Yamaha 55be (circa1991) service manual & general help with under-powered performance

[Neils6896]

This is what it says the mix and plug should be.... Being in the UK i assume its the EU model as the sticker inside the cowling says to use the the BR8HS-10 plugs..

[Neils6896]

sorry it's not a very clear picture..

[panasonic]

Getting off track here now. Mixing 100:1 only shortens the life of your engine.,mix it 50:1 and all will be good. As already mentioned the R just stands for resistor in the plug.
Both of these will not cause the trouble you are having with your engine.

Look in the front few pages of the manual you have and there should be a chart showing the models of engines that are applicable to that manual.

You have to start troubleshooting with the advice you have already...spark.,compression ect

Then report back.

[boscoe99]

100/1 is normal for certain Yamaha models. No evidence that I have ever read that indicates a reduction is engine life.

[panasonic]

100/1 is normal for certain Yamaha models. No evidence that I have ever read that indicates a reduction is engine life.

Both my engines have a sticker on the side saying 100:1 but I run them 50:1 with no issues.

I only have here say to go on about whether running them at 100:1 may shorten their life. Probably a load of crap...who knows.

[99yam40]

100/1 is normal for certain Yamaha models. No evidence that I have ever read that indicates a reduction is engine life.

I do not think the running is a problem, it is a problem when set up for periods of time without fogging to make sure bearings and other shiny surfaces do not rust

[TownsendsFJR1300]

Both my engines have a sticker on the side saying 100:1 but I run them 50:1 with no issues.

I only have here say to go on about whether running them at 100:1 may shorten their life. Probably a load of crap...who knows.

Logic and how the auto lube system works, really tells the story.

The auto lube should pump more oil at higher RPMs..

IMO, low RPMS don't need the same amount of oil as high RPMs (that, again IMO is a given)


So, with that said, depending on how you'll run it, IE higher RPMs-I'd run the 50:1, lower RPMs, 100:1.


Agreed with Pan, I'd run the 50:1 regularly, un-less all day tr00ling / mostly low RPMs.



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[boscoe99]

I do not think the running is a problem, it is a problem when set up for periods of time without fogging to make sure bearings and other shiny surfaces do not rust

Think about all of the oil injected Yams that are running at 200/1 when at low RPM's. Just before being shut down and stored for a period of time.

Think about a Yamaha OX66 EFI model. Where the oil gets mixed with the gasoline in the VST. Guy idles for quite a while. 200/1 mix in the VST. He powers up to WOT. Motor is now running at WOT on a 200/1 gasoline/oil mixture until the VST can refilled.

Interesting subject for sure. Psychological. If a certain amount of oil is good then more has to be better. Same with torque to a fastener. Same with oil pressure. But voltage is just the opposite. Too high becomes a concern.

[Neils6896]

moving away from the oil debate for a moment.... I'm doing the compression test tonight, what sort of reading should i be looking for?

Also this may sound silly but would running it on 75:1 mix perhaps be a good solution? I'll be using it on the river and at sea so will be a mix of gentle low rev cruising and (hopefully) going hell for leather at WOT....

[Neils6896]

Compression and spark test done, both seem fine? Took the carbs off and gave them a spray with carb cleaner. tried disconnecting one HT lead at a time and the top cylinder runs perfect but the bottom cylinder doesn't run...

[Neils6896]

How do i check the timing?

[99yam40]

I would think that it would be like any other gas motor and use a timing light hooked to #1 spark pug wire.
should be a timing pointer somewhere with timing marks on the flywheel to point the light at.

if the fuel pump leaks fuel into the bottom crankcase, the bottom cylinder will run too rich to burn properly
was there spark on the bottom plug when you pulled the plug wire off?

[Neils6896]

Also now no water ejecting from the "pee hole" when i'm running it using the muffs. Is this most likely the pump impeller that needs changing?

[Neils6896]

I would think that it would be like any other gas motor and use a timing light hooked to #1 spark pug wire.
should be a timing pointer somewhere with timing marks on the flywheel to point the light at.

if the fuel pump leaks fuel into the bottom crankcase, the bottom cylinder will run too rich to burn properly
was there spark on the bottom plug when you pulled the plug wire off?

Yes both plugs sparked fine (tried uploading video of both for analysis but file too large)

[99yam40]

blow some compressed air up it while running to see if that unblocks it
ir maybe a piece of weed wacker line pushed up it