Only runs on one cylinder!!

[brad-450Lz]

Hello good people,

I am currently having trouble getting my new (to me) bike started after a carb clean.

Here are my specs:

'82 gs450L
stock exhaust
K&N brand pod filters (not my choice!! came with bike... don't have stock airbox)
Carb settings: pilot jet #20 (17.5 stock), main jet #130 (115 stock)
Needle shimmed by replacing nylon washer with washer stack of 1/2 original height
pilot screw set to 2.5 turns out

Recent work done by me:

Carb clean following procedure on this site including overnight dip, spraying out with cleaner, and using a wire brush bristle in every oraface.
Ordered and installed new o-ring set from cycle-orings.

Tightened starter clutch bolt after it managed to loosen itself (two weeks of chasing "ignition" problems and it was a loose bolt ahhhhhhhhh!!!!! haha that problem solved anyway)

My Problem:

Bike will only start with left cylinder plug removed. Tried swapping plugs and got the same result. Both plugs are sparking when removed and placed on cylinder head. Right plug is very sooty when removed and very very hot. Left plug (when left in) is dry, no sign of gas, and is not very hot at all.

Things I am planning on checking for:

-clogged pilot jet
-holes in my CV diaphragm
-hole in petcock diaphragm (checking for gas leak into vacuum hose)

What I would like to know:

-What else should I add to me "things to check" list
-Do you have any time tested methods for verifying the above.

Thanks in advance for your consideration

[BassCliff]

Hi,

Thank you for the complete history and letting us know everything that you've done to your bike. Very good work.

You're thinking and procedures are good and it seems you've got just about everything covered. Not that is has much to do with your issue, but have you also adjusted the valve clearances?

There has been a few times when symptoms such as these were caused by a float bowl gasket that did not have the proper perforation punched out. Compare your old gaskets to the new gaskets to be sure that all the necessary passages are clear. Keep us informed.


Thank you for your indulgence,

BassCliff

[Calvin Blackmore]

so a dry plug pretty means no fuel getting to the cylinder


orifices were clear prior to rebuild?


clogged fuel pipie mebbe? which carb has the gasline attached?
if its the right side then the pipe is a good place to start

(oh an cliff loved the cliif rides vid well done)

[brad-450Lz]

Hi Bikecliff,

It's a pleasure to finally be speaking with you, thanks for the helpful site and positive approach to stubborn problems!

Regarding your points:

Not that is has much to do with your issue, but have you also adjusted the valve clearances?

I have not check clearances, though I have borrowed a set of feeler gauges and it's on my test matrix for Saturday AM... will post results

Compare your old gaskets to the new gaskets to be sure that all the necessary passages are clear.

bowl gaskets were in good shape and holes lined up from what I could tell... though I must admit I did not check specifically for any mis-alignments on the various tiny holes. I will be sure to do this tonight as I check for the other carb related issues above.

[brad-450Lz]

Hello Mr. Blackmore,

orifices were clear prior to rebuild?


clogged fuel pipie mebbe? which carb has the gasline attached?
if its the right side then the pipe is a good place to start

yes I cleaned everything I could see, though I did have to knock the needle jets out with a dowel and some very firm whacks from a rubber mallet. I suppose some wood bits could still be stuck in the hole for the needle jet. Will check that tonight.

The fuel line on my bike runs to a "T" junction right inbetween the carbs (only two on my 450). So I know the main fuel line is not clogged or I would not be getting fuel through the right side correct?

The vacuum tube to the petcock comes off of the left carb (side which won't start). Think this would have anything to do with it? I've seen previously posted that a leak in the petcock diaphragm could cause fuel to come into the vacuum tube. Would this cause extra fuel flow in the left carb or block flow? If it would block flow this could be the problem too. As a data point the petcock was functional before I did the carb clean.

thanks for the wisdom...

[brad-450Lz]

**update**

This morning I had the chance to take a look at my bike again... I took my freshly charged battery out to the parking lot and did the following:

1. Checked for a plugged pilot jet: It was clear. Cleaned it again thoroughly and sprayed out the linkages between the pilot jet hole and needle jet oraface to ensure proper flow in the pilot circuit
2. Checked for a plugged passgeway behind the pilot screw: Didn't find anything. Sprayed out pathway from pilot air jet to pilot screw and from pilot screw to opening in the bottom of the carb. Fluid sprayed through so I could only infer the entire pilot circuit is free and clear.
3. Checked for proper bowl gasket alignment: BassCliff brough this one up. After checking them out both gaskets align properly including the locating tab which only fits in one orientation.
4. Checked for hole in diaphragms: Went into a dark room and shined a bright light on the opposite side of the diaphragm. Neither had any signs of holes.
5. Remounted carbs and started bike: Bike started on both cylinders but idle raced to 5k+. Hit the kill switch. Adjusted master idle screw (large screw between the carbs) out and tried again. Bike would not start. Continued adjusting the screw a few more times. Bike would crank and show signs of picking up momentum but would not start.
6. Pulled plugs: Checked for spark against the cylinder head. Both plugs sparking. Both plugs are very very sooty at this point.
7. Checked for leak in petcock diaphragm: Pulled vacuum line from left carb to check for evidence of fuel. No fuel found.

