1969 T100c Running Rich

A few months ago I purchased a 1969 T100C that had sat for 10+ years due to numerous problems that I guess could not be figured out. So being mechanically inclined but knowing nothing of Triumphs, I decided to take it on.

Long story short, I replaced the piston rings cleaned out the head/ports/valves and reseated the valves and did all of the other typical tune up routine stuff.

I took apart the carb, its an Amal 626, and took every part of it apart and thoroughly cleaned everything so it looked almost brand new. Jet sizes appear to be the standard 180 main and didnt see a number on the needle jet it just says Amal but I presume it to be the standard as nothing in the carb appears to have been tampered with. And at least from a visual standpoint, nothing about the carb appears to be excessively warn/damaged in any way.

Upon getting the bike running, Iv spent the last month trying to get the carb tuned correctly. Iv gotten to the point where it starts and runs reliably, but according to the plugs its still running rich despite having the needled on the leanest setting (top notch) and the air screw turned almost all the way out. Removing the air filter makes little difference, but makes it better if anything and the air filter is brand new. Iv even already gone through a set of plugs in a month due to fouling.

So my question is, should I consider rejetting it? I live in a warm, humid climate at sea level. Are the standard jet sizes not ideal for that environment?

Also, I cannot get it to idle steady below 1500rpm. At least according to the tach which may not be entirely accurate, but it does seem to need to idle high. Right now, a smooth idle for it is around 1800rpm.

 

I havent measured it, but just eye balling it the float level looks good. Iv also been suspecting the float sticking, but when I take it apart the float appears to operate just fine but I ordered an overhaul kit that has a replacement float needle so maybe that will fix it.

Oddly enough, yesterday randomly when I started the bike after just riding a bit ago, it jumped up to idle at 4k rpms. So I took and lowered the idle screw and the damn thing went all the way down to 1k rpms steady!

But, of course, today it refused to idle lower than 1500 again even after riding it and warming it up.

So, I am going to replace the float needle, the float itself....floats so I assume it should be fine. Also, how would I go about "adjusting" the float level? Its a plastic float that doesnt look to have any way of adjusting.

 

So update, installed the overhual kit with new orings, tuning screws, new spacer for the manifold, new manifold gaskets, new float needle and it made everything worse. Its running so rich now to the point where its smoking and wont idle without significant throttle. Removing the air filter does nothing.

Also triple checked the operation of the float, and float levels before putting it back together. Float level was right on .06 inch and fuel flow stopped at the appropriate level so needle is seating properly. Emptied and repeated this test numerous times to see if it would ever stick, it did operated perfectly each time.

So after running it a while with no improvements, I decided to adjust the float level by hamering out the seat a bit. The float is now set at about 0.12 inch and no change in the fuel mixture, still rich.

But, I did notice taking off the air filter and feeling inside the throttle bodie not only is it freezing cold (Im assuming from the vaccum created) but its wet with fuel. And from the air filter, it appears as if fuel is spraying back out as well.

Possible blow-by coming back through somehow? Often times when I kick it to start it, it will kick back at me and puff out the intake but not fire.

Edit: And, noticed oil is getting into the points somehow. But today, thorough testing shows the ignition system working perfectly. So, I guess new plugs again and more trial and error.

 

Not really sure why my reply was rejected, but I guess Ill just figure it out on my own then.

 

Yes, I made a whole post about testing my ignition system as it appears as if my right side is not firing correctly. It was pending and then removed for whatever reason.

I have a boyer ignition system, dual fire single 12v coil. Using a test light, left side fires correctly although a little advanced from where it should be, the right side appears to fire randomly. I dont know if it appears that way due to the dual fire aspect of it. Swapping plug wires did nothing, wires are both good tested them seperately. Swiping a magnet over the pickups each side appears to fire correctly.

I took the stator out, cleaned it really good and discovered some frayed wire so replaced that hooked it back up and today will put the bike back together and see if it runs any different.

 

So upon taking it back apart, noticed that the needle had come off the clip. So fixed that, now its back to idling and revving just fine but still too rich. Blue smoke strong fuel smell on throttle, no smoke slight fuel smell at idle. Idling at 1k rpms now steady.

I measured the float level 2 ways. 1st way was with the float as high up until the needle seated. But that gave me a reading of a quarter inch, so then measured it to where the float touches the bottom of the needle once its seated and that gave me the 0.06 inch so I went with that. I then adjusted the float to 0.12 inch after not seeing an improvement.

Fixing the wiring for the ignition made no difference.

I do appreciate all the help. I guess I havent replaced the jets and needle yet, but I dont see anything visually wrong with any of them. Not really sure how a jet could enlarge over time, the needle doesnt appear to have any wear marks on it. But, that doesnt mean it wasnt replaced with one thats the wrong size. Should I try replacing the needle or the jets? Seems more likely the needle may be the issue right?

 

As far as the timing cover seal, I cant find a part number for the whole thing. I found the seal that I assume goes around the camshaft but not the timing cover body.

