MISSING AIR FILTER ON MY NEW PURCHASE..... <--- NEWB NEEDS HELP

[Laughter13]

Well... I just picked up a 1977 Honda CB400 four Super Sport.


Finally got to looking around the bike and seeing what it needs. Everything looks awesome except one thing, 6 parts missing from the intake assembly as shown on Bike Bandits Schematic (http://www.bikebandit.com/houseofmotorcycles/1977-honda-cb400f-air-cleaner/o/m9441sch402783).


I am missing the following parts:


1) #2 (on Bike Bandit List) Element, Air Cleaner
2) #21 Plate B Gasket
3) #19 Element B
4) #8 Net Air In
5) #7 Duct
6) #9 Band


So I guess i have two choices.... I either try and track down the OEM parts, and i have no idea where to find those.... or I upgrade to POD filters and re-Jet.


With that said, what should i do?
If i rejet, can a newb do this? I have a older Haynes manual that might help.
How do i know what size jets to purchase?
Any ideas on where to track down the OEM parts?


Just so you guys know, i contacted the seller and he bought the bike two years ago and has run it this way since he bought it... any problems i should look for because of this?


as always, thanks for any help you guys can provide!

 

[Tim]

eBay is your best bet for those parts, or swap meets etc. But cheap Emgo pod filters are a good option at least for now. You might not have to re-jet.

Do you have pics of it as it is now? He ran it without any air filters at all?

 

[Laughter13]

No.... no pic right this sec, but i will try to load one tomorrow....


I am definitely leaning to the pod filter approach, but how do i know whether or not i need to rejet?

 

[Laughter13]

Another note:


I do have the stock exhaust on and guy said he had the carbs cleaned 1,000 miles ago.

 

[Tim]

If the bike doesn't run right, you'll need to adjust things. But if the guy ran it as-is, then it might have already been jetted (someone took the filter box off for a reason).

Get some cheap filters, and get the timing / valves adjusted to factory spec, fresh plugs etc. and see what happens.

 

[Laughter13]

the bike is running right, as far as i can tell (being a newb to bikes).


The air box is there, but no filter or intake assembly (as shown in the bike bandit schematic), so if someone removed the parts, i have no idea why.


I am worried that if i take it to a mechanic, they will say i need to do alot more than i need..... should i just rip out the original air box and put pods on and see how it runs... even though i probably wouldn't know if there was something wrong?

 

[Tim]

Ok, I took the time to look at the diagram and missing parts.

Skip the pods. The bike will run WAY better on the stock box - it's engineered to distribute even airflow to the 4 carbs. With pods the outer two get more air etc.

Get an airfilter. Doesn't have to be OEM Honda. UNI might make a nice replacement which is washable / oiled.

#19 and #21 are for filtering the gasses which are passed from the crankcase breather back into the bottom of the airbox for re-burning. Is part #18 there? The tube from the engine head area (I think) to the bottom of the airbox? It flows air pushed out of the engine crankcase (air pressure is constantly changing inside your engine block) with oil vapor in it etc. into the airbox to be filtered (the drain hose is to release built up fluid from the bottom of the airbox) and burned along with the fresh air. It's mostly an EPA thing. Lots of people ditch this and put a filter on the engine breather to keep oil from spraying all over when pressure increases. I just run a long tube off mine routed to below the engine so whatever comes out, comes out.

You have #14 - the airbox lid? If so, good.

The intake tube is there mostly to pull air in from under the seat vs just sucking turbulent air in from the backside of the airbox. You have an inner fender etc. to keep crud out, so no worries about #7/#8. If you find one at a swap meet someday grab it.

Most importantly get an air filter and slap it in there. The rest is less important.

 

[Laughter13]

Tim..... what can i say, you are the @#$&!


Thank you sooo much for taking the time to look at this. I will follow you perfectly detailed instructions and get her running right!

 

[Big R]

+1 to Tim- he is the shiznit.

But before searching around for insanely expensive stock filters, look around at some of the 400F builds on here. And K&N makes all sorts of filters, not just pods. They make a dual intake filter- get 2 of them if they fit and your carbs would "share" air.

 

[crazypj]

400F runs much better with stock filters.
The stock airbox is a real tight fit (REALLY TIGHT) so it's no wonder the connectors are missing
You need extra short K&N filters or they hit the frame tubes
You WILL need to re-jet, even with stock exhaust.
Luckily, they are real easy to do as it's a pre CV carb, although getting the slides in and out can be a challenge if you don't know what your doing.
It's easy to lose pieces or re-fit in wrong order

 

[Laughter13]

Looks like bike bandit has some OEM filters in stock. I will order one of these and i should be pretty good as the crank case breather line to the air box is no longer connected. Seems like someone knew what they were doing with this happened to the bike, but stupid previous owner missed the fact that an air filter would be better than no air filter.


Any thought on whether 1k miles of riding without an air filter could have caused any problems?

 

[crazypj]

Depends how dusty it is where bike was ridden.
1,000 miles won't do much harm, unless it was on dirt roads?
It will accelerate ring/cylinder wear, but, if it ain't smoking, leave it alone