Piston slap and Oil?

[XS1100_OEM4ME]

Oem

Yes, all lines, vac and fuel are OEM hook up

[XS1100_OEM4ME]

Oem

Yes, "ALL" are OEM hook up, gas, vac, advance, octy, all just like yamaha set up.

[cywelchjr]

Just double checking that the vacuum advance is hooked to the number 2 carb body and not the manifold? There should be 2 hoses to the #2 carb, one to the boot for the octy and the other to the carb body for the vacuum advance. One of the tests to see if it's the vacuum advance that's the issue is to remove and plug the vacuum advance and see if the knock goes away. Also as stated not being in sync can cause a knock and a bench sync may not be good enough, it really needs to be done with good vacuum gauges to match the engine.

[XS1100_OEM4ME]

thanks

going to do the vac adv test when it stops raining, lines are hooked up right. will buy some syc gages and do that also, runs so great other then stated, hope it is just a tweak, thanks

[cywelchjr]

Well, I know I haven't been able to get mine to go away. But it's less with mid-grade gas, and it hasn't really changed that I can tell in almost 9 months and 3 oil changes. I've also found it gets worse as the engine gets hot. I don't know what that means, but if I didn't have a fairing I'm pretty sure I wouldn't be able to hear it over the wind noise in my helmet. Again, I don't know what that means, but I THINK it's not something I need to worry about too much, I figure it will get louder before I have to worry about it.

[XS1100_OEM4ME]

Gas

I am using prem gas only, are you saying the lower grade makes it sound better then prem?

[cywelchjr]

I am using prem gas only, are you saying the lower grade makes it sound better then prem?

At least in my case it runs and sounds like crap on premium. My engine rattle (whatever it is) is a bit quieter on the mid grade, and mileage is about the same so I run that now.

That's the other thing, if you'rs runs good on premium, it will get lower mileage than on mid grade or regular. Unless premium is required and the engine it tuned for it (more compression/advance) gas mileage will be less as less of the fuel will be burned before the valves open (which means it would not run as clean I would think, but on that I could be wrong. I know some high performance engines on autos have a knock sensor and will adjust the timing to take advantage or the higher octane, but even then mileage may be lower, with a little more horsepower, but IIRC with static timing curves like ours you won't even get more power, possibly even less. There really is NO reason to run an engine on higher octane fuel than it was designed for, your just wasting your money (there is debate on whether the design of our engines is more suited to regular or mid grade, but Yamaha says regular, and premium is IMHO over kill and a waste of money).

[XS1100_OEM4ME]

high oct. gas

The higher the oct. rating the lower the pre-ing. and slower the burn. The low oct, require less timmming advance/ less compression. The higher combustion of lower oct gas "can" give increased MPG as well as HP in the right motors. The 9.2 to 1 comp. of "most" 1100's could do well on low oct. If no knock with your tune, use it and save$$

[Dragon Tamer]

Several years back I was running premium gas because I could get it without ethanol in it. It actually made the ignition rattle worse! I found that it was because the engine ran almost 200 degrees hotter with the premium fuel and the warmer the engine the worse the rattle. On the '79's I have found that if you first make sure that everything is set up correctly and is funtioning properly (timing, sync, vac and centriugal advance etc) and you still have ignition rattle, retard the main timing by about three to four degrees and the noise will go away. I have done this on several '78's and 9's and it worked every time.