Carb soak

[uncledj]

I'm focused this Winter on turning some of the old projects I've laying around into functioning machines again.   Got my old Polaris 4 wheeler sorted out and ready for action...been sitting for 3 or 4 years.

Got a 10k generator back up and running after (someone else) left it sitting for about 5 years.

Now I'm working on getting my old Honda Nighthawk 700s back up and running.   It's been sitting about 6 years.   I had Seafoam in the gas back then, and now, with a tank leak, had no gas in it.   I loosened the bowl drain screws on the outer carbs and it appears the bowls are dry as well.

I'd like to fill the bowls and let them soak for a day or three, but don't know what I should use.   I don't think Seafoam is meant for actual cleaning....I know some carb cleaner is not friendly to rubber parts.

SO...What should I fill the bowls with to dissolve any varnish that won't damage anything.....???

Edited January 10, 2021 by uncledj

[luvmy40]

Berryman B-12

Don't leave it too long, it is fairly aggressive. Just follow the MFGs directions.

[cowpuc]

Hi Unc!! @uncledj , those Nighthawks were fine scoots - you got yourself a worthy project there of which I implore you to work thru it step by step and end up getting to experience the breeds real/full potential.  Because of that Honda's vintage and also the demand for them back in the day I ended up refurbishing more than one of them. From that I divulge my amature knowledge of such. They did have some particulars you might want to be aware of:

The Nighthawks real achilles heel from my experience can be found in Honda choosing to use hydraulic lifters in them.  All of the ones I brought back to life had to have those lifters addressed. The lifters are tiny, about the size of your pinky finger from the 1st joint forward. The tiny feed holes that feed the lifters love to plug up causing lifter collapse and ending up destroying the top end, especially found with bikes that have not been run for a while.  Another issue therein also has to do with cam saddles being dry from sitting and ending up smudging at first start up after a long sitting time. The answer to both is not trying to start the bike but to pull the covers and make sure the lifters are cleaned, cams prelubed before cranking her up. 

I ALWAYS also double check the fuel tank to make sure no rust is in there. If you find rust,  a product called Red Kote will become your best friend. BAR NONE (and I have experimented with many), Red Kote is the best of the best.

As far as the carbs go you can always safely use spray carb cleaner as sold at Menards or Auto Zone iinjected into the carbs with a syringe like I have mentioned on the site many times if you dont want to pull the carbs and/or do the full tear down of the top covers on the valves like I mention.  Simply remove the throttle slide from an outside carb so you can look inside of the carb body and watch the amount of fluid you are injecting.  Now open the drain, fill the syringe (large horse syringe like found at Farm/Fleet) with the spray, fill up but note on the syringe where you are starting the injection. Hook up with hose, inject and watch the emulsion tube where the metering rod attached to the slide slips into the emulsion tube (that metering rod controls the amount of fuel entering the carb thru the main jet). Keep pushing cleaner in until you see cleaner coming out of the emulsion tube hole. When you see the fluid coming out of the emulsion tube hole STOP - close the drain and note how much fluid you have used from the syringe. Now do all the other carbs with the same amount of cleaner. You can let that spray cleaner set for days,, wont hurt a thing.  I have tested numerous cleaners and found Seafoam useless for active cleaning, as mentioned - Berrymans B-12 works great but you gotta not leave the stuff for extended times or it will effect rubber parts - I have used B-12 successfully for years.  The very very best cleaner I have ever used is Chem-Dip but that stuff is real active,, any more than 1/2 hour soak without a good thurough cleaning/flushing and stuff inside will be wrecked. I have successfully used Chem-Dip though - just gotta work fast and beware that you eventually may be rebuilding carb

Unc, I know you have been inside of our V-4 carbs,, remember those 700's carbs are only 1/2 the size of our V-4's. The idle circuitry in their will be hair size in spots BUT if those hair sized passages are not open and clean the bike will never run right.  Looking at what I see in your post, if it were mine I would just go ahead, pull the top down, prelube, put a teaspoon of Mystery Oil in each jug, spin the motor with drill motor with the plugs out, drop a compression guage on it to make sure it had good compression, pull the carbs if it does, and do a real good thorough cleaning of the carbs with a CHEM-DIP soak of the disasembled carbs. Seal the tank if needed.   Put it all back together, put a 1/2 teaspoon of raw fuel in each pot and screw in new plugs each gapped correctly so it pops right off at first push of the button.  

Beware when ya go to riding her ya lop eared varmint.. Those little 700's were big twin slayers!!  Been a long time since I saddled one but I am thinking your looking at 80/90 horse at the wheel there and on that light little sucker,, FUN!!! 

[BlueSky]

Yep, my Kawa ZN700 4 carbs will plug up really quick from sitting.  I use gumout in the fuel a lot and try not to let it sit for more than a couple weeks without running it.  

[uncledj]

7 hours ago, BlueSky said:

Yep, my Kawa ZN700 4 carbs will plug up really quick from sitting.  I use gumout in the fuel a lot and try not to let it sit for more than a couple weeks without running it.  

  I've been putting ethanol free gas with a heavy dose of Seafoam in it in these machines as I bring them back.   That should keep 'em for a while.

[BlueSky]

5 minutes ago, uncledj said:

  I've been putting ethanol free gas with a heavy dose of Seafoam in it in these machines as I bring them back.   That should keep 'em for a while.

Yep, I use only ethanol free gasoline in my motorcycles, boat, and lawn tools.  I also mix gumout with PEA with the gasoline for those engines.  It helps.  My wife will only buy ethanol free premium for her hot rod 325hp EX37 Infiniti.  I'm too cheap for that. I use the ethanol gas in my car and truck.