Roxy: Free at Last!

Finally got around to freeing up the stuck float pins in both Roxy's first carb as well as the spare that came from the PO.

To brace the posts, I used a small piece of the scrap 22ga steel from the alternator cover project and cut two notches with the cutting wheel, taking only a little material off at a time so as not to overcut.

Then used a C-clamp to start the pin moving, one end braced on the steel and the other one pushing the end of the pin.  Once I got one end flush with the post, I used a wooden punch to knock it out further.  Finally pulled it free with some needle nosed pliers.  Started with the S90B carb.  For reference this carb has 85/35 jets in it at the moment.

Able to get to the 1.7 float pin for the very first time.

Then went on to the S90K1 carb (Roxy's first carb) and found the pin had notching that matched notches inside one of the posts.

Also discovered, and this was somewhat expected, that the needle jet is unmarked.  Not only that but even though it's "close" to 8mm, an 8mm socket does NOT fit it!  Luckily the socket fit just enough to get it loose. For reference, this carb has the 85/38 jets that came out of the CS90C carb that's in Roxy now.

The tool itself was remarkably simple but completely effective.

Astrid: 69 Cents Saves the Day

Thankfully, a $0.69 rubber #14 o-ring from the hardware store solves Astrid's carb leak.

Roxy: Quick Fix

It's been a couple months since doing any serious work in the garage; took some time off since doing all the work to fix Roxy's carb issue.

But today I had nice weather and all the time in the world to work.  The clutch cable replacement took all of five minutes, given that the new cable I'd bought awhile back for Viola was a perfect match to the one that broke.  Slipped right into place.  I tested the shift into first and neutral, and it felt the same.  Will need to do a quick road test to check all the gears.

 

Roxy: You Always Remember Your First

First breakdown!  On the way home after a nice afternoon ride, and I felt something snap when I pulled the clutch in.  Next thing I know, the lever is moving freely.  Clutch cable snapped right at the lever.

Luckily she broke down on 40th and Clement, and it was all downhill to get home.  So I ended up pushing her all the way back, sometimes riding her like a bike on the particularly steep sections.

Roxy: The Smallest Things...

Did the simplest thing first to check the racing idle, and found the throttle screw was very loose.  Removed it and found the spring was missing!  Obvious...  Re-adjusted and got back to a gentle idle speed.

Will need to test it on another long ride...


For reference, the throttle screw is backed out 5/8th of a turn.  The air screw is 7/8th out.

Roxy: No More Leaks

Whew... the oil leak at the breather hose really was just a case of the hose being loose.  When I detached it, I found that the rubber had become rock hard at the end.  Is it possible that it was baked by the overheating engine?  Being rigid it must have then leaked.  I snipped off the hardened portion and reattached the now pliable end along with a ziptie.  Problem solved!

Roxy: Sizzling!

After Wednesday's ride, noticed that oil was leaking from the intake cover again.  Also, water would sizzle on the fins of the head, which I'd read was a sure sign of an overheating engine.  A lean mixture can cause overheating, and it seemed probable that switching back to stock jets had leaned things out too much.

I was hoping for an easy fix, so I just swapped out the stock jets with the silver ones that were in the bike originally.  So now I have the two silver jets in the "C" carb.

She started up cold on one kick after the swap, but wouldn't idle until I dialed in the air screw.  It's now only 7/8 turn out!

Rode Balboa again today, and was worried when I saw the oil leaking again on my way back.  I thought the oil leak was another symptom of the overheating.  But after getting back to the garage, I found that water wouldn't sizzle anymore.  The head was definitely much cooler.

The oil leak is still worrying.  I wonder if the overheating may have distorted the rubber or somehow caused it to loosen up.  I'll just try tightening things up first.

So now it looks like the silver jets are larger than the stock 85/35.  I just ordered some micro drill bits so I can figure out exactly what size they really are.  You find the largest drill bit that fits through, then you measure it with a caliper.

Roxy: Idle Problem Fixed! (sort of)

Hallelujah, she runs!  But I cheated a bit in that I just swapped out the carb with Viola's carb (labeled CS90C), which I'd already cleaned.  She started up and ran like butter.  Actually had a better, lower purring sound than with the old carb for some reason.  Idled strong for 5 minutes with no signs of hesitation, and it was a warm day so I think the running rich issue is gone.

I suppose I'd still like to figure out what's wrong with the newer carb, but first I'll have to figure out how to remove the stuck float pin.


