Topic: '72 cb350k4 mild custom

[johnspeck]

hello all.
been lurking here for a long time.  thought you might like to see the progress on my cb350 redo.

i picked the bike up off a friend, it was his girlfriend's (she wanted something a little bigger, and i'm 5'8", 150 pounds...perfect for me)...it's been ridden and maintained for the past 8 years.  it was clean, decent running shape, and cheap.

i went down the list once i got the bike, making sure everything was a-ok.

sadly, the compression was low, most notably the right cylinder.  60 right, 120 left.  a squirt of oil brought the compression up to 150.  we're thinking rings.
it also had a weeping head gasket.

since i'm an obsessive-compulsive bike geek, of course i have to tear this thing down and give it the full once-over.

i started the work about three weeks ago.  here's the progress so far...


this is the day i brought it over to a mechanic pal to help with what tools and space i don't have.





it's in such nice shape, i don't want to cafe it out, rather a 'mild custom', compared to bone stock.

we removed the engine, tore the top end down, and waited for parts to arrive.  in the meantime, i've been cleaning up everything i can get a rag or toothbrush on.






blasted the barrels and cylinder head cover clean.

the base and cylinder head gaskets were practically welded on, that was probably the worst step so far.  took a LOT of time and patience to get things off without gouging the mating surfaces.

ended up getting everything clean.  extracted a broken exhaust stud.  removed the battery tray and ground off the tube attaching the stock air filters.  blasted it clean, repainted and ready to go.


honed the cylinders, new cam chain tensioner bits, new rings, valve job.  cleaned up the engine and reassembled.
just started polishing it a bit to see how it would look.  ended up really nice for doing it by hand.


just started ^
not bad for first round of hand-polishing? v






the old tensioner wheels were pretty chewed up.




some parts came in the mail.  brand new points plate/assembly, hondaman ignition, stator and rectifier/regulator from rick's.


more parts!  hagon shocks spec'ed to the bike/load, really nice side covers, new chain.


i have the wheels off, getting ready to do the front end.




next step is to finish assembling the engine (install points assembly, stator, etc.)  waiting on stainless fasteners.  i have a brand new set of mikuni vm30's, k&n filters, and new throttle cable coming.

i got an email from hondaman, telling me the low compression (since the old rings looked fine) is due to the cylinders warping oval, a common problem with these little twins.  around 5000 miles, the metals heat and warp.  this is easily cured with an overbore and new pistons...sadly, it's not in the budget currently.  hopefully i don't start burning oil and losing compression in a few thousand miles, or it's gonna be another tear down sooner than later.

tapered steering bearings and front end cleaning are the other projects for this week.
we're going to blast the top triple tree down to bare metal and polish, along with the various hardware.  clean the fork assemblies and change the oil, preload the springs a half inch.  install euro bars (gotta route the wiring, ugh!)

i cleaned up and polished my wheels over the weekend.  i'll be dropping those off to get a spoke replaced, true the wheels, then install and balance the new avon roadrunners.

basically, i'm hoping by next monday, it's ready for the inspection to get it on the road!

i'll update with new pics, etc., after i get back home (out of town working until thursday, the wait is killing me!)

[hoodellyhoo]

Now that's what I call a first post! Great looing bike. Glad to know it won't be getting the cafe treatment, it's just too pretty. I ran into one just like it at the local burger joint the other day.

[kghost]

Nice clean bike

[johnspeck]

Thanks!
Got a call today from my pal, he's working on it while I'm out of town...stator is installed, need to scribe a timing mark.  Strange the new stator doesn't have one, even though it's made specifically for this bike.

The engine is back in the frame.

I'll post more pics when I get home later this week.

[BeSeeingYou]

Is that your 76 XS650 in the background?  Looks to be in nice shape.

[johnspeck]

Is that your 76 XS650 in the background?  Looks to be in nice shape.

it's chris' (affectionately known as the limey), the guy who's helping me with mine.  all original, perfect running shape.  he just cleaned it all up and tuned it.  pics don't do it justice.

