93 merc 90 HP/3cyl. reed inspection

[Eriespider]

I am currently waiting on parts to rebuild the 3 carbs and while I have them off, I was wondering how to inspect the reed valves in this engine. Do they go bad? I am having a difficult time getting this engine to idle at 1000 RPM. I hope the rebuild on the carbs will do the trick, but before I assemble it all back together, was wondering about the reeds!

 

[Laddies]

Re: 93 merc 90 HP/3cyl. reed inspection

I have had a couple 80/90 HP engines that the reeds were bent and did not seat well, replaced them and the engines ran much better at idle and startup. To check them just remove the plates behind the carbs the reed plate is next, don't try to reuse the gaskets install new.

 

[Eriespider]

Re: 93 merc 90 HP/3cyl. reed inspection

I checked the top reed last night and it looked good. I checked the seating and also the gap. All within specs. With the reeds removed I was able to get an incredible view of lower piston chamber, rod etc.

Thanks for the help. I will reassemble with new gaskets!

 

[sschefer]

Re: 93 merc 90 HP/3cyl. reed inspection

Your reed block assemblies have a series of 3, 3 petal reed units per reed set for a total of 9 petals per block. The petals lay perfectly flat against the reed block and are under light and equal tension.

If the reeds are not flat or if the tension on each petal is not equal, replace them. These run about 25.00 per set and you will need 3 sets.

Soak the reedblocks in Mineral Spirits (solvent) overnight to help get the old gaskets off and use plastic scraper to avoid damaging the blocks.
Note: If your gaskets come off really easy then that's probably where your air leak was.

A good practice is to clean the blocks and all gasketed mating surfaces with alcohol and clean compressed air just prior to assembly.

Torque all bolts to spec and in the exact order that the manual states. Wait 24 hours and then re-check the torque.

Once the torque is set then re-install your carbs and you should be good to go.

 

[Eriespider]

Re: 93 merc 90 HP/3cyl. reed inspection

sschefer
You are exactly correct on your description of the reed block assembly, 9 petals per block. I noticed the bolts were not very tight at all when I loosened them. Also you are correct in the way the gaskets came off. They came off easy with only the gaskets sticking a little around two bolts. The petals all lay flat except one, however it still is within tolerance of .020 mm. when I slide the gauge under the tip, it slightly raises! This was the top cylinder. I did not check the other two because I thought I was good to go. I have about $150 in the carb rebild kit, new floats and feul pump. Would you reccomend anothe $40 for set of reeds and gaskets at this point?

Original problem is engine would not idle very good! Could not get below 1300rpm and top carb would not choke out during adjusting screw all the way in until it was lightly seated. Engine kept on running!

Thanks in advance!
Rusty