Ian's TX/CBR500A Yamahonda whatever

my-79-750-k

Therapy is expensive. Riding is cheap. You decide.
So, long story short. I've been waiting 2 years now to get another bike. This past weekend, the wife asked me if I'd seen anything on CL that piqued my interest. After looking at a few projects here and there, I zeroed in on this little TX500 that a guy wanted to get rid of for a very nice price, and the most important thing, it had a title. So we made the trek down to Auburn, WA. It should have taken about 2 1/2 hours, turned into 6 because people forget how to drive on July 4th weekend and back traffic up for 8 miles for absolutely no reason. But I digress... Brought it home on Sunday night and immediately tore into it. By that night, I was 3 engine bolts from pulling the motor.

Fast forward to Monday night. Engine came out without too much fuss. Definitely a lot lighter than my Cb750. I set it aside for a few and took a crack at the framework. Harness, headlight, controls, battery box, signals, fenders... All came off. Harness is shot :/ along with all the regulators, coils, rectifier, condenser, etc. Both forks need to be rebuilt. Shocks aren't bad, just need a good sandblasting and cleaning. Tank is pretty bad inside, haven't decided yet what I'm gonna do about that. Seat is trash, so is the pan. No big loss there. Brakes are in need of complete replacing on the front, rear is yet to be determined.

Tore into it today. Little farther in. Met with some bad news. One of the intake lobes has some fairly noticeable scoring on it. Not what I wanted to see. New (used) cams are 25$ on Epay. Not to mention the starter chain and balancer chain are a bit loose for my tastes.

So here's where were at right now. Externals of the engine are torn apart. Frame is basically just a roller. Harness, and most every electrical component, needs complete replacing. Forks need rebuilding. Engine is gonna need some love. Right now I'm just starting to make a list of the parts, and prices, for everything and contemplating what direction I want to go.
 

my-79-750-k

Therapy is expensive. Riding is cheap. You decide.
Re: Ian's Bastard child TX500 build

So got some more time in the garage today. Down to the frame now. Wheels, brakes, forks, triples... all off the frame. Basically ran into more of the same crap. Everything on this bike is just corroded and thrashed. However, it's gonna be a long process. I've already relegated that this isn't gonna be done this year. At least I have something to keep me occupied for the winter. On to the pics:

 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
Re: Ian's Bastard child TX500 build

Pretty. I know you'll keep those handlebars. They're pure sex.
 

my-79-750-k

Therapy is expensive. Riding is cheap. You decide.
Re: Ian's Bastard child TX500 build

They were secretly the main reason I bought it :/

Newest development:


The scoring isn't very deep, but it's there and can be felt with a fingernail. Used cams on ePay go for 12$-25$ each, NOS cams run $150+. I'm just a bit upset. We'll have to see how the budget goes the rest of the month to figure out if I'm getting used cams reground or just getting used cams. :/
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
Re: Ian's Bastard child TX500 build

That blows. IIRC, you're looking at $80 for so for a regrind anyway. New isn't much bigger of an investment if you have to buy used ones and have them ground. Do they make a high performance cam for that motor? Maybe there can be an opportunity here.
 

my-79-750-k

Therapy is expensive. Riding is cheap. You decide.
Re: Ian's Bastard child TX500 build

You know, I already emailed a company up here about regrinding the cams hotter but have yet to get a reply. I haven't found any aftermarket cams, or even grind specs, but I do know they make high comp pistons that raise it to 9.5:1. Stock is only 8.6:1. Doesn't exactly scream high performance.
 

jimmer

New Member
Re: Ian's Bastard child TX500 build

Late model stock'78 pistons are 9.6/1 comp. and Webcam will grind you some cams for about $300 a set. But don't bother unless you have carbs,exhaust,ignition to go with it.
 

my-79-750-k

Therapy is expensive. Riding is cheap. You decide.
Re: Ian's Bastard child TX500 build

Yeah. I just got quoted 400 for a mild performance cam job. I think it's gonna stay stock for now until I get it running and get some miles on it. I just wanna ride.
 

my-79-750-k

Therapy is expensive. Riding is cheap. You decide.
Re: Ian's Bastard child TX500 build