[johnspeck]

got another batch of parts in the mail i was waiting for.  tapered steering bearings, stainless fasteners for the engine, and euro bars.





also, while i was out of town for work, i stopped in a great used bookstore in portland, OR., called powell's.
i found the original shop manual for the bike!  i have it saved to my computer, but a hardcopy is way beyond cool, especially for 12 bucks!




i'm headed to the limey's place today, we'll get the front end off and replace the steering bearings, go through the forks internals and make sure all is well, and clean up the top triple tree and assorted hardware.  also, drill the bars and route the wiring.  not looking forward to that!

does anyone have any recommendations for wheel truing in the austin area?  i have one bent spoke on the front wheel, and i'd like to replace it, true the wheels, mount and balance the new tires.

tomorrow, i should see the carbs, filters, and throttle cable.

we're really close!

[johnspeck]

new carbs!





they look thirsty.
sadly, the filters i ordered are the wrong size.  hard to find k&n regular round filters to fit.


spent a l-o-o-o-n-g time polishing the exhaust, to get some of the gunk off.  looks pretty good, compared to where it was.



i'm thinking of a stainless exhaust in the future, so this is fine for now.

i also cleaned up the wheels and got the tires mounted and balanced.



new avon roadrunners, tubes and rim strips.

[Ecosse]

wow! i just discovered this thread and have to say kudos to ya! i really like the jewel like smaller honda, and admires twins.

i respect the direction you chose as well; nothing against hot rod bikes but it looks like you're preserving the special character of the cb here. extra points for the manual too.

those carbs are pretty! and if ya can, get some pix of your pal's bike in 'other bikes.' drool....

great work so far. 





i dig miata's!

[johnspeck]

wow! i just discovered this thread and have to say kudos to ya! i really like the jewel like smaller honda, and admires twins.

i respect the direction you chose as well; nothing against hot rod bikes but it looks like you're preserving the special character of the cb here. extra points for the manual too.

those carbs are pretty! and if ya can, get some pix of your pal's bike in 'other bikes.' drool....

great work so far. 





i dig miata's!

thanks!

made some progress today...

steering bearings in, triple tree blasted clean and back on, handlebars are wired and mounted.

new chain is on.  wheels are mounted, brakes sorted, clutch adjusted.

stainless fasteners utilized on engine.
carbs mounted.  exhaust mounted.

still need to:
wire/install hondaman ignition
sort neutral switch
install throttle cable/assembly

need to pick up:
radiator hose (to mount the filters to the carbs)
coupla' odds and ends of hardware, like the clutch adjustment lock nut
oil
fork oil
chain lube
plugs
epoxy to affix one of the 350 badges on the side cover

still need to:
get it tuned

transfer title
get insured (tonight)
get inspected
get registered/plated
get riding.


soooooooo close!


pics:

deglazing the rear brake


new points assembly and stator installed


blasted




battery area a LOT cleaner, new rectifier/regulator installed under the tray

[johnspeck]

[Frankenkit]

...subscribed so I can watch.   She's beautiful!

[johnspeck]

yesterday was equally exhilarating and mega-frustrating!


got oil in it, and fixed a teeny weep (improperly installed gasket).
went through the checklist, and it fired up literally right away.  once we timed the bike, and adjusted and sync'ed the carbs, the bike would idle steadily at 400 rpm!
checked the charging system, and it's putting out almost 14v at 2000 rpm, over 12 at idle.  my pal was really impressed.
the hondaman ignition was sparking fine.

took it for a test spin, and first thing i noticed was the steering bearings needed to be tightened.  took it back and took care of that, then back out again.
i noticed the revs start to stumble when it gets up near 5000 rpm, so i brought it back and had the limey take it for a test ride.

he comes back and says, let's try new jets.  so we pull the main jets, which are 200's in my new mikuni vm30's (supposedly set up for my stock bike with k&n's).  we try a 220, then a 190, to see if anything seems better.  nothing.  we go back to 200.

we know the timing is spot on, points gap is set, plugs, throttle cables, sync'ed, etc.  the thing idles perfect, and will rev up smooth sitting on the centerstand.  under load, it acts different.

