Topic: Naive question from a mechanical noob

[gregwaits]

This '78 K8 I picked up has a mere 8,000 miles. It has been stored inside. The tank is dry - and completely rust free.

My question is this. What are the odds of the carbs being clean enough as is to fire up the bike successfully? Is it unheard of for someone to find a relatively clean barn bike with low miles and a clean tank to be able to fire it up with minimal hassle?

Admitted, this one has sat in storage for 24 years, but something tells me I have nothing to lose by trying. The throttle cable moves easily, indicating (to me at least) that the mechanics of the carbs are pretty much in order.

Next step, buy a new battery, replace all the fluids in the bike, flush and fill the tank - and cross my fingers.

Before I try to start it up I will kick the engine through several times to get oil circulated throughout the engine. Should I go ahead and squirt something in the spark plug holes to give the old lady a better chance?

Any feedback? Thanks!

[ekim98]

What's the most that will happen, you suck some stale gas and varnish a little farther into the carbs, or it might start. Mine had not sat near that long and I had varnish collecting in the bowls and jets. You can clean those with out taking the carbs off so why not do it and be sure that much into the carbs.

[nomadwarmachine]

Provided you change the oil first, you have nothing to lose by firing up the engine.  However, you would probably want to drop the float bowls in the carbs first.  If they are filled with varnish, it will likely run like crap, if it starts as all.  If they are as pristine as your tank, you may just need a tune-up!  Keep us posted and good luck!

[mgmuellner]

The mechanics of the throttle returning tell you little about how the inside of the carbs look.  It just means that a few moving items move.  The bowls could still be full of nasties & the jets could be clogged.  If you want to start it, just to hear it run - have at it!  Hearing a bike you're working on can help motivate you for sure.  If you think though that cutting the corner of not inspecting the carbs has a good chance of resulting in a good running bike you're probably mistaken.  It's possible though that the PO could have drained the gas before storage so all you'll have is small deposits.

[Jerry Rxman Griffin aka MuthaF'er]

50-50 at best. Dry tank rust free is good but that doesn't mean the bowls didn't have gas in them which evaporated and left varnish deposits after it last ran. They should have been either run dry at least or drained.

Drop the bowls and check the condition. If varnished up you might be better off with a full cleaning (not necessarily a rebuild) including removing the "non-removable" slow jets. I haven't been into your pumper carbs before but one thing I'd be interested in would be the condition of the pump diaphragm also. If you're feeling lucky I'd at least include some Sea Foam or BG44K (my preference but more expensive) mixed in with the gas. AT THE VERY LEAST, pull the petcock and clean/check it.

[Bodain]

The throttle not being stuck is a good indication, however if the pilot jet is clogged it's not going to start on it's own.

[eurban]

The throttle not being stuck is a good indication, however if the pilot jet is clogged it's not going to start on it's own.

Yes, probably won't start with clogged pilots.  Still, if she does manage start, running lean due to impeded pilots/ mains, improper fuel level in floats, dirty main jet needles might put the motor (and blue/gold up the exhaust pipes) at some risk if you run this way for a while.  There are plenty of good posts here on the 77/78 carbs and even an off site rebuild walk thru (not sure of the link). Basically, if after some exploration you decide that you want your 78 to really run correctly, you will most likely need to clean/adjust the carbs (and perform a full once over all the bikes systems for that matter)

[gregwaits]

Thanks to all for all the great suggestions and advice.

I just spoke to my tech who rides a '78 too (albeit majorly modified and chopped). He told me that overhaul kits are hard to come by for the '78 carbs and that I might consider switching over to 78's. (he did the same)

Anyone else in here do this? I am in negotiations for a set with a fellow sohc/4 member.

Thanks as always!

[333]

Yes, squirt some oil down the spark plug holes.  If it has sat for 24 years, the cylinders are most certainly dry.

[mj_honda]

The rebuild kits are not hard to find just a little expensive. Go here:

http://www.siriusconinc.com/default.asp

Make sure to choose the kits for the 78K. I found them cheaper at one time but can't remember where.

[TwoTired]

I just cleaned and rebuilt a set of 77 CB750F carbs without a rebuild kit (Same design as the K).  Save your money for new intake and filter box boot couplers.  Unless you have corrosion inside, the only bits that need replacing would be the bowl oring seals and the accell pump diaphragm.

I suggest you remove number one float bowl while it is still on the bike.  Decide from there, or post a pic of the insides. 

Because of the accel pump, the 77-78 carbs are much more operator friendly than prior years, as you can grab a handful of throttle and get reliable pickup instantly without the need to learn the travel limits, or running the bike way rich all the time.

Cheers,