First thing I did since the engine was cold was to check valve clearances.  Happy to see they were .002" on both intake and exhaust.  Also learned from the forum that the reason the PO probably added the breather tube was to accommodate a bigger cylinder or higher RPM.  Since there's a piston in the old parts bin from the PO, I wonder if the cylinder has been bored out.  We'll find out eventually.

Beautifully clean alternator compared to Viola's.

Then did a compression test for the first time.  Again, thrilled to see that I was getting 120 on a cold engine, especially since I was worried about an oil leak into the cylinder.  Odometer at 17,571.

Noticed there was this hole in the bottom of the muffler, though it seemed like someone put it there on purpose.  Another PO mod to increase breathing?

Also took the opportunity to switch to the new shorter filter (Visu-Filter Mini) that came in the mail today.  Much easier to squeeze between carb and petcock, and doesn't kink the line.

And finally everything installed.  Whew.  She idled and revved smoothly, but I'll have to take her on the road to really make sure everything's sorted.

Roxy: Carb Swap?

It would be nice to replace the carb entirely just to see what happens.  If it's the exact same problem (stalls at idle when warm), that's a big clue. 

Then again, I don't know if the replacement carb has problems of its own.  I'd really need to take a carb from a good working bike to be sure.

But as a test, I suppose it can't hurt.  So I started prepping the "C" carb (Viola's original) for duty.  Tested that the floats worked and then she was water-tight.  All in all, she looks to be in good shape.  The only problem I found is that due to heavy corrosion on the back threads, the throttle screw doesn't want to screw all the way in.  But it does go in far enough to just barely lift the slide.  So maybe that's enough.


Testing for leaks.

Testing to make sure the floats aren't leaking.

Roxy: Stalling when Idle continued...

Today I swapped out the slow jet with the Keyster one.  No change.

Swapped the air intake along with the gasket and insulating rubber, just to rule out leaks.  No change.

But did notice something new.  The bike actually idle ok (a little ragged, but held on) for about 2 minutes, when the engine got warm.  That's when she started to want to stall.

At that point, I happened to pull the throttle slide out, and white wispy smoke came out of the top of the carb.  It wasn't just one puff, rather it continued for 30 seconds or so.

I then pulled the plug and noticed it already had oil on the node, despite being only a day old.

So definitely seems that I have oil leaking into the cylinder, the question is just whether that is also affecting the idle problem or not.


The replacement intake is the one from Viola that I had painted with engine paint as a test.  The insulating gasket is in a lot better shape than the original one.

Roxy: Nothing Worse than Intermittent

There's nothing worse than a problem that is sometimes there and sometimes not.  After spending an hour last night where the bike would not hold idle for more than 10 seconds, today she idled strong off a cold start and never even wavered.

The one thing I did was I jury-rigged the choke handle lever back on using electrical tape followed by a zip-tie.  But with the engine running, I pulled it off to see if that caused an air leak, but the engine continued to idle strong.

The only thing I can think of is that overnight, the stoppage in the slow circuit dissolved away.  But if that's true, it means it could come back at any time.  I should change the fuel filter and clean the air filter just to be safe.


Not pretty, but I'll put a good one on eventually...

Roxy: Not So Fast!!

Arrrghhh!!  Starting her up again today and she won't hold idle anymore!  I rode Golden Gate Park yesterday and she idled beautifully start to finish.  But now I'm getting the exact same exact symptoms as before.  I repeated my steps from Friday to clean out the slow jet and circuit, figuring maybe it just got clogged again (in which case I'd know I'd have to replace the filter).  But even after a cleaning, there was no change.

Again, I tried messing with the screws, but it was either a weak idle, or a racing one.  There never seemed to be anything in-between.

Troubleshooting brainstorm:

1. Maybe it was the long ride yesterday that actually just gunked up the circuit again, maybe more than just the WD40 spray could fix.  Maybe I should replace the filter, clean the circuit out yet again (I just realized I didn't spray out the air screw hole), then if she holds idle after several rides, I know it was gunk from the tank getting through the old filter.  I guess if I clean out the air screw hole (thereby repeating ALL the steps from Friday) and she at least holds idle for awhile, then that would prove that it's just getting gunked after a long ride.
2. I noticed the rubber gasket on the choke handle was ripping off.  If that creates an air leak, then there's my problem right there.  Wondering if I can temporarily seal it with vaseline just to test it.  But then again, I think it was ripping this whole time, so surely it was in bad shape even for yesterday's ride (in which case, it has no effect on idle).
3. Replace the kinked throttle valve spring.  It's possible the weak idle is just a bad setting of the screws.  Maybe when it races, that's the correct screw setting, and maybe it's the racing idle that should get fixed.  The racing idle could be a sticky slide.  But then again, she ran fine yesterday.
4. I prepped the original carb (labeled S90B) that I cleaned yesterday with new parts from the Keyster kit.  I can swap it out, but since I might need to cut the old fuel lines, I should be ready with new tubes and a fuel filter.  One difference is that the S90B has the fuel line on the opposite side of the carb body.  Just for reference, Viola's carb is labeled CS90C.
5. Finally, I'll just try pulling the current carb (labeled S90K1E05) and give that a thorough Pine Sol dip.
6. It may also not be the carb at all, but rather a faulty advance unit.  But given that the problem was intermittent, seems like it must be the carb?