i'm waiting to hear from the guy i bought the carbs from, what his baseline set-up for the carbs was.

my only other thought is the exhaust.  the right side muffler has something loose and rattling, but we can't get the muffler off the header without cutting something.  the left muffler has the end cap partly rotted away, so it's much less baffled.

i've ordered shorty reverse megaphone mufflers, which i think will look a little cooler, as well as solve my muffling problem.

today, we'll get the mufflers off, and see if it runs with just the headers.  that will hopefully tell us whether the exhaust was an issue at all.
we still need to get the jetting dialed in.

other than that, the bike is great!  compression is really good, it's getting oil, charging...
the ride has improved on the brief testing i've done.  the front fork oil still needs to be changed, but that's something i can do on my own time.

some more pics from yesterday:

got the ignition sorted




tank back on!


needs some cleaning and washing, but we were in tuning mode.  still, it's looking a lot better!

[johnspeck]

update:
changing mains to 190's (smallest size the limey had), and dropping the needle as far as it will go, the bike will now pull hard to 9000 rpm. 
tomorrow, i'll pick up some smaller size jets (140-180), and go from there.
insurance today, and inspection friday.
there's a bike show this weekend, ski shores.  looking forward to seeing some cool stuff!

[Ecosse]

update:
changing mains to 190's (smallest size the limey had), and dropping the needle as far as it will go, the bike will now pull hard to 9000 rpm. 
tomorrow, i'll pick up some smaller size jets (140-180), and go from there.
insurance today, and inspection friday.
there's a bike show this weekend, ski shores.  looking forward to seeing some cool stuff!

 

sounds like the carbs were tuned for open element filters and freer exhaust? are you running oem air box?

[johnspeck]

update:
changing mains to 190's (smallest size the limey had), and dropping the needle as far as it will go, the bike will now pull hard to 9000 rpm. 
tomorrow, i'll pick up some smaller size jets (140-180), and go from there.
insurance today, and inspection friday.
there's a bike show this weekend, ski shores.  looking forward to seeing some cool stuff!

 

sounds like the carbs were tuned for open element filters and freer exhaust? are you running oem air box?

no, stock side covers, but with k&n filters located centered behind them, with a length of 2.25" ID hose connecting them.

i bought the filters from the carb vendor at the same time as the carbs, so he knew the specs to set them up for the bike.

like i said, the idle is good, and now we're getting closer.  i need to get it at least close, so i can ride it enough to actually take a plug reading.

can't jet the bike properly until the mufflers get here...just waiting to get the shipment info.

[johnspeck]

IT LIVES!!!!

!!!!!!!!!!!!!!!


oh yeah!  bike is back!

installed 150 mains, 6F4 needle with the clip in the highest position, 25 pilot.  it's good, plugs are reading better.
need to mess with needle size.
still, it runs hard.  pulls, goes fast, stops pretty fast for an old drum bike.  the limey thinks they're the tightest drums he's ridden in recent memory.
tomorrow, i change the fork oil for something thicker, and possibly preload the springs.  you definitely notice the soft front end with the stiff shocks.
i'll ride it tomorrow, re-torque the cylinder head bolts in the afternoon, and attach the crossover tube for the gas tank.

the new mufflers made ALL the difference!  they really complete the look of the bike.  i still need to polish up some stuff, and clean up the seat, etc., but it's looking pretty nice so far!

some pics:









i'll take some better pics tomorrow after it's plated and legal.

here's some detail of my carb/filter set-up behind the side covers:





fits perfectly behind the side cover with no mods:





more tomorrow!
thanks SOHC4forum!

[Ecosse]

looks great! the air filters turned out well too.


congrats.

[johnspeck]

tried some much smaller jets per a recommendation here in the 'other bikes' section...didn't work.  still runs best so far with 150 main jets, needle clips at the top.

repacked the mufflers with new baffling, the tissue paper that comes stock from jc whitney was gone in a day, and the sound was so loud, it was like being at the racetrack.  not ideal when you're trying to cruise 40 mph through town in the morning.

the new baffling is much better sounding, still loud, but not so frickin' obnoxious.

changed the fork oil today, filled it with 15 wt, much much better front end.  it's STIFF, but i don't mind that, way better than the diving front end anytime i looked at the front brake.

it's coming along nicely!

