Topic: fmctm1sw: 1981 CB650 custom AKA The Nifty 650

[fmctm1sw]

Well, Sunday was start up day.  Although I had it running before I considered this a "first run" since the actual gas tank is being used.  Since I'm still waiting on my choke cable, I held the choke closed and it started after a few seconds.  Ok, problem number one.  Petcock leaks but thankfully only in the "on" position.  So I teaked on that for a little.  Started it up again and found it dies the minute you give it any throttle.  Also a little popping now and then.  The timing was good but I took it all apart anyway and cleaned the advance mechanism and points shaft.  After all that, I realized I never turned the fuel back on.  So...  got it going again, all pipes hot.  Running much better but I notied the small screw I used to plug the carb #2 connection (temporary I assure you) to the (removed) fuel pump was trying to spit the screw out.  Hmm, valves too tight?  I set it according to my manual and found all of them were tight.  Possibly from the PO tightening the lock nuts and having the adjuster turn with them?  Normally, when all of the valves don't seem right, it's just me doing something wrong.  Didn't seem like it this time though.  I'm certain I was at TDC compression stroke when I started (I watched the intake valve).  I don't know if I'm going to try running it again before I get the choke cable.  I did get a disk brake caliper as well that hopefully I can salvage the piston out of.

[fmctm1sw]

I got the brakes cobbled back together and my master cylinder seems to be working too.  I'll bleed the brakes this weekend.  I think I posted about my riding experience before but in case not, I have issues at anything approaching more than about 1/4 throttle.  I decided to go back to stock exhaust.  I picked up a left side of the original 4 into 4 and it's on the way now.  I decided to sell my 4-1 that's on it now and as I started to removed it from the head, more surprises awaited me.  It was missing half the exhaust studs.  The rest were just bolts threaded into the head.  I was able to chase all the threads except for one that looks like it was stripped and tapped way off center.  Hopefully a helicoil will resolve that for me but the hole is a mess.  Luckily I had studs from some other old four that worked.

[wedoo2]

Did you replace the accelerator pump?  I see the mention of it earlier but not sure if you did it.  Also, I take it that you cleaned all of the carb passages good with carb cleaner and compressed air.  There are so many danged things that can cause your problems that you have to look at it all.  Timing, plugs, carbs, valve adjustment.  But, you are being methodical.

[fmctm1sw]

Did you replace the accelerator pump?  I see the mention of it earlier but not sure if you did it.  Also, I take it that you cleaned all of the carb passages good with carb cleaner and compressed air.  There are so many danged things that can cause your problems that you have to look at it all.  Timing, plugs, carbs, valve adjustment.  But, you are being methodical.

Yeah, I put a new accelerator pump in it.  I'm trying to figure out how to make sure it works properly though as the carbs are already on the bike and I don't want to take them back off.  It ran much better with the choke on leading me to believe the main jets were too small.  All of the "3000 mile" type stuff was done.  Timing, valves, etc.  The carbs were completely cleaned as well. 

[wedoo2]

You mentioned earlier that the fuel pump was goofing up.  Maybe that is the source of your problems.  Do you have an inline filter?  Those can be suspects.  I understand about removing the carburetors, good way to loose your religion.

[fmctm1sw]

You mentioned earlier that the fuel pump was goofing up.  Maybe that is the source of your problems.  Do you have an inline filter?  Those can be suspects.  I understand about removing the carburetors, good way to loose your religion.

I took that pump off and ran a line (through a new filter) straight to the carbs.  I have the left half of a stock exhaust coming so once I find the other side, I'll see what the exhaust does.  On another note, I got the brakes working today!

[Killer Canary]

Are you sure that's an accelerator pump and not the vacuum switch?

[fmctm1sw]

Are you sure that's an accelerator pump and not the vacuum switch?

Ah.  Yeah, the vacuum petcock is what I removed.  AS for the accelerator pump, I have to figure out a way to see if it's working with the carbs still on the bike (if possible)

[Killer Canary]

Acc. pumps were covered fairly thoroughly in "750 Lucky". G'luck.

[lucky]

Did you replace the accelerator pump?  I see the mention of it earlier but not sure if you did it.  Also, I take it that you cleaned all of the carb passages good with carb cleaner and compressed air.  There are so many danged things that can cause your problems that you have to look at it all.  Timing, plugs, carbs, valve adjustment.  But, you are being methodical.

