Topic: What should I do? (CB350F Bobber)

[altf4]

Hey guys, I have a 73 CB350F custom bobber. I just replaced the float bowl on one of the carbs (had a vertical hairline crack in the overflow tube, or whatever you call it). It runs ok, i guess, but i really have nothing to compare it to. You can see it has straight 2" exhaust (no baffles), pods for air filters. It also has, from what I can tell, a leaky head gasket. It is seeping a little oil out of the sides of the head.

Is the head gasket easy to do? A local shop (who has an unbelievable collection of these vintage bikes and an excellent service record) will do the gasket for $200 + gasket kit.

As far as getting it to run better (carbs), what do you suggest? Anything I can do myself?

Thanks,

BTW - the pics below are just so you can get a look at the setup on the bike....

donny (noobie)

[Cvillechopper]

That's a nice looking bike. 
$200 doesn't sound unreasonable for the labor to replace the head gasket.  Do you know any history on the engine.  Does it have an oversize bore/piston kit in it?  Have teh carbs been re-jetted for the pods and open pipes?  The performance will be $h!tty if you don't re-jet when you go to pods and open pipes.

The head gasket wouldn't be very hard to do if you take your time and get the manual.  It can be done in the frame (big help) and will allow you to learn more about the machine.  There are plenty of folks on here that can help you through it.

Good luck.

James

[Badger 5]

Just a little drool.  Great looking bike.

[altf4]

I did see the donor bike that the motor came off of, it had about 8500 miles on it. The carbs were cleaned, but not rejetted, atleast I dont think it was. When I took the float bowl off I had to replace the main ject o-ring, and if i recall correctly, it had a 95 imprinted on it. I'm not sure if this is stock for this bike or not, though.

BTW - what would you reccommend for rejetting? I am around 800-900ft above sea level. (Ohio, USA)

I also know that nothing has been done to the motor, other than painted black. And I would like to learn more about the motor, so maybe this is something i can tackle.

Thanks

[goon 1492]

man that is a sexy lookin beast, maxxis makes whitewall front tires and matching rear too if you want white on the front and rear. Then yuo can get "the look" fron people as yu drive by. Don't be shy to do carb. searches on this forum you will find more than your looking for. you'll want to make sure you know what jets you got in the carbs it will help tell you alot when tuning.

[Cvillechopper]

Real basic theory is that the jets from the factory are sized to provide a set amount of fuel given a certain level of restriction from the air filter and back pressure from the exhaust.  When you put pods on you are reducing the restriction (lowering the suction on that pulls fuel through the jets).  Solution, larger jet to keep the same air/fuel mixture.  Same idea with pipes, only not as drastic a difference (I think).

Those sound like the original jets.  Check your plugs to see if you're running lean.  Like goon said, don't be afraid.  Spend some time with the search function and you'll quickly become familiar with the basics of carb work.  From there you can start monkeying around and get that bike runing like it should.

Good luck.

[JLeather]

I think you need to sell it to me.  That's your best bet.

Seriously, though, it's a great bike.  I don't know about the CB350F, but on the 750s you can get a little oil out of the head when the rubber buttons under the cam-holders go bad.  The oil leaks under the cam holders and travels along the fins and drips out looking like a headgasket, but not.  $200 ain't a bad price in parts/labor for a headgasket, but if you get a shop manual and you've wrenched on stuff before you can do it yourself.

As for running better, I'd be willing to bet that the carbs are incorrectly jetted and definitely out of synch.  That's the kind of stuff that sucks money down.  Best way to tune the carbs is pick a good sunny afternoon and spend it riding and checking plug colors (after the carbs are synched of course).  You can probably start a notch richer than stock jets and one clip up on the needles.  Just a good starting point.

[heffay]

from one 350 guy to another...






absolutely rockin' 350!  no, seriously, dig the ride.
it will be nominated for the next bike of the month!

performance mods?... you ask.
dyna electronic ignition.

[altf4]

Haha - well thanks for the response! You guys are great!

I will definitely try to do some more searching around here. I appreciate all the feedback about the way the bike turned out. I was a little uncertain of it's acceptance on a site like this. (I understand there are enthusiasts out there who wouldn't dare modify a classic bike this way, and I can respect/appreciate that).