[johnspeck]

update 13 july:

just got back from a long work trip, so i've been able to spend a little time dialing it in.

when we got the bike back on the road, one thing i definitely noticed was the front-end twitchiness.  we had raised the fork tubes about 3/8" in the triple trees.  at speed on the highway, the bike wasn't as stable as i'd want, and i didn't feel like the steering was too slow, so i lowered the tubes to flush, per stock settings.

the steering stabilized nicely, the overall feel of the bike seems much better, at all speeds.

most importantly, i really need to get the carbs jetted properly.
the bike has been running rich since i streeted it.  i've gone down progressively in main jet size, but per my other thread, i need to get into the needle jet and needle as well.

the carbs were bought 'set up' for my bike, but the sizes/parts were off.  i need new needle jets/needles, and even smaller mains than i have now.
i'm ordering the parts once they're back in stock at carb warehouse.

other than that, the only other thing i notice is the battery.  the heat here, as well as the charging system actually working on the bike, are causing the battery the give off some gas.
it's not sealed, and the overflow tube is spilling down onto my right muffler mounting bracket when i'm riding.  i need either a small overflow collector, or a longer tube.  eventually, a gel battery.

things to do in the future:
gel battery
have brakes re-done by vintage brake for serious drum stopping
halogen headlight conversion
thinking about some cut down fenders, maybe aluminum, with a smaller tail-light?
different seat, lower rise with small bump-stop?
emulators and new springs for front end
maybe some day, shouldered aluminum rims and stainless spokes

that, and clean up the little things...replace worn/pitted hardware, repaint/refurb gauges and other assorted small parts, general clean up and polish.

once the tuning is sorted, it should GO.  it's already pretty quick running way too rich.

[poomwah]

I just wanted to chime in and tell you that I think you did an absolutely AMAZING job

[wingman]

I agree with the others - nice bike!  Great job so far!

[johnspeck]

I just wanted to chime in and tell you that I think you did an absolutely AMAZING job

thanks!
it wouldn't have been possible without the assistance of chris, the limey.  he's a good wrench here in town, and he's got the shop space, tools and expertise.
i had him help with whatever i couldn't do myself.  having just moved, i'd lost my network of detroit gearhead pals.

now that the big stuff on the bike is out of the way, i can see about setting up my garage and getting what tools i need.

[johnspeck]

update:

spent the past few days trying to find the proper needle jets, needles, and mains for my carbs.
mains aren't much of a problem, but nothing locally.  ordering the needle jets and needles has proved to be much harder.
sudco is back ordered for at least a month, and carbs parts warehouse is backordered 90 days on the needle jets, the needles have been on order for 6 months!
the 176 series just aren't very popular.
finally, a guy at carb parts warehouse found a pair (exactly what i needed) that weren't in inventory.

so, i've got proper needle jets for the bike in one size bigger, on the way.  i'll be using my needles (6F4) for now, along with slightly smaller mains (#125's to start, down from #140's).

also noticed a slight weep from the head gasket, so i removed the upper motor mount and re-torqued the head studs to 14.5 ft-lbs in the proper pattern.

spent the rest of the afternoon polishing aluminum with my new dremel.  got the left side engine covers pretty much done.  right side tomorrow.
also used the dremel to clean up some fouled plugs (with the nylon bristle brush attachment).

i'll get the carbs off in the next day or two, for the jet swaps.

[hkelley]

i've ordered shorty reverse megaphone mufflers, which i think will look a little cooler, as well as solve my muffling problem.

today, we'll get the mufflers off, and see if it runs with just the headers.  that will hopefully tell us whether the exhaust was an issue at all.

Beautiful work!  I'm trying something a bit less ambitious with mine (for now) but do need to address the same muffler situation you had.

What did you do to separate the mufflers from the headers?  Were they spot welded or mechanically fastened? I haven't begun disassembly so I'm still trying to figure out if this will be a knife or a gun fight.