Granted it's gonna take a lot of work to get it back to riding status, but 3-400 on a set of cams, and the subsequent $$ for upgrading the carbs, exhaust, ignition, suspension, etc is just beyond the budget for this bike. Body wise I'm not limited by anything as I have a full machine shop of metal and tools at my disposal (along with making my own other pieces that are impossible to find). I'm trying to keep this one on track and on budget. If I wanted something with 100hp, I'd have bought an R6 haha!
 

my-79-750-k

Therapy is expensive. Riding is cheap. You decide.
Re: Ian's Bastard child TX500 build

Just ordered starter relay, clutch pushrod seal, clutch cable, throttle cable, plugs, wires and caps, Condenser and rear brakes. Well see how far that 100$ goes.
 

my-79-750-k

Therapy is expensive. Riding is cheap. You decide.
Re: Ian's Bastard child TX500 build

Parts came in today! Everything fit like it should except for the clutch pushrod seal, I ordered the wrong one :/ Gonna have to eat the 8$ and buy a different one. Just placed the order for the rectifier as well. So far, with me working at a machine shop and being able to make stuff out of scrap pieces for free, I've been able to keep it on a (tight) budget. It's late now, pics tomorrow.
 

my-79-750-k

Therapy is expensive. Riding is cheap. You decide.
Re: Ian's Bastard child TX500 build

New Starter solenoid:

Going, stopping and engaging taken care of...

Oooohhhh, I wonder what it could be...?

Other than a brand new one, about the best shape cam I could find anywhere :/
 

my-79-750-k

Therapy is expensive. Riding is cheap. You decide.
Re: Ian's Bastard child TX500 build

So, after being stalled due to other projects, and having 0 budget funds for about 2 months, we have new parts.

Backstory: I took the original forks to work in order to use all the awesome tools we have there to tear them apart. After putting it in 4 different vises, and going to town on the caps with a 1/2 impact, I realized these things weren't coming apart. Also, the uppers were just way too rusted and pitted to be saved anyway. So I threw out a frustrating post on FB, like any good biker does, and lo and behold, a fellow rider in Portland said he had a front end for super cheap (Actually, 2 people offered front ends, I picked this one). At the same time, I had been trying to get the chance to go to P-town to pick up another engine from another FB friend and had to cancel on him twice so this time, I was making sure I was going to make it. I called them both and headed down to the traffic and red lights or Portland (which is horrible from a traffic standpoint). I grabbed the front end and the engine, met some awesome dudes and headed back home.

The front end:
It's off of a first gen CBR600 Hurricane. 37mm UJM style forks, and as luck would have it, LONGER than my old forks, so I don't have to worry about trying to fix any rake and trail issues. I will be using the triples, but swapping the stems. They are in great shape, and simply need some dust seals. Also, I get air assist again! (had it on my CB750 project)

The engine:
This is a different story (and I'll leave names out of it)
Got out into the garage today and started messing around with the engine. I noticed there was no compression when I turned the kickstarter. Hmmm. So I dove deeper and found the stuff nightmares are made of. :mad: This engine supposedly came out of a running bike, and was given a visual once over by the guy I bought it from, but sat in someone else's shop for over a year. Then my guy bought it from him to use in his own project, and that fell to the wayside. At that point, the only time he had looked into it was when it was first pulled. FF to now; I pull the cam cover and find... No cam chain... ??? So I then notice there's a gap between the cylinders and the block. Uh-oh... Long story (sorta) short, I pulled the top half off, and the pistons and con-rods come with it. There weren't any rod caps on the con-rods; and they were nowhere to be found. At this point I was a bit miffed... I contacted the guy I bought it from, and he was very apologetic and said he had only looked at it when it was first removed, and at that point, it was a complete running engine. Now, I have no reason not to trust this guy, as many, many people I know have been dealing with him for a long time, and never has anyone said 1 bad thing about him. So I'm certain that he didn't do it on purpose, and he has been more than helpful today while I was talking with him. I can use parts off of the new engine to replace the ones on the old engine, which honestly would still be worth what I paid for the other engine. So in the end, it will all work out, it was just a bumpy journey to get there. Anyway..pics-

New CBR fork on the left.

