Problem cranking a 97 XP

[timmyboy76]

Speculating, but with mod being done, more than likely, he messed with the jetting. Heres stock settings w/ needle and seat assy psi..etc

1997 XP 787 270500333 270500329 BN-40I (SB) MAIN-(MAG - 142.5 PTO - 147.5) PILOT-65 1.5 28 - 48 LOW- 1-3/4 HIGH- