Topic: luders new 750 project

[luder]

Pulled the pan and oil pump today, I wanted to get all that washed oil out of there. I was glad to see just a little carbon and no metal. Just changed oil, set my idle screws down to 1 turn and again after warm up she will idle when warm but she is still rough intermitten fire on #4 so we fouled another one-she sure stinks up the shop, also put the timing gun to her and it seems like we are on there. Any suggestions? I might try to make a little video and see if I can post  it....Thanks luder                     

[akinz]

I had an intermittant fire problem. I thought it was the coils since I wasn't seeing a nice thick blue spark, but it ended up being a couple of things with the carb.

1. The vent tube was clogged, and the hose was as well, which was puking gas out into my intake
2. The float height was too low
3. Took off the idle jet, mine is a 77 550 k with the press in idle jets, cleaned and soaked it with carb cleaner and compressed air, then did the same with the idle circuit.

It runs great now.
Hopefully that points you in the right direction.

[luder]

Thanks akinz, I have not pulled the pressed in jets and inspected them, but I have been reading about it. Would those being dirty cause your bike to run rich? Luder close but so far......thanks

[akinz]

It did run rich. Which I can't really explain that. When I pulled the plug it was wet or black and sooty.

If you take off the intake boots and look into the carb you will see two little brass tubes. I believe one is a main emulsion tube and one is the idle emulsion tube.

This link explains it well.
http://forums.sohc4.net/index.php?topic=65186.msg714654#msg714654

[akinz]

Sorry I didn't add, put carb cleaner through those emulsion tubes, take your floats, needles and seats out then blow with compressed air. You might need to repeat this a few times. I did this I don't know how many times, putting those carbs back on just to find that it didn't fix anything. Kept cleaning it and finally dislodged something when it started running on all 4 cyl's

Good Luck

[luder]

Thanks akinz- yesterday I pulled the carbs again, I pulled out the pressed in jets,cleaned (boiled,carb cleaner and a strand of copper wire,compressed air) all holes are open. Took out the emulsion tubes,etc etc. Carb cleaner and air thru all again. Put back on the bike (which I am getting pretty good at) wintergreen oil and xylene is one of the best tips Ive read. I tried to start her but she was fuel starved-Today I noticed no fuel would come out of the petcock on reserve, which I was happy with as I was going to pull the carbs again. So with the petcock on I started her up, when she would idle for about 3 seconds at 1100rpms then go up to 3000 for about 3 seconds then drop back to 1100-over and over with no variation, then I fouled #1 plug again. I hope somebody has had to happen and point me in some direction-much appreciated......luder     I will also put this in the regular forums.....

[akinz]

is the bike revving up on it's own? You may have a vacuum leak also. The o-rings that seat in between the cylinder and the intakes usually go hard and crack. I also had this problem it would idle real irratically.

Is there any rust in your tank? Mine didn't look bad at all but when I drained it and saw what was in the bucket afterwards I was shocked. Lots of little pieces of rust.

Did you say you checked your float height, and removed the needle and seat?

[luder]

Thanks again-yes it was a vacume leak.  OK I'm trying again-The idle increase seemed to be a leaking carb boot as she stopped after I modified some clamps. If this video works you can see I have to give her gas to get her started and she still seems rich as looking at my exhaust. Idle screws were out 1 turn as I tried to tape this-any suggestions-maybe check my valve clearance again,timing,etc,etc,etc   thanks luder- Yes I pulled the pressed in jets-tank is clean-heres the video

[luder]

Sorry trying again

[traveler]

Luder,

Keep your attitude up.....ANY progress, no matter how small....is still progress.

(That's how I have kept from just giving up, and selling all this stuff off!  Would have been alot easier to just go finance a new 600)

~Joe

[luder]

video try again

[Little_Horse]

I know I probably will be of no help, but the exhaust doesn't seem rich to me in appearance and the bike is cackling like it is extremely lean. Also, have you made sure all the plug wires are right? I don't know if yours have the numbers still on them I once had two of them mixed up and the bike ran it just didn't stay running and it sounded an awful lot like yours. I worked on my dad's 81 cb750 and it took me two months to get the carbs right (mostly becuase I was stupid and didn't hook the airbox up for a number of tries). That just to say hang in there you will find it.

[Ogri]

Sounds to me like any four cylinder Jap bike does when it's practically out of fuel: not enough fuel in the carburettors' bowls or just running lean due to air leaks. Have you tried sraying the intake rubbers on either side of the carbs with WD40 while it's running? Does the engine note increase/smooth out?

Air screws should be 1 3/4 - 2 turns out. Can't remember if 'out' is more fuel or more air - anybody ?

Biggest deal is the smoke though,.that doesn't look like fuel smoke to me - looks like oil smoke. You say you're continually fouling spark plugs ? My guess is the valve stem oil seals are perished and it's sucking oil down past the valve stems into the combustion chamber. That's what's fouling the spark plugs, IMHO. Four strokes don't foul plugs as a result of a rich mixture..surely ?  Are the plugs sooty or oily ?

[luder]

I found this forum, my bikes been covered up since my last post. I just ordered some aftermarket carb boot, I might have to get into this again. Where does the time go?

[newday777]

I found this forum, my bikes been covered up since my last post. I just ordered some aftermarket carb boot, I might have to get into this again. Where does the time go?

Welcome back aboard
What is the bike anyhow? All your old pictures have fallen off of viewing (probably dropped your picture host?)and no mention of what it was on the 1st page.

[luder]

Sorry 78, yes all those pics. every piece off the bike, painted etc. I jumped into it real hard and never got it to run minus a very poor attempt at idle. I have a small body shop and have had the spare time but it turned into a forgotten project. thought maybe I might look into getting back into it. Is inkscars still around? we swapped a few things back and forth. Decals, beer if ya can believe that, etc...When I get some time ill read a few of the things going on. Happy Holidays all...