Topic: 77 550F supersport Revival

[Bandit18]

If you come across another F model for a 100.. I'll take it 

[PGF550F]

Some of you may have seen my other thread about my terrible fuel consumption. http://forums.sohc4.net/index.php/topic,159203.0.html

Well Im starting to think it wasn't me that over-oiled my air filter... It was my motor!

I checked the condensation airbox drain pipe and it was almost full? I pulled the plug and drained it before I headed home It was pretty light(viscosity and color) so I thought alot of gas maybe? This had me suspecting a poorly adjusted valve and I was somehow getting gas this far back in my airbox.  I got home and checked it and lo and behold ~50km of driving and here is how much "stuff" is in it.


I drove back to work this morning and ran the petcock only party open and it seemed to run better so I think I need to check and confirm the fuel level/float height. I suspect that the fuel level is too high in the bowls(which would make it run rich).

Out of curiosity, I pulled the air filter out this morning and watched to see how much blow-by I am getting. Well I took a video but cant upload it to photobucket for some reason will post it as soon as I get that figured out.

[Stev-o]

Is that a bolt in the end of that line??

[PGF550F]

[youtube]https://www.youtube.com/watch?v=b63ZcIQafBM[/

Yeah it's a bolt, never got around to finding a better plug. It fits along with the "aftermarket" solution to the crankcase breather filter element  in the video. Parts are NLA and missing when I acquired the bike.
I don't think the oil is overfilled, I checked it when the bike was on the centerstand and its right at the hash mark/line.

[PGF550F]

Hopefully this works


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[CBGhia]

I believe that would be blow by. 
I would pull the heads and take a look at the valve guide seals to start, but I am betting you are going to need some rings.   
How many miles are on that engine?

[PGF550F]

~23000 km (14000miles) on the odometer.

Plugs:

Compression tester numbers:

I'm thinking rings too but if the oil is contaminated with gas, could it be cooking off gas in the crankcase once it gets hot enough?

The plugs are sooty black, not oily? I'm in uncharted waters here for my motorcycle knowledge, I appreciate any suggestions or comments.


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[Stev-o]

Sooty black = rich carb settings [too much fuel]

14,000 miles is very low, doubt you need a rebuild unless the bike has been abused or neglected.

[flatlander]

i agree with stev-o.
you mentioned earlier that you were looking for new needle valves. did you install those? while at it, did you check fuel level in the carbs with the clear tube method?
often, one of the first things these bikes need, after they've been sitting around at some PO for a while, is to go over the carbs. don't replace the brass parts as the original keihin bits are better than any of the aftermarket stuff, just make sure they are clean and everything works. and make a note of jet sizes and needle clip position for future reference.

[PGF550F]

Thanks for the advice guys  The history of the engine is unknown to me, but my hot compression numbers seem ok.

I havent got new needle/seats yet as I can't find any kits that have keihin brass. I'll reuse my stock brass(needle&seat included) and use the o rings out of some rebuild kits. i Plan to use the clear tube method to adjust the floats/fuel level when I have them off the bike.
Needle clips are 2up from the bottom so I think I'll move them up one notch(leans it out right?)
Got a few things on the honey do list this week so I can't even get to it until Thursday, maybe from Friday.

I think I should change to oil as well. Want to eliminate the possibility that its contaminated with gas and the vapour is just gas cooking off once it gets hot enough.

Maybe I'll take the chance to find a better plug for my drain line, its been pointed out that the bolt isn't to spec. I think its SAE as well

[Stev-o]

Yes, change that bolt to metric!

And use a motorcycle specific oil and not synthetic (not good for wet clutch)

[luvmy71]

Stev-o

What do you recommend/use for oil for the early 750s?

thanks,

[Stev-o]

Stev-o

What do you recommend/use for oil for the early 750s?

thanks,

I use either Valvoline 4 stroke motorcycle oil or Shell Rotella Heavy Duty diesel motor oil. Yes, diesel oil, buy it by the gallon!

[flatlander]

And use a motorcycle specific oil and not synthetic (not good for wet clutch)

ok not trying to turn this into an oil thread... but if a synthetic oil is specified for use in motorcycles with wet clutches - why would it not be good for wet clutch?

[Stev-o]

And use a motorcycle specific oil and not synthetic (not good for wet clutch)

ok not trying to turn this into an oil thread... but if a synthetic oil is specified for use in motorcycles with wet clutches - why would it not be good for wet clutch?

It should be but I've read reports that synthetic oils cause oil leaks, since it is "thinner".

I just easily avoid that possibility by using dino oil. You use it FL?

[flatlander]

yeah i've used synthetic before rebuilding the engine. i had no particular oil leaks. i'm still on the last bit of dino oil since i bough a batch of it for break-in. plan to try synthetic next and see how it works out.

[Stev-o]

yeah i've used synthetic before rebuilding the engine. i had no particular oil leaks. i'm still on the last bit of dino oil since i bough a batch of it for break-in. plan to try synthetic next and see how it works out.

I'm not really against it, just think it is an unnecessary expense. Let us know how it goes!

BTW - this has been discussed before.  Be sure to click the link in this thread to read the rant...hilarious!

http://forums.sohc4.net/index.php?topic=75962.0

[flatlander]

there seems to be nothing wrong with the good old dino stuff i use but do want to see what happens when i put some synth in there. especially now that the engine is completely leak free, it should show if anything starts pouring out just through changing the oil. is suspect, not.

that rant is funny. but i'm brave or stupid enough to do this anyway!