how can i gets more RPM in my yamaha

[pr-550yamahadriver]

i have a yami 30 3 cylinders.....

my question is

if i gets more advance the ignition coil the engine gets more rpm??


sorry for my english....

[Roy Hodges]

i have a yami 30 3 cylinders.....

my question is

if i gets more advance the ignition coil the engine gets more rpm??


sorry for my english....

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It all depends. Most stock fishin ' motors are a little on the rich side , from the factory. If you're already revving it above factory advertised rpm , you might advance the timing 1 or 2 degrees and get a gain. Or you may burn (&stick ) a piston. When we raced SPORT E , back in the late 1970's , on our 1975 year model 75 johnny -rudes , we were advised by Tom Ireland, that the hot setup ,for that particular motor was 1 step leaner jet, (main)
and 2 degrees MORE advance on timing. He only learned that by burning many pistons .

[looseunit225]

the first thing i would be doing is trying to increase the compression ration on the engine!

stock out boards run a very low compression ratio so you can almost get away with running any fuel!
i would advise you to rip the heads off and start shaving some meat off them and than i would do plug chops and see how they look!

[pr-550yamahadriver]

guys thanks for your opinions i try get moer power....jajaja

[Fast Fred]

no. more timin does Not mean more RPMs. thare is apoint ware too much timin and high RPMs will clash and she will burn down. more comp from the head would help max rpm, could try jackin it up on the transom as well.

[Miss BK]

When we raced these motors, one of the first mods (of many) we did was put 50hp Yamaha carbeurators on them. This meant a whole new adapter plate for the intake manifold had to be built as well. And you would also need to make some room for these bigger parts by modifying (holing) the bottom pan.

Shaving the heads, like Looseunit described, was also among the first mods.

Handmade dry tuners added more boost. Large exhaust holes at the base of the tower made them VERY LOUD!

Later, the motor builders did more radical things like installing special pistons. I don't recall exactly what pistons they were (this was top secret at the time!!), but I seem to remember they came from race motorcycles.

Not sure how radical you are allowed to go - but those are some things done here that enabled them to set kilo records of nearly 90mph.

Val

[OUTBOARDER]

What are the rules?

We had a drag skiff and found that the Yamaha 30HP 3CYL could be modified to use the 40 HP sleeves and pistons.

[pr-550yamahadriver]

val you have any images of this carburators on the 30 and this special part...

[John (Taylor) Gabrowski]

From what I learned from Modified enthusiasts because my backgound is stock outboard its more complex than any one thing but being conservative one change at a time is the way to go even though you may end up doing more than one thing.

Being that the engine may be slightly rich on the fixed jets one of the most obvious changes would be to put in 1 or 2 numbers more a cooler set of sparkplugs without altering the ignition timing.

Then go one larger a size mainjet to feed the colder running sparkplugs. There should be an increase in power right there without risking lean out and overheating the engine.

Once that route is established get a portable digital meter that has a under the sparkplug temperature sensor and with that increase and or yes decrease BTDC timing with the objective of keeping the at sparkplug and head water jacket temperature no higher than about 205 degrees Farenheight or it equivilent in Centigrade by also juggling the high speed jets to get optimum air fuel. Power should be optimized.

Assumptions and extras for good tunning also included:

*That you are using a tachometer.
*Remove factory water jackets coolant thermostats.
*That your using a good high load test wheel.
*That your fuel's octane and quality is the same for consistency.
*That your lube is the same and of high quality a for 2 stroke product be it petroleum or synthetic and mixing rations are always the same.
*That you are using a good bright and accurate timing light with well painted indicators the beam stops and can be seen. Even an apparently properly retimed engine can be fighting itself, its own ease of rotation due to overtiming even though it won't be overheating leaving ignition un-optimized.
*That your using good, reliable ignition products (sparkplugs etc.)
*That you have and can use an ignition discharge reader per sparkplug wire. (a properly firing cylinder uses less voltage to get good ignition where one not at optimum can require markedly more) (also weeds out ignition problems like poor coils and bad secondary wiring)
*Install a thin phenolic spacer under each carb gasketted base to kill any possible heat transfer from crankcase to carb therefor air/fuel to keep it all cool as possible.

Anyone want to take their kick in the cat on this subject as I might have gone too far or not enough?

[quty06]

Handmade dry tuners added more boost.

can u show us with pict(s).

my experienced with saw engine(single piston) which i put it on R/c boat like @ my avatar, by advancing the timing will give extra top end. But in multiple piston outboard, i guess it'll different & way to do it.