Additive to clean carbs on a motorcycle.?

Question

I am resurrecting my 1884 Honda Nighthawk 700sc. It hadn’t ran since 95 but now that I have cleaned the tank; replaced oil, plugs, fuel filter, and air filter; it actually starts and runs. It has a hard time idling however and seems to backfire sometimes on a quick down-throttle. Is there a fuel additive anyone can recommend that will help clean the carbs?

Answer 1

If you haven't run the bike in over 10 years, you need new carbs.  That bike will never run good with old carbs.

I know - I've owned 3 bikes so far.

Good Luck...

Answer 2

You do not need to get new carbs if the only problem is sitting unused with gas in them.

The best thing, as mentioned, is to take them apart and totally clean them. Or, you might want to try this first. Get a product called Seafoam. Put in the tank and run the bike at speed. It will run rough at first but if you can ride it at speed then this MAY (depending on how bad the carbs are gummed up) clean them out.

This may take as little as 15 minutes riding time or as much as a tank of gas. If it still doesn't run properly after a tank then definately have to revove and clean the carbs.

Answer 3

Seafoam in the gastank & Seafoam Deep Creep in the carbs.

Answer 4

Use one of the powerful cleaners

Chevron Techron Concentrate,

Gumout Regane,

Redline SI1,

Add about 2 oz per gallon to a 1/2 tank of gas.

Reason why 1/2 tank,,

is you'll want to eventually Add Fuel to dilute the actually Too-Rich "2oz:1 gal" mix

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Let bike Idle on that for about an hour

Put a FAN or 2 blowing on it to avoid over chance of heating

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Reason it Needs to idle  is because when the Carbs are closed it restricts ALL of the engine Vacuum to  the IDLE CIRCUIT.

That cause the Highest Volume of fuel to go Thru the Idle Circuit,,,and the highest wash rate of cleaner flow.

By about 1/4 Throttle there is virtually NO fuel flow thru the Idle circuit,,,,And Vacuum drops off QUICK & Steep ,,,

so "No Cleaner" flow is occurring.

It's VERY Difficult to "Drive/Ride" a CARB clean using Chemical Additives because the bulk of Flow occurs thru Intermediate  Circuit,,which is discharged thru same place Main /Hi-speed Circuit flows thru.

Over Time,,solvent effects will Coincidentally allow the Idle Circuit to get sucked clean eventually.

But "Eventually" is the key word.

You need to Target the Idle sys,,and cause Focus of BOTH Hi-Flow of Cleaner Volume And Hi Mechanical action of Vacuum thru that section.

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If it simply Starts and Runs,,,,that is a Positive Indication  that Mid- and Hi- Speed circuits are flowing  to some good degree.

The Chemicals will clean those up easy and soon enough.

If it IDLES at all,,,thats a positive Indication that At Least SOME of the Carbs are flowing SOME fuel.

Which suggests fairly Good Odds that They too can be cleaned up without disassembly and manual cleaning.

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The Cleaners suggested above are all High Concentration PEA's.

That's a chemical which will also clean the c**p-from-Sitting,,,from combustion chamber,Valve surface,,intake surfaces,,,

and most importantly from Piston Rings and their grooves.

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It's a Crapshoot as to how effective or how quick You'll achieve through results.

No Gaurantees.

But it's a Good Odds $10~20 Crapshoot,,,,which is beneficial in Other ways in any case,,,

Vs a "Gauranteed" Several $100 few-day trip to a Repair Shop.

My OPINION,,it's worth a try.

The KEYS to any Chance of it working are;

a)Specific Chemistry

b)Specific Procedure

You'll know in a couple days if You're going to get satisfactory results.

I beleive Odds favor that happening.

Good Luck

** The Pop on De-Cell,,,is stereotypical of a too-lean condition,,,,aka clogged low speed circuit.

That should go away as the carbs clean-up.

***** Seafoam seems to be a popular choice.

It's a Good Product,,I recommend it sometimes myself.

It's

30% Basic Cleaner

20% Rubbing Alcohol--"Fuel Dryer"

50% Stabilizer

It's good stuff as an "all-in-one" type additive.

Might do the trick in your case.???

If You wanna boost Seafoam performance as a Cleaner,,,simply add  either Coleman Camp Fuel or Kingsford brand Charcoal Lighter Fluid.

Both are "same chemical" but a Higher,Purer Grade and come packaged in 100% Concentration.

Personally,,,I would chose a hi-perfomance ,high concentration advanced chemistry cleaner for a carb which has sat as long as yours.

Hydrocarbon deposits and some of the residuals in mogas tend to sorta,,"dehydrate " overtime making them very hard and mineral-like.

Carbs that sat for 1 Year are Lots Nastier,Gummier,Slimier.

That's ONE condition

Carbs which HAD gas at one time,,,but haven't seen Gas for 10 years & just sat DRY,,,

that's a whole different set of conditions to deal with.

Answer 5

There is NO spray on goo that will clean your carbs. You have to take them off, apart and to a shop that actually cleans carbs ( probably not your bike dealer). These go in a bath of fairly toxic liquid and then come out CLEAN! I don't think you will have to replace them. Beware of the needle in the carbs. These are very expensive to replace. Good Luck.

Answer 6

if you want to clean them you'll have to take them off the bike, take them apart, and actually clean them.  then they might work.  otherwise, yeah, get new carbs.

Answer 7

YOU DO NOT NEED NEW CARBS ! Try sea foam 1st as others suggested{or follow directions on can}. It may smoke like crazy but don't freak out this is normal. If that does not work they will need to be taken off and cleaned by hand.

Answer 8

Go buy yourself some Seafoam [add as directed] ask a bike dealer about it or go to your local Walmart you might find it there.

Answer 9

Fuel additives will not clean the idle circuit.

The pilot jets are as small as a pin.

The fuel would rather go through the large opening of the main jet, than squeeze through a pin hole.

The back fire on quick down throttle is from the air cut off valves not operating properly, due to bad gas causing them to stick.

The carbs will have to be removed and thoroughly cleaned.

The carbs are cleanable - they don't have to be replaced.