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98 6hp 2Stroke Wonbt Start Yamaha

L

lofty

New member
"Hello,

I'm hoping some

"Hello,

I'm hoping someone can help me or point me in the right direction. I've tried everything I can think of and just can't get this motor running.

Last time I ran it, it wouldn't run at full throttle. Even when I gave it throttle it would was only at about 30% power. It would bog down and die if I left it at WOT.

Here's what I've done:
-Changed gas line & tank
-Tried new gas
-Changed fuel filter
-Changed spark plugs
-Checked compression on both cylinders
-Checked spark on both cylinders
-Thoroughly cleaned the carb
-Confirmed gas is getting into the bowl of the carb

What else could it be? Thanks in advance for the help."
 
That's one thing I'm a

That's one thing I'm a little confused about. Since gas is getting to the carb shouldn't it at least start?

The fuel pump hooks on the side of the carb and sends fuel directly into the carb bowl.

Thanks!
 
so yes the carb is filling up

so yes the carb is filling up then

so you got sparky?
what where the compression numbers

when was the last time it ran
 
compression is 121 & 117.

compression is 121 & 117. I just tested the spark against the block and it was fine. I ordered a spark tester so I can can check it again though.

It ran a few weeks ago. It would start and idle but die whem I gave it gas.
 
"Just-In-Time/Chad - sounds a

"Just-In-Time/Chad - sounds a bit like "stuck" reeds.

Chad, you stated that you cleaned the carb - was it giving you trouble which was corrected, or did you clean it to try and fix the problem you are currently experiencing?"
 
Graham Lamb - The motor would

Graham Lamb - The motor would start and run at about 25% throttle but would bog down and die when I gave it more throttle. I use this motor as a kicker for trolling but it wouldn't go any faster than trolling speed so I thought it might be the carb and cleaned it.

JUST-IN-TIME - I thought it could be a reed valve and removed those. They looked fine and sat flush. When I have the carb off and attempt to start it they barely move. Should they totally open in this situation?When I pressed on them they opened freely.

One other thing I noticed when I had them removed was that one side had gas/oil on the back side but the other was prefectly clean. This reeds have 3 valves on each side.

Thanks for all your help!
 
"yes they are fine
i say eith

"yes they are fine
i say either a dirty carb still, you did not clean right, kinked or clogged fuel line, which you said you changed
clogged vent, but you would see the tank collapse

double check the fuel lines again and re-sync the carb"
 
I'll re- sync the carb tod

I'll re- sync the carb today and give that a try.

I'm confident it's not the gas line/tank. I've tried multiple lines & tanks. I was hoping that's what it was but I wasn't that lucky.
 
"looks like one of my posts th

"looks like one of my posts the other day didn't make it on the thread.

I checked spark/compression again and everything was fine.

Sprayed soapy water around the crankcase to see if it was leaking and didn't see any noticeable leaks.

I put a timing light on it and when I try to start it, it's sparking at 9 degrees BTDC. I'm confused, the manuals says set the static timing at 35 degrees BTDC. Could this be the problem?"
 
"Chad, I don't have a Yami

"Chad, I don't have a Yami manual, but they built most of the little Merc's for years.

At idle most of the little motors are timed at 8 degrees +/- 1 and max advance would be 36 degrees BTDC..."
 
"Alright, so it doesn't ap

"Alright, so it doesn't appear to be a timing issue then.

I really haven't been able to find any info in the manual abouting sync'ing (sp?) the carbs on the 6hp motor. I'll still reading over the book though and think I will try adjusting the throttle cable and going over the carb one more time.

I'll let you know if this does anything."
 
No luck so far. After I adjus

No luck so far. After I adjusted the throttle and tried to start it a few times I pulled the plugs and they were dry. Shouldn't they have at least a little gas on them or should they be really covered with gas.

I'm about to give up and take it to the shop but I really want to figure this out myself. Stuff like this is good to know.
 
I don't think it's a s

I don't think it's a stuck needle. When I checked compression the other night the bowl still had gas in it and the end of the compression tester had gas on it. I've probably had the carb apart about 5 times and checked to make sure the needle wasn't damaged and moving properly.
 
I know I'm getting spark.

I know I'm getting spark. My thought is that for some reason it's not creating the vacuum to pull gas from the carb.
 
"no such thing as vacuum in a

"no such thing as vacuum in a motor
biggrin.gif

it is a high and low pressure system

well no wet plugs???
time to do a leak down test

what were the compression numbers"
 
Compression was 121 & 117.

Compression was 121 & 117. What's a leak down test? Is there someplace online I can find instructions.

I really appreciate the time you've spent replying on this thread!
 
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