Topic: CB750 Lucky

[lucky]

I am having a very hard time to get the valve spring on and ke the keepers in place.

i made a special tool and it worked very well to get the spring compressed and get the keepers out- but putting them back in seems impossible.
Never had this much trouble.

If you want to read a very funny BAD SELLER story,  go there to "HF...Unbelievable" and read what happened when I tried to get a valve spring compressor.

[lucky]

OK...I modified my tool and increased the depth it would push down the valve spring by 1/8 inch and I finished the job very quickly.
Now I will get everything hooked up and ready to run the engine.

[lucky]

well I have been working on my engine test stand . I am making all the connections to get ready to start it up.
Just electrical now.
Click on photo for larger version.

[Freaky1]

Makes me wish I had kept my old oil tank in one piece! Looks good, I'm guseeing you'll come up with some type of chock for the wheels on your stand?

[lucky]

I will be holding onto the throttle. LOL

I tried starting it up. First thing the float bowls start leaking.... I tapped on them and in a minute or so they stopped leaking. GOOD. They all had brand new float needles after all.
Then It would turn over but I was not seeing any oil pressure. Started to freak out a little.
No pun intended LOL

I went down to the store and got ........wait for it, STARTING FLUID!!! Oh yeah.
Came back and gave it a couple toots of that. Bang! it ran for 15 seconds then quit.
My old tired car battery in the shop, was so weak it would hardly turn the engine over. I had oil pressure too now. GOOD. Feel'n better already.

I will wait till tomorrow and let the battery fully charge up.

[seanbarney41]

well I have been working on my engine test stand . I am making all the connections to get ready to start it up.
Just electrical now.
Click on photo for larger version.

....slick...

[lucky]

Thanks Seanbarney.

[lucky]

Today I took the carbs off because I felt that the engine just was not getting any gas.
plugs dry.
When I had worked over the carbs one of the most important issues is the idle jets. Making sure they are not clogged. I was afraid to take them out because they were the press in type.(I hate those). Anyway I was told by others how to get them out so I took a chance and got them out and they were all clogged. I had cleaned them out previously with a .010 guitar string but they must have got clogged up again.

I put it all back together hit the intakes with some starter fluid and it started and I was able to keep it running until it got hot. Now after I wait for my old shop battery to charge up I will start it again and try to get the carbs synched.

Then I will post a video for you. One small oil leak by the oil pressure guage I installed. Common. Other than that it seems good.

Getting ready to synch the carbs.

[akinz]

Now that is a setup all of us should have. I think thats my next investment, the engine stand. It would make everything so much easier.  I should have invested in dremel stock before you started your project. I'm sure they love you for purchasing all those wire wheels hahahaha

[lucky]

Right. I am glad I am getting all this straightened out before putting the engine in the motorcycle.

[Retro Rocket]

I haven't read your whole thread but if you are going to do the carb sink with the engine on the stand, use a pedestal fan to help keep the engine a bit cooler...

[lucky]

I haven't read your whole thread but if you are going to do the carb sink with the engine on the stand, use a pedestal fan to help keep the engine a bit cooler...

It does not take that long. Once it is warmed up it can be done in two minutes.
First start up and I calibrate the manometer.
Then I let it cool down a bit, and on the second run it is warmed up and all the adjustment screw nuts are loosened. (Cylinders 1,3,&4)

But you are right if it to be run for 10-25 minutes it should have a fan blowing.
I live in northern California and it is 60ºF during the day.

By the way it is not carb sink (like bathroom or kitchen sink, it is carb sync as in  synchronize  .

[lucky]

This morning I restarted the engine and this time I put the pod air filters on to do the final synch.

It is interesting to me that with just putting the pods on gave it immediate improvement of the throttle response. I will be drilling  the pressed in slow jets. They are #35(0.35mm) or about .013 thousandths. I will make them About #40(.040mm) or .014 thousandths.
I will use a #79 drill.

That is only about .001 larger.
I am also going to put shims under the needles.

[Retro Rocket]

By the way it is not carb sink (like bathroom or kitchen sink, it is carb sync as in  synchronize  .

Yeah, my mistake, Its been a long day....actually, a long week    

[akinz]

I will be drilling  the pressed in slow jets. They are #35(0.35mm) or about .013 thousandths. I will make them About #40(.040mm) or .014 thousandths.
I will use a #79 drill.

I would maybe order a second pair of slow jets... I have heard once you disturb the original precise tooling of the slow jet, it dramatically affects the way the bike runs if not drilled completely true. Just the swirls left from the drill bit can cause disruptions. I don't think it's worth drilling them. Your only using them for the first 1/8th of throttle.

[lucky]

By the way it is not carb sink (like bathroom or kitchen sink, it is carb sync as in  synchronize  .

