951 top end technical questions.

[68ragtop]

951 DI top end technical questions.

I have noticed many of the used 951 DI heads can have a substantial amount of pitting on the surface of the heads.
How much can be cleaned off of these heads & is it ok to adjust them with a thicker 4 or 5 hole gasket? I realized this will move the ports upward a bit & reduce the volume of compressible air. Is that a problem? or completely insignificant?

Any issues running 1.5mm oversized pistons? Other than rave clearancing? Is WSM my only option, I see BRP only has .5mm oversized available & Im already past that. its at 88.52mm with some scraping that needs to be cleaned up.

thanks, 68RT

 

[68ragtop]

One other thing, Is it common for these heads to have a un-smooth surface in the chamber? Most I see have what almost looks like pitting, or detonation marks in them. Seems like this should be smoother than what most are.

 

[Dr Honda]

The heads will look pitted because of overheat, detonation, and pistons breaking apart.

If you aren't building a race engine... a lightly damaged head is fine. Just file off any sharp edges. (using a small jewelers file) If you leave sharp points, you will make hot-spots, and cause detonation.

FYI... I have assembled at least a dozen engines with beat up heads, and never had an issue. AND... the center, port side head on my Islandia engine was BEAT. It's been running fine since the rebuild. (2 summers ago)


Since the 951 engine has such a short life... I wouldn't try to go to far over-sized. If you go to a 1.5 oversize... then make sure your squash band is SPOT ON !! If you just put in a thick gasket... that's not good. It could put your squash out of spec on the large side, and in turn, you won't cool the piston ring. Not to mention, you will be giving up HP also. On the 951, yes... this means you may have to buy another head gasket... but it's the only way to be sure.

 

[racerxxx]

http://www.ebay.com/itm/SEA-DOO-GTX..._Watercraft_Parts&hash=item19e4adc17c&vxp=mtr

Verify fitment

 

[racerxxx]

Jugs

http://www.ebay.com/itm/Seadoo-Cyli..._Watercraft_Parts&hash=item3cd2b7c567&vxp=mtr

 

[68ragtop]

Jugs

http://www.ebay.com/itm/Seadoo-Cyli..._Watercraft_Parts&hash=item3cd2b7c567&vxp=mtr

Sounds like those need an overbore as well. I think the ones I have will clean up at 1MM oversized. Is it worth picking these up to stay .5mm smaller?

http://www.ebay.com/itm/SEA-DOO-GTX..._Watercraft_Parts&hash=item19e4adc17c&vxp=mtr

Verify fitment

I see what you mean about fitment. BRP shows the 2002 RX uses 2906 13681, & this 2003 GTX uses 4206 13681

So far I can't find information on whats different. Physically they appear to be the same. Hhhmmmmmmm.

 

[68ragtop]

The heads will look pitted because of overheat, detonation, and pistons breaking apart.

If you aren't building a race engine... a lightly damaged head is fine. Just file off any sharp edges. (using a small jewelers file) If you leave sharp points, you will make hot-spots, and cause detonation.

FYI... I have assembled at least a dozen engines with beat up heads, and never had an issue. AND... the center, port side head on my Islandia engine was BEAT. It's been running fine since the rebuild. (2 summers ago)


Since the 951 engine has such a short life... I wouldn't try to go to far over-sized. If you go to a 1.5 oversize... then make sure your squash band is SPOT ON !! If you just put in a thick gasket... that's not good. It could put your squash out of spec on the large side, and in turn, you won't cool the piston ring. Not to mention, you will be giving up HP also. On the 951, yes... this means you may have to buy another head gasket... but it's the only way to be sure.

Thanks for the information! I assume your talking about keeping the squish tight enough to keep the flame/heat off the top ring land?
But on the flip side, I would imagine a resurfaced head, or too much piston area with the correct squish band may bring detonation in to the picture as the compression might raise. So I can see where these shoudn't get messed with too much. Is that what your leading up to Tony? Thanks, 68RT

 

[racerxxx]

I based the head off a part# search nothing else.

On the jugs, I'd prefer to stay as close to stock, especially if I could get a set of OEM first overs for a 951. Again, verify. There are 2 different part#'s for the first overs. These appear to be coated, almost makes you wonder if BRP knows something.

http://www.ebay.com/itm/2-Seadoo-95..._Watercraft_Parts&hash=item2a33346d69&vxp=mtr

 

[racerxxx]

Sounds like those need an overbore as well. I think the ones I have will clean up at 1MM oversized. Is it worth picking these up to stay .5mm smaller?




I see what you mean about fitment. BRP shows the 2002 RX uses 2906 13681, & this 2003 GTX uses 4206 13681

So far I can't find information on whats different. Physically they appear to be the same. Hhhmmmmmmm.

That is a revised part# almost all Seadoo parts now start with 420 IIRC. SHS posts old and new part#'s
http://www.shspowersports.com/fiche...y=Watercraft&make=Sea-Doo&year=2002&fveh=2370

 

[Minnetonka4me]

DIs used different parts between 00-01 and 02+ b/c of emission regulations.

The cylinders, injectors, and MPEM are different. Mix them up and it will not run correctly.

Ive got cylinders that need bore but are currently at std. and good clean heads available if you are lookin.

