Topic: Paddy - '78 CB750 - Version 3.0 Coming Soon!

[theofam]

I drilled the petcock "rivets" (see above petcock thread for all the info), tapped the petcock body and got it back together using 6/32" allen head screws. . . no leaks!


I ran around today getting an in-line fuel filter, fuel line and carb vent line (Honda shop), tank overflow line (Carquest) and fuel line clasps (second Ace Hardware had them).  Two hours later, I was back in the garage.

Got everything hooked up, and I tried to start Paddy with no luck.  I checked spark on the 1 & 4 cylinders and they were working.  So, I figured I'd try again with some choke . . . VIOLA!
1978 CB750 First Start

Paddy was running for the first time since about 1999!  The #1 cylinder was cold.  So, I pulled the plug and it wasn't sparking like it had earlier . . . hmm.  Tried a new plug - spark! - but no spark plug wrench to install the new plug.  Back to the old plug . . . spark!   Put it in the cylinder, started Paddy, again with the choke on, and the #1 pipe started to heat up.  Don't know what would make the spark so inconsistent.  Maybe a spotty connection at the coil?  Ideas are welcome.

So, with all four cylinders warming up, I decided to give it some throttle - Paddy instantly died! 

I got rid of the choke, and he started with the aid of some throttle.  In fact, he revved very quickly from 2-5K RPM.  I was PSYCHED!  Until I let off the throtte, and, you guessed it, Paddy instantly died!

If you have advice, I'm all ears!  In the meantime, I'll be searching the forum for answers.

[theofam]

I'm stumped.  I couldn't get Paddy to even start again.  I thought he might be flooded, so I decided to drain the float bowls and start over.  Plus, carbs 1 & 4 were overflowing, so I needed to adjust the floats.  I drained carb 4's bowl, and got this !@#$:


There are some black chunks/liquid mixed in with the gas!  I thought my petcock washer I made might not have been safe for gas.  Took it off and it's fine, hasn't swelled or lost any material.  I'm using 5.5mm fuel line I bought from Honda with an inline fuel filter.  The filter is clean.  This lead me to think it's the carbs.

I've removed the carbs and completely disassembled them.  I figured the black chunks were plugging the slow jets and not allowing the bike to get any fuel into the combustion chambers. . . wrong.  All four slow jets and main jets/emulsion tubes are perfect.  I'm left to wonder if my lines between carbs are safe for fuel.  They're not marked, so they're getting replaced with the fuel line I purchased today.  If that doesn't clean up the black garbage floating in my carbs, I won't know what to do!

Has anyone seen this?

[MoMo]

Yes, I have seen fuel lines disintegrate on my GL500I.  The lines were not fuel safe and the lining would go into the bowls and block the jets.  Never use lines that do not say fuel on them is my advice...Larry

[Stev-o]

In response to your spark issue, have you checked resistance of your spark plug caps?
And I would trim the plug wires too, if you have not already done so.

[theofam]

Thanks, Larry. I'm racking my brain wondering what else it could be. I'm really hoping the line I used was the issue.  I put a section of it in gas for a few hours, and it swelled to nearly double in size along with some discharge in the gas. Bingo?!

What's really affecting my sleep schedule is the carb jets were clean, so gas could easily get to the combustion chambers. But, Paddy simply wouldn't start again.  I'm thinking I could also have a timing or an electrical issue. The points are old and don't seem to be sparking as strongly as I remember on my high school VW bug. I'll replace them as well as put in fresh plugs.

I've the carbs reassembled, but I need fuel line before I can complete the entire assembly. 

I hope to get them on tomorrow. Today, my buddy Philip has located a free "450" for me to check out!  I've fingers crossed it's a CB. We'll see.

[theofam]

Stev-O, no, I haven't checked resistance on the spark plug caps. I'm an electrical moron and I'm not yet sure which setting to use on my volt meter to check that. Advice would be great!

I'll look into trimming the ends. I haven't done that, either. Yesterday was the "plug everything in and cross your fingers" day. I wanted everything to just work but realistically figured it would be more complicated. Otherwise, why would the PO (twice removed) have parked it?