I found this https://www.thebonnevilleshop.com/product/triumph-650-750-timing-cover-gasket-1-pn-71-7263/

Also, I shouldnt have to drain the oil to take the timing cover off should I?

 

Ok thank you. I have the parts catalog for my bike, physical copy and the workshop manual. Neither of them had that part listed in there for some reason.

But, as of now the bike wont even start. Not even a fire. Ran great yesterday and this morning and then just decided it was done.

Already $1200 deep into parts for this heap, and now Im looking to dump another $1500 into it in an entire new ignition system, new pistons, machining the head, new carb. If it doesnt run after all that, then it will be up for sale for $5k as thats about what I would have put into altogether including purchase price.

Im beginning to see why this bike was abandonded....Iv rebuild car engines, done engine swaps, brought many engines back to life but this thing is cursed.

For a bit of why the hell not, I cut out a higher notch on the needle. It made absolutely no difference. Which further makes no sense.

 

Yes my carb does have an idle mixture screw, but it doesnt effect the mixture.

And I am also coming to the conclusion my main issue is most likely the ignition system. Even though when I tested it everything appeared to work fine, my guess is its having some kind of intermittent hissy fit for some reason.

So, for now, ordering an all new boyer mkiv ignition system, new dual lead 12v coil, new plugs and wires, and will replace the jetting, needle, and float in the carb as well.

 

Dont know if the tiger and competition models were the same, Iv read that the naming for these bikes was confusing. But according to my parts catalog, my main jet is supposed to be a 180, which it is. According to the workshop manual it should be a 170 like you say. All else is the same, 4 slide and 106 needle jet.

So I am replacing the jet with a 170, as well as the entire ignition system.

Thank you for all the help, will post back in a week or 2 when parts get here and see if shes ready for a cross country trip by then haha.

I am also going to take apart the engine and thoroughly clean all the carbon deposits out of it again and reseat the valves so it will have a nice new clean chamber to combust in with new spark.

 

So took apart the engine to do some cleaning...it wasnt actually bad, probably could have even done without. Valves are still air tight, so no need to mess with those. But this is what it looked like after 2 months of running rich and even beating it up a bit with throttle from time to time. And then a light cleaning with PB blaster. I forgot to take a picture of the pistons clean, but you get the idea all of that carbon came off easily they are silver in color again. The damage done to the chamber and pistons I was told by a machine shop is just cosmetic and shouldnt effect anything, was most likely caused by hard chunks of carbon deposits breaking off and bouncing around. Never seen that before on any engine Iv worked on, but this guy was in rough shape when I got it. I had to scrape caked on oil out of the exhaust ports that was thick and nasty from it burning so mucb oil before. That damage was pre existing when I got the bike. But I suspect previous owner was having the same issues I have been.

He told me it just kept fouling plugs and he couldnt figure it out. When I got it, I figure the burning oil was the cause. But, after fixing other issues the bike had Im now realizing the problem was deeper. I suspect that at some point someone rejetted it with the wrong size, most likely because of the workshop manual that got handed down to me that has the wrong size so thats what they went with. Probably ran rich from that point on, and like me they chased everything but the carb. Although they should have figured it out given that they were the ones who did it. I suspect over time and fouling so many plugs eventually damaged the ignition coil and now its been acting up and has finally given in. I probably dont need to replace the entire ignition system, but every time I solve a problem a new one pops up so Iv learned just replace it all and be done with it.

 

Yes its been bored out before, not by me. I havent had any measurable amount of oil consumption in the 2 months I had the bike running. And yes, I took the barrels off to install new piston rings I cleaned, honed, and did measure the pistons and cylinders before reinstallation using a micrometer and a bore measurement tool. I remember the cylinders both measuring 2.73in, measured north- south and east-west top middle and bottom of the cylinders. Cant remember the exact diameter of the pistons, must have been close enough for me not to worry about it. Theres very slight play in the pistons, but I dont think theres enough to be concerned about. I also gapped each ring to the specs that were given to me in the workshop manual.

I did check the play in the valve stems when I rebuilt the engine the first time, there was next to none in each one. Just enough to get the valve through and not a measurable amount of play. There was also no indication of oil on the back of the valves, they were the cleanest part of the valves.

The reason it was burning oil when I got it, was because the previous guy put the standard size rings in there not 0.020 overbore he should have put, so ring gaps were way too much.

The head gasket is copper, and the guy gave me 2 of them he had, but I bought a new one on my first rebuild just to be sure because the 2 he gave me looked rough. No annealing done, never done that.

Im pretty sure its no longer burning any oil since I put the correct size rings in, theres no oil consumption and it never even smoked until recently and that smelled more or just unburnt fuel not oil.

However, it was concerning that when I did the rebuild the first time, my compression cold measured about 95psi on both cylinders. Wet and dry. And I checked the head for warpage both first time and this time, if there is any its less than 0.002 of an inch which I dont think would be an issue.

Heres some pictures from my first rebuid with it