 

[SabrToothSqrl]

lol he said jugs.

 

[68ragtop]

Thanks Racer, that was a great peice of information. I just purchased the head & talked to the seller. He also has the cylinder from this same engine & says its clean with scuffs, no grooves, stock 88mm bore. I'll see what he comes up with on a price, but he informed me there are 5 port & 6 port cylinders. His is a 5 port, I am not sure if this RX supposed to have a 5, or 6 port. Like you mentioned in the other thread, the cylinder has been changed, so who know if what I have is the correct one in the first place.

68RT

 

[68ragtop]

DIs used different parts between 00-01 and 02+ b/c of emission regulations.

The cylinders, injectors, and MPEM are different. Mix them up and it will not run correctly.

Ive got cylinders that need bore but are currently at std. and good clean heads available if you are lookin.

Tonka, you must have made this post at the same time I was making the last one.

Is this emmisions change where the change in intake ports come in? I did allready grab the cylinder head listed above. It was hard to pass up for $120. I am thinking my cylinders (if they are the correct once for this ski) will clean up at 1MM, so I would stillinterest in a cylinder that would clean up at .25mm as then I could still use the BRP replacement pistons instead of WSM.

BTW, do you guys know if there is a complete BRP gasket kit availble?

Thanks again, 68RT

 

[Minnetonka4me]

Hard to pass up?? I would have sold you one for 80...DOH!

Looks like the pistons are still available, gasket kit isnt.

 

[dsteinmann]

Sounds like those need an overbore as well. I think the ones I have will clean up at 1MM oversized. Is it worth picking these up to stay .5mm smaller?




I see what you mean about fitment. BRP shows the 2002 RX uses 2906 13681, & this 2003 GTX uses 4206 13681

So far I can't find information on whats different. Physically they appear to be the same. Hhhmmmmmmm.

Those are actually my Jugs! And They are in pretty good condition! not perfect though I can take some better pics, I would run that with out an overbore if I remember correctly. I Probably just copied another listing

 

[racerxxx]

Tonka, you must have made this post at the same time I was making the last one.

Is this emmisions change where the change in intake ports come in? I did allready grab the cylinder head listed above. It was hard to pass up for $120. I am thinking my cylinders (if they are the correct once for this ski) will clean up at 1MM, so I would stillinterest in a cylinder that would clean up at .25mm as then I could still use the BRP replacement pistons instead of WSM.

BTW, do you guys know if there is a complete BRP gasket kit availble?

Thanks again, 68RT

Part# 290888134 or the new number 420888134 List is $234 I can get is for $187 so anything cheaper is a deal. On an engine as critical as the 951 I would only use an OEM kit.

http://www.ebay.com/itm/Sea-Doo-Gasket-Set-420888134-/140845374733?hash=item20cb09dd0d&vxp=mtr

 

[68ragtop]

Hard to pass up?? I would have sold you one for 80...DOH!

Looks like the pistons are still available, gasket kit isnt.

Sorry, I made that bad assumption on price.

When I did a quick ebay seach, most of them were listed closer to $200 & in completed history some of them sold at that price. I just made an uneducated decision. Seller did say however, he would throw in some bolts that have not been previouly removed with vise grips.. lol

 

[dsteinmann]

I bet your 40thvett, Ill find out about that bracket for you also, Everything off that ski looked really good all the electronic boxes looked Brand New!

 

[68ragtop]

Part# 290888134 or the new number 420888134 List is $234 I can get is for $187 so anything cheaper is a deal. On an engine as critical as the 951 I would only use an OEM kit.

http://www.ebay.com/itm/Sea-Doo-Gasket-Set-420888134-/140845374733?hash=item20cb09dd0d&vxp=mtr

Man, how did you find that part number? I couldn't find that last night. Part of your P.I. background?

Do you have any idea if that comes with crank seals too? or is it not a complete kit. I will try to research it....

But I will probably grab that seems like a very good price for oem.

 

[68ragtop]

I bet your 40thvett, Ill find out about that bracket for you also, Everything off that ski looked really good all the electronic boxes looked Brand New!

OK, now that's too funny. we just went full circle....... What are the odds?

That would be me, my AKA's are all car related.

 

[racerxxx]

Its on the cylinder and manifold page of the microfiche. Yes it's complete less some gaskets I would assume. On a 787 carbed engine they never give you the carb base gaskets or pipe to exhaust manifold IIRC All my 787 kits have come with the end crank seals.

 

[68ragtop]

When I google the part number, I am not finding much, but it would appear it has a $200 plus list price, so it must be pretty complete.

There I go making assumptions again.............

 

[racerxxx]

They show them as a bag lunch, LOL. I have stolen 787 OEM kits for not much more than an SBT kit. Patience is what it takes. A 951 DI SBT kit is $120 plus shipping

http://www.shopsbt.com/seadoo-jet-ski-complete-gasket-kits/48-111.html

 

[68ragtop]

Lol, I looked right past that. Which is somewhat surprising becasue I am hungry & haven't had lunch yet.....

I agree on the oem stuff, worth the few extra bucks. I would have to beleive for the cost of that kit, it would have to be more than just the top end gaskets.......