1980 Rootbeer Bobber

Small update: received most of my OEM engine seals yesterday along with some progressive fork springs. Need to order one of Hugh's 2" lowering kits for the forks so I can start rebuilding those and shaving the tubes. I'll likely run a left front brake so I can use the other brembo on the rear caliper.

Did some soda blasting yesterday, got my old BS34's, PWK's and the EX500 carbs all blasted up. Need to finish cleaning them up in the ultrasonic cleaner, then I'll start sourcing some replacement gaskets, seals and other hard parts, probably JBM boots for the BS and EX carbs. Also posted up a sale thread for the BS and PWK carbs, they'll be rebuilt correctly, so check it out if interested.

Mounted the 19" conversion to the wheel and have them primered, but it's been so cold I can't paint anything.

Ordered a 5th OD from a member on here as well.

Also nearly finished with my port cleanup. removed a little material here and there, but didn't get too aggressive. still need to do the final polish on the exhaust ports.

finally need to start cleaning up the fins on the cylinder and head. I'm going to try to clean up all the welding flash and make everything appear as smooth as I can before painting. Should look a little nicer, especially with the polished edges.
 
Shaving my front forks down is one of my to do items. I have all my new seals and springs but don't have the necessary tools to take them apart and put them back together. There are some great how to's, to do it on the form, gotta make some tools to do it.

Keep the update coming, like to hear what your doing.
 
Well picked up some tools for the fork rebuild. still need to order hugs lowering kit. Just ordered some parts for my EX carbs too, then I'll put those back together.

Also debating on whether or not to weld the crank up through Hugh. I'm leaning pretty heavily on yes, but it's a good chunk of change for me now (have to pay for wedding and wedding band here very soon) and $300 isn't chump change for me after the holidays. I'm trying to sell the PWK's and my old carbs, which will foot the bill for most of the crank rebuild.

So since I'm not doing much extra oomph with the motor, any thoughts regarding the crank work? Keeping it 360 firing order. From everything I've read it seems like its a great thing to do to prevent anything wonky from happening down the line. Thoughts???
 
I saw that thread awhile back, but still didn't get a warm fuzzy either way. I haven't done a full inspection of the crank, but my initial measurements put it within spec. I mean I won't be flogging the motor all the time, but I would like peace of mind if I'm keeping in the power band or hanging around at a higher RPM...

Still can't decide if it's worth it or not!!!

If I want to scare the s**t out of myself, then I'll just go ride my VTR hard, haha!
 
If you plan on full throttle runs to redline or are used to higher horsepower bikes yes I feel welding the crank is money well spent. If you don't go hammer down it's probably not needed. I have a couple cranks that need it done.....
 
wannabridin said:
I saw that thread awhile back, but still didn't get a warm fuzzy either way. I haven't done a full inspection of the crank, but my initial measurements put it within spec. I mean I won't be flogging the motor all the time, but I would like peace of mind if I'm keeping in the power band or hanging around at a higher RPM...

Still can't decide if it's worth it or not!!!

If I want to scare the s**t out of myself, then I'll just go ride my VTR hard, haha!
Click to expand...

Welding the crank is money well spent.
You don't want to find what I found
 
ouch, that would be a bummer!! My inspections show it's in good shape, but I think i'm just going to do it for peace of mind. That way I get a full inspection and I don't have to worry about anything for quite some time.

Now someone please buy my PWK's, I'll give you a good deal, help fund the crank!!
 
If the crank is in good shape and hasn't walked it probably won't need welding. If abused exceeding redline causes crank problems. I've been running an unwelded crank no problem with it walking.
 
you run an unwelded crank with all those go-fast goodies? How aggressively do you ride and how much high-RPM do you see?

I don't know the history of the bike before I got it, as it had been sitting for many years and changed hands a few times.
 
I have run the bike pretty hard over the years. Most of the time I use 7000 RPM as a shift point. I have had the motor over 8000 rpms more than once although I don't make a habit exceeding the red line 7500 rpms. I have over 20000 miles on the motor.
 
A lot of cranks are welded unnecessarily my opinion. The Yamaha 650 has always had a good reputation for having good bottom end. A few bad cranks and now welding it is a must do. Even in carbons worst case scenario the crank can be repressed with a new pin. If it presses at the proper tonnage no welding is required. Welding is another option for a loose pin.
 
scabber said:
A lot of cranks are welded unnecessarily my opinion. The Yamaha 650 has always had a good reputation for having good bottom end. A few bad cranks and now welding it is a must do. Even in carbons worst case scenario the crank can be repressed with a new pin. If it presses at the proper tonnage no welding is required. Welding is another option for a loose pin.
Click to expand...

Glad to here someone else singing this tune. Be saying this for a long time.

Another way for piece of mind + welding without destroying the crank is to spot weld in 2 or 3 places just to strengthen.

Another of Hugh's popular misconception believed and repeated by the masses, just like he states about the throwaway bad XS650 charging system.
 
measured the crank more accurately last night and the little end is well within spec, but I can get an .024" feeler gauge between the big end and the counterweight. Thoughts on this??

Inspecting the little ends of the rods didn't warrant any useful information, so I need to get the flashlight out and check for how much copper is remaining. I didn't notice any gouges, but I also don't recall seeing a bunch of copper color either, so fingers crossed they're in good shape. Thoughts for what to be looking for specifically?

I did notice that the pins did not sit perfectly flush with the counterweights on each end of the crank. How deep should the pins set inside here, or is this a sign of the crank walking starting to walk away? There is no scoring on the engine cases or counterweights, so if it is walking, then it hasn't pushed out too far yet.

Thanks again guys.
 
Last edited:
Interestingly, the manuals show that the bigend side play should be:

0.012" - 0.024" -- for the 256 and early 447 -00 cranks
0.006" - 0.016" -- for the later 447 -01 cranks (starting with XS650E???)

In both situations, the manuals recommend that if the bigend side play is suspect, that the flywheel assembled widths, and overall assembled width, should be checked...
 

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