[Stev-o]

Use the ohmmeter setting to check resistance. Do a google search for more info and specs.
Mine were bad on the 550, NGK replacements are only about $4.

Since the bike has not run in so long, a "3000 mile tune up" is highly recommended.
This will eliminate some guesswork on what your issue could be.

Good Luck...

[theofam]

I'll do the 3k mile checkup and go from there. Thanks for the ohmmeter tip.

[theofam]

I completed the 3K mile tuneup, except for condensors.  After getting the timing dialed in I readjusted the cam chain tensioner.  I put in new NGK D8EA plugs today and replaced the spark plug caps with 5K OHM caps.  I hope this is OK.  I couldn't find 10K OHM caps, even though those were stock on '78 CB750s.  So, I'm questioning if I'll have enough resistance (not sure what less resistance even causes/means).

Above I spoke about intermittent spark on my #1 plug.  I think I found the culprit:

That was my ground connector coming off the wiring harness for the bullet connectors off the coils, spiderweb ball and all.  One of the bullet connections was making inconsistent contact, and the other was literally wedged sideways into the plastic cover (which was intact prior to my slicing it for the photo).  I soldered a connector on from a donor wiring harness - hope it works!  Good news is this is the only wiring item that's been buggered up.  I think my other electrical issues are just bad connections (ah, the optimism of a noob)!

I reassembled the carb assembly and got everything buttoned up.  Then I reinstalled the carbs, airbox and tank.    Tried to start Paddy, and smelled gas . . . AGAIN!  Carbs 3 and 4 were overflowing out of their tubes, plus I noticed I had mistakenly installed carb 1's bowl on carb 3 and vice versa.  Off came the airbox and carbs.  Got them on the bench and adjusted floats on 3 and 4.  On went the carbs, and 3 and 4 were AGAIN overflowing!  Turns out I'm pretty sure it was because the carb drain screws weren't fully seated.  I hope to prove this tomorrow or Monday.  I've also got an inop accelerator pump, so I need to troubleshoot it, too.

I guess the good news is I'm getting much faster at installing the carbs, throttle/choke cables and gas tank!

[Stev-o]

Ok, sounds like your making progress. Isn't it a good feeling when you find a possible cause for an issue?!
Clean and check all elec connections while your at it.
Float issue could be wrong height or possibly sticking?

Good luck...

[theofam]

Stev-O, the floats all seem to move easily without dragging or sticking. 

My biggest question is how tight should the float valve fit in its seat?  All of my float valves slide in and out of the seat easily.  For instance, when the float is hanging with the carb upright, a portion of the float valve will slide out of the seat (maybe 1/3 to 1/2 its length).  As the float rises, it slides back into the seat and then the float arm starts to depress the float valve's plunger.  I think that's OK, but I'm not sure.

I also can't tell from the manual's photo what angle to hold the carb when setting float height, because the photo doesn't match the text. The manual reads, "Remove the float chamber and set the float arm as shown in the Fig. 6-7 so that it just barely touches the valve and in this position, check the position of the float with the gauge set vertically (italics mine)."  For the gauge to be set vertically, the carb needs to be upside down.  This also results in the highest shutoff point of the float valve, resulting in the setting most apt to overflow.

If I orient the carb in a more sideways fashion as depicted in the manual's photo, because of my float valves slide in their seats, the float arm just barely touches the valve at a much higher float setting than the 14.5mm required of these carbs.

I'm dreading the answer that my float valve seats are worn, because they weren't included in my Keyster carb rebuild kits, and I can't think of a place where I've seen them for sale.  So, do you start over with another set of carbs if this happens?

[Stev-o]

I have not used the Keyster kits, but have heard negative comments about them (sorry!)

[theofam]

I've had a busy few days. The carbs' floats are set (the clear tube to measure fuel level worked great). The bike is very cold blooded, which I understand is characteristic of the PD42B carbs. I popped the carbs off yesterday . . . AGAIN . . . pulled the bowls and blew out the pilot/idle jets. No need, they were still clean. I also blew carb cleaner through all the various orifices. Everything is very open. There's simply no way I can have an idle circuit issue. I buttoned everything back up and called it a day.

