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Old 20-07-2013, 09:37 PM   #1
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XR2 intake carb plate and fuel pump question

I have a XR2 power head, the carbs don't have a front plate or something on them which I'd except them to have. Its just the flat face of the carb itself. Now I know this affects airflow, and thus power.

I don't know the name of the part that should be on this can anyone help?

Also I was trying to find a mechanical fuel pump for it, as the previous owner on here had an elec one. However on cross-referencing the engine SN, all I could come up with was an electric one.

Am I right in the fact that a dual diaphragm vacuum pump will do the job?

Any help would be great, just trying to get this together so I can get it going!
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Old 20-07-2013, 09:50 PM   #2
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Probably an SST120 powerhead. Only uses an electric pump. Carb Plate is 13443A1 gaskets are 27-892211 x3 bolts 10-36137 washers 12-29245 x 6 vacuum pump holes are blocked in a 120 powerhead.
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Old 20-07-2013, 10:50 PM   #3
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That's very helpful, thank you.

Re the inlet trumpets, by searching SS120 I just found a picture (attached) that shows the trumpets I mean... I don't have these and I'm guessing finding some (will message the seller) may be hard...

Also just turned the engine over for comp test. which is good all read the same. However also discovered I only have spark on one bank when I tested that too. I swapped over the two red and blue stator wires and the problem moved to the other bank. So seems I have a dead stator too....
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Old 20-07-2013, 11:58 PM   #4
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Ok just done a stator test to confirm, swapped the red and blue around on the switch packs, and the problem moved.

I've done the impedance testing as per the manual, and find one of the stator outputs is almost short circuit, and the other about 3.6 Kohm.

Bummer! Will see if I can get another.
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Old 21-07-2013, 08:20 AM   #5
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Originally Posted by beyondhelp View Post
I have a XR2 power head, the carbs don't have a front plate or something on them which I'd except them to have. Its just the flat face of the carb itself. Now I know this affects airflow, and thus power.

I don't know the name of the part that should be on this can anyone help?

Also I was trying to find a mechanical fuel pump for it, as the previous owner on here had an elec one. However on cross-referencing the engine SN, all I could come up with was an electric one.

Am I right in the fact that a dual diaphragm vacuum pump will do the job?

Any help would be great, just trying to get this together so I can get it going!
Aren't these just velocity stacks. Thought bobs machine shop did them.
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Old 21-07-2013, 11:24 AM   #6
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That's very helpful, thank you.

Re the inlet trumpets, by searching SS120 I just found a picture (attached) that shows the trumpets I mean... I don't have these and I'm guessing finding some (will message the seller) may be hard...

Also just turned the engine over for comp test. which is good all read the same. However also discovered I only have spark on one bank when I tested that too. I swapped over the two red and blue stator wires and the problem moved to the other bank. So seems I have a dead stator too....
Those are not SST120 parts. I gave you the part number for the correct parts. No reason why the pictured parts could not be used other than the jetting would need to be checked.
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Old 21-07-2013, 11:40 AM   #7
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Ah ok, Its strange just been reading about them, I wasn't sure what their 'official' name was strange the consensus is that they are not needed. But there must have been an airbox or something there before?
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Old 21-07-2013, 03:06 PM   #8
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Yep probably just black plastic airbox if motor is xr2 200 race motor. Most say velocity stacks do nothing for performace.
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Old 21-07-2013, 03:49 PM   #9
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Xr2 parts diagrams

Might be useful...http://www.mercruiserparts.com/selec...R+XR2%2FMAGNUM
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Old 21-07-2013, 04:13 PM   #10
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And here for SST120 http://www.mercruiserparts.com/selec...oc_nbr=SST+120
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Old 21-07-2013, 06:12 PM   #11
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I must be in some wierd sort of alternate time dimension thing.
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Old 21-07-2013, 06:56 PM   #12
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Aren't these just velocity stacks. Thought bobs machine shop did them.
Adam Younger normally stocks them.
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Old 24-07-2013, 12:00 PM   #13
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Ahh a newbie eh, can't they be a pain. Ask me anything you want about EFI systems on 4 strokes turbo conversions or electronics and I'm sorted. I don't know a thing about whats what on these 2 stroke things.. but I am learning fast...

Right, So I need an airbox or something then. No wonder people don't see a gain if that's what should be there already. I just new that nothing there at all was not right. I've done airflow work on other performance road engines and having inlet trumpets or whatever makes a noticeable difference to power.

Ill put a post in buy and sell and see what I can come up with.

As a little update I found a mech pump from a 200EFI and also managed to get hold of another stator so I've actually had this out for test now. Please consider I'm no racer this power head is on a 150v6 Long shaft mid with alu prop on a 17ft Fletcher. Prop def has to go in the bin, and I'll be asking soon about something more suitable, I need to test fuel pressure and may go to elec pump if needs be as the previous owner had.
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Old 25-07-2013, 12:04 AM   #14
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Right, So I need an airbox or something then. No wonder people don't see a gain if that's what should be there already. I just new that nothing there at all was not right.
13443A1
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Old 25-07-2013, 01:19 AM   #15
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Adam Younger normally stocks them.
Did try to call earlier but answer phone. Will try again tomorrow.
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