Franken 550

Welp, bad news. Something happened with cylinder #2 and it lost compression. It was always a bit cold blooded and didnt like to run cold but that cylinder finally quit working.

Did a compression test and found it a 25psi with fuel all over the plug/exhaust header. Everything was as it shouldve been (valve lash, timing) so i expected the worst and pulled the motor. I believe most of the issue came from using a kz550 timing advancer and using the TDC mark on that to set timing. When set to TDC on the advancer, the pistons were not at TDC in the bore. Looks to be about 10degrees off on the crank.

I went through all the valves and they were surprisingly decent. After lapping, the seating surfaces were even and nothing leaked when i tested them... *shrug* ill take it.

The piston ring gaps were out of spec and the bores were in good shape but pretty shiny.

I'm going to give it a hone with new rings and hope for the best. Parts will be in tuesday!

Just a quick update here. I received the new valve shims so the head is now ready to go.



I'm still waiting on gasket kit and rings which should be here tomorrow. But I did figure out that it's the crappyish Athena brand kit so I bought an OEM base gasket and will reuse the old headgasket with some copper spray.



I also found a bore gauge set for a good price which was extremely helpful while honing the cylinders. I didn't really trust the caliper as it was only measuring the top lip of the bore which doesn't see any wear. Anyways, after the hone, all the cylinders are at 62.01mm which is a bit out of the standard diameter but well within the 62.10mm service limit. Good enough for me.



Also, I've been using coffee filters for the final prep of the mating surfaces/bores as they dont leave any crap behind and show contaminants super easily. You guys should try em!



Oh and I soaked the carbs in a gas/diesel mix for a couple of days while waiting for parts just to be sure they were clean.

Got it assembled over the weekend ! I ended up using the Athena headgasket but did use the oem base gasket. The timing was a total pain but I got it all set in the end. There was lots of removing and reinstalling cams before I realised I could just wiggle the chain and make it skip at the crank gear to get the exhaust cam on the right link. The 1 and 4th exhaust valves are not open when the cam is set on its mark so the engine can be rotated a bit without damage (the cam as well) .

I'm guessing the exhaust and intake cams were one tooth off before and it must've been enough over time to cause interference or bad seating. Maybe I'll pickup a 650 advancer some time but they're hella expensive. Valves tested ok and is running great right now so I think it'll last. Glad I took the time to replace the valve seals as well.

It started just fine once I figured out that I left the coil pickups unplugged :laugh: Took it for a test drive and all seems ok but the AFRs and carb sync need to be verified. Hilariously, the big issue is the exhaust.... Now that all the cylinders are firing, it's VERY loud. It resonates around 3-4.5k (cruising would be literal hell) and past that is generally loud. My ears ache from an hour of riding and i'm sure other drivers hate me. So i need to do a test with a large straight through packed muffler and see if that packing will be enough or if i need to do baffles.

Oh... and it starts on the first kick in the dead of winter!!! hell yea!

Bit of an update here: I ordered a 650CSR timing advancer so I can double check my cam/ignition timing.

Got the new muffler made. Its totally jank as it was made out of scrap sheet metal that I had laying around but oh well, It sounds great! Its essentially just a large glass pack which has been stuffed with insulation. It makes a nice, deep tone instead of straight pipe scream (dunno how people deal with that?!). I'll probably use a glasspack of some sort on future builds as the sound is great!



Last, I was fed up with the shitty gauge method for carb balancing, so I came up with this lil do-dad.



Just a bunch of vacuum sensors and a microcontroller so I can graph each cylinder as a percent difference from the average of all the sensor values. So, yeah, carb sync is spot on now!

Interesting carb tool. Did you have restrictors in the lines? If not, I wonder if they would smooth the signal enough to make smoother graphs?

That's the beauty of it!! At the fastest refresh rate, without averaging or data manipulation, I could see each cylinder's pulse! This means I can do all the averaging and smoothing in code. At first i just averaged over a time period which seemed to work well, but I figured the percent difference would be the best way to go.

It looks like i'm sync'd within 2% so I think that's pretty good considering that a slight movement of the screwdriver while tightening the nuts would throw it off .5%

If anyone wants the code or schematics etc, I could draw something up. Maybe post in the tools forum?

Yup, that looks like a good candidate for the tool forum.

Welp, shes running a lot better after the 650 advancer was installed. I leaned out the pilot jets a bit too cause it was idling around 13.6 AFR.


Now i'm waiting for the 60mph wind gusts to stop!

I finally dug around in my headlight wiring and figured out why the high beam was always on. The reserve lighting unit doesn't like the LED headlight and thought it failed so it was powering both beams. I removed the module and jumpered the blue and blue/yellow wires (thanks loudhvx)

I don't know how I didn't catch this before but cyl 2 is running super rich even with the fuel adj all the way in. The afr gauge was reading ok so I dunno what happened. This is the same cyl that has the carb with the drilled out fuel adj hole, so no surprise there. I've ordered some 15 and 10 pilot Jets which will hopefully fix the issue. It's running so rich that the cylinder refuses to run at idle and causes the transmission chain to rattle. I've been searching for a vm22 carb body as backup, but no luck yet (if you have one, reply or pm ).

These dang 22 carbs are proving to be a pain!