FZRSupport: the FZROnline Archive

Ok I have a project 89 3en2 fzr 400. It has 63000 km on the clocks. Sorted the no charging with a second hand stator.
Ran to a fashion. Carbs have been cleaned. Valve clearances were none existence on the inlet valves so I've done them. Trouble is it's still back firing back up carb 2 ( worst than before) and still doesn't run right. Was thinking valves were shot so got a new set. As I've started tear down I took the carbs off to find the inlet rubber on carb 2 ( on head) still very wet from fuel. Have not started bike in a week. So could I just have a bad issue with the carb? The choke also doesnt seem to work as it should.Help would be appreciated as I don't want to take the head off for nothing. Many thanks

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If the choke is sticking then it will spit back through the carb. It might run on all 4 higher in the rev range but drop to 3 lower down.
Obviously check through the choke mechanism, take the cable off the carbs then the mechanism as well to see if it makes a difference. It might be a very high float setting, the float valve, or a cracked float (petrol gets inside weighting the float so it sinks), or somebody stripped the carbs and got the idle / main jets reversed, I know it's easy on the 3TJ carbs.
This carb sounds like the problem, so if you can't cure the fault change the carbs for another set.

Just a update.... done a compression test. Very low across the board. 50 to be 70 psi. Bike is booked in with a bike builder in sept. He's going to go through the carbs and tear the engine down. Hopefully get back by the end of the month running beautiful.

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Sounds expensive, get an estimate first.
Remember a 3en2 isn't worth more than a grand

Cost isn't a issue. The value of the bike when all done doesn't matter. It's being restored as a gift to my partner and won't ever be sold.

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