No Idea

the manual states that but you can only read cylinder one at that point because the others are not at top dead center ( another is but on exhaust stroke) . you start at tdc read valves that are in position to be read then rotate motor until you can read more valves. compression or exhaust stroke does not matter , what matters is position of lobes pointing away from top valves.

if you want you can use a stick in each cylinder as you measure to ensure it is tdc it will rise and fall with piston

 

So messure the valves when that piston is at its highest.

 

yes but most important is when lobe is at its farest point away from valve

 

You don't want the cam lobe to be engaging the valve. This would affect the gap you're trying to measure.

 

So your saying it dont matter where the piston is. Long as the lobe is pointed the oppisite way of the valve?

 

if you have play in the cam chain(stretched) you will not get perfect tdc and cam alinement .
and yes thats what I am saying .
as the lobes come into position to measure clearance , measure it, and stop thinking about the pistons. the only time you will care where the piston sits is when you have to R&R them to change the shims

 

I pulled the attached image from an earlier discussion on this same topic.

 

Well vlaves were quit out of spec. Got all numbers right now.
Who has the shim pool here?

And can they do underbucket shims/pads.?

Thanks again everyone for bearing with me. I truly apreciate it..

 

So i just got the bike running.
Full rebuild kit to carbs, valves are spot on.
Just tried it in the parking lot. Has a bog almost wants to die on takeoff. Seemed like this was happening before the rebuild as well.
Carbs are fresh. Needles are fine, floats are fine, sync might still be off i think.
Can out of sync cause a bog on take off?

 

I would say it's possible but there are others who know better than I. Did you set your mixture screws to about 2.5 turns out from a soft bottom?

 

Yes 2.5 turns out

 

Only thing I can figure out is maybe cause my intake boots arnt in the air box all the way..

 

Out of sync can very easily cause that…

 

In sync now. Still doing it, must have an air leak issue.

 

Propane test

 

link says this its site has a shim pool http://www.maxim-x.com/notes.html

to answer his 11/02/17 post a little late

 

Update**

No leaks what so ever around any of the boots or intakes.
Everything is set.

She's going up for sale.

 

One last thing. That I know for a fact.
The carbs have a fresh rebuild.
Its in sync. Its been colortune. The floats are fine. The lines are fine. The peacock is fine. The flow of gas is fine.
This problem started a month before I laid it up last season. Which gives me reason to believe its nothing at all to do with carbs .

 

I think Chitwood was on the right track. I would tweak the mixture screws out a 1/4 turn and see if it makes any difference. If not try tweaking another 1/4 turn. If still no improvement try going leaner for a few goes.

 

Has ignition/electrical been tested/verified in any capacity?

If it were myself - I would be performing a full system(s) check. Can't burn all that fuel if you haven't got sufficient spark across the rev range.

 

Coils checked out fine.
Not sure how to check the rest .

 

you test the pickup coils by disconnecting a connector at the tci and doing an ohm test gray and orange wire to the black wire it will be the connector that does not have the red/white wire.
tci test is to send it to someone who is willing to put it in their bike and run it around for a few days.

how is the charging system ?

 

Ill give that a try tomorrow.
Charging system seems to be fine. Not sure how to test it though.

 

Pick-up coils:
120 ohms +/- 20% = 96 ohms to 144 ohms acceptable range
Spark plug caps:
1985 XN/XNC models: 10K +/- 20% = 8,000 to 12,000 ohms per cap acceptable range
1986 SX/SXC models: 15K +/- 20% = 12,000 to 18,000 ohms per cap acceptable range


Spark plugs:
1985 XN/XNC models: 0 ohms per plug
1986 SX/SXC models: 5K ohms per plug


put a voltage meter on battery and check voltage at
* 3000+ rpms: 14.2 volts up to about 14.8 volts, with a maximum of 14.8 volts (all XJ700-X and XJ750-X)

this thread explains testing and how
The Ultimate Relay, Switch, Sensor, and Diodes Guide

 

I absolutely sure there's no leaks anywhere..... Next thing to check will be the head gasket or cyl base gasket

 

Did propane test around each side of the carbs.
Will double check with starter fluid .
Head and cyl base gasket are tight and sealed.

 

Silly question, @Joe34, but have you done a compression/leak down test?

 

1.Did you test around all 8 ends of the carb to manifold boots?
2.how do you know that the gaskets are tight and sealed?
3.doublecheck the exhaust collars, too

I'm still gonna say it's a leak at one of the boots

 

Are all four cylinders firing? Are exhaust headers equally hot?

 

how hot is the rectifier supposed to get.
Had the bike going for 10 minutes and its fairly warm.

Also checked pick up coils. Both are in spec.

 

It's ok for it to get warm.

 

What I'm stumpped on is yea it starts hard. But whenI warm it uo I can rev it up smooth. Sometimes it drops down below 1 grand. Other then that it won't bog down until I sit on it and try to take off in first .

 

Bog under load? Possibly fuel related?

Have you checked the fuel tank/petcock for proper vacuum and flow? Assuming its got the vacuum operated petcock. Could always plug in a hand-held vacuum pump into the petcock vacuum and pull some negative pressure on it and see if it will pee into a cup. Probably 5min worth of time. Additionally, all of that rubber vacuum and fuel hose is super inexpensive and worth replacing as well.

My TTR230 has a petcock with plastic pre-filters, rather, screens. Upon replacing the original it had degraded to a point of collapsing in on itself and was partially ingested into the brass petcock. It doesn't take much fuel to idle/briefly rev up a 230 but that might not be the case on a 750 and could be worth a look.

TTR230 Petcock part example: https://www.amazon.com/Aitook-AIT-PT2509-Yamaha-TTR230-Petcock/dp/B00EEKMZI2


Good luck to you sir. Don't give up on it!

 

Update**

Checked for leaks again with some carb cleaner . Still idels perfect..took it for a ride up the road. Wouldn't open up all the way.
I did take my plugs out though.and this is what they look like.
Is it behaving this way cause I'm getting to much gas?

What should my next step be .

 

It's because you're missing a plug

 

Its there just didnt get it in the pic

 

All same color

 

That was a joke…

 

I'm curious… Remove your air filter element itself. Then go for a ride, see if there's any change in performance

 

When the carbs were off did the throttle slides do a nice clunk test? (Is that the right nomenclature?)

 

Yes clunk test was good .All even across the rack.

 

Ill give that a try tomorrow . what would it mean if the performance would be better .Or same .

 

Plugs say you're running rich... too much fuel or not enough air... no filter = air increase.

 

I did read that this could be from a lean setting to. But I'm just reading stuff lol

 

Black plugs = Rich
Tan Plugs = Just right
White / Eroded Plugs = Lean

https://totallyamaha.com/snowmobiles/aaTECH/sparkplug/Spark Plug Information Overview.htm

 

Correct

 

Tried this today works alittle better with air filter out. Takes off better but hesitates on pick up while giving it more gas. Engine sounds deeper like overloaded around 4g and up.
Tried outting filter in turned pilot out more but still the same .

 

Maybe I have to much gas in my bowls could that be my floats are making me rich?

 

Absolutely, I posted this in another thread for a 550 that was acting like yours when hot:

" This is exactly what my bike was doing when I bought it and was a result of the carb bowls overflowing. Seemed find when cold (Wanted rich) and got crappy when hot. My commute is 30 minutes and a few miles from home it would start acting up. Turns out it was also masking throttle shaft leaks as when I got the levels close to correct, the bike rpms would start running away when you take the choke off...

That's when I sent the rack to hogfiddles . Been ok for about 1K miles now...."