......🙂

Share this post


Link to post
Share on other sites

With the timing set correctly, it's quite usual for it to kick back and hence the necessity to retard the ignition by 1/3 to 1/2 for start up. The engine will usually tick over better if retarded a bit as the slow momentum of the piston is trying to be pushed backwards by the advanced spark and will often result in a lumpy tick over.  But you need  full advance for normal running. Ron 

Share this post


Link to post
Share on other sites

Great! Now I know the timing is right I can get some shake down miles on it. 

Out of curiosity:-

Is there any special prep work I should be doing to the exhaust before repainting? I assume I need to get a good few coats of paint onto it so it’s not to thin?

currently I am running straight 40 oil in the engine, I and wondering if 50 might be better and maybe I will get less Valve/general engine noise?

All the best

Steve  

Share this post


Link to post
Share on other sites

I just start with a bare metal de-greased exhaust and give it a few coats of VHT paint.

I use classic SAE 40 in all my bikes, summer and winter. But 50 won't hurt for summer. 

Ron

Share this post


Link to post
Share on other sites

In light of the journey ahead I am thinking it would be a good idea to check the valve clearances.

Is this a doable task without any specialist tools or best left to experts?

Its more for piece of mind I guess...

Share this post


Link to post
Share on other sites

Yes tappet clearances are important but straight forward. The engine should be cold and get the piston somewhere near TDC on compression stroke. ie where your points open for ignition. Take the cover off and adjust them by slackening the lock-nut and turn the tappet up or down to get the correct clearance. 4 thou inlet and 7 thou exhaust. Sometimes re-tightening the lock-nut can alter things. As with the timing, turn the engine over a couple of times and re-check.  Ron

Share this post


Link to post
Share on other sites

Is the glass one of the commercial replicas ? How did it seem, size-wise ? 

There is something odd going on with the wire 'W' clips.  They shouldn't be visible as they should be holding the reflector from the rear.

Share this post


Link to post
Share on other sites
Posted (edited)

Yes Steve I think you need to start again with that job! Also the pilot bulb should be at the bottom. 

The glass with the reflector on top are offered into the rim and four 'W' clips are fitted  evenly around the rim to clamp the whole lot together. Ron

Edited by Ron

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...