Triumphrat

glw

As some of you may remember i had new Amal carbs put on my 76, the plugs were black and fouling after one ride. I dropped the needles to lean it out, (pin in the top notch) and the bike no longer fouls the plugs, and runs really good now. It is now cold blooded though and takes about 10 mins to warm up. I have a couple of questions:
1) Why do i get a strange kind of rattle now like its got a bad bearing during warmup (low rpms). seems to go away when it warms up. Never made this noise before... (doesn't seem to ping anywhere in the rpm range or under load)
2) I also changed the plugs one heat range (hotter) to B7ES and the plugs look "absolutely perfect". I am a little surprised, I have had the bike around a year and have been fighting the black plugs the whole time. I have never seen the plugs look this good.
I am a little worried that it may be running lean but the plugs dont show it
I dont like the rattle in the engine... could the timing be off now..
3) Could the primary chain be loose and causing the noise? Whats the best way to check that?
Starts ok but need the choke now, before i didnt. I am in Florida so its still been warm. I also have the Boyer ign, and new coils. Let me know what you guys think.
Thank you.
*Happy New Years to everyone.
Gary

McQueen

Where is the noise coming from? Top of the motor? Primary case? Timing side?

Have you checked the valves lately?

Double checked you have oil returning to the tank?

For the primary chain, there's an inspection plug on the top of the primary side near the barrel. Take that out, slide a finger in there and wiggle the primary chain up and down. Book says you should have about 1/2-inch of free play. Naturally, you do this with the engine NOT running.

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Mecchanica

If you check and set the primary chain tension, and you still have a rattle when cold, it's likely to be piston slap. The short rod engines have a larger bore and shorter piston skirts, to clear the flywheel while using a half inch shorter con rod. This combo does three things, it makes the piston less stable in the bore...more inclined to rock, it induces more side load on the pistons and alters the torque curve to give more midrange torque and less at the top end, compared to the earlier long rod engine. The factory raised the pin hole in the piston relative to the crown to minimize this, but it didn't remove it completely. So you get more wear on the pistons and more noise when the bore and/or skirt wears, especially when cold. As it warms, the piston expands and the noise diminishes, or even disappears.

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Triumph old, Triumph new, any Triumph will do.

glw

Thanks McQueen, and Mecchanica.
I checked the primary chain, it's not loose. thanks for the instructions to check.
Guess the piston slop makes sense, I had a harley that made that noise also and thats what my boys said it was, was just wondering why i never heard it before i did the carb work.
Oh well, i'll try not to worry about it, and just ride the crap out of it.
Got almost 18k miles on it so maybe in the next year or 2 I'll think about a rebuild.
Should be good for a while though i would imagine.
Thanks again.

Mecchanica

I should have mentioned that another source of rattle is the carb slide. Use the old screwdriver in the ear as a stethescope trick to locate the rattle, carb or cylinder, or elsewhere.
I rebuilt a guy's engine and gave it to him to install in his chopper. He showed up at my house with his clubmates to gripe about my rebuild and I quickly found that he had a worn out slide. The quieter engine and stronger draught caused the rattle to be much louder. I chided him for jumping to conclusions and for being a cheapskate in not getting a new carb for his new engine. I made him buy one right then or else no warranty if the slide shattered and did damage. He rode off with a nice powerplant and a little more humility.

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Triumph old, Triumph new, any Triumph will do.

glw

LOL... I have new carbs but ill check it out anyway as i've heard the new ones arent that great of quality.. screw driver in the ear... hmmmm this will be a first.. My guess is the handle not the tip... :-)

Mecchanica

Good guess, but you could try it the other way and let us know if it works better.

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Triumph old, Triumph new, any Triumph will do.