True Tdc

[thewiz]

Hang in there, Rob ... you'll get it. Know what ya' mean about feelin' a little burned out on wrenchin' though .... my three projects get me feeling like that more often than I care to admit .... FINALLY ... my SF with the low mileage motor feels like it wants to wheelie in top gear when I snap the throttle open at 60mph ... gratification enough for the lotsadollars and time I've put into it ...

[79XS11F]

WOW ... UNBELIEVABLE :-)

I just did a compression test. This is on what would be best described as dry cylinder walls and the numbers are as follows:
#1 = 130 Lbs
#2 = 130 Lbs
#3 = 130 Lbs
#4 = 135 Lbs

SO it would appear that doing yesterdays VALVE JOB was well worth the effort. At least i now know that all cylinders will draw fuel / air equally for the carb sync.
Rob

[LoserShoes]

Just for info, the "correct" way to find TDC, is rig some sort of stop for the piston near TDC. Run the piston up to the stop in one direction, note the position, usually with a degree wheel, then run it up against the stop from the other direction. Both reading should the same, if not then adjust the indicator. That is, true TDC is halfway between the two readings.

Steve

[79XS11F]

You mean a dial gauge??

I don't have one of those dial gauges that fits in the plug hole. I should try to find one and see what they cost
Rob

[TopCatGr58]

Hey Rob, Harbor Freight has them!



1'' TRAVEL MACHINIST'S DIAL INDICATOR

Delivers precise readings to one-thousandth (.001) of an inch! Meets or exceeds A.G.D. and Federal specifications.

Revolution counter hand.

Lug back positions: 90° increments
Bezel adjustment: 360°
Dial face: 0-100 and 0-50-0

ITEM# 623
$13.99

You'll need something to hold it with!
*****************************
They aren't listing prices, but are usually around $15.00 for these holders!

GAUGE HOLDER WITH VACUUM BASE

Item # 93476>>

Accepts gauges with 5/16'' & 3/8'' stems
Multiposition angling with fine adjustments
Securely attaches to most flat, non porous surfaces
Quick action suction/release base lever

*************************



MULTI-POSITION MAGNETIC BASE WITH FINE ADJUSTMENT

Attach this powerful magnet to flat or round surfaces. Reach as far as 12'' with multi-positional joints and easy-adjusting posts. Knurled thumbscrews give a positive grip. Features magnetic base, upright post swivel, upright post, swivel snug, gauge rod, and indicator clamp.

ITEM# 5645

T.C.

[mro]

Just for info, the "correct" way to find TDC

Use a WD40 straw, comes free with purchase of oil


mro

[79XS11F]

Better but not good

Well yesterdays work proved to be almost all for not. I installed the perfectly cleaned carbs (they are as clean as they can get inside and out) and then could not get them synced. The engine fired right up with out needing the chock and would idle but did so rather roughly. I can sync 1 & 2 to each other no problem and I can sync 3 & 4 together no problem. The issue appears when I try to sync the pairs to one another. All that happens is the vacuum reading on 3 and 4 goes up a lot and 1 and 2 stays study. There is also a pretty big difference between the pairs. 1 & 2 running at about 10 on the dial and 3 & 4 running around 20. 3 and 4 will clime to as much as 30 while 1 & 2 stay at around 10. I also noticed that the vac advance unit is pulsating which it did not do with the other carbs. i know the carb bodies are not mixed up and I know that their butterfly actuators are properly engaged between the sets.
So I am going to remove these carbs and pop on my original carbs and see what's up. Hopefully my next post will include a SMILE... because now I'm beginning to get pissed off.

Rob

[mro]

All that happens is the vacuum reading on 3 and 4 goes up a lot and 1 and 2 stays study

Does that mean that when your adjusting one and two, to three and four...three and four are changing??? or that one and two won't change when when adjusting with two???

Screw on two should only change one and two's adjustment.


mro

[79XS11F]

Yes that was what was happening. I already have the carbs off and the throttle actuator was binding against the sync actuator so when trying to match the pairs I was really just increasing the throttle on 3 and 4. I will have the carbs back on soon and let you know what I got.
Rob

[79XS11F]

I have the carbs back on and have them dialed in pretty good. I still see the auto advance moving at idle. Not bouncing from stop to stop like when it's hooked up wrong by still movement happening there. Maybe an 1/8 of an inch back and forth.
Is this normal or should it be dead still at idle?
Rob

[randy]

Should be dead steady at idle. Sure you have the advance hooked to carb #2, NOT the boot nipple, but to the nipple on the carb itself?

If hookup is correct, I'd venture to say that you have a vacuum leak either in the petcock vacuum line or the boot/head joint or the boot/carb joint on #2 carb.

[79XS11F]

Yes it is in deed hooked up to carb #2 at the carb body and not the nipple. I sprayed "quick start" all around the carbs, the boots and butterfly's with no change in idle so I guess I will have to test that vac advance unit again. It was good last year on my other engine.
If it's being moved at idle would that not indicate too much vacuum? as compared to a vac leak? That is unless it does not sit at it's non running position when the engine is running. Is there a small amount of pre-load applied to the unit when the engine is running?
Rob

[79XS11F]

I changed out the vac advance unit with no change. The unit is advancing when the bike is fired up and jiggles back and forth even at idle. I just got back from a run and once the engine was well warmed up the idle was over 2K so I reset it back to 1100 RPM with the main adjusting dial. Should I be using the 4 idle screws at this point?
I will bet that the next time I fire it up she will be very COLD blooded.
So I am at a loose now as to why the vacuum operated auto advance is advancing as soon as the engine is started up and jiggling back and forth at idle. How could I have too much vacuum if that's what is happening. I tested both units and they hold a vacuum perhaps I should look at restricting the air flow in that vac line?
Rob

[TopCatGr58]

Hey Rob,

Another member, think it was in Australia or NZ had this same thing, was properly connected to the carb body port, but was having vacuum pot pulsating!

Turned out the PO had reamed out the hole in the carb body so that it was much larger than it was supposed to be. He put something in line to create the proper restriction, and it stopped the pulsing and worked properly!

You should be able to find it with a search.

Also, you could put a vacuum gauge on the carb body port and see how much vacuum it's getting? The book reports should only take about 9psi IIRC to reach full actuation and travel of advance pot!
T.C.

Found it:Goldcoast guys advance problem

[79XS11F]

I will pop one of my sync gauges on that port tomorrow. i guess it's safe to say that there should be next to no vac at idle. I also for the life of me can't understand why the idle changes sooo much between a warmed up engine and a hot engine. I can't wait to receive my color tune kits so I can really see what's gong on. The engine sounds and smells like it's running rich but the plugs look OK. Off white tips, light dry black on the base ring. Dirty tan on the insulator on one side only ... other side unaffected.
I would have guessed that tuning with STOCK set up would be EASY. every thing is STOCK.
Rob