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Starting a full restoration on my 1967 Triumph T20SM Tiger Cub

Motorhead

Subscriber
Age
67
Last Subscription Date
07/09/2019
I asked the machinist about balancing and he said it wasn't a big deal on the Cubs...We'll see.
Saturday, 3-20, 2020: Got a bunch of parts in the mail today. Went through and categorized them and got what I needed to put my cylinder head together. Cleaned and inspected everything. I had a new set of valve springs and new valves that went into the head. I replaced the small adjusters with a set of "Mushroom" head adjuster screws. Cubs pit up the valve stems so these should cure that issue. The head assembly is labor intensive. You have to align the rocker shaft, shims and what Triumph calls a "Thackery" spring which is a thrust spring and manage to press the rocker shafts through all the parts and into the head. I found a rare set of WEBCO valve covers years ago on ebay and had them put away for when I rebuilt the engine. The exhaust cover has a vent.
Tomorrow, I start putting the Primary side back together with a new modified clutch and the electronic ignition and trigger. There are NO timing marks what-so-ever on a cub engine. Everything is set up with a degree wheel and a dial indicator once the piston and cylinder is installed to set up the ignition timing. With the TRI-SPARK ignition, I have to set the engine to 35* BTDC and put the trigger and pick up on. It has a LED so you can hook up a battery and check your degrees BTDC. The ignition module apparently retards the timing for idle and low speed and then gives it full advance at higher RPM. IMG_4286 (1280x960).jpgIMG_4287 (1280x960).jpgIMG_4288 (1280x960).jpgIMG_4289 (1280x960).jpg
 

Motorhead

Subscriber
Age
67
Last Subscription Date
07/09/2019
Ordered a Degree wheel and got it today. The T20 Triumph Tiger Cub came with NO timing marks. So with the Tri Spark electronic ignition, I will find TDC with a dial indicator mounted to the cylinder and set TDC with the piston crown. The Tri Spark calls to set the crank at your FULL ADVANCE, which in my case is 35* BTDC. I then set the Static timing to fire at 35*. The ignition module will then retard the timing approximately 25* to 10* BTDC and start advancing as the RPM increases. It is FULL Advance at 3500 RPM. In my case, it will be approximately 35* BTDC. I will assemble the primary side with the primary chain and clutch so I can kick start the engine with the primary case off. I will have timing marks and will then use a timing light to check IDLE timing to full advance. https://www.trispark.com.au/

I am running a WISECO forged piston. This piston fits a 90's Honda XL/ATC 185-200 cc motorcycle and all terrain trikes. I was checking my piston ring END gap and it seemed a bit more than multiplying my BORE size by the quotient clearance that WISECO calls for. I called WISECO and talked with a real knowledgeable guy in sales. He is sending me another set of piston rings at NO charge. He says they can vary and even though I was on the high side of ACCEPTABLE ring gap, He said that the rings can vary and that he would find me another set and to get back with him to see if I get a closer gap or not. NOW THAT IS SERVICE!!! WISECO Performance Products, A GREAT AMERICAN company!!! http://www.wiseco.com/
 
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Motorhead

Subscriber
Age
67
Last Subscription Date
07/09/2019
Did the Ignition Timing today. So I was going to mow the yards today....Luckily it RAINED!:clap:
I set up the degree wheel and dug through my late Dad's lathe drawers and grabbed one of his Starrett dial indicators. I placed the piston and wrist pin on the rod and slipped the cylinder over the piston without the piston rings installed. I "Jimmied" up a reference pointer and set the piston at TDC, ready to FIRE, according to the dial indicator. I set the wheel at "0". I double checked several times rotating the engine to make sure the timing wheel and the pointer mark corresponded to the dial indicator at TDC. I need 35* at full advance, so I set it and installed the trigger rotor at a mark I had previously made on the engine case. I tightened down the rotor which on my engine, seats into a taper in the end of the cam shaft. I turned the crank backwards past 35* BTDC. I hooked up a battery to the adjustable plate with the red diode indicator and moved the plate and turned the engine just until the diode lit. I checked that it lit at 35* BTDC. Job done!IMG_4291 (1280x960).jpgIMG_4292 (1280x960).jpgIMG_4295 (1280x960).jpgIMG_4294 (1280x960).jpg
 

