Author Topic: CB350F trouble  (Read 6031 times)

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Offline flybox1

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Re: CB350F trouble
« Reply #25 on: May 24, 2010, 12:31:43 PM »
with an engine blip, it should come down to <2krpm pretty instantly.  it shouldnt linger up there.
is your choke lever (on left side of carbs when sitting on bike) pressed all the way down whenyour bike is warmed up?

it may be that your slides are still too far open when you idle set screw is out all the way.
suggest setting your idle screw to touching the idle tang thingy, + 1 turn in, and then set your slides with the 1/8" drill bit.  you can do this with your airbox and tank off. this will allow the slides to close hearly all the way when your idle screw is turned out.

really need to do a vac synch to get them dialed in completely.
sounds like you are getting closer, though.
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
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"Knowledge without mileage equals bullsh!t" - Henry Rollins

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Offline Vlad

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Re: CB350F trouble
« Reply #26 on: May 24, 2010, 01:31:02 PM »
I pulled the tank off and re-synced the carbs.

It's a lot better now but still not perfect, idle is close to 2K.

I'm going to have to get them vacuum synced tomorrow or sometime this week.

I rode it around the block, very hesitant at low rpms - but that's expected.

Otherwise, pretty smooth running. If a little clickety clackety from the valve chatter.

Offline Vlad

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Re: CB350F trouble
« Reply #27 on: May 24, 2010, 01:32:32 PM »
On this note,

Anybody in Chicago with the right tools to vacuum sync my carbs?

Preferably someone that works for beer and/or dinner.

I'd rather take this route than $90/hour shop rate (1/2 hour minimum).

Offline Vlad

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Re: CB350F trouble
« Reply #28 on: May 24, 2010, 01:34:01 PM »
One more and I'm going in the shower before work:

Flybox what kind of white do you have on your bike? I wanted to get it done in GM "Diamond White" (the Cadillac Escalade white).

Thank you all for all the help.

Offline flybox1

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Re: CB350F trouble
« Reply #29 on: May 24, 2010, 01:56:54 PM »
set your valves yet? 
what about timing, cam chain adj, and the rest of a 3k mi maintenance?
really should get to those first before doing a vac synch.

1974 chrysler spinnaker white #2033 (got the 1974 paint shop slip from the PO)  ;D
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline Vlad

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Re: CB350F trouble
« Reply #30 on: May 24, 2010, 04:57:42 PM »
set your valves yet? 
what about timing, cam chain adj, and the rest of a 3k mi maintenance?
really should get to those first before doing a vac synch.

I will do that next.

Then a carb sync.

Quote
1974 chrysler spinnaker white #2033 (got the 1974 paint shop slip from the PO)  ;D

Very fancy :D

Offline Vlad

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Re: CB350F trouble
« Reply #31 on: May 25, 2010, 01:07:13 AM »
Quick check-in:

In 5th gear, 4K rpm is 40 mph, 5K is 50, 6K is 60 - or something along those numbers.

Does that make sense? Or are those numbers way off?

Offline CrashBar

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Re: CB350F trouble
« Reply #32 on: May 25, 2010, 01:56:41 AM »
Yes, 6000 RPM is 60MPH indicated (probably more like 55MPH in reality, the speedo runs a little high).

There is no real power below 4K, and they love to spin, so don;t let the RPMs freak you out.
....to trade in these wings on some wheels...

2017.5 BMW R1200GS
1973 CB350F
1978 CB550K
1973 TR5T

Offline flybox1

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Re: CB350F trouble
« Reply #33 on: May 25, 2010, 06:30:52 AM »
set your valves yet? 
what about timing, cam chain adj, and the rest of a 3k mi maintenance?
really should get to those first before doing a vac synch.

I will do that next.

Then a carb sync.

Quote
1974 chrysler spinnaker white #2033 (got the 1974 paint shop slip from the PO)  ;D

Very fancy :D

i'm sure it was fancy at the time.  its in need of a repaint, but the weather is nice and i cant bear to have it down for 2 weeks.

valves and cam chain adjustment will take some, if not all chatter out of your 350F. 
i typically ride around in anywhere from 4500-7500 rpms.  it loves that range.  ;D

your speedo will be off by roughly 10% from what your rpms indicate you should be going.
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline midnightrider

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Re: CB350F trouble
« Reply #34 on: May 25, 2010, 09:42:01 AM »
set your valves yet? 
what about timing, cam chain adj, and the rest of a 3k mi maintenance?
really should get to those first before doing a vac synch.