Yeah, I put a new accelerator pump in it.  I'm trying to figure out how to make sure it works properly though as the carbs are already on the bike and I don't want to take them back off.  It ran much better with the choke on leading me to believe the main jets were too small.  All of the "3000 mile" type stuff was done.  Timing, valves, etc.  The carbs were completely cleaned as well.

Because it ran better with the choke on does NOT mean the mainjet is too big.
The idle jets could be clogged and it will have the same symtoms,( as mentioned)
To check the function of the accelerator pump nozzles, make sure the float bowls are full and the engine is OFF, just turn the throttle a couple times and the brass tubes in the venturi should squirt gas. You will need a bright flash light.

[fmctm1sw]

I gained a lot of insight from Lucky and F16Viper's threads.  I made the mistake of locating the spring for the accelerator pump on top of the diaphram instead of under it.  Judging from F16's thread, my accelerator pump shaft appears to be too long also.  I also didn't clear the accelerator pump passages.  The nozzle is on the front (pointing toward the slide) so when I looked at them, I assumed they were just dummy brass plugs.  Once I understood how it worked, I was able to figure out what was happening.  Once that's all cleared up, I'm going to look at the linkage again because of some questions I have over washer placement.  But I'm confident now this is going to run well.  And nothing like doing stuff wrong and learning the hard way...

[ABikeNamedTrouble]

Yeah, carbs are usually a headache but it sounds like you're getting it done!  I love the blue tank; look exactly like mine except mine's black.

Quick tip:  make sure you get the air cleaner duct to mount properly to the airbox/manifold.  (You can see it's bent out of place in one of your pics).  I used some weather-stripping glue and a couple carefully placed drywall screws and it worked like a charm.  Went a long way towards keeping my carbs balanced!

 

[fmctm1sw]

Well, so much for confidence.  I shaved a mm or two off the pump shaft and had carb cleaner flowing through the nozzles.   I put it all together and...  nothing.  The only thing that happened was gas started flowing out of carb #4 (not the nozzle but the venturi) somehow.  Based on some reading in the other threads, my check ball in the bottom of the pump may be dead causing the fuel to be forced back into the bowl of carb #2?  Unlike others I've seen, that ball and spring in the bottom of my pump will not come apart.   

[fmctm1sw]

Well, after finally prevailing over the frustration of my accelerator pump I turned my focus to the fuel tank.  There was a liner in there but I could see rust and fuel coming out of the tank was going to immediately foul the bowls.  MEK seemed to be recommended here so I bought a gallon ($23) and put it in my tank.  It immediately went to work on it.  I cut up an old chain and threw a hunk in it.  It's going to sit for a few days but I'm well on the way to a clean (if not pinhole'd after I derust it) tank..  Photos added.  You can see a brown cesspool at the bottom.

[F16Viper68]

Well, so much for confidence.  I shaved a mm or two off the pump shaft and had carb cleaner flowing through the nozzles.   I put it all together and...  nothing.  The only thing that happened was gas started flowing out of carb #4 (not the nozzle but the venturi) somehow.  Based on some reading in the other threads, my check ball in the bottom of the pump may be dead causing the fuel to be forced back into the bowl of carb #2?  Unlike others I've seen, that ball and spring in the bottom of my pump will not come apart.   

I'm sorry to hear your accelerator pump issues continue.  Believe me I know that particular pain.  I had my carbs apart today (rejetting) and thought you might find some photos of how mine sits in the housing useful.





Dave...

[F16Viper68]

Well, after finally prevailing over the frustration of my accelerator pump I turned my focus to the fuel tank.  There was a liner in there but I could see rust and fuel coming out of the tank was going to immediately foul the bowls.  MEK seemed to be recommended here so I bought a gallon ($23) and put it in my tank.  It immediately went to work on it.  I cut up an old chain and threw a hunk in it.  It's going to sit for a few days but I'm well on the way to a clean (if not pinhole'd after I derust it) tank..  Photos added.  You can see a brown cesspool at the bottom.

If you are able to get the rust and crud out of the take I would highly recommend you seal it with POR-15.  I discovered I could get the tank clean with muratic acid but as soon as it was removed the tank would flash rust.  I've had no issues with POR-15 so far.

Dave...