Yeah, my mistake, Its been a long day....actually, a long week   

I did not mean to be too hard on you. My wife is a school teacher and we are always talking about language and how cell phones are changing our language and spelling etc.,. LOL

[lucky]

I will be drilling  the pressed in slow jets. They are #35(0.35mm) or about .013 thousandths. I will make them About #40(.040mm) or .014 thousandths.
I will use a #79 drill.

I would maybe order a second pair of slow jets... I have heard once you disturb the original precise tooling of the slow jet, it dramatically affects the way the bike runs if not drilled completely true. Just the swirls left from the drill bit can cause disruptions. I don't think it's worth drilling them. Your only using them for the first 1/8th of throttle.

How is that build of yours going?
I liked the yellow paint.
Not the foot brake though.LOL

I have drilled mainjets before and I have seen no difference in drilled jets from factory machined jets. It is just a hole. Thats all.

On my 1978 the slow jets are pressed in and there are no jets available.
That first part of the throttle is VERY important.
I used to race motorcycles and i want an engine that responds instantly to any amount of throttle no matter how quickly it is applied.
I do not want to "work with it"
See this video and this is what I mean by good throttle response.
Must See! Mean 572 BBC "Alien" Intake manifold Dyno. Nelson Racing Engines.

[akinz]

Build is going good! I got the crank, transmission etc all back together this morning and the cases back together.

I agree snappy throttle response would be ideal, I don't know myself, but have heard of buddies that ended up drilling the slow jets and since they didn't have them 100% level, it ended up ruining them.

I'll be interested in seeing the results of this. Let us know if there ended up being a change in response!

I noticed on mine that when I took the baffle out, which leaned it out, the throttle response was a hell of a lot better

[Retro Rocket]

By the way it is not carb sink (like bathroom or kitchen sink, it is carb sync as in  synchronize  .

Yeah, my mistake, Its been a long day....actually, a long week   

I did not mean to be too hard on you. My wife is a school teacher and we are always talking about language and how cell phones are changing our language and spelling etc.,. LOL

No offense taken.  Which by the way, could be spelled {or spelt}  with a c instead of an s, depending where in the world you are....

[lucky]

Build is going good! I got the crank, transmission etc all back together this morning and the cases back together.

I agree snappy throttle response would be ideal, I don't know myself, but have heard of buddies that ended up drilling the slow jets and since they didn't have them 100% level, it ended up ruining them.

I'll be interested in seeing the results of this. Let us know if there ended up being a change in response!

I noticed on mine that when I took the baffle out, which leaned it out, the throttle response was a hell of a lot better

I will go back and check out your thread. I want to see that.
As far as drilling out this slow jet I am just running a drill bit through an existing hole and making it only .001 larger. About the thickness of a human hair. No problem.

[lucky]

Monday I should have the carbs back together and they will have 4 upgrades.
Slides cut by Cycle -X, Shims under the needles, drilled pilot jets, Throttle spring loosened up to get rid of that heavy feel.  I made sure the check ball in the accelerator pump is working too. Then re-sync.

[lucky]

Working on the carbs.

Had the engine on the test stand with the carbs all hooked up and running.
I could not get it to start without starter fluid.
The slides have been cut down now and i thought everything was good.
Finally I thought about the problem and I did not see any gas squirt out of the accelerator pump nozzles.
I removed the accelerator pump and cap there is a square brass plug in a round hole and I lightly pried on the 4 sides gently and finally the little square plug came out with a spring on it. Down in the hole I could see a steel ball. when I tried to dump the steel ball out of the hole it would not come out.

I was VERY happy because i had found something actually wrong with the carbs !!!
I GENTLY pried on the ball with a minature screw drier and the little steel ball finally fell out. Half of it was covered with black gunk.

So i am on the path to finally getting these carbs to work correctly.
CLICK on photo for larger photo.

[akinz]

I don't really know too much yet about accelerator pumps, does the ball kind of act as a float and seat as to let gas into another circuit or to increase/limit flow through to the carbs?

[lucky]

I don't really know too much yet about accelerator pumps, does the ball kind of act as a float and seat as to let gas into another circuit or to increase/limit flow through to the carbs?

No it is just a spring loaded ball to keep the flow only going one way. Like a check valve. When you pull the throttle it pushes a rod down and pushes on a diaphram which squirts fuel out of the SIDE of that tube sticking up in the venturi.

I personally do not like it,one more thing to go wrong.
Motorcycle carbs never had it before and the motorcycle worked fine.
Just gets more complicated and more little things to get clogged up.
On a car it is ok because all of the passages are huge.
Also this design is not really meant to be fixed and they do not sell the parts.

[GRock]

Hey Lucky,
You had better luck getting that pump apart than I did, good job. But you can get a new at www.babbittsonline.com. Not cheap though, lists for $75.88 but they sold it to me for $56.56 about a year ago.