Radiomike

Registered
Your Hummer looks nice, I have the BSA equivalent the Bantam. Mine is 1949 with a solid rear end. Wipac electrics, no battery, slow down and all the lights go dim.
Mike
 

Motorhead

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Age
67
Last Subscription Date
07/09/2019
Today, I was waiting on the Mailman for two tiny parts...
I got the parts and got to work. I assembled the entire primary side and clutch. With upping the horsepower, I added a competition clutch assembly. It uses thinner steel plates and allows you to add a FOURTH friction plate. I replaces the REAR chain wheel that is part of the clutch. It's nice to dig into my "Stash" of new old stock parts that I have gathered for at least the last 20 plus years for just this "Event". I had a brand new RENOLD, double row primary chain so it went on too. I replaced the ALTERNATOR with a high output, 16 amp, single phase alternator. That will run the electronic ignition and take care of my lighting needs with NO Battery to screw with. Last picture is a rare Smiths Chronometric speedometer. I will send it off to Nisonger instrument repair. It works but I want it cleaned, lubed and repainted. The chronometric speedos hold the pointer still at what speed you are running at. Best way to explain is that the pointer "Ticks" up and down as your speed changes.
Next and last is to install the piston, rings and put the head on. I am waiting for the rings from WISECO.IMG_4296 (1280x960).jpgIMG_4297 (960x1280).jpgIMG_4298 (1280x960).jpg
 

Vanman

Subscriber
Last Subscription Date
07/10/2019
That is the reason I do not like digital speedometers though. You cannot tell if your speed is drifting up or down or not at all until it “ticks” to the next number.

Conversely, locomotives have an extra instrument that would be quite handy; an accelerometer. It reads in MPH per minute. When it reads zero, your speed is not changing. I’d like an analog one, which has the pointer straight up at zero acceleration. Have never seen one though.

Keith
 
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Motorhead

Subscriber
Age
67
Last Subscription Date
07/09/2019
I have the original small round Smiths speedo for the bike. I just always liked the chronemetrics. I have the big round chrono on the Cub now. The "D" shaped one as shown came on early Cubs.
 

Motorhead

Subscriber
Age
67
Last Subscription Date
07/09/2019
Got the head on today and it looks like a complete engine now. Because of the over bore, I had to modify the stock, solid copper HEAD gasket. I took 2 hours to open it up so it was the same size as the bore. So while annealing it, I got it too hot and ruined it! Luckily, I had another new head gasket and took about an hour to open it up. The Cub engine is a real "Hands On" engine, not a production Honda.
The design of the head, you can't get a torque wrench on two of the head nuts. So, it is a hand tighten with a wrench and guess what torque you are at. By the way... I called the speedometer place and they want $300 for a basic clean, lube, calibrate and paint. Got to think about that.IMG_4299 (960x1280).jpgIMG_4300 (960x1280).jpg
 

Motorhead

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Age
67
Last Subscription Date
07/09/2019
I have decided to test run the engine first. I installed it in the frame and am in the midst of cleaning the oil tank out, lengthening the throttle cable to fit the AMAL Concentric carb and I have to switch over the electrical temporarily to run on the new electrical system. If all is well then I will start on the mods for the frame for my new seat. Pictures later. http://rover.ebay.com/rover/1/711-5...0001&campid=5335872123&icep_item=113754149276
 

Motorhead

Subscriber
Age
67
Last Subscription Date
07/09/2019
ENGINE runs!!! :clap: Still sounds like an old Triumph single.
I will now do all brackets and re-fit of the new ignition and black box. After all the fitment is done, I'll take the bike back apart, engine out and have it powder coated.
 
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