Saving a 1980 750 twin.

getting a move on this. Engine is going back together! I sent the whole crank/piston assembly out to be balanced, and i thought they would remove the crank oil gallery plugs and clean them but they did not. I cleaned them as well as i could without removing the plugs, then got a nagging feeling and decided to dremel out the plug screws. Im glad I did because all that black shit was in the crank oil gallerys still. I didnt have a good punch to stake the gallery plugs with so my buddy suggested i tack the screws in with silicon bronze. The bottom end is assembled with new bearings, new cam chain and APE HD studs. I honed the small end of the connecting rods with a 320grit brush hone to remove the glaze. they haave a nice cross-hatch now. It specfically says in the manual "DO NOT REUSE CONNECTING ROD BOLTS" but after talking to the dudes at Falicon Cranks they said it would be fine. I'm waiting on a buret so I can measure the piston dome of these custom pistons so I can determine the new compression ratio.

Nice work Doc, have you weighed your pistons?

The custom pistons are 310g the stock are 330g. Falicon balanced the whole piston assembly with the crank so this thing should be super smooth.

Cool, smooth is good ,
when I did mine I found the number 3 piston was 3.7 grams heavy, I evened them out with a small ball grinder, a little here a little there.
Weighed the wrist pins but didn't have the chance to weigh the arms, it's great you did

Nice job,
If you do decide to look for new bolts I woulld call ARP bolts
They are the best I know of
Dave

I found a set of connecting rod bolts for a Mitsubishi Evo that ARP sells that i believe would work, however the guys at Falicon, told me it wasnt worth the trouble unless the bolts I have had been torqued many times. I used a spare set of bolts for torquing when I was measuring the journals for new bearings.

Finally some updates here. I took a little break and saved up for some goodies. RS34 carbs all the way from Germany, and a custom grind from Web camshafts!

I ended up decking the head .050". that , combined with the higher compression Venolia pistons, puts static compression at 10.6/1

WOW!

leon

I slotted a second set of cam sprockets properly on the mill because my original job that i did with the file was pretty rough and i wasn't happy with it. I also finished machining the starter clutch. I thought it would be tougher and need to be ground but a carbide cut it just fine.

I have been screwing around with my tool setup to time these cams. A lot of trial and error to get make a feeler that can touch the tappet AND not get in the way of the cam AND go that deep into the head, finally got it right only to break my dial indicator! I then borrowed a friends dial indicator only to break my tool holder! I was getting super irritated with my cheapy Chinese dial indicator setup anyway, I just couldn't get consistent numbers with it here for some reason. I did what any sensible human does when they get pissed at their tools and splurged. I got a nice Mitutoyo drop dial and a NOGA magnetic base. Ive never had so much trouble timing a cam.

TLDR; I don't want a pickle, i just want to ride my motor-sickle

i love my NOGA base!

leon

DoctoRot wrote:
I have been screwing around with my tool setup to time these cams. A lot of trial and error to get make a feeler that can touch the tappet AND not get in the way of the cam AND go that deep into the head, finally got it right only to break my dial indicator! I then borrowed a friends dial indicator only to break my tool holder! I was getting super irritated with my cheapy Chinese dial indicator setup anyway, I just couldn't get consistent numbers with it here for some reason. I did what any sensible human does when they get pissed at their tools and splurged. I got a nice Mitutoyo drop dial and a NOGA magnetic base. Ive never had so much trouble timing a cam.

I have the luck to get a good set of analog and digital dial indicator too.
Got a set of Mitutoyo drop dials for a tip that have must be renovation for the ISO 9001 certification (European Quality Standard) out of my Company workplace.

The new tool setup is soooo much better, I can zero the dial in 5 seconds as opposed to 5 minutes. The adjustability and rigidity is much better as well. However, I am still getting a small bit of variation on the degrees.

The indicated degrees will fluctuate +/- half a degree on my target, despite the dial coming back to zero every time. This means the lobe center can be as much as 1 degree off target. I have tried many things to try and tighten it up and nothing has removed this. I checked to see if the feeler was dragging at all and it clears everything completely. I called Web Camshafts up and they thought it could be variations in the cam chain or the OEM style spring cam chain tensioner. The cam chain is brand new, so im scratching my head. Right now the cams are very close to where they need to be, but they're not perfect.

After I got the cams timed I clayed the pistons to make sure there weren't any problems. You can see in my tool setup I cut off most of a spare cam cover so i could access the cam sprocket bolts without moving my tool setup. this made dialing in the timing much easier.

Any suggestions on what I could look at to remove the small degree variations? I'm stumped.