Bonneville America Forums Forums General Motorcycle Forums Other Bikes 1972 Triumph T120 Project Bike....@$%#&*

So I got her all together, got her running really sweet, took her up the road, and suddenly distinctive "rattle" from inside engine...Pulled her down, left cylinder sleeve broken off and rattling around crankcase...Engine totalled...back to drawing board....@#%^$%!!!!

Oh the humanity! I feel your pain.

I've felt your pain. Mine was self-induced. My first engine rebuild was on a '66 Mustang, 289 HiPo Fastback, when I was a teen-ager. Guy at the auto-parts store sold me rail-type rocker arms when I needed the flat type. Wore through the soft grommet holding the valve spring retainer in place and sucked a valve. Cracked the block and I still have the new piston with part of a valve sticking in it somewhere as a reminder to not trust the parts man implicitly.

Yours may not have been "self-induced", but I know how you're feeling right now. Take a break and give it another go (purse strings willing) ......

Regards,

Tom

any idea what caused it? Faulty casting? Dropped and cracked sometime before install? Other?

My Uncles bad luck story. Rebuilt small block V8. Installed in car. Started it up, rigged the throttle to keep the RPM up a little. Went inside to have some toast, while waiting for the engine to warm up enough to set the choke. Came out the door and the engine was steaming and banging. The water pump picked this time to totally blow! Back to step one.

The right connecting rod bearing came apart at the crankshaft...just kinda "mush". I gotta say, I enjoyed riding her up the road the few times I got to...I have the engine out, and on my bench with the shop manual trying to figure out how to get to the "beef"...Got an e-mail yesterday from a "BritBike" .com member that has a lower end for me...just waiting on a price. Its gonna be allright...will take pics.

If by beef you mean how to disassemble the bottom end, don't try and remove the cam gears without the right pullers/pushers. You will damage the cams and maybe the case. Same with the crank gear, I have seem more of those mushroomed than I can count from not using the right tool. Good luck.

A guy e-mailed me with a bottom end that he says is in great shape, he wants $400..what do ya'll think....

Not too bad a price if it doesn't need rebuilding, personally I would still want to go through it and mic everything and replace the rod bearings. Does it include the tranny parts and complete primary? If so then it's well worth it. If your bottom end is salvageable might just redo it. Don't know how bad your crank and rods got beat up.

I just finished watching a Brit tv series called 'a Bike is Born' where the guy rebuilt a 1970 T120 , very interesting show ,especially as i never seen a bike rebuilt from the ground up before,not an easy job from what i seen . so i have a wee (very wee)bit of an idea how you must feel ,gutted (excuse the pun), sound about right?. well if that was me ,with my superior knowledge....... (of british comedies),i,d be beating the sh!t out of the bike with a big tree branch ,basil fawlty style . best of luck mate, getting it back up and running.

Got everything off that could possibly be holding the case halves together, still won't budge...any ideas..the shop manual simply Sux out loud....

Best to remove at least outer tranny case (don't have to but easier) remove jugs,oil pump, oil lines,cam and crank gears, disassemble primary,pistons off of rods (best to pad the rods or be sure to keep them a BDC) If you simply can't get the case split you can VERY LIGHTLY tap the end of the crank with a rawhide mallet but only do this as a last resort.Some times if you can put it in the oven to warm it all up to expand the metal it will loosen them but remember when you remove it from the oven to wear gloves. Also I did mention ignition, timing cover case bolts, etc... since I figure those are obvious. Sitting here trying to picture it in my head and can't think of anything else that you need to remove. You don't have to disassemble the tranny but I do to lighten it up for ease of handling. I also don't warm the cases or tap with a mallet but if they won't come apart you may have to do one or the other.If you tap be very careful don't want to bend anything or mushroom the end where the oil seal to feed the crank is, this end mushrooms pretty easy also don't want to get any dirt in there. Don't forget to clean the sludge trap.

did you get the 2 screws inside the cylinder hole in the top of the case

There was one last through bolt hidden underneath the gearbox side panel. Came right apart after that..never did see any screws inside the cylinder hole in the top of the case...Crank ruined...right connecting rod bent, cylinder jug busted. Talked to a couple people...my best estimate right now is around $650. Both case halves okay, camshafts okay, I need to hit the lottery....

Look on Ebay I see parts on there all the time,becareful buying a crank on there though. I have seen quite a few with the seal end mushroomed like I warned about in my earlier post. I haven't seen any with screws inside the jug opening either but it could be in the late 70s to early 80s models since the newest one I have ever worked on is 72. I got cyl with fitted pistons. The bore was fresh and the pistons never installed. I didn't get rings with it or the wrist pin clips but I only paid $150 for the set and they were 40 over. Just have to keep your eyes open for one that has slipped through the cracks and isn't getting bids. That bottom end you mentioned is one way to go with the amount of damage you report even if you need to put new rod bearings in it. If it has seen moisture you may need more than that though and mains are expensive. Plus if that bottom end nees cam bushings thats another minor can of worms. Requiers pulling the old ones out pressing the new ones in then reaming same with wrist pin bushings. Although there is a trick to those you can use a deep well socket large enough for the wrist pin bushing slide inside and a bolt with washers. Put the socket on one side of the rod and the new bushing on the other with the bolt through them and a washer on each end. This is best done with the rod heated. when you tighten the bolt it forces the old bushing out and the new one in. I heat them in an old pot full of motor oil on the stove so you heat them in oil to prevent un even heating or over heating and also prevents warpage.I heat pistons the same way so the wrist pin slides easily, always remember if doing that to have the one pin clip in so the pin doesn't slide right through. I also heat the cases to remove or install and bearings or races. It expands then and prvents shaving any aluminum off from the pressing process.

Pipes came in today...man, they are SWEET...