30% of the way there...

Lol. Take a deep breath and a step back my friend, you've done some nice work, don't spoil it now.
Work through the issue carefully and methodically.
Your engine sucks air and any fuel it can past the butterflies - are they all aligned, and very nearly all closed?
Can you open your bowl drains and get fuel out? measure how much from each one.
Where are the mixture screws set? 3 turns out should be a good start.
Did you check the fuel enrichment jets in the bowls?
I could go on, but it's for you to think about this, I've just given you a start.
Edit to say, I've skimmed through your 8 pages. One thing jumps out at me - you bought a carb rebuild kit from an ebay seller? If so, dig out all the jets you removed, one by one check they are the same as the ones fitted - by looking through them, but ideally you should clean and refit them, all of them. It's been said here time and time again, original Yamaha or JX forever parts are the only ones you should put in your carbs....

 

When you have it running like that are all 4 pipes hot?

 

I ended up not using the fleabay kit because it was shit.

Absolutely EVERYTHING is EXACTLY as it should be. And the pile of shit refuses to run.

How is it not pulling a vacuum without any vacuum leaks anywhere?

 

I see no reason to continue to pour time and money into it.

 

Patently you are wrong. And the funny thing is, you have made the error, but you blame an inanimate lump of aluminium and steel for your failure.
Does that hurt, well it should. Time you grew up young man.
Start from scratch, cam timing, carbs, spark (although I suspect provided the timing is correct your spark is where it needs to be).
If you bothered to ask, there are people on here who would sell you a rack of carbs, all set up and ready to run, just not running synched. Just ask...

 

Found the problem.

Only 80psi across all four cylinders. (Should be 156psi) So it's not creating enough vacuum.

It's the shitty internet head gasket.

No one has the good ones, dealers can't even get them because no one is making them anymore. The only head gaskets available for it anymore are Chinese shit.

 

Hard to imagine a head gasket causing low numbers on all cylinders, but maybe as stated above

 

Was the throttle full open when you did the compression test?

 

Surely if the gasket was that bad they would not all be 80psi? Len @chacal I bet he has the right head gasket. Full open throttle check. You ain't far away now.

 

Hmph. Suck squeeze bang blow...
Don't see how a lack of squeeze would affect the suck at low rpm?
Aand, if you're having to give it fistfulls of throttle to make it run you won't have any vacuum anyway.
Cam timing...

 

It's not the carburetors, valves or timing.

 

The obvious issue is you have your engine protectors upside down and left to right....

But seriously, is the head gasket twice the thickness? Even if it was it would drop the cr by one point or two (I can't be bothered to work it out), and millions of bikes have run over time on 8 to 1 cr...
Rings? squirt some oil down each bore then do a comp test, if the rings have miracurously worn out between you fitting them and starting the engine it will prove you're right..
So that leaves you still with carbs issues, assuming you have checked your cam timing correctly - easy visual check is the inlet valve starts opening just before tdc, as the exh valve closes - in days of pushrod engines this used to be called "on the rock", it's actually the overlap period. It takes minutes to do, using one of the outer cylinders.
Done all this? all correct? Then I suggest you either send your carbs to one of the gurus on here (i'm not going to name them) or ask to buy a good working set.

 

I assure you, it absolutely is not the carbs.

I know this because even with the carbs off the bike, the cylinders are still only reaching 80psi, which has nothing to do with the carbs. This is a compression issue. And compression issues only come from valves/timing, rings, gaskets, a hole in the piston, or a cracked head.

I just lapped the valves, and checked their clearance, and it is spot on. The timing has been checked and re-checked and is perfect. The head has no cracks, the pistons have no holes. That leaves the shitty internet Chinese head gasket and rings.

 

I can’t imagine how frustrated you must be. You’ve put a ton of time into this bike.

As Minimutly said, you can prove if your rings are the issue fairly easily, and even without tearing into the engine.

As far as the head gasket being the issue - I think the bike would run even if the head gasket wasn’t perfect. I don’t think it would run well.. But I think it would still run / idle.


