Goin in, 79 carbs

daves79x
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Re: Goin in, 79 carbs

Post by daves79x »

Yes, should have said to put choke shafts in before joining halves. The rubber plugs just squeeze in with the help of a bit of lube. Assume you mean the pilot jet tower plug. Just grasp each old o-ring with needle-nose pliers and rip it off the tube. Alternately work a small screwdriver under each old o-ring and pry it off.

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Re: Goin in, 79 carbs

Post by EMS »

I was always curious...: When you drill and tap the pilot jets to pull them out, can you re-use them? Does the drilling and tapping affect the jet size?

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Re: Goin in, 79 carbs

Post by tevan »

EMS wrote:I was always curious...: When you drill and tap the pilot jets to pull them out, can you re-use them? Does the drilling and tapping affect the jet size?
You don't have to drill them. Just tap them with a 4/40 tap and screw your bolt with nut in it and the come right out. The jet hole is at the very bottom and the tap and bolt does not go down that far.

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Re: Goin in, 79 carbs

Post by FalldownPhil »

Or, you can just screw in a 2-56 screw. No tap needed. In answer to your question mike, Yes you can safely reinstall the old jets after cleaning, no damage done.
Best,
Phil
When you are up to your ass in alligators it is sometimes difficult
to remember that your objective was to drain the swamp !!

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Re: Goin in, 79 carbs

Post by whatscooking »

Got the two half's mated together with fuel hooked up testing for leaks, so far good, and the accelerator pump is squirting out all of nozzles good. I haven't put the choke plates in yet until I see no leaks. Really surprised how nicely the tubes hooked up between the carbs and went together.

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Re: Goin in, 79 carbs

Post by herdygerdy »

Be very sure to follow the shop manual procedures for aligning and tightening the carburettors onto the various mounting plates and doing them up strictly as per the procedure - a bit like bolting down the cylinder head on an engine and kind of for the same reasons.

In particular, when it is all tightened down, check the choke shafts and throttle plates for smooth operation from WFO to closed and ensure instant return to home position once released.

Tighten each very gently & slowly , little by little, checking operation after every step should see you through.

Have fun!

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Re: Goin in, 79 carbs

Post by whatscooking »

Going together smoothly but slowly. I have to work around/ with several other ongoing projects, retirement is a job.
I think I know how the accelerator pump spring and stuff goes back on but I want to ask. Is it the plastic piece then the little washer then the spring and then the cotter pin? I see it is suggested to stretch the spring out.
Since the engine is tilted to remove the carbs this would be a good time to look in at the valves and chains. But I do wonder if it would be a good idea to run this engine for a few miles to let things get back seated in as I know the bike has sit since 09 but it only shows 7100 miles. The first thing I did to the bike was to remove the oil pan plate to clean the screen and found very little residue anywhere. Assuming the combustion chamber and valves have deposits on them the valve clearances will be off. Tilting the engine seems to be no big deal.

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Re: Goin in, 79 carbs

Post by NobleHops »

whatscooking wrote:Going together smoothly but slowly. I have to work around/ with several other ongoing projects, retirement is a job.
I think I know how the accelerator pump spring and stuff goes back on but I want to ask. Is it the plastic piece then the little washer then the spring and then the cotter pin? I see it is suggested to stretch the spring out.
Since the engine is tilted to remove the carbs this would be a good time to look in at the valves and chains. But I do wonder if it would be a good idea to run this engine for a few miles to let things get back seated in as I know the bike has sit since 09 but it only shows 7100 miles. The first thing I did to the bike was to remove the oil pan plate to clean the screen and found very little residue anywhere. Assuming the combustion chamber and valves have deposits on them the valve clearances will be off. Tilting the engine seems to be no big deal.
Replace the valve guide seals if the head is off. I wish I had. I will before long. You could lap the valves lightly to ensure a good seal and I bet your valve adjustments would be just fine.
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)

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Re: Goin in, 79 carbs

Post by EMS »

With only 7,100 miles, the head and valves should still be rather clean and would not require the head to be taken off. However, as Nils pointed out, the valve stem seals are the weak point. The original material ages and replacing them with Viton seals may be a worthwhile thing to do, if you want to go through the effort. You need some special tools for this and one you cannot do without, is a valve spring compressor.