I will do that next.

Then a carb sync.


i'm sure it was fancy at the time.  its in need of a repaint, but the weather is nice and i cant bear to have it down for 2 weeks.

valves and cam chain adjustment will take some, if not all chatter out of your 350F. 
i typically ride around in anywhere from 4500-7500 rpms.  it loves that range.  ;D

your speedo will be off by roughly 10% from what your rpms indicate you should be going.

+1 Get those valves adjusted first.  It's a pretty easy (but will take you a little while your first time doing it).  You will likely still have some rattle from the cam chain; it's pretty common among these bikes, just gotta adjust that baby.
Enjoy!
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Offline fastbroshi

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Re: CB350F trouble
« Reply #35 on: May 25, 2010, 10:06:01 AM »
  I just rode a 350 not too long ago, pretty smooth little bike.  Like a little gas burning sewing machine.  Pretty popular with the racers. 
Just call me Timmaaaaay!!!

Offline Vlad

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Re: CB350F trouble
« Reply #36 on: May 25, 2010, 04:09:44 PM »
I have to go to Sears to pick up a set of feeler gauges so I can do the valves but in the meantime:

When riding, the front wheel goes clang clang clang clang - or at least I THINK it's the front wheel because the clanging (?!) gets louder when braking.

The front end doesn't wobble and doesn't act in a weird way, just makes clangy noise. It's more noticeable when decelerating while engine braking and/or applying the brake.

What could it be?

Offline fastbroshi

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Re: CB350F trouble
« Reply #37 on: May 25, 2010, 04:17:40 PM »
I have to go to Sears to pick up a set of feeler gauges so I can do the valves but in the meantime:

When riding, the front wheel goes clang clang clang clang - or at least I THINK it's the front wheel because the clanging (?!) gets louder when braking.

The front end doesn't wobble and doesn't act in a weird way, just makes clangy noise. It's more noticeable when decelerating while engine braking and/or applying the brake.

What could it be?

It's your chain, you need to adjust the slack out by moving the rear wheel back.  Get yourself some chain lube.  Do yourself a favor and don't ask what kind, lol.  Make sure you get feelers that go down to .002" (.05 mm), a lot don't. 
Just call me Timmaaaaay!!!

Offline Vlad

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Re: CB350F trouble
« Reply #38 on: May 25, 2010, 05:11:01 PM »
I have to go to Sears to pick up a set of feeler gauges so I can do the valves but in the meantime:

When riding, the front wheel goes clang clang clang clang - or at least I THINK it's the front wheel because the clanging (?!) gets louder when braking.

The front end doesn't wobble and doesn't act in a weird way, just makes clangy noise. It's more noticeable when decelerating while engine braking and/or applying the brake.

What could it be?

It's your chain, you need to adjust the slack out by moving the rear wheel back.  Get yourself some chain lube.  Do yourself a favor and don't ask what kind, lol.  Make sure you get feelers that go down to .002" (.05 mm), a lot don't.  

But I swear it's coming from the front of the bike (I'm thinking the wheel since it gets louder while braking).

I'll take a looksie at the chain just in case.

What lube should I use for the chain?  ;D

Offline flybox1

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Re: CB350F trouble
« Reply #39 on: May 25, 2010, 05:42:44 PM »
check your front spokes.  the spokes aligned in the same direction should 'ping' the same tone.
might be a loose one in the bunch.

..any kind that comes in a can will do.  :P

(Fastbroshi's trying to derail this thread..he's already got his popcorn out lol)
make your chain adjustment with someone sitting on the bike
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline fastbroshi

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Re: CB350F trouble
« Reply #40 on: May 25, 2010, 08:48:55 PM »
check your front spokes.  the spokes aligned in the same direction should 'ping' the same tone.
might be a loose one in the bunch.