Anyway, I stumbled upon the "project" section, so I will try to post updates/progress.

Thanks again, I'm sure I will be asking other questions again soon.

donny

[fuzzybutt]

THAT is one sweet looking bobber! welcome to the board too.

[chopstar500]

That's one totally #$%*in' 350/4 - looks fun!

[dusterdude]

nice bike,is that an old sportster front end?

[altf4]

It is a wide glide front end.

donny

[cb650 bobber]

bad ass bike love it.

[Triffecpa]

stock main jets on a CB400F (which is the same basic engine and carb set up) are 75's.  Even with being at sea level and with pods and an open exhaust, I can't imagine that the bike would need 95's for main jets.

TR

[altf4]

Actually, you are right. And I meant to post back about that. Last night I popped the float bowl off and looked, and they are 75's. I guess I need to upsize them to compensate for the 2" open exhaust and pod filters? What would you guys recommend?

donny

[Cvillechopper]

I know there are a few posts on here that give general recomendations on jetting for the 750s, but I can't recall any for teh 350 off the top of my head.  I think the general rule of thumb is something like 1 step for exhaust, 2 steps for pods, with a step being 2.5.  You could order some 85s and/or 90s and try them out. 

[Triffecpa]

I have a CB400F race bike with open exhaust and velocity stacks.  Although I am at much higher elevation than you (5000').  I think that I run 85's in mine.  There was a guy on Ebay who sold CB400F jet kit packages that were pretty resonably priced.  You got four sets of main jet.  75, 80, 85 and 90 (I think).  I would think maybe 80's or at most 85's in your bike.

TR

[LoopsAndLogic]

That is one nice looking 350f!!

I will certainly nominate you

Where in Ohio are you? I'm more towards Akron.

 I noticed that when I placed a MAC muffler on my 400F stock headers and stock setup, that my midrange was toast!!!

Since I knew the needle jets control my midrange, I just raised them 1 click, assembled everything, and took off on the road.

Wow! What a difference. What area of the throttle are you having trouble??

My suggestion, is to do a plug chop!! Cause if your plugs look good, it could be your ignition advance module that sits right behind your points plate not advancing. And it turn, not allowing the timing to advance for proper performance.

Cheers,

LL

[Ecosse]

You probably don't get this very often, but... that's a really nice looking bike you have there.   

[altf4]

Thanks! I am currently trying to figure out why the starter isnt working - maybe its the switch, maybe the starter motor - not sure yet. I'm checking the wiring.

[kghost]

from one 350 guy to another...






absolutely rockin' 350!  no, seriously, dig the ride.
it will be nominated for the next bike of the month!

performance mods?... you ask.
dyna electronic ignition.

+1

I'd ride it

[jasburbak]

Droool......that is a gorgeous bike i must say.... off topic a bit, but would you be able to tell me where you got the rear fender? I've been looking for a rear bobber fender for ages now, and that style might fit my 750, i'm afraid i'm gonna slide off   the back a bit and smoke my butt   thanks...

[altf4]

www.suckerpunchsallys.com

This is where alot of the parts came from. Email them and I'm sure they can help.

donny

[altf4]

That is one nice looking 350f!!

I will certainly nominate you

Where in Ohio are you? I'm more towards Akron.

 I noticed that when I placed a MAC muffler on my 400F stock headers and stock setup, that my midrange was toast!!!

Since I knew the needle jets control my midrange, I just raised them 1 click, assembled everything, and took off on the road.

Wow! What a difference. What area of the throttle are you having trouble??

My suggestion, is to do a plug chop!! Cause if your plugs look good, it could be your ignition advance module that sits right behind your points plate not advancing. And it turn, not allowing the timing to advance for proper performance.

Cheers,

LL

Thanks, I live on the west side of Cincinnati.

I haven't had much time to ride yet (with the weather), so I can't say specifically where or if there is any power loss in any particular throttle range. I took it around the block last night and it seems to be running ok, but could still be better.

I'll need to get it out on the open road for a while to figure out exactly where the problems are. I am a little unfamiliar with the components of these carburetors, so I'm not sure which jets i will need to tinker with to get the right results, but that is where you guys come in

Not sure what the plug chop is either?? enlighten me....

donny