Yamaha 130 V4 Project Build.

[baja200merk]

Key words- under load (in-gear = 800-1000rpm) as long as all 6 carbs are completely closed.

In neutral it idles at 25-2800. Start in gear only, shifting is out of the question. The setup is a trade off, do you want to be able to shift it or do you want better hole shot?

99.9% of people who use the choke solenoid/advance method are drag guys. With friends like yours (dago... cough cough) it would not be hard to make the linkage do what ever you want.

I would put a bunch of timing to it and try a couple short holeshots first. It only takes 2 mins to change the timing just to make sure the gain is worthwhile on the v4.

[Mr. Demeanor]

Key words- under load (in-gear = 800-1000rpm) as long as all 6 carbs are completely closed.

In neutral it idles at 25-2800. Start in gear only, shifting is out of the question. The setup is a trade off, do you want to be able to shift it or do you want better hole shot?

99.9% of people who use the choke solenoid/advance method are drag guys. With friends like yours (dago... cough cough) it would not be hard to make the linkage do what ever you want.

I would put a bunch of timing to it and try a couple short holeshots first. It only takes 2 mins to change the timing just to make sure the gain is worthwhile on the v4.

I start in gear now and have it down pretty good. I boat in salt and have to flush when I get home. I hate starting it and having it rev up higher than the 1700rpm its now on the hose, sometimes with a cold motor. The way its set up right now, its full advance almost immediate. It would be easy to make a little removable shim for the base timing screw for running it on the hose. I had to get a much longer screw for the base timing to get it higher as it is. The stock screw with the timing pickup linkage arm shortened only got me to about TDC.
Part of the high idle issue might be that the Yamaha carbs dont have holes in the throttle plates. You have to crack them open a little to get it to idle at all and maybe they just wont idle down as low as typical carbs with holes. I do have extra plates and thought about trying some holes. Evrything is pretty good for now though. Just passed 20 hours on the motor.
You guys going to Lake Placid this weekend?

[baja200merk]

I start in gear now and have it down pretty good. I boat in salt and have to flush when I get home. I hate starting it and having it rev up higher than the 1700rpm its now on the hose, sometimes with a cold motor. The way its set up right now, its full advance almost immediate. It would be easy to make a little removable shim for the base timing screw for running it on the hose. I had to get a much longer screw for the base timing to get it higher as it is. The stock screw with the timing pickup linkage arm shortened only got me to about TDC.
Part of the high idle issue might be that the Yamaha carbs dont have holes in the throttle plates. You have to crack them open a little to get it to idle at all and maybe they just wont idle down as low as typical carbs with holes. I do have extra plates and thought about trying some holes. Evrything is pretty good for now though. Just passed 20 hours on the motor.
You guys going to Lake Placid this weekend?

Motor looks and sounds great, just figured u'd be interested since it responded so well to the 8* you have now. We are doing it on beefs 06 3.3 e-tec block with old carb front half and 1988 225 carbs with yami ignition. Its a mutt but your right the plates do have holes in them. Ive screwed with enough bike carbs and played with sync gauges to feel your pain. Luckily a bunch of timing under load with closed plates hides part of the carb issues.

If you try the timing trick, make sure its back to stock when the 15x34 goes on it at suwannee.

98.6 saturday morning

[Mr. Demeanor]

Motor looks and sounds great, just figured u'd be interested since it responded so well to the 8* you have now. We are doing it on beefs 06 3.3 e-tec block with old carb front half and 1988 225 carbs with yami ignition. Its a mutt but your right the plates do have holes in them. Ive screwed with enough bike carbs and played with sync gauges to feel your pain. Luckily a bunch of timing under load with closed plates hides part of the carb issues.

If you try the timing trick, make sure its back to stock when the 15x34 goes on it at suwannee.

98.6 saturday morning

Would have been 100mph Sunday morning with the better air. Congrats!

[CharlieN]

Low throttle timing,
If you go back to a small roller on the carb and adjust it will allot of space to the cam you will find you can set the timing back providing a lower idle and as you open the throttle you gain advance before the throttle plates open.
You can also reprofile the cam to change the advance curve. If the cam is shaped so the first half of throttle pedal barely opens the carbs and then the carbs swing open in just the later half of pedal, this will give you allot of early advance.
Visually looking at the V4 cam you run compared to the V6 cams it looks like your engine already has aggressive low end timing.
From you comments of a floppy cam it appears the pivot is worn and the cam might best being replaced, you might consider reshaping it to slow the carb opening a bit more in the early travel. This will give you allot of early advance.

The holes in the throttle plate are to allow the plates to be in position with the idle progression ports drilled in the carb body. If an engine is such that one needs to crank the idle speed screw open to gain proper idle speed this opens the fuel ports too early and hurts carb response. So with engines that need allot of air at idle one drills the plates so they can remain in position with the fuel ports in the carb body yet allow enough airflow for the idle speed desired.

When all this is setup right the engine should be able to idle down low and come on hard as the pedal is opened.

[Markus]

I slipped a piece of hose over the roller that fit perfect, re-adjusted the roller arm, and now it lines up perfect from fully closed to wide open and moves freely. Somewhere out there, Yamaha has a larger roller. I may have found a fix for now though.

Attachment 286035

Funny. It brings back old memories. We did the same with some grey Gates fuel hose on a V6 many years ago.

[baja200merk]

Would have been 100mph Sunday morning with the better air. Congrats!

no I meant your boat with the big wheel

My budddy stole my 34 i ran his 30 chopper thursday it quickly went 102 bashing the rev limiter.

[Mr. Demeanor]

Nothing to report.

After many months, 41 pages, 40,000 views, I have been waiting to say that

[chris3198]

Nothing to report.

After many months, 41 pages, 40,000 views, I have been waiting to say that

Well you better come up with something to tell us

[Mr. Demeanor]

Finally got a chance to string it out with the CCM reeds today. Boat went 1.5 mph faster then it did with the Boysens. Everything else was the same and the weather was very close to the same. 90mph vs. 91.5mph with a 30ET.
Wish I would have had the bigger prop today. That would have been a solid 94+ mph pass with a 32ET.
I couldnt tell any difference in low/mid but thats a hard thing to measure with your azz.
Boyesens were two stage with no reed stops.
CCM were single stage with stock reed stops.

More importantly, the Boyesens broke every time I took them over 7000rpm. The CCM's have been spun higher than that many times now and still going strong.

Chris wants me to try a lighter set of reed material when I get some new cages done leaving a little more sealing area.

[71V153]

Outstanding MrD!

Lake ex?

[BoomerMuskoka]

my mind has officially been blownt, thank you mr.D

[chris3198]

I'm blown away in hearing these speeds you keep achieving with this thing, you may get your goal of 95 mph when you get the new prop, as always please keep us posted.

[Mr. Demeanor]

Outstanding MrD!

Lake ex?

Yes aka Fake lake.

[magnum2.5]

CONGRAT'S that is faster than my 19' ACTION with a 2.5 MERC OFFSHORE, and it felt fast at the time...that is one BAD ride.....be safe.....