This morning I started on the dreaded electrical issues. My right blinkers and horn weren't working.  I couldn't for the life of me figure out the blinkers, so I figured I'd disassemble the left switch. Yuk, it was messy!
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The horn wasn't seated well, so I figured it might not have been grounded properly. Turns out it was that simple!  But, it didn't fix the blinkers . . . Hmmm.

I knew the front right blinker wasn't the issue, because the running light worked. I had power to the light blue wire off the switch, but when I connected it to the front and rear turn signals and idiot light, the voltmeter fell to zero. I figured I was missing a ground in the rear or the idiot light. First, I wanted to see if I could get power to the rear right signal.

I disconnected the rear light from the loom by the fender, stripped a wire on both ends, and held one end to the light's positive wire and the other on the battery's positive terminal - Holy Crap!  Fourth of July sparks off the battery!

I followed the positive wire back to the rear turn signal and it was severely pinched between the frame and fender. Here's the culprit - it's flatter that squirrel roadkill!


I cut out the roadkill and soldered a new connection, hooked it up, and I HAD RIGHT SIDE BLINKERS!!!

At that point, all electrical worked (for awhile). The clutch hasn't worked since I adopted Paddy. So, I pulled the clutch cable and lubed it. Got it reinstalled - nothing. I then adjusted the clutch itself, and , WOOHOO!! The clutch worked!

I turned on the ignition to marvel at my progress and NO NEUTRAL LIGHT?!  Even when the bike's in neutral?  Now, the only way to spin the starter is with the clutch lever pulled in - even when in neutral. This one really confuses me!  Ideas are welcome!  Troubleshooting resumes tomorrow.

[Jerry Rxman Griffin aka MuthaF'er]

WE ARE RIDING!!

Neutral light = neutral switch or the wire that snakes around and under the engine to it in all likelihood.

[theofam]

Jerry, you may be right!  I feel like I'm making progress toward riding with you and IT!

[theofam]

Sorry for the lack of updates. I've been scrambling to get Paddy running by Monday to meet up with the Relay crew!

I farmed out the rear wheel due to lack of time. It now has new bearings, new mounted and balanced tire and is trued. It's cleaned up and on the bike with a new sprocket. I get the dip$&@# award for thinking a 630 o-ring chain would fit. DOH!  I found a straight roller chain in town that I'll pick up tomorrow.

I had a stripped bolt on the front sprocket cover and couldn't drill the head off it with the transmission cover installed.  I proceeded to strip two of those bolts in the process (yes, I was using an impact driver). So, I drilled the heads off two of those. With tranny and sprocket covers off, I found years of 1/4" oil grime caked in there!  Tons of cleaning was involved. Although Paddy hasn't experienced a chain lash through the case, the case is a bit chewed up from either a loose chain or a yahoo installing a 630 o-ring chain.


I pulled the old sprocket seal by drilling two holes in it, screwing a wood screw into each hole, then grit teeth and yank!  I replaced it with a new seal, bu the install didn't go great. Some of it was sheared off by the lip on the case. We'll see if it leaks again - no time to redo it now!

The PG (previous goober) put orange silicone all over the tranny gasket - another fun, cramped removal process!  So, I'm awaiting a hex head bolt set to reinstall the tranny and front sprocket covers (after I mount the new chain tomorrow).

I also cleaned up the swingarm, lubed the bolt, and mounted it back up. I also installed new shocks I had planned on using for Seamus (bummer, guess I'll have to buy some Race Tech's for Seamus)!


I polished the tranny cover and drum brake cover (Dirty Jobs needs to do an episode on Polishing companies)!  Replaced these old pads where a spider family used to reside.
 

On to the aggravating neutral light. I pulled Paddy's spinal cord.

And proceeded to unwrap anything having to do with the neutral light. Continuity was a bit weak from the soldered splice to the headlight bucket, so I stripped, twisted and soldered a suspect area where the wrap was barely chafed. Wrapped it back up, installed the spinal cord and, WOOHOO, I have my neutral light again!

I now need to fix a few blinker issues (I hooked everything I. The bucket together too quickly late last night), then install the headlight and wrap up the headlight bucket trim.

