Ray, where are ya? Yamaha performance guidance.

[brownies]

I have a 98 150 v-max. (perf heads, reeds, reed plate, intake plate, carb jets, exh plate, tuner). Compression 175psi across the board.<br /> Thinking about a 225 Excell now though. <br />Are there any parts that I have that would help the Excell? <br /> OR, Are there any preferred parts off of my 150 that would work better on the Excel than what came on it?<br /> Any tips, tricks, thoughts on this since too much is never enough.

 

[Ray Neudecker]

Re: Ray, where are ya? Yamaha performance guidance.

Most of the items listed were most likely off the Excell or patterened after them. It is the combination of the best high performance parts ever produced by Yamaha.<br /><br /> The Excell porting and carbs are far superior to the later models. The heads off the 150 would be a boost but you will need to run a combination of premium and racing fuel, one gallon of racing fuel mixed with four gallons of 93 to keep the engine from detonating with the higher compression. Having the present block ported and a set of Excell carbs would be the alternate option for more HP. The knock sensor on the Excell while keeping it from detonation will also limit the timing and prevent the motor from ever performing without the higher octane.<br /> Normally when trying to hop up the Excell we remove the computer and go to manual timing. This gives a lower timing at take off than the computer allows and helps to reduce detonation. Hope this helps.

 

[brownies]

Re: Ray, where are ya? Yamaha performance guidance.

Any thoughts on this plan?<br />Use the excell the way it is. Use the V-max oil injection system and the timing system off of the V-max as well. (if that's even possible?)<br /> OR<br />Same scenario with the hydro tech heads off of my Vmax on the excell. (and mix my own fuel).<br /><br />If either of those is possible, any idea of hp that can be obatianed from the excell? AND/OR a new almost safe operating RPM?

 

[Ray Neudecker]

Re: Ray, where are ya? Yamaha performance guidance.

You can use the oil injection off the V-max on the Excell if you change the shaft as well as the pump. The electrics won't interchange, but you can use the Excell without the computer bypassing it. You will need a stator with a movable arm and can use the other parts of the control arm assembly on the V-max to complete the job. With the changeover of the heads to the Excell and bypassing the computer, you should be close to 255 HP. You would need to rejet the Excell to at least 174 starboard and 180's port and set the max timing to 24-26 degrees. The other option would be to use the carbs off the Excell. If you have the Hydro Tec bored carbs or the stock V max ones with different jets this will give a big boost to the V-max.<br /> Be very careful to get the jetting right when doing all of this swapping around.

 

[Ray Neudecker]

Re: Ray, where are ya? Yamaha performance guidance.

You should be able to turn the Excell 6800-7200 all day with no problem if you have the jetting right. I would add some oil to my fuel if you leave the oil injection on and turn over 6400.

 

[brownies]

Re: Ray, where are ya? Yamaha performance guidance.

The V-max now has 170-174 jets staggered here and there. Installed according to Hydro Tech instructions. ALL that stuff and I sure thought I'd get more results than I have so far. (which is why I'm looking at an Excel).<br /> The list above was Hydro Tech parts and I've raised the engine 4" and am seeing 500rpm improvement.<br /> 1st time out to lake, started and went.<br /> 2nd time out, boat would not start. Plugs were gas fouled. Cleaned em up and FINALLY got it running. Sat in one place throttled up just a tad for 5min. It stopped spitting and sputtering after about 5min and was good.<br /> Changed plugs about 30min later. Boat still ran the same.<br /> Not been back since. Wondering why it gas fouled the first plugs?<br /><br /> Just thinking a closer to "stock" Excell would be a big improvement over what I have now?

 

[Ray Neudecker]

Re: Ray, where are ya? Yamaha performance guidance.

Sounds like the jetting is a bit rich. They are cold natured though. Unusual to gas foul the plugs but it does happen. Be sure the battery is hot before you try to start or it will spin a little slow when starting and foul the plugs before it spins fast enough to fire. The hot heads make it harder to spin.