Topic: Air filter and plugs!!!

[Jim Shea]

I changed the plugs and air filter today and the bike did not run properly (I did not gap the plugs as I assumed they were set??) It was not revving freely and would stall.
I took the new plugs out and cleaned the old ones and put the old ones back in and the bike ran better, but sounded like there was too much air being mixed!! I went on a test drive(old plugs new air filter) and when I stopped there was a lot of fuel dripping from the rubber pipes under the engine? this had not happened before.
I then put the old air filter back on(gold colour with Honda CB 750F F stamped on it), I took it for another run and when I stopped this time, the fuel leak had stopped! So, the bike is back to original plugs and air filter and runs great again??
Was this problem due to the air filter not seating properly, it did not seem to fit well like the old one? The replacement was the one suggested by David Silver.
Jim.

[Jim Shea]

I recently bought the bike and as far as I know the carbs are standard, but the exhaust is a Motad replacement. As I said when I put the old filter back in(which looked like a new one anyway!!) the bike runs fine and does not drop fuel now.. The filter from David Silver is supposed to be for my bike, bur it did not fit well, it was like it was slightly oversized!!
Jim.

[Jim Shea]

Any idea where I can get an original from(in UK) Silver only does pattern air filters and it definitely does not fit properley!

[Jim Shea]

Thanks Dave. I notice that DSS has an original filter for K3/4/5, 7 &8, I wonder if these are exactly the same as the 76 F1?

[Jim Shea]

I agree, but it is nice to have that extra bhp!!
I drove Steve D's immaculate 550 today, a beautiful bike, but after a 750 you really miss the torque and acceleration.

[Jim Shea]

Ouch, fighting talk... I await the interesting comments coming from 550 lovers.. 

[Jim Shea]

Just out of interest what do you think of the 500? Hopefully, this will stimulate a healthy debate?
I will say that the F1 does not sound anywhere near as good as a 4 into 4..

[Jim Shea]

I bet point to point, country roads, A roads etc, my big old 750 would get there first.

[Dennis]

Thanks Dave. I notice that DSS has an original filter for K3/4/5, 7 &8, I wonder if these are exactly the same as the 76 F1?

If you cross check the honda part numbers you will find that all of the SOHC 750's (at least up to '76, K6, F and F1) use tha sqme air filter. I am presently using the K & N replacement in the original air box in tn both a '75 and '76 F (or F1 - what ever you want to call it) with no problems. They are probably about the same price as original Honda.
I have no idea of the fit of DSS patern filters.

Also, I'm sure (and that is 100%) that the air filter did not cause your carb bowls to over flow. Probabvly got some smal patriculate from the tank holding the float valves open. I would wait and see if it happens again. If it does, check tank, petcock, filter (above petcock on that model) fuel lines and carbs.

BTW: I have no idea why some people are under the impression that spark plugs are supplied pre gapped. This "may" be true but it is also true that it could be for some other application. ALWAYS CHECK your PLUG GAPS prior to installation. (See bike and plug manufacturers' literature if you have any doubt about this.) Also be sure to properly torque your (NEW) plugs in order to properly compress the plug gaskets. The gaskets are already compressed on the old ones.

[Jim Shea]

Dave,
Hopefully one day I will.. not sure of any in my area?

[Jim Shea]

Dennis,
So it is a pure coincidence that the fault happened after I fitted the air filter and stopped when I put the original back in?
Also, when I ordered the plugs I asked DSS if the were gapped for my bike and they said yes! I will check the gap, I beleive it is .6-.7mm for my bike.

[Dennis]

Dennis,
So it is a pure coincidence that the fault happened after I fitted the air filter and stopped when I put the original back in?

It sure seems that way to me!!

Also, when I ordered the plugs I asked DSS if the were gapped for my bike and they said yes! I will check the gap, I beleive it is .6-.7mm for my bike.

I'm rather surprised that they (DSS) told you the plugs were pre gapped for your bike. Many times thay are very close but I always check them per manufacturers recommendation. I have a small stock of spark plugs (NGK) and when I get a chance I will check a few.
BTW: What number plug are you using? Same as the old one?

[Jim Shea]

Yes, the plugs are NGK, DR8ESL.

[Einyodeler]

DR8ESL are resistor plugs,if you`re running the resistor caps with those plugs you`ll be losing spark strength.
Standard plugs for your bike are NGK D8EA and I always gap mine as these plugs fit a multitude of other makes and models,each with a slightly different gap setting.