I had my tank media blasted and picked it up yesterday. I plan on priming, bond, repeat tomorrow along wih getting the side covers primered. Unfortunately, I don't have time to paint, stripe, clear and buff before Monday.

I got insurance and tags earlier this week, so I'm legal!

I also owe Pamadori a BIG THANK YOU for getting me an ss cable for my front brake so quickly. I need to install it and bleed the front brake. I also need to adjust the clutch. It doesn't seem to disengage the clutch when the lever is pulled in.

So, lots of work done, lots of work to go by Monday!  My anniversary is Sunday, so I really need to be wrapped up by Saturday afternoon. Wish me luck!

[Stev-o]

Don't miss the Rally - it was a great time last week as it rolled through Texas last week!

Good Luck!


PS. Take the spouse out sat night to celebrate, then you'll be clear for Sunday to work on the bike!

[theofam]

Stev-O, good to hear you were able to join Texas' Relay team!

Nice idea on Sat night dinner, but we've plans through her work, so I turn into a pumpkin late Saturday afternoon. I'm gonna need eight arms!

[MasterChief750]

I had a stripped bolt on the front sprocket cover and couldn't drill the head off it with the transmission cover installed.  I proceeded to strip two of those bolts in the process (yes, I was using an impact driver). So, I drilled the heads off two of those. With tranny and sprocket covers off, I found years of 1/4" oil grime caked in there!  Tons of cleaning was involved. Although Paddy hasn't experienced a chain lash through the case, the case is a bit chewed up from either a loose chain or a yahoo installing a 630 o-ring chain.

ps the 78 750 came stock with a 630 oring chain

[theofam]

Man, am I glad Friday/Sat AM is finally OVER!  What a long day.  The daylight hours were spent setting up my makeshift paint booth:

 running to the paint store to buy lint-free wipes and etching primer, running to Steele's for a 630 chain, running to Ace for some headlight screws and back home for . . . UGH . . . bondo time on the tank!  I'm crappy at, er, let me change my attitude . . . I presently struggle with body work.  I thought the bondo felt smooth, but became apparent while priming the tank early this evening that it still needs work.  Oh well, it'll give me more practice.  It reminded me of my VW Bug in high school.  60 HP and 4,000 lbs - 2,000 lbs of which were my bondo handywork!

Earlier this week, I realized I had way too much to do to even consider painting, striping, clearing and buffing Paddy's bodywork to be able to ride this coming week with IT.  So, I ended up priming the tank, gas cap and lid, side covers and an extra seat pan I may play with a bit:


While the primered pieces were resting, I:

• installed the 630 non-o-ring chain (MasterChief, I didn't realize these scoots originally had o-ring chains, but there was no getting an o-ring chain on Paddy - he wasn't having it)!
• adjusted the chain about five times!
• rear axle torqued
• rear brake adjusted
• left exhaust pipe installed
• front caliper adjusted
• front brake bled (thanks to my helpful son)
• sprocket cover installed
• installed new gear shift seal
• tranny gasket and cover installed with hex-head bolts
• headlight trim polished
• headlight bucket all buttoned up with headlight
• installed chain cover
• reassembled tank with lid and gas cap
• installed tank
• installed side covers
• installed and cleaned seat
• installed seat lock
• all that, and what do you get???

BOOYAH!


I bet my face was priceless when I snapped the seat into place after finally installing the tank.  Paddy looks AWESOME!  But, I think he was spooked by something high up on the wall he was eyeing.

Still to do are:

• add fork oil
• attach license plate
• gas him up
• cross fingers for efficient internal combustion!

I'm going to bed!

[Stev-o]

WOW - incredible progress!  Consider putting a little oil in the cylinders before firing to help lube, it's been quite a while since last run, right?

I'm jealous, my K7 has set untouched for the last four weeks. At least my 550f is running.

[theofam]

Stev-o, I had Paddy running a few weeks ago when I originally installed and synced the carbs.  I didn't put oil in the spark plug holes, so it's probably too late for it.

I put some fresh gas in today and got the license plate on (lots of family commitments didn't allow me to get everything wrapped up).  Tomorrow, I'm going to fill the forks with oil and start Paddy up.  I'm not sure I have the clutch adjusted properly (doesn't seem to disengage when the lever is pulled in).  So, if I can also get that dialed in, tomorrow will be the FIRST RIDE!