[fmctm1sw]

Dave, I actually got the pump figured out and squirting fuel.  I posted some things in the tech forum instead of here.  The carbs are on the bike now but I still need an exhaust pipe.  I have the sealer portion of a POR-15 kit on my shelf that I plan on using.  I did a tank about 3 years ago with POR-15.  It's still spotless.  I saw your thread.  Good to see yours on the road!

[F16Viper68]

Dave, I actually got the pump figured out and squirting fuel.  I posted some things in the tech forum instead of here.  The carbs are on the bike now but I still need an exhaust pipe.  I have the sealer portion of a POR-15 kit on my shelf that I plan on using.  I did a tank about 3 years ago with POR-15.  It's still spotless.  I saw your thread.  Good to see yours on the road!

Awesome, glad you got it figured out.

Yeah, I can't help with the exhaust.    Although I have seen some aftermarket kits but they are expensive as heck! 

On the road and trying to get it perfect before I rip it apart to sandblast and paint the frame. 

Dave...

[fmctm1sw]

More tank work for me.  After soaking in MEK and rattling an old chain around in it for the better part of 3 days, I tried to drain and filter the MEK so I could use it again.  that didn't work very well so I just dumped it all back into the can unfiltered.  I figured I give it another soaking after I washed out the tank.  I was afraid the stuff would clump back up inside the tank with the garden hose water.  And it did, but not to the point I expected.  There just wasn't much liner left in it.  It created a lot of small balls that reminded me of how a shingle feels when I picked one up.  The MEK did a great job on the old liner.  I rinsed it for a while and got all of the larger chunks out.  A small dusting of liner remains in spots so I hope with one more MEK soak (and 1 day probably would have been plenty) I can get all that softened up and out.  Then the derusting part...

[fmctm1sw]

Here's the latest tank photos. I planned on one more MEK soak but I spilled it everywhere (see other thread).  I put 1 bottle of the Works toilet bowl cleaner in it and filled the rest with water.  It sat over night.  I dumped it out, blasted it with the garden hose and refilled it with 1lb of baking powder and water to the top.  I let it sit all day and drained it.  There are still some stubborn spots where the old liner is stuck to.  I picked up this stuff called Naptha (?) at Lowes the other day.  It was half the cost of MEK.  I'll let it sit overnight and look at it in the morning.

[fmctm1sw]

Just a quick note while I'm on the simple green soaking stage.  I picked up these little LED flashlight things with flexible handles at Harbor Freight today.  They are very handy for looking inside your tank.  http://www.harborfreight.com/2-piece-flexible-shaft-led-light-95414.html

[F16Viper68]

Whoa!  I just remembered I left a tank filled with muriatic acid soaking in the backyard. 

Dave...

[fmctm1sw]

Whoa!  I just remembered I left a tank filled with muriatic acid soaking in the backyard. 

Dave...

I'm back to the solvent stage, I'm using Xylene this time.  It was a little cheaper.  Then one more soaking with simple green and then a final toilet bowl cleaner/water soak. 

[F16Viper68]

Whoa!  I just remembered I left a tank filled with muriatic acid soaking in the backyard. 

Dave...

I'm back to the solvent stage, I'm using Xylene this time.  It was a little cheaper.  Then one more soaking with simple green and then a final toilet bowl cleaner/water soak.

Well after three days of soaking in muriatic acid the liner is still in there.  It's loose but there's not way I can grab the pieces and pull them out of the bottom of the tank.  There has to be a way to dissolve this crap. 

Dave...

[fmctm1sw]

Whoa!  I just remembered I left a tank filled with muriatic acid soaking in the backyard. 

Dave...

I'm back to the solvent stage, I'm using Xylene this time.  It was a little cheaper.  Then one more soaking with simple green and then a final toilet bowl cleaner/water soak.

Well after three days of soaking in muriatic acid the liner is still in there.  It's loose but there's not way I can grab the pieces and pull them out of the bottom of the tank.  There has to be a way to dissolve this crap. 

Dave...

Dave, one of the things I picked up reading here is that you need a solvent like MEK to dissolve a liner.  The MEK and xylene worked well on my tank liner which appeared to be Kreem.  I managed to spill some xylene too but I think I'm going to have a real good surface to seal after repeated uasage of solvents, degreasers (simple green), and acids (toilet bowl cleaner).  And those little LED lights have already paid for themselves.  I've never been able to see that far into a tank...  Oh, and rinse with hot water.  The garden hose works well but I thinnk the colder water caused some of the liner to lump and string back up.