Here's Roxy's original S90B carb cleaned, rebuilt, and ready to go.  I took the intake (the one I painted), gasket, and insulator Viola's carb.  From the Keyster kit, I used:

1. air screw
2. throttle screw
3. slow jet
4. main jet
5. bowl gasket

I also replaced the intake gasket (finally opened the gasket set), hoping it could be a simple air leak, but no luck there.

Keyster Carb Rebuild Kit

Photo reference.  Everything you get in a Keyster kit.  Fourteen pieces (if you count everything on the float set as one thing).

So far I've used:

1. Bowl gasket (in Roxy's "C" carb)
2. Throttle screw spring (in Roxy's "C" carb)

But also added back a throttle screw spring from eBay I'd bought awhile back.

Roxy: Pine Sol Soak

Since my head was into carbs, I decided I may as well attack the gunked up original Keihin carb that came from the PPO.  It was such a mess that the two halves wouldn't even separate.

Bought a big jug of Pine Sol and just dunked the whole thing, letting it soak for 2 hours.  The pictures pretty much say it all.  The Pine Sol worked miracles.  Now I'm thinking I could use the same technique on some of the other engine parts, maybe even the bottom end.

Unfortunately, I found the float pin wouldn't budge.  I know you can try to knock it out with a punch, but since the posts are easily damaged, you have to support them and do everything very carefully.

Also, the intake o-ring had been sealed into place with some white rubber cement type substance, which was used in a lot of other places to seal gaskets. 


Before...

Two hours in a Pine Sol bath.

And after...

 

Roxy: Mechanical Milestone

All right, so I did fix the brake lights earlier, but let's face it, that was an electrical issue (and a rather simple one at that).  This time we worked on the carb - perhaps not true "engine work", but certainly another significant baby step toward the goal of a complete engine overhaul!

During yesterday's ride, I noticed that problem again where she just wouldn't hold idle.  She was good for about 10 seconds before before stalling. I rode the whole loop through Golden Gate Park feeding her throttle the whole time.

I checked a couple of easy things that night.  Battery voltage was still good at 6.4V.  Also, I tried using the air and throttle screws to see if that did anything.  It barely had any effect.  Based on a lot of reading on the S90 group, that symptom pointed to a clog in the idle circuit.  (For reference, the screw settings were 2-1/4 out for air, and 3 full turns out for throttle).

So today, I actually opened the carb up.  Was a little nervous, despite having opened and dismantled the carbs on the other bikes dozens of times.  Again, it's different when you're working on the bike you actually ride versus one that just sits in place.


A reference shot of the screw settings.

The drain screw comes out.  After the gas had drained from the bowl, I realized that there was still plenty of gas left in the filter and I realized it was being held there by vacuum.  Next time I suppose I could run the engine with the petcock closed and thereby drain it completely.

Inside, the carb is actually nice and clean.

And here's the culprit, the slow jet.  I couldn't see daylight down the length when I first took it out.  Also noted that these are definitely not factory.  And they didn't even have a size on them.  I suppose it would be nice to clean up the original carb and get it back in, but then again, if this carb works with this engine, maybe there's no need to muck with it.

Pine Sol soak for a few minutes, followed by WD40 and then air.  While that was soaking I also checked the entire slow circuit by doing these 3 steps:
- with the air screw removed, shoot WD40 into the inlet and it should exit through the screw hole
- with the screw back in and the slow jet removed, shoot WD40 into the inlet and it should exit the slow jet hole
- cover the slow jet hole with your finger and shoot WD40 into the inlet and it should exit into the chamber

All back together, and then the moment of truth.  Took a couple of kicks to start her and I was sure I'd buggered something up.  But then she fired, and wouldn't you know it - SHE IDLED!

And in conclusion, don't run in Reserve unless you have to!!!  I think that's how it ended up clogging in the first place.