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1991 225 hp reed valve

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pipoloco

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chriss carson reed 1.jpgI HAVE A 225 AND I PUT NEW REED VALVES THE FIRST START UP BACKFIRE AND ONE OF THE REED VALVES BROKE WHAT COULD COUSE THAT ? thank you.


chriss carson reed 2.jpg
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Do a comp test.
If you find a low cylinder corresponding to the valve that blew out, time for strip down.
Note that port side carbs feeds stb side cylinders!
If comp test turns out ok, time for a carb and throttle plate cleaning/rebuild.
Backfire is normally related to lean-burning unless you have a 'double firing' powerpack.
(fires 2 cylinders at the same time)
Mark the flywheel with each cylinder at TDC, use a timing light, and check that you may only find one reading for each cylinder tested.
 
When you say it backfires do you mean it backfires out the exhaust or are we talking about a lean spit? We'll assume it's a lean spit. If so, there's an air leak somewhere. To burn a steel reed it has to be a pretty bad leak. If the reeds are Boyesen, they can burn on a single spit. Anytime it "spits" there is fire in the reed and carb throat area. There rae several places it can be sucking air from. What cylinder is this reed on?
 
There's nothing wrong with CC reeds just like the Boyesen reeds are very good too. They have the potiential to last a very long time. Obviously if you are using those type reeds you're looking for rpm above 6500-6700, no big deal. High rpm will not harm them. About the only thing that will burn one is a lean spit. That's why when we install those type reeds we make darn sure the motor does not spit. The other thing is to pay attention to the instructions. Make sure the reed box is flat (surface it) and if the CC reeds are like Boyesens you do not use the reed stop. If you do they will split and break.
 
how do you surface the reed box?
and manufacturer told me to use the stops iput new gaskets everything new rebuild carbs there are no couses for a lean spit. don't know what is going on is driving me crasy.
thanks for the help anything will be apreciated.
thank you again
 
There will be a reason for the spit. A very common leak is around the side plate on the carb.

When we cange reeds we surface all 3 sides of the reed box on a surfacing machine or use some 400 grit paper on a piece of glass.
 
If the rubber coating is cracked /split or missing it will cause this. The reed blocks must be sanded flat when you install fiber reeds. If it backfired at 300rpm its not a air leak as cylinder would have done melted down, you have a timer base/pack or flywheel issue as the flywheels are known for slipping the hub magnet. Index the flywheel and check timing on all cylinders...
 
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