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Discussion Starter #1
I picked this '74 TX500A for $120 off Craigslist. I pulled the motor and am in the process of stripping it down to clean up the frame.



With the tank and super heavy seat!



Dismounted engine

 

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I'm currently rebuilding one of my own. I'm glad there is someone else out there that enjoys pain as much as I do.

Keep in mind that some parts are rare. Things like oil filters, cam chain master links, and other engine parts are not produced anymore. I just bought a cam chain link for $55 on ebay and an oil filter adapter from an xs500proboard member for $100. The adapter will allow the fitment of a fram ph6607 filter. Works perfectly. There is a good reason you got the bike for such a low price, it costs out the ass to get parts! Please keep this post going. I'm interested in seeing what you can do. FYI, join the xs500proboard site too. Its a whole community of guys who are gluttons for punishment, like us. :)
 

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The chain does not operate anything except the cams. Double row camchain is necessary, though, considering the volcanic power of the mighty TX500. :D I'm considering converting to triple row chain, since I put pods and open mufflers on mine.
 

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Wait till you see what she can do with set of VM32's and velocity stacks!

I do believe the cam chain was slightly over engineered, but what do I know, I'm definitly no engineer.
 

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Also, fill out your profile. Youre more likely to get priceless advice and info if you do, otherwise, be prepared for a good dose of sarcasm and BS!
 

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quote:Originally posted by 550Kafe

Also, fill out your profile. Youre more likely to get priceless advice and info if you do, otherwise, be prepared for a good dose of sarcasm and BS!
I'll start with the BS!

So how does it run?
How was the compression?

Leading up to:

Why did you pull the engine before you did any diagnostics?




Ken
 

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Discussion Starter #14
Haven't run it yet! When I bought it the carbs were removed and there was no battery. I need to get a compression gauge to test the compression. The guy that I bought it from mentioned that it has replaced heads and he also gave me the original and a new set of gaskets. I wanted to see for myself what was under the hood so to speak and see if he was BSing me. Looks like he was talking straight, he certainly wasn't asking much for it so I inclined to believe him. I am picking up a gauge this weekend and until then I am going to check the valve gaps, replace the points with the additional ones that came with it and clean up the frame and engine. Then I will remount the engine and do a comp test. I know it's a little backwards, but this is my first time so call it a newb move. I can live with that!
 

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Josh, some info for you....

yeah, the head you have on that engine is not the original TX500 head. It is from a '76- '78 (or '79) XS500. You can tell from the head's cooling fins. In the photo of my TX engine below on the right, you can see the first 4 rows of fins are smaller on the TX head just below the valve cover and the 5th fin goes all the way across. Your later XS head has larger fins and the 5th fin is very different. The '73-'74 TX and '75 XS heads are all two part heads, the '76 and up XS are a single casting. Look at your exhaust ports too, if they are oval, the head is from a '76-'77 motor. If the ports are round, they are from a '78 XS500E (the best heads)

check the serial number on the engine, if it starts with 371 it and matches the vin# on the neck of the frame, it is your original engine with a newer head. ( all TX's and the '75 XS all start with 371) If the number does not match, you have had an engine swap. If the number starts with a 1H2 or 1J3, it is a later XS engine.

Since the head gasket has a bad oil leak and the condition of your points area are so nasty, I would be suspect of the engine condition in general. As many of the early TX heads developed cracks between the exhaust valves, simply having a later head is no indication of anything else with the engine . too bad you pulled the engine before doing any testing......

 

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Discussion Starter #16
The SN does start with 371 and it does match the number on the body. I have the original heads and they have the cracks between the valves as you described. The original heads are 2 piece. I am not sure if the head leak occurred before or after the heads were changed out??? The exhaust ports are oval and look similar in condition to the ones that you have pictured
 

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This weekend I will be checking the valve gaps, put on new gasket and cover. Remount the engine in the frame and check the compression. What else should I test/check to get a complete diagnostic check?
 

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You should try to start it, to see if it has a problem that needs diagnosing. But don't just pop the motor back in the frame and try to start it. Follow the normal procedure for trying to start a long-dead bike:

1. Make sure the ignition wiring is all plugged together, and the battery is fully charged.

2. Change the oil. Inspect the old oil for bits of shrapnel.

2. Make sure the carbs appear to be reasonably clean inside. You have the carbs off the bike already, so go ahead and remove the carb float bowls, the CV piston cover and the CV piston, and the floats, jets, plugs and emulsion tubes. Clean the carb body, and all passages (and everything else) with carb cleaner, carb dip, or ultrasonic, until they look spotless. Reassemble and install carbs.

3. Look inside the fuel tank and see if it looks clean. If the inside of the tank looks badly rusted, set the tank aside for now (you'll do a full tank cleaning later) and rig up a temporary fuel supply. If the inside of the tank looks fairly clean, rinse it out with fresh gas, and pour the gas into a clear glass jar. Look carefully at the gas in the jar; check for flecks of rust, dirt, etc. If the gas is clean, install the tank, and in-line fuel filters, and put a couple gallons of fresh gas in the tank.

4. Make sure fuel flows from the fuel tank to the carb bowls (with no leaks!): turn on the petcocks, remove the carb bowl drain plugs, and see if fuel flows out of drain plug holes.

5. Remove the spark plugs and put a half a teaspoon of oil in each bore.

6. Use the kickstarter to turn the motor over a few times; listen carefully and feel the way kickstarter moves as the engine turns over. Is it stuck? Or does it feel/sound like the engine's innards are properly connected together?

7. If the motor's innards move smoothly and sound/feel intact, and you haven't found any other obvious problems in the previous steps (such as fuel leaks, broken parts, disconnected ignition wires, etc.), go ahead and try turning the motor over with the electric starter (with the sparkplugs out). Any nasty clanking sounds yet? Hold your hand over the spark plug holes. Do you feel compressed air from both cylinders?

8. If everything looks good so far, now you should check for spark. See if you have a nice fat blue spark at the plug tips (ask if you do not know how to do this).

9. If you have good spark, go ahead and install the plugs, turn on the fuel, and try to start the bike. You should have the headers installed (and the mufflers too if they are serviceable).

10. If you get it running, go through the tune-up procedure in your manual (setting ignition timing, setting valve clearances, synching carbs, etc).

A compression test may be necessary if it runs but smokes, or is low on power, shows signs of having a burned valve, etc. If it runs well, and shows no sign of compression loss, a compression test is optional.
 
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