Somethings missing here...
 

my-79-750-k

Therapy is expensive. Riding is cheap. You decide.
More development on the engine side of things. Had time at lunch today to get the valves out of the new head. Leaving the head in our solvent tank over the weekend to try and loosen up as much corrosion and carbon as possible, then I'll clean it next week. Gonna make 3 custom angled valve seat cutters to re-establish the factory 3 angle valve job, then back cut the valves, lap them in, etc.

However, I was met with some... resistance, when dis-assembling the head. First, Yamaha left ZERO room for spring compressors, so the ol' "cover with a socket and give it a tap" technique was used, with good results 7 out of 8 times. 1 valve was obviously stuck in the guide, so I took extra care with that one and after about 4 hits it came out... in 2 pieces. :( Good news is, I have my old head full of valves! So I'll be able to use one of those to replace the broken one. Other than that, this thing is just dirty. Lots of carbon buildup and corrosion from sitting for so long.

 

my-79-750-k

Therapy is expensive. Riding is cheap. You decide.
Short update. The new triples wiould have worked with the old stem. Unfortunately, the old stem got ruined while I was trying to press it out of the old triples. Yamaha has the great idea to put some sort of worthless, useless "spacer" type thing in the bottom of the stem. I had machined the welds of the bottom of the stem and had started pressing the stem out and somehow it got hung up, and that spacer broke loose and got wedged down into the tube about an inch, effectively mushrooming the bottom inch of the old stem.


So new plan was to make a new stem. I cut a length of 4140 steel, drilled it, turned it, and pressed the new blank into the new lower triple tree.


Turned down the new stem today, roughed out anyway. Unfortunately, it was premature. I didn't have the measurement for the bearing areas, and since I'm switching it to tapered bearings, the distances would be different anyway. So until I order new bearings, and can get the new races in and get the correct measurement, I'm at a standstill.


Looking at the neck on the frame, I found yet another monkey wrench from Yamaha. Someone in 1974 decided it would be wise to make the upper race area only 5/16" deep. New tapered bearings measure 14mm minimum. Basically, 1/4" of the bearing would be sticking out of the neck. I came up with a solution that basically involves making an extension piece that would make the upper race area longer to fit the new bearings and keep them from being exposed, while also giving the needed room underneath the new top triple tree.

Good news is, the brake caliper came in today. The 1st gen CBR had anti-dive on the left fork and caliper. I bought a used left caliper on ePay and it came in today. Even came with pads... with life left! Ha! CBR axle should be here this week as well. Gonna have to make a hanger bracket for it, but that shouldn't be an issue.
 

xb33bsa

New Member
nice work !@ thats sure a good size lathe to have.my little 12" swing craftsman is a toy compared to that :-\
yeah i would say on that top bearing that it actually has enough support and register at 5/16 and just a decently thick ring lightly pressed over the remainder would aleave any worries about it and make it look normal as well.
you could also of course fit a bearing cup like a bicycle or harley headstock but that would increase the vertical distance
but compared to what the tapered bearing can actually endure in loading it is a very small load in use on our motorcycles
 

my-79-750-k

Therapy is expensive. Riding is cheap. You decide.
I ordered my neck bearings last night, so when they arrive I can check the clearances and figure out the measurements for the new stem and bearing points, and see what needs to be done as far as the upper bearing to triple area. Good news is, my brake caliper and front axle arrived today! The caliper is the original 1st gen CBR600F left side caliper, which has the anti-dive connection on it. It's in decent shape. I'll tear it down and check the seals and cups, replacing if needed. It came with pads installed that appear to have life left in them, but probably need to be swapped out before I actually ride. Just using them for mock up at this point. I'll be swapping the front wheel around and using the Yamaha rotor which originally was on the right side. With the axle and caliper in hand now, I can mock up and measure for the front hub spacers and get some preliminary measurements for a hanger bracket for the caliper.
 

xb33bsa

New Member
yerr marchin along im just waiting for the motogp live coming up soon :D
i sure like those aloris tool holders you can git down and boogie there solid as
izzat an 80 degree diamond shaped insert ? always was my fav
 

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