My stock '75

[mseriously]

Starting this thread for ease of keeping track of things.

I bought a stocker that's in pretty good shape. Carbs look like BS38 at first glance, original ignition and wiring throughout, original gauge clusters and controls...all of it looks good and stock. It ran pretty well when I bought it but had a few "dead spots" in the rpm range. Acted like it just needed some fine tuning. It'd been sitting for a few months but apparently was tuned/timed/carbs cleaned/cam chain adjusted and running like a top at the beginning of the riding season.

Only thing not stock is the shorty mufflers and pod filters in place of the stock airbox. (aside from front fender being from another model)

My thinking was this is the reason it's not running so well right now...I immediately drained the gas and put new fuel in it. Gas smelled old, and this is usually where I start with old bikes/cars anyway. The bike woke up. Idled well, pulled through the rpm range. Ran smooth. I was surprised.

Not for long. This only lasted for a few 30 mile rides.

Now the left side petcock is leaking. Bike is now stumbling and you can't open up throttle without it bogging down. Bike only tops out at 45mph.

So here's what I'm thinking: rebuild petcocks, replace inline fuel filters, fuel line, disassemble carbs and clean, check float height, reassemble.

I'm also wanting to replace the pods with uni foam filters and replace the shorty exhaust with commando's or something closer to stock pipe length. Question is, should I get it running in it's current configuration? Or should I do it all in one fell swoop?

Let me know what you think of my plan of action...suggestions welcome. Thanks.

 

[mseriously]

Here's a pic

 

[nj1639]

I'd fine tune it with the Uni's and longer exhaust on.

 

[mseriously]

Welp. Whole slew of parts ordered. Gonna try the commando's after looking at a few threads...rebuilding the petcocks, new fuel lines, new fuel filters in petcock, new inline fuel filters and uni foam air filters and a carb cleaning session. I'm sure I'll be back with questions and pictures...

 

[650Skull]

Have a look at the advance weights and check for spring snap back. Won't do an harm to dismantle and service them with a lithium grease, in saying this the advance rod should be checked and greased as well.

 

[59Tebo]

SWEET!!! IMO the '75 was the sharpest looking paint scheme of them all...
My "Basketcase" needs all new plumbing and petcocks rebuilt. A possible side effect of E10 (or higher in some places) gasohol. That stuff just eats the rubber parts. I don't know how much the back-pressure is going to change with new mufflers, but Unipods will make a huge difference in performance.
And check those tire date codes. No matter what they look like, they're only good for 5-6 years, tops. Not a gamble I'd take. Best of luck!

 

[5twins]

If original, I like to replace the plug caps and wires too. Yours look original from what I can see. At the very least, trim a little off each end of the plug wires to get to some fresh wire. I like to go a step further when doing up the wire ends. I trim about 1/8" of insulation off and fan the strands of the wire out like so .....

This insures a good connection and contact when I stick the wire back in the coil and/or mount the plug cap. And speaking of plug caps, test yours while they're off. They can go bad. Their resistance begins to climb and eventually that will start choking off the spark. The stock caps have a rather odd rating of 8 or 9K ohms. Most of us replace them with NGK 5K ohm caps, the LB05F. Get the "F" type, not the "E". They snap onto the plug more positively .....

You'll also notice a rubber protection sleeve covering nearly the entire length of the old plug wire. A bit of protection is beneficial where the wire exits from under the tank, but you don't need the whole thing covered. I remove the sleeve from one of the old wires, cut it in half, and use those shorter pieces on each of the new wires .....

 

[bluesman650]

SWEET!!! IMO the '75 was the sharpest looking paint scheme of them all...
My "Basketcase" needs all new plumbing and petcocks rebuilt. A possible side effect of E10 (or higher in some places) gasohol. That stuff just eats the rubber parts. I don't know how much the back-pressure is going to change with new mufflers, but Unipods will make a huge difference in performance.
And check those tire date codes. No matter what they look like, they're only good for 5-6 years, tops. Not a gamble I'd take. Best of luck!

I agree on the paint scheme. I bought my '75 new and still love it. It has been reliable and fun to ride. I still have points ignition and it will start with one kick.if tuned properly. Please don't repaint the tin. You have a very good looking tank. They are hard to find in that condition and if you do you will pay dearly!