How to check Reed Valves.

[Leonard Ray]

I have an 1986 Mariner Magnum 150hp that does not start good.When it does start you have to to give it some gas or it will shut off and it will not run at all when you put it in the water.I have rebuilt everything but the reed valves.I can hold the intake up to the light and some of the valves are not all the way closed.I don't think that is good,am I right in saying they need to be replaced? should there be stops for the valves?

 

[Faztbullet]

Re: How to check Reed Valves.

I can hold the intake up to the light and some of the valves are not all the way closed.I don't think that is good,am I right in saying they need to be replaced?

Not necessarily as you are allowed up to .020 of reed gap....you will always have one or two pedals that stand open a tad. What is your compression as this isnt a reed problem.

 

[Leonard Ray]

Re: How to check Reed Valves.

120 on all cyliners.That is what is was doing before i rebuilt it.When you put it in the water it starts poping,and back firing.

 

[Faztbullet]

Re: How to check Reed Valves.

Double check your wiring of trigger and coils as sounds like you got something miswired...

 

[Leonard Ray]

Re: How to check Reed Valves.

Let me tell you some history on the boat. When I first got the boat, you always had to give it a little throttle to get it to idol but you could put it in the water and it ran great.After about 3 trips to the lake the throttle got lazy.When you open it up it would take about 5 seconds before it would react.Then it started to get harder to start.Then it got to where when you put it in the water it would pop,crack back through the carbs.So I took it to a shop to get it worked on and he said the number 1 cyclinder was low (40pds) and the # 4 coil was bad so he replaced it (coil).I took it to the lake and it changed nothing.I rebuilt the engine, 3 new pistons, reringed the rest and now there is 120pds on all cyclinders.He checked the fire,timing and rebuilt the carbs and it fixed nothing so he told me to come and get it because he had know idea what to do (good tech man).I have rebuilt the fuel pump,Recleaned the carbs and it still will not run when you put it in the water.Triggers and stator are new.I am at the end of my rope with this thing.ANY IDEAS?

 

[Faztbullet]

Re: How to check Reed Valves.

Could be broken seal rings on crankshaft...these will effect low end if damaged. Also did you mike cylinders as they can be worn past limit and still have good compression with the new rings.

 

[CharlieB]

Re: How to check Reed Valves.

Could be broken seal rings on crankshaft...these will effect low end if damaged. Also did you mike cylinders as they can be worn past limit and still have good compression with the new rings.

Two strokes wear the cyls most in the port areas as less surface to support the piston. This causes a reduced ring seal and less vacuum to the crankcase and carbs, causing poor fuel flow to start and low throttle performance. This is very hard to gauge without actually measuring the cyl.

V6's have the advantage of pulling a head, in-lines not so easy.

 

[Leonard Ray]

Re: How to check Reed Valves.

Had it completely down and check all that and everything was in spec.

 

[Leonard Ray]

Re: How to check Reed Valves.

Check all the wiring and it is all right by my book.

 

[Leonard Ray]

Re: How to check Reed Valves.

Check all the cyl top to bottom an were good.

 

[CharlieB]

Re: How to check Reed Valves.

Time to go back to the basics, forget everything you have done and start over. Do NOT assume anything is 'fine' because I 'just' did that!

Compression test, what are each one?

Spark test, does EVERY cyl arc a fat hot blue across a 7/16 inch gap? Remember, trigger wires flex and can be broken, and we have all seen defective new parts. So disconnect the throttle cable and slowly move the throttle/timing lever from idle to WOT and back while testing EACH trigger. It will save a lot of battery and starter life if you remove the spark plugs and ground all the wires except the one you are testing.

Just because you have a good spark doesn't mean you have good timing, Check timing ON EACH cyl, a bad Bias on a switchbox, or crossed wires in a new trigger can cause a lot of problems.

Verify all this, I'll bet you find a problem. If not, then we'll get back to the carbs and intake.

 

[Leonard Ray]

Re: How to check Reed Valves.

Took your advise and started over.Did a compression check all cycliners have 120pounds,all plug have great spark.Did find that the trigger time was off. It made a 100% defference in the way it starts and now it will run in the water.The only problem now is the trottle is still lazy.When you open it up it take it about 10 second for it take off.I took the boat out today and once it takes off it runs great.If before you put it in gear you open it up (not in gear)and clear the carbs it takes off better.Would the trigger stop affect this?

Thanks Guys

 

[CharlieB]

Re: How to check Reed Valves.

Idle SPEED is set by adjusting idle timing.

Idle quality is set by idle MIXTURE.

If you have adjustable idle mixture screws, they may still be set too lean, which reduces idle power and causes a bog or hesitation on throttle opening in gear.

Throttle opening cam should have a small amount of 'gap' that allows an amount of timing increase as the throttle is opening in gear such that there is an increase in timing before the carbs actually begin to open.

The complete 'Link and Synch' proceedure is very well spelled out in the FACTORY service manual. If not set very close to perfection, motor performance is less than stellar.

If you do not yet have a FACTORY manual, check this link

http://forums.iboats.com/showthread.php?t=309079&p=2072211#post2072211