Thanks to all for your help (some of ya didn't even know), but I need a bit more

[Prez]

1st let me start off by expressing my gratitude for this board and many of it's knowledgeable members: Nessim, Cafekid, Frankenzuki, Keith Krausse, Basscliff, and many more who's ID's I don't recall. I didn't ask many ?s myself, rather used the search function as much as possible...resulting in a subscription list 40 threads long. I'm a diesel tech by trade, been riding & tinkering with bikes for 10 yrs now, but this is the 1st carb'd bike I've been into this deep.

Now for the most recent before & after pics (have done more work this week, have yet to take pics).




Now for the current problem, let me first give a rundown of what's been done: valves checked & adjusted, new intake o-rings & good boots, compression check (forgot to note reading, will be re-doing that), new exhaust gaskets, carbs synced, new plugs, point gap set, PO did the carb disassembly/cleaning & left airbox off (replaced the box w/new filter), and someone along the way de-restricted the mufflers.

Ran when I bought it, but only with choke on, valve adjustment cured that. Runs pretty good now, seems to be lacking power in the upper gear ranges, pulls to near redline in 1st & 2nd. Big problem is fuel consumtion is way too high, I'm talking 100 +/- miles/tank or 21-22mpg, nearly half of what it should be. Seeps a bit from the petcock, and appears to seep from #1 & 2 bowls when sitting, just not enough to explain the amount of overall consumption.

Do I start with petcock rebuild, fuel levels & float height or look elsewhere? My guess is that it loses more in motion (like a cracked overflow tube in the bowl?). [-o<

Also, where does the second vacuum line go? the left one goes to petcock I'm certain, but the center one puzzles me.

[n1elkyfan]

The center vacuum port on the carbs goes to the petcock the outer two just vent.

[BassCliff]

Hi Mr. Prez,

Visit my website and check out the page entitled "Where Do These Hoses Go?". Maybe it will help.


Thank you for your indulgence,

BassCliff

[Prez]

Hi Mr. Prez,

Visit my website and check out the page entitled "Where Do These Hoses Go?". Maybe it will help.


Thank you for your indulgence,

BassCliff

Must have missed that one before.

[Outlander]

The old cliche' always comes to mind here. If you want something done right, you gotta do it yourself. I read your post about your PO rebuilding the carbs, but if they are leaking, you may want to go ahead and rebuild them yourself. Check float level, and perhaps replace the needle valves.

I don't even like taking my scoot to a shop to have them adjust anything. Next time I get it back, I have a load of things wrong, that weren't wrong before. Makes me wonder about the shops....

Before long, I am sure you will have your scoot in tip top shape. Remember, patience and perserverce will pay off in the long run.

Good luck, and keep us informed:-D

[Skateguy50]

Hi Mr. Prez,

Visit my website and check out the page entitled "Where Do These Hoses Go?". Maybe it will help.


Thank you for your indulgence,

BassCliff

Nice to see that as I have been mostly putting things back as I took them apart. My carb didnt have any hoses on those vents so it would be a good idea to pick up some vacuum rated hose and vent them behind the airbox as you showed.

Also I didnt really understand the pri spot either, and was curious if one is supposed to be "off" but seems just leaving it on will do the trick if the engine isnt running.

Thanks for all the info here as well been doing a lot of searchs to find what I need since so far pretty much everything has been asked / answered already. ~knock on wood~

[Nessism]

In case you didn't know, Basscliff's site has links to the factory service manual for your 750; lots of good info available.

I concur with Outlander, go through the carbs and verify everything yourself. Slam in an O-ring kit while you are at it. You might also want to check the jet sizes against stock - something is seriously wrong with your mileage.

Good luck.

[Skateguy50]

Had my bike running for a bit, but was getting low power and went through half a tank in like 15 miles. My case turned out to be a broken main jet in carb 2, so yea... anything spraying the gas wrong could cause it to not fire right and just come out the pipes resulting in poor mileage.

[Prez]

In case you didn't know, Basscliff's site has links to the factory service manual for your 750; lots of good info available.

I concur with Outlander, go through the carbs and verify everything yourself. Slam in an O-ring kit while you are at it. You might also want to check the jet sizes against stock - something is seriously wrong with your mileage.