Conclusions:

1. Bike is runny very rich through at least one of the carb circuits. No way to know which one currently. My rev up through 5kRPM would have used all the circuits in sequence. Since the bike won't start plug chops are out of the picture for the moment
2. Carbs are most likely clean. After my overnight dip and three separate instances of pulling apart and spraying/needling every hole and passageway I am beginning to think there is no more gunk/stoppages etc... This does not mean, however, that the carbs are adjusted properly

Variables:

1. Pilot screw setting: For all of the tests above the pilot screw was left at 2.5 turns out. This could make a difference.
2. Choke setting: In all instances it seemd that the bike preferred to have no choke whatsoever. By "preferred" I mean sounded closer to starting... though obviously it never did!!!
3. Float Height Setting: In my first round of carb cleaning I measured the float height to be 24.7mm on each float. My suzuki factory service manual calls for 22.4 +/- 1mm. So I adjusted them down and they now both measure 23.0 mm.... whithin spec. Going too far with lowering the height would mean more gas ... or too rich. So this could be an issue
4. Sooty Plugs: Even though my plugs looked very sooty after pulling them they still sparked against the cylinder head. Could they not be sparking "well enough". Next time I go out (Saturday AM) I'll be using new plugs.

So that's my list of things that would affect the pilot circuit in the carb and or the bikes inability to catch.

So fellow GSer's what do you think.... check my logic .... what else would keep my bike from starting given the data?

[brad-450Lz]

Back at it ... I need some feedback!?!

OK last update the idle was hanging around 3-4k, this symptom has not changed during the following steps

1. Replaced intake boots and o-rings
2. Cleaned carbs twice
3. Removed PODS and installed stock airbox with stock filter, replaced pilot and main jets to stock settigns.
4. Tried a new (to me) set of carbs, cleaned and jetted as above.
5. Adjusted pilot screw at 1/4 turn increments from 0 to 3 turns out
6. Adjusted valve clearances to between 0.05 and 0.1mm spec is (0.03 to 0.08) I know it's not perfect (a hair too wide on two shims) but from what I've read this is unlikely to be the problem.
7. New set of caps over the vacuum plugs
8. Brand new petcock

I believe there is an airleak on the left side because I took the pods off while the ilde was hung and put my hand over the left and right venturis separately. The bike would die very quickly with my hand over the right side but could keep running with my hand over the left side.

This means extra air getting into the chamber somehow on the left .... airleak right?

So....... along comes this evening.... I've broken off a compression gauge adapter in my left spark plug hole (no comment ) and have since taken off the head to try and get it out. I'm putting up another thread regarding that adventure........ but here's the relevent point:

After scraping my head gasket scraps off with gasket remover and a razor blade I ran some water over it to get the remover fluid off as per the directions.... but while I'm shooting some water down the exhaust ports I see something weird..........here's a pic:




Yes that's water pouring through the left side exhaust valve. Shouldn't be happening right? When I tried this on the right hand side no water came through.


So here's the million dollar question(s)

1. Is this as significant as I think it is (very)? Is this an obvious hanging idle suspect?
2. Do I need to take out and/or replace the valve/seat/seal/springs to rectify the issue
3. What kind of skill level and monetary investment would this require?

Thanks for your consideration,

Brad

[Flyboy]

Assuming you have no cam in there and that valve should be closed snug against it's seat, you are right, that is not good at all, and judging by that stream coming out there, there must have been very littlecompression at all on that cylinder.
But it is not the end of the world or all doom and gloom, the first thing to do is pull the valves and cheack them and the seats for condition, it may be a slightly bent valve, or a burned valve and seat, how badly is the question.
I don't know what sort of budget you are on, but if it is not burned too bad, a bit of grinding paste and some elbow grease will have you back in business, but if it is burned quite badly, then you will have to take it to the machine shop and have the valves and seats recut, a bent valve would just need to be replaced.
Now that you are in there, I would measure the wear on the valve guides as well.

Personaly, I would put in new valve guides, have the seats and valves recut and then I know the head is good for another 100 000km at least.

[Steve]

Your leaky valve could be several things, including merely dirty seats. Could be bent or burnt valve, to, so removal will be necessary to check. It appears you already have the head off, so it's not much more work. While you have the valve out for checking, use some lapping compound to clean the seats before putting the head back on the bike.


One other thing, this statement has me puzzled:

7. New set of caps over the vacuum plugs

What vacuum plugs?

The only "vacuum" related stuff on the bike is the vacuum hose from one carb to the petcock and the screws that plug the vacuum ports for synchronizing the carbs. Are you saying that you replaced those screws? Or is there something else on there that has been modified?

.

[brad-450Lz]

Hi Steve,

I've done a bit of searching around and I'm not sure about the terminology, are the "seats" a part of the head or are they a separately installed part? Here's my valve diagram for reference:





Which of these components (other than the valve itself) will need to be cleaned/inspected?

What vacuum plugs?

.

Yes I mean the sync ports, the PO replaced the screws with rubber plugs to make it easier to get them on and off.... I checked for leaks around that area with some WD-40 and starting fluid and they aren't leaky

[Flyboy]

Hi Brad
The seats sit in the head casting, they are the steel inserts that the valve face seals against when it is closed.
They need to be removed and inserted by a machine shop.

[brad-450Lz]

still more questions

hey flyboy,

Thanks for the help, gotcha on the seat. You also suggested I check out the "valve guide", where can i find that?

Others have suggested replacing the stem seals while you're into the valves... do you agree ... and what part is the stem seal? Is it #20 on the fische a couple posts back?

Also I just found a head for sale (450TX) that will fit my bike (450LZ) for $40, all valves included. Think this would be a good buy for all the valves and other parts on the head? Seller says it came off a strong running bike. Could be a drop-in replacement.

brad