Xb tuner

[BayouAl]

Is there a new tuner out there yet for the 250xb that will help any?

[EuropeanAM]

Welcome to BBC!

When you say "help any"... could you be more specific as to what you're looking to accomplish?

Also- might want to look at the following post. Perhaps the best improvement may be had by simply CLEANING the tuner.

http://www.bbcboards.net/zerothread?id=637339

[BayouAl]

If I remember right the xb don't have the idle holes in it. I was wondering if there was an after market tuner out there that would help hp top end, mid range, hole shot and such.

[BayouAl]

Found one

[Todd D]

Mad Efi
Hydrotech
Dave Bush

all offer aftermarket tuners. I have tried them all but a Dave Bush one since he hasn't released them yet..... Everybody has a different opinion on what the best is. Eric Simon suggests that you just cut 5" off your factory one...

[EuropeanAM]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Choupiqueangler &raquo;</td></tr><tr><td class="quote"> If I remember right the xb don't have the idle holes in it. I was wondering if there was an after market tuner out there that would help hp top end, mid range, hole shot and such.
</td></tr></table>

The XB tuner does indeed have idle reliefs.

Looks just like the one pictured in this post:

http://www.bbcboards.net/zerot...-mods


From what I've seen... there may be some small gains (in some cases) from changing the tuner. Some indicate their holeshot actually suffered. ALL indicate an increase in decibel levels.

Before you "cut" your tuner- check the price and availability of a replacement (some of these, such as the one for the XB) are now NLA.

[BayouAl]

Why does the xb have a deeper rumble at idle than the 225 efi and the 250 xs?

[EuropeanAM]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Choupiqueangler &raquo;</td></tr><tr><td class="quote">Why does the xb have a deeper rumble at idle than the 225 efi and the 250 xs?</td></tr></table>

Tough comparison... for the following reasons:

225 EFI's (especially prior to 1997) utilized a totally different (smaller diameter) tuner. MUCH quieter design. Also, around the same vintage- the 225 EFI and 250 XB had DIFFERENT EXHAUST PORTING.

250XS/ProXS is ported differently- and utilizes a different tuner also.

[BayouAl]

Is there a big difference between the xb tuner and the 225 efi tuner? If so what's the difference?

[EuropeanAM]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Choupiqueangler &raquo;</td></tr><tr><td class="quote">Is there a big difference between the xb tuner and the 225 efi tuner? If so what's the difference?</td></tr></table>

That's going to depend on PRECISELY what serial number (225) you're comparing it to.

Prior to 1997- there's a HUGE difference in the 225 tuner. Doesn't even look "similar".

Example parts drawing with the "XB" Tuner: http://www.mercurypartsexpress...r1885

Earlier style tuner was essentially a smaller "tube" attached to the adapter plate with a flange (with small idle relief). Substantially more restrictive.

[BayouAl]

It's a 1999 225 efi and a 2001 250 xb

[EuropeanAM]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Choupiqueangler &raquo;</td></tr><tr><td class="quote">It's a 1999 225 efi and a 2001 250 xb</td></tr></table>

Both utilized the same 833116A7 Tuner (now NLA).

[BayouAl]

Hey, thanks alot you've been really helpful. Thanks to our conversation I'm not gonna cut my 250 tuner. Thanks.

[BayouAl]

One more thing, I had the heads shaved on my 225. Will they fit and help compression on my 250? It raised compression on my 225 from 85 or 89 to about 115 per cyl. My 250 already has 120 per cyl. Don't want to get the heads shaved if I have some that might work. Thanks.

[EuropeanAM]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Choupiqueangler &raquo;</td></tr><tr><td class="quote">One more thing, I had the heads shaved on my 225. Will they fit and help compression on my 250? It raised compression on my 225 from 85 or 89 to about 115 per cyl. My 250 already has 120 per cyl. Don't want to get the heads shaved if I have some that might work. Thanks.</td></tr></table>

Would need some more details- such as the serial number the donor heads came from, and precisely how much was cut from these heads.

More than likely, they'll NOT be suitable, based on your past compression increase (with the 225). Too aggressive... IMHO, compression above 130-135 on this engine is excessive, and "could" contribute to Detonation (just not suitable for a fishing motor).