Good luck.

I did download the manual, and have tthe Haynes as well, but these older ones can be sometimes vague. My factory for the SV is much more detailed, in comparison. I just recieved my o-ring kit from Mr. Barr, and had planned to rebuild the carbs myself. Thought I'd give the PO the benifit of the doubt, he probably just cleaned them, likely used the wrong method like a wire brush & wallowed out the jets.

I hope it's not going into the crankcase, going to redo the compression test this evening to make certain the rings are ok.

[BassCliff]

Vacuums suck

Also I didnt really understand the pri spot either, and was curious if one is supposed to be "off" but seems just leaving it on will do the trick if the engine isnt running.

You are correct Mr. Skateguy.

On these vacuum operated petcocks, there is no "OFF" position. If I may paraphrase what Mr. bwringer has so eloquently stated: "ON" is OFF when the bike isn't running. "ON" is ON while the bike is running. "RES" is ON when the bike is running too. "RES" is also OFF when the bike is not running. "PRI" stands for 'Prime' and is ON all the time whether the bike is running or not.

Don't leave your petcock on "PRI". This allows fuel to flow freely via gravity. More than likely it will flood into your crankcase and dilute your oil. This is a very bad thing.

The vacuum petcocks will allow fuel to flow only when there is a vacuum applied to the vacuum port, as in when the engine is started and running. Otherwise you can leave the petcock in the "ON" position and fuel will cease to flow when the motor is stopped and vacuum is no longer applied.

And Mr. Prez, don't worry about missing that page. I had just finished putting it up, just for you! :-D Well, not really. We get asked questions like that a lot and I thought, why not?

Thank you for your indulgence,

BassCliff

[Prez]

Well, I went to se the PO yesterday evening. Asked him about the carbs, said he'd only cleaned them, at the time he'd just gotten it running before a cash crunch forced the sale. Obviously he didn't have any money to put into it, so no o-rings.

Also managed to score a KG adjustable luggage rack that was on it when he bought it off ebay last march. I'd been loooking for one anyway, and had planned to nonchalantly mention seeing it in the ebay pics while I was there. He said "oh yeah it's hanging on the wall in the barn here, it's your's buddy". I took the backrest off it since my topcase has a built in backrest.

Tore into the carbs this evening and the main jet o-rings were toast, the fuel & air screw o-rings weren't too bad. Getting ready to crank it up & see what happens.

[Prez]

Ok, yesterday I only did the bottom end o-rings on the carbs, for the sake of time, probably really need to the replace choke plunger & fuel tube sets....was hoping to ride it tomorrow.

My son & I fired it up last night and it was way rich with the fuel & air screws set to factory settings of 1.25 out for air & 1.0 out for fuel. Ended up turning the air screws out 2 additional turns. It idles smoother, pulls way better from lower rpm than before. According to my wife's uber keen sense of smell it's still a tad rich, I have virtually no sense of smell and have to rely on burning eyes with the garage door closed or how it runs.

Also did a compression check while the carbs were off.
1 155
2 132
3 141
4 126...this one bothered me since it was well over 10% lower, wet checked it with 4 squirts (the boy got carried away) of ATF from the oil can & it shot up to 170psi, telling me there's likely a ring problem there.

[Prez]

Took it out for it's first twisty run/serious shakedown today, and I must say I'm rather impressed. Fuel economy is better, yet still under par @ 30.5mpg. Handling was ok, given the worn/aged/weakened springs & such.

Power was marginal knowing there may be some ring problems in #2 & #4, torque seemed a bit low, lost steam rather easily on uphill grades forcing downshifts. Had planned to ride it this season, then rebuild the top end.

Maybe this week I'll have time to pull the carbs again & replace the choke plunger o-rings, have a set of those machined aluminum spools to install too....provided I can ever find them. [-o<

[Prez]

Looks like #3 is the one still running rich, went into the garage 3 times yesterday and noticed there was a small fuel puddle forming. Cleaned it up each time, and glanced at #3 bowl, it was wet. Thinking it's between the float & valve assy, or there's a hairline crack in the bowl or the overflow tube.