72 CL350 uneven exhaust pressure

fluke12

Been Around the Block
Short version:

ENGINE: new 1mm over Pistons, new exhaust valves and seats cut, both done by a machine shop. Engine is all back together and compression is even but low (120psi). It's the first time I've adjusted valve tappet clearance myself so I THINK I did it right.

CARBS: carbs were cleaned before engine went back together and are synced. Pod filters. And I think one or two sizes up on the jets but I can't remember (it was well over a year when I changed em) The plugs look like they might be carbon fouled but that could be from before. I need to get new ones.

No matter what I do to the carbs, I can't get even exhaust pressure.


Any suggestions/ideas of what could be wrong?
 
Oh, also I think there may be a small hole at the front of the lower pressure muffler.
 
by exhaust pressure you mean what you feel coming out the pipes ?
did you cable pull synch the carbs ? you must do this first before any other carb tuning, athough it won't effect idle synch when you are on the idle speed screws it is still important to start out right
 
Xb, yes, sorry. I meant the pressure coming out of each pipe.

And I THINK I cable synched if you mean make sure when you roll the throttle, the two cables pull at exactly the same time.

I think I read somewhere that the low compression matter less than them being even... Any truth to that?

If my valve clearance is a little off equally, would that drop my compression? Do the oversized pistons lower the compression?

Obviously, that doesn't solve for the uneven pressure out of the exhaust.
 
the uneven pressure is likely just uneven carb settings
the valve adjustement is tricky to get just right never hurts to double check that
the butterflys will always pull at the same time,even if they are far out of synch, anytime they are off the idle speed screws
they must be synched to be OPEN exactly the same amount when hanging on the cables
 
I guess maybe someone can talk to me like the idiot I am and give me some tips for the feeler gauges. Usually I start overly loose and sort of clamp down on the gauge and back off just enough to be able to slide it out and back in.

As far as carb syncing, I'll go back through my clymer book and reread it to make sure I'm synced.
 
fluke12 said:
I guess maybe someone can talk to me like the idiot I am and give me some tips for the feeler gauges. Usually I start overly loose and sort of clamp down on the gauge and back off just enough to be able to slide it out and back in.

As far as carb syncing, I'll go back through my clymer book and reread it to make sure I'm synced.
you got the right idea on the feeller gauges, being slightly off on valve clearance will not effect running very much anyway
in order to get the hrottle valves same opening you can use a popsicle stick on edge on each side so the throttle plate keeps them captured or a 1/4" rod whatever
as soon as you pull throttle tension they both should loosen up at the same time
this means they are hanging on the cable the same,adjustemnt is at cable housing on carb
it is easier to dot this with carbs pulled out of the intake so you can work thru the throttle plate side
once you get cable pull even then you can set idle screws to where they just hold open the plates and go from there you can use something like a piece of piano wire to get this initial idle screw setting the same,using it as a gauge to set the opening at idle of the throttle plate on each carb with the idle speed screw
 
Stock carbs and....I know... Emgo, eventually to be replaced with k & n hopefully soon. Here are two photos the first is the left and stronger exhaust
02c2b0578d25d811499558b8f7d44509.jpg


The second is the weaker side - note the gap at the bottom. Could that be the issue? Are those pieces an easy swap?
3dfbd2e6e2bc55df2c6fb8d096b32bf5.jpg
 
dude :( that is the choke plate and is only closed for cold starts
you really got me flusterd :-\...those are to be wide open when running
 
Yeah. That was a momentary lapse of logic. I know it runs open. The damn lever says open right on it. I'm just grasping at straws, trying to figure out how to make everything right.

Next step I guess is to make sure my carbs are synced properly and check everything.
 
one step at a time you can do it ;) maybe clean up the bell mouths on those babies that girt will find a home inside the motr
 
Having the tank and seat off definitely makes any adjustments a little easier so I'll try resyncing the carbs soon and let everyone know how it goes. I'm interested to try your method with the Popsicle stick spacer. That's a trick I hadn't heard before.
 
fluke12 said:
Having the tank and seat off definitely makes any adjustments a little easier so I'll try resyncing the carbs soon and let everyone know how it goes. I'm interested to try your method with the Popsicle stick spacer. That's a trick I hadn't heard before.
yes but you really gotta pull the carbs and turn them to look into at the THROTTLE plate
think of it thisaway
the throttle plates are hanging on their cable when partly open being pulled by the twist grip and resisting with their return spring...the adjustement of the cable housing length where it comes to the carb determines the degree of opening of the plate
the opening of the plate should be as close to exact as can be each side
once you do this adjustement, never touch those cable adjusters again, they are done
 
Bradj, should i worry about replacing those, or just get to them when i get a chance? The bike has no problem starting up at all.
 
fluke12 said:
Bradj, should i worry about replacing those, or just get to them when i get a chance? The bike has no problem starting up at all.
look for fatigue and cracking/loose/screws, if they continue to fall apart it will or could very well scatter yer motor
 
If there broke they will continue to break the top of your piston is the part that will pay the price I would replace now
 
I'm curious as to what type of carb cleaning you did. The one looks fairly clean but the other looks pretty sketchy. A tear down with a nice long dip in an ultrasonic cleaner would do wonders for them. Make sure floats are set correct and jets/passages are absolutely clean. Also as someone else said broken carb parts always end up inside the motor so get that handled straight away.

Lastly, read the sticky on why not to use cheap pod filters. You will need to switch to another brand.
 
fluke12 said:
Stock carbs and....I know... Emgo, eventually to be replaced with k & n hopefully soon. Here are two photos the first is the left and stronger exhaust
02c2b0578d25d811499558b8f7d44509.jpg


The second is the weaker side - note the gap at the bottom. Could that be the issue? Are those pieces an easy swap?
3dfbd2e6e2bc55df2c6fb8d096b32bf5.jpg
i can actually see a crack digital cameras are wonderful things i actually use them for reading dirty/worn serial numbers
 
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