50 Yamaha - Page 2

A1an · 28 March 2014, 18:35

Finished up today too. All decals on.

I couldn't get a 11.5x13 at my local dealer, they didn't have on in the catalogue. What they did have was a 11 1/8 x 13. I'm hoping it won't make too much of a difference.

RIB-Teccie · 28 March 2014, 18:44

PM me the place you get the decals from and price!!

9D280 · 28 March 2014, 19:12

....and do they do Merc?

A1an · 28 March 2014, 19:20

Quote:

Originally Posted by 9D280

....and do they do Merc?

It's just my local sign writer Ralph.

If you take the old hood in it to your local place it wouldn't take much to copy the artwork.

spartacus · 28 March 2014, 22:06

Excellent job guys. You've just given a couple of Yammies a new lease of life.

Brings a tear to my eye.

A1an · 28 March 2014, 22:18

Quote:

Originally Posted by spartacus

Excellent job guys. You've just given a couple of Yammies a new lease of life.

Brings a tear to my eye.

Go on..... have yourself a wee cry....

spartacus · 28 March 2014, 23:26

Feel better now.

RIB-Teccie · 29 March 2014, 19:20

Anyone Agree??

Fired up the 50 today, ran fine for 30 seconds and stopped dead.

Ran it on cylinder 1 only, stopped dead after 30 seconds. Repeated the exercise on pots 2 and 3, exactly the same result.

Engine is fully rebuilt and all systems seemed fine.

I am thinking the CDI is kaput, causing the ignition to cut out after 30 seconds.

I've never seen a fault like this before. It's a weird one.

samt · 31 March 2014, 10:54

Quote:

Originally Posted by RIB-Teccie

Anyone Agree?? Fired up the 50 today, ran fine for 30 seconds and stopped dead. Ran it on cylinder 1 only, stopped dead after 30 seconds. Repeated the exercise on pots 2 and 3, exactly the same result. Engine is fully rebuilt and all systems seemed fine. I am thinking the CDI is kaput, causing the ignition to cut out after 30 seconds. I've never seen a fault like this before. It's a weird one.

Weirdly I am having the same problem with Bingosuck's Yam 50 on his SR4. Starts, runs and cuts out. Just timed it and its exactly 30 seconds as well. Same on each cylinder running individually. I swapped the ECU for another one I have, and its acts the same. Will let you know if I solve it.

9D280 · 31 March 2014, 13:16

How high tech are they?

I had both a Suz and a Ford Fiesta that did something similar - turns out it was the throttle position sensor on both - on the Suz the sensor had died, the Fiesta was a broken wire. Both put it in "limp mode" after exactly 30 seconds.

matt h · 31 March 2014, 13:48

poss look at the crank sensor.

RIB-Teccie · 31 March 2014, 15:33

There was not a crank sensor on the 50, at least not on one of this age.

I am going to check resistance on all coils, pulsar, charge and ignition before I fit a spare ecu. Trouble is, how do you know if a spare ecu is ok, usually parts that fail do so with a common problem.

On the USA message boards, these CDI packs are occasionally known to give out, there is quite a big aftermarket scene for these. They wouldn't make them, if none ever failed.

I have tried everything so far and spoken with others who know their stuff. Everyone's stumped. I think it is ignition and will report back if I find it.

samt · 31 March 2014, 19:42

Update... This was solved quite easily in the end, I found that by switching open the emergency enrichment valve the engine would keep running. It seems that there is exactly 30 seconds of fuel in the pipe that runs to the inlet manifold, so this is what was throwing me, along with the fact it would start immediately after stalling at first flick of the key. This confirmed it was fuel, cleaning the carbs and adjusting the mixture screws one turn out from the workshop manual spec solved it. I think these may need changing due to being over tightened by a previous owner, judging by a few other 'fixes' on the engine, and the complete lack of gear lube in the gearbox!

RIB-Teccie · 31 March 2014, 20:10

I will give this a try tomorrow.

I would have thought a problem with the enrichment mechanism would only affect the bottom cylinder as it only floods the bottom carb to work.

My carbs are spotless and the mixture screws have not been over tightened.

I will let you know how I get on.

samt · 31 March 2014, 20:24

Quote:

Originally Posted by RIB-Teccie

I will give this a try tomorrow. I would have thought a problem with the enrichment mechanism would only affect the bottom cylinder as it only floods the bottom carb to work. My carbs are spotless and the mixture screws have not been over tightened. I will let you know how I get on.

This engine is 1988, it has a solenoid operated valve, along with a small pump, that opens then allows fuel to flow through a hose to the top of the inlet manifold. The fuel comes is drawn from the bottom carb. That's how I understand it works anyway.

RIB-Teccie · 31 March 2014, 20:32

I will inspect tomorrow.

I can't understand why a problem with the enrichment valve would cause fuel starvation across a 3 cylinders if the float bowls are full.

Also the needle valves in the uk usually work best at 1.75 to two turns out. Factory spec is 1.25 to 1.5 but they never run well at that.

RIB-Teccie · 31 March 2014, 20:37

I'm looking at the manual. I think the bottom carb supplies the fuel into the enrichment valve. The needle lifts allowing excess fuel to be drawn up the small pipe to the top cylinder.

Mine has had a new solenoid. Other than bad starting, I can't see why it would cause the problem I have.

I still think I have an electrical problem, yours looks like mixture. Weird that the symptoms are the same.

samt · 31 March 2014, 20:46

Quote:

Originally Posted by RIB-Teccie

I will inspect tomorrow. I can't understand why a problem with the enrichment valve would cause fuel starvation across a 3 cylinders if the float bowls are full. Also the needle valves in the uk usually work best at 1.75 to two turns out. Factory spec is 1.25 to 1.5 but they never run well at that.

The problem wasn't with the enrichment valve, but it caused me to overlook the fuel problem at first. I had them set at 1.5 and it would not run at this, now at 2.5 it runs okay. The fact it was cutting out at exactly 30 seconds and restarting easily at first flick of the key and cutting out at exactly 30 seconds again also threw me to thinking electrical and ecu.

RIB-Teccie · 31 March 2014, 20:52

Have you checked the float heights???