I think everyone that has owned one of these bikes has gone through their own trials & tribulations dealing with the carburetors. I certainly have. I probably worked on the carburetors by themselves for 50+ hours (over four carb racks), before I got my bike to run properly - and it’s still far from perfect.


I would try to prove the issue before anything drastic.

 

I don't see anywhere in the thread where you mention honing/deglazing the cylinder walls. That might cause a compression issue with new rings.

 

Have you tried another compression gauge?

 

Yes, I did that a few months ago when I had the engine completely torn apart.

 

Does my finger count?

The braille method.

 

The charity run is tomorrow.

I'm attempting a zero hour Hail Mary play.

 

After a VERY long day, I have a dumb question.

Will just changing out the shims correct this, or do I have to do some more grinding?

 

Yes, thinner shims will give you more lash. More grinding would reduce it further.

 

In the skip then?

 

Update:

Got some shit parts from fleabay, the seller refuses to issue a refund, eBay says they don't have the ability to issue a refund from a seller on their own site. So my bank is just going to reverse the charge and get my money back. And I'll never buy anything from eBay ever again.

I ordered parts from MikesXS, thus far I'm not overly impressed with their operation.

...so I'm just waiting for some parts to come in, and I'm only ordering from Len from now on.

 

My experience as a part time seller is anything that is received by the buyer and doesn't work the buyer can return within 30 days, no questions asked. The seller doesn't have much of an option other than to dispute that you didn't return what was shipped. If they don't send you a shipping label to return the non working item eBay doesn't care, they will still pull the funds from the sellers account and the buyer will be told they can just keep the defective item along with the refund. Unfortunately, this policy that favors the buyer also causes sellers a lot of grief as unscrupulous buyers will pull good parts and install bad parts and then submit a does not work claim.

 

And that's is highly recommended by many here to get the known good parts, quick delivery, and a lot of shared knowledge from Len

 

Which parts then?

for carbs I would only use genuine, and if I was in the states I would only buy from Len @chacal , think I've said that more than once...

 

You just keep going on and on about the carbs. Those are like new.

I ordered new valve shims, a new clutch lever, and new starter solenoid. The latter of which, doesn't work (2nd one in a row from two different suppliers, most likely coming out of the same Chinese factory).

 

This is because you have never answered the question about the starter jets in the passage at the bottom of the bowl. Everything can look like new and still have those jets clogged. That will affect starting.
You never answered if you tried another compression gauge. I thought I had low compression using a Harbor Freight gauge but it was junk.

 

I have a nice Snap-On compression gage, but the hose developed a leak. Same thing...I thought I had a motor problem. It was a tool and user problem.

 

I did answer it, you may have missed it though. Yes ALL carb jets, passages and orifices are clear.

The gauge 'could' be an issue, but the valve lash measurements confirmed the issue is the valve clearance is wrong (the valves are being held open just enough to not build sufficient compression. Can't blow up a balloon with holes in it. lol

 

A shot in the dark maybe, but since you did a full teardown, did the TDC indicator bracket by the coil pickups get disturbed? Or did you check it's position with a dial indicator?

 

No, it didn't get bumped or moved, then I did verify with a dial indicator that it was where it had to be.

I'll be wrenching on it in about a half hour here, it 'should' be running tonight...

 

Help me understand...

 

Is the inlet cam on the exhaust side and vice versa?

 

Do you have a running bike that you can compression test with the same equipment?

I was getting odd results on my one of my bikes. I decided to run a compression test on another running bike with the same method and Equipment. I ended up with getting the same odd results and decided to disregard the information. I ended up finding that the enrichment jets in the bowls of my carbs were plugged.
Once I fixed this the bike started right up.

 

The cams are in the correct positions, I quadruple checked.

I know with forty-seven trillion percent accuracy that this is not a carburetor issue as they're sitting on a different workbench twelve feet away from the bike.

However, when I get back to the shop later today I will test the compression tester on a different engine to verify that it's accurate.

 

Sounds good.

