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Upside down inlet rubbers.....

Started by mr blackstock, Today at 07:16:16 AM

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mr blackstock


Hello,

So I recently found a wrecked FJ1100 nearby for a few hundred.  I thought "well, you never know, supposedly 100k on the clock, the motor might be worth getting"

So getting it home and closer examination revealed an absolute tosser of a P.O
For starters they made their own 4 into 1 exhaust system that blocked access to the oil drain plug... so who knows how many kms between the last oil change....

The compressions were healthy on three cylinders, bad on one.  Looking over things, everything seemed gunked up with oil.... exhaust ports were oily! SO I'm guessing bad valve seal and being parked on its side stand for years.... the plugs were carboned up, running too rich, and checking the oil it had around a litre too much.

So, I thought I will take my good bank of carbs off my running bike, throw them on, and run the bike, spray in copious amounts of seafoam through the engine and see what happens.

Taking of the seriously messy filthy original bank of carbs, I noticed the carb balancing ports were on the bottom of the rubber inlets.... strange way to put them on.... looking into the inlet ports I discovered the P.O had installed them poorly, all were upside down and sitting askew of the port, effectively 15% of the rubber inlet was blocked.   

Now maybe there was an urban myth years ago suggesting this mod.... perhaps increase the ventury effect to better mix the fuel and air ratio? Or perhaps the P.O was just plain wrong...So wrong... The inner gasket surface of one of the rubbers was seriously messed up with carbon build up... so this bike ran for years like this.... wow.  The 1st pic shows the imprint of where the rubber inlet was sitting, second pic shows the head protruding into the air/fuel intake, 3rd pic gasket surface.

By now I am thinking this motor has got be totally shot.... but as I have gone this far, I may as well see it through and discover how bad an engine can get and still run...

I'll upload a youtube video of the resulting motor torture over the next few days...
Squeaky wheels always get the grease...

Yamaha FJ1100 1985

Pat Conlon

That looks terrible. I have heard that there were "restricted" inlet boots put on the FJ's for the Asian market. I've never seen one, so I wondered if maybe that's what you have...?

 I can't believe someone would install these inlet rubbers like  this....

The horrors of unskilled labor.
1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don't store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3

mr blackstock

I hear what you are saying.  I don't think these are restricter inlets as the carb synch ports were on teh bottom of the carbs and impossible to reach with the carbs installed....

This FJ has been seriously neglected/abused by the P.O
Squeaky wheels always get the grease...

Yamaha FJ1100 1985