..any kind that comes in a can will do.  :P

(Fastbroshi's trying to derail this thread..he's already got his popcorn out lol)
make your chain adjustment with someone sitting on the bike

Haha no seriously I'm not, just wanted to nip that in the bud before someone chimed in "no waxed is betterr, blah blah".  If it were truly a spoke, a pinging would mean a spoke is hitting something.  If it were, it most likely would do it every single time around, no?  Couldn't hurt to give them a once over I guess.

Amsoil is the best!!  :D
Just call me Timmaaaaay!!!

Offline flybox1

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Re: CB350F trouble
« Reply #41 on: May 26, 2010, 06:46:34 AM »
 :D amsoil...lol
a really loose spoke might cause that clicking noise as it shifts under load, but it is always good to 'ping' them to find ones REALLY loose and adjust them while you true the wheel.

every few hundred mi I use *(^&$@#%$@#%  :D spray can chain lube.  ride your bike a bit to get the chain warm.  put it on its centerstand and hand spin the rear while applying the lube.  WITHOUT the bike running, i gently wipe off any drips to prevent excess from being thrown everywhere. dont want to lose any fingers  :P
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline Vlad

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Re: CB350F trouble
« Reply #42 on: May 30, 2010, 11:43:35 PM »
Update,

I got the feeler gauge from Sears, did a valve adjustment job but now the bike bogs down between 2 - 3K rpm and pops (backfires?) out of cylinder 4.

I obviously did a poor job and I'll have to redo it but I'm having issues with 2 things:

1 - the valve adjustment screws have a square head. What do I use to drive them? (please don't say needlenose pliers / Leatherman).

2 - how can I be sure I'm at TDC with the right pistons at the right point in the power cycle? What's a sure way to know?

P.S. On the upside, the idle is MUCH smoother now.

Offline fastbroshi

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Re: CB350F trouble
« Reply #43 on: May 31, 2010, 01:11:02 AM »
   Okay so it needed a valve adjustment and that improved things.  Back to square one.  Your bike won't idle.  It's popping out of one of the pipes (4 into 4?).   Sometimes the air bleed screws on the carbs need to be adjusted because of someone's ignorant fiddling, but I don't think that's the case here.   I don't think the bike would neglect to hold an idle even if they were all grossly out of adjustment.
   I think it's carb clobberin' time for you bud.  If you've never had them off and don't know their condition, it's a good chance to get in there and get more familiar with them.
   Check the FAQ on tips for doing it, it's not as hard as you think. 
Just call me Timmaaaaay!!!

Offline Vlad

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Re: CB350F trouble
« Reply #44 on: May 31, 2010, 12:39:08 PM »
Update:

I got a 9 wrench from sears and a duckbilled plier and redid the valve adjustment job.

As a result, the bike starts up right away and idles buttery smooth. It would take me a few tries with the starter and/or a few kicks to get her going but now it's instantaneous and awesome.

It also revs smoother and just overall sounds like a happier engine.

But now there's another issue: increased valve chatter.

Is it normal?

Offline bender01

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Re: CB350F trouble
« Reply #45 on: May 31, 2010, 06:14:30 PM »
http://www.z1enterprises.com/detail.aspx?ID=2870
 This will help! Its worth it! I dont have a 350f any more but I think the tools fit older 750s? too. You will be tuning that 350 over and over trying to get a little more out of it. It will make life easier.
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So, the strategy is to lie to people you are asking for help?

I think I'll be busy going for a ride.

Good luck!
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Offline Vlad

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Re: CB350F trouble
« Reply #46 on: May 31, 2010, 10:07:33 PM »
http://www.z1enterprises.com/detail.aspx?ID=2870
 This will help! Its worth it! I dont have a 350f any more but I think the tools fit older 750s? too. You will be tuning that 350 over and over trying to get a little more out of it. It will make life easier.

omg this would've saved me so much annoyance and aggravation !! But the wrench/duckbilled plier method works, I'm vouching for it.

I just took the bike out on Lake Shore Drive, did an Irving Park Rd to Loyola run.

It is absolutely incredible how different it runs. Like night and day different.

Next stop is points & ignition, I just have to find someone with a strobe light.

I think I can get even more out of her once all these procedures are done.