I'll keep you all posted.

[theofam]

This morning I was able to get fork oil in the forks and started up Paddy.  Things were a bit rocky getting going, often stumbling and quitting at lower RPMs.  But, I hopped on the steed and off I went for the first ride!

Paddy ran OK for awhile then died on me at an intersection.  WTHeck?  Oops, helps to turn the petcock on!  He started back up and was stumbling around 4,500-5,000 RPM - made a mental note to tweak the main jets.  Paddy died as I rolled off the throttle coming up to a stop sign.  No problem, started him back up and away I went.  This time, he revved all the way up to 9K RPM without stumbling - maybe the earlier 4.5-5K RPM stumble was from sitting 12 years and now I was "getting the carbon blown out!"  I did this a few more times running through the gears up to about 80 - everything felt smooth and I was loving life!  Wow, my first build, and I'm a total rock star!!  Then, he died coming to another stop sign.  Took a few minutes to get him running.  Back to choke on to start him then push it off to be able to rev.  Paddy ran well until I got home.  Here I am in my post-initial-ride glory!  Check out my awesome new Bell 500 Stunt helmet I picked up especially for Paddy:


Ten minutes later, I figured, I've gotta go show my dad!  Off I went, and Paddy died at another intersection when I stopped.  Dangit!  Turn the petcock back on!  He started right up again . . . then . . . the trouble . . . started.

I needed to rev him up to about 4K to launch.  Even buzzing at 4-5K RPM, he started bogging down and would die.  I could drop the clutch while rolling down the road to start him back up, but it wasn't for long.  Then, it got to the point where I could only start him with the choke on, immediately turn it off to get some revs up, and take off at about 6K RPM, followed shortly thereafter by him bogging and quitting.  Finally, it got to the point where I didn't even have time to get him back in gear before he promptly fell from 6-7KRPM and died.

My legs now look like Eric Heiden after pushing Paddy home (luckily only about 1/4 mile). 

I'm guessing I either have a massive air leak, thereby only allowing him to run at high RPMs when more fuel is being pulled into the main jets, or my idle jets are plugged.  I'm really struggling with why Paddy was running through the RPMs for awhile and now it's simply not happening?!

Advice?  Otherwise, I think I'm off to pull the carbs . . . AGAIN!

[Little_Horse]

sounds like overflowing carbs to me, I could be wrong though but one way to check is to see if it starts running better for second or two when the petcock is off. Also check spark plugs to see what they look like. If they are fouled then you know there is an issue either with the main jet size or the float level. I was reading back through a few of your earlier posts regarding the fuel lines and I just wanted to say one little chunk of the line can block open the float needle it only needs to do this on a carb or two before the bike can't handle it anymore. Off with the carbs again I am afraid...

[theofam]

LH, thanks for weighing in.  I thought I was running lean, because my engine cutting out coming to a stop seemed consistent with folks running lean (most of them with pods, although I'm running a stock airbox).  However, you think rich.  I really need some lessons in reading the tea leaves, because I'm leaning your direction after seeing the plugs:

Cyl 1:

Cyl 2 (I really need a head gasket - check out the oil in the threads of this new plug):

Cyl 3:

Cyl 4:


They look pretty dark - Cyl 4 even looked fouled.  I had to pull the #4 plug early on and make sure the spark plug wire was seated, because its pipe was cold upon initial startup today.  It seemed to catch up in terms of heat after that, though.

I've pulled the carbs and will go through them tomorrow.  I checked the float bowl heights with a clear line a couple weeks ago, and they all looked great.  So, I'm hoping to find something glaring in the carbs. 

I'm also running 115 mains (110 are stock).  The air is thinner up here at a mile high, so I think I'll drop down to stock 110s.  That said, the '78s were set up to run lean for '70s emissions, so I jumped to 115s after hearing it'd be better for my motor. 

If it's not the above, I'm concerned my extremely leaky head gasket could be the culprit - being that compression is one of the four goodies I need for an engine to run.  We'll see.  If that's the case, my dreams of riding with IT this week are squashed (hope not).