In my previous post I was just sharing my personal experience. I wasn’t trying to insinuate that your carbs are (or are not) the issue.

 

Well, if your cams are correctly set, your valve clearances exist (bet better still in spec), you have spark, and the carbs are correct it will run. If not who's products will you rubbish then?

 

I think valve clearances have to be very tight, at least so that no feeler can be used, for it to affect compression. I'm still in the defective gauges camp. As for carbs and the bike starting problems, if they are clean and the starter jets in the float bowls are not clogged, the bike should at least start (if mixture screws are at a good starting position).

 

Assuming everything else is correct, there can only be three possibilities that I can think of - or some combination of the three:

1. Bad gauge
2. Valves - bad seats
3. Leakage at the cylinder wall (rings and or surface)

If it were me, the first possibility to eliminate is #1. Test it on a known good engine or get a different tester.

Once that possibility is eliminated, the next step would be the old school test of adding oil to the cylinders and see if it effects compression. In theory, if the compression improves it points to the cylinder wall surface or rings, if it does not improve it points to something wrong with the valves - and since lash is correct, it must either be bad seats or incorrect timing

That’s my $.02 at this point

 

Leakdown test.

 

I didn't get around to wrenching on it yesterday I took down a 60 foot maple tree, by myself, in the heat. By the time I was finished I was beat and sunburnt to a crisp. But it was posing a safety risk so it had to take priority.

 

This only addresses the supposed issue with low compression. Go back to the original issue of not running on idle jets (bike only runs on full throttle), which absolutely points to the main jets only working. ie holding the throttle open makes the enrichment circuit (from main jet) work, and over 3000rpm you are on main jet anyway. So the primary/idle jet is not working - on all carbs, so that tells me the idle jets are wrong. I don't deny the valve clearances need to be right, but there are many bikes out there with tight exhaust valves running reasonably right. If the inlet valves aren't sealing that is another matter, but is this the case?

 

I have an acquaintance that said he'd take a look at it... one day. He's working 12 hours a day, 6 days a week right now, and he lives an hour away. So I'm not going to pressure him on his only day he really has to spend with his family.

 

Sometimes taking a break from a frustrating project is the best thing. The answer will click and it will be a great bike.

 

A contractor that works for me has already offered to buy it, as is. Because he likes how well I did everything else on the bike. But I don't think I'd feel comfortable selling him a non-working nightmare.

I'm debating on setting a deadline for it to be up and running, or crushing it with a front end loader so it can't cause anyone else anymore grief.

 

Persevere you will get it fixed.

 

Stop debating and grow up. Or should that be grow up and stop debating?
Anyway -
Do your pistons have rings fitted - tick surely?
Do you have valve clearances - I've not taken the time to read through the stuff you posted, but tick?
When you turn the engine over by hand, on no1 or 4 pot, does your inlet valve open at or just before tdc, close just after bdc, and as you get towards tdc both valves fully closed? Then stay closed until bdc when the exh valve opens? tick?
We know you have spark, we've heard it, tick.

If all these are ticked, swallow your pride and box up your carbs and send to the resident carb expert over there, maybe post a question on who would do them for you, they will be back in a week, maybe two, cost you peanuts, and lo, your bike will run, and you can (deservedly) enjoy all the hard work you've put into it.
Or, strip them, with pics posted here, starting with the complete rack as removed, and someone will spot your error.
Better than having, or repeatedly threatening to have a tantrum and scrap a nice bike.
Just my 2 pence worth....

 

I appreciate your input, but for the love of everything holy and sacred STOP asking and/or insisting about the carburetors that aren't even on the bike! I can assure you with forty-seven trillion percent accuracy that it's not the carburetors.

And frankly, it is my bike, and if I want to crush it with a front end loader, I will.

 

Results of the leak down test...

These readings are after ten minutes on each cylinder.

But, I'm not experienced with performing these test.

I heard minor air leakage, and I don't know if I performed the test correctly.

I set it at 100psi.

The minor air leakage I heard wasn't even enough to blow cigarette smoke around.