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Re: Goin in, 79 carbs

Post by herdygerdy »

whatscooking wrote:Going together smoothly but slowly. I have to work around/ with several other ongoing projects, retirement is a job.
I think I know how the accelerator pump spring and stuff goes back on but I want to ask. Is it the plastic piece then the little washer then the spring and then the cotter pin? I see it is suggested to stretch the spring out.
......Tilting the engine seems to be no big deal.
WRT the accelerator pump spring, the small washer goes on first and butts up against the small clevis pin located about two inches up from the bottom of the shaft. This gives the top of the spring something to seat against. Then the spring goes on, many stretch them out a bit to give it a bit more 'oomph' to operate the accel. pump circuit. Next on goes the white plastic sleeved collar - the end of the spring sits on the collar - and then (I recall but could be wrong) another small washer under the bottom of the spring, followed by the tiny cotter pin which secures the whole thing. Others here replace the spring entirely with another stronger one (perhaps from a braking system) and I have padded mine out with a bunch of extra flat washers to achieve a similar result.

Once you have it assembled, its a good idea to operate the throttle butterflies vigorously while observing the action of the accelerator pump circuit actuation from the rear of the carbs. Ideally, as soon as the throttle moves, the pump plunger should start to move. You may need to bend the tang sllightly so it has the smallest amount of clearance (ie; almost, but definittely not quite touching) between it and the top of the accel. pump plunger shaft.

You would be wise to check the valve clearances while you have plenty of access with the engine tilted. When tilting it back up, don't forget to re-install the earth HT lead that goes to the LH bolt of the starter motor just above the countershaft sprocket. Leave all engine mount bolts loose and you can then wiggle the engine around on the jack or lift it up/down a little just on the bolt to crankcase clearances on the holes so each bolt can at least be started and almost screwed fully home by hand. Be sure to clean and lube all threads on the engine mount bolts.

Keep us posted and enjoy the journey.....(and I want your 'job'!)

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Re: Goin in, 79 carbs

Post by daves79x »

On the '79 carbs, there is no 'first washer', and anyway, it has to go on before you join the carbs. The late model carbs have that washer. The plastic seat goes up against and seats into the plunger arm, the stretched spring, then the small washer and the cotter pin.

Final adjustment is to have no clearance between the pump arm and the plunger, then make sure the whole thing actually squirts fuel. Adjust the stroke by opening (decreases stroke) or closing (increases stroke) the fork.

Dave

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Re: Goin in, 79 carbs

Post by whatscooking »

Seams like there are just not enough hours in the day some times. I have been working along on this bike as I can. I went ahead and looked under the valve cover while I had her tilted and of course that means more tools and parts to buy and a whole lot of adding and subtracting. Did it by the book and found two intakes tight. No problem just order them :handgestures-fingerscrossed: . Got the shims one was right and one not even close, order more wait more rebuild a couple chainsaws kids and Christmas and so on and on. Found out I will check valves sorta by the book and sorta the way I think works from now on. Anyway, back together yesterday. Turned on the fuel, what a rush that is looking for fuel leaks the first time. A little cranking and she is alive although I hope that is not a rod knocking I hear. Didn't really thing it was so I had to go burn her out a little. Ran strong and really responsive but had trouble idling down. I had the tubes on and everything ready when I got back to do a balance, that's when things got tense. Everything I did seemed to make it worse even to the point I knew I was lost with the throttle screws so I thought I would just try to start from scratch some how, bad to worse. Well I had one of those walk away moments, already planning tilting the engine :sad-roulette: . Got up today, had some of the keep things at the home front happy type chores to do first then I go take another look.
I just adjusted the screws to the point there was no spring pressure fighting back on each in order hit the button and I could tell I was close. Hooked up my Motion Pro, by now I am getting pretty good with a screw driver and went to lining up the carbs. I couldn't wait to get the tank and seat on, low 30es around here today didn't matter I got gear. Wished I didn't need my full face and balaclava so I could hear better but I could tell things were hitting on all six. What a hoot this bike is to ride.

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Re: Goin in, 79 carbs

Post by NobleHops »

Nice post. Felt like I was turning the screwdrivers :-).
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)

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Re: Goin in, 79 carbs

Post by daves79x »

Thanks for following up on your carb rebuild. Not sure from your last post whether you think you got them synced or not. This is where careful bench syncing comes into play, and it's not covered in Mike's book. His is a guide to basic cleaning without separating the bodies and was written back in a time where that was mostly not necessary (O-rings were still in pretty good shape). But as time goes on, nearly all the original O-rings will start leaking, so separation is necessary.

Bench syncing is the most important part of this procedure and often overlooked. But sounds like you may be close this time. Let us know how it all works.

Dave

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Re: Goin in, 79 carbs

Post by whatscooking »

I believe that it is pretty close. I fired her up this morning with hardly any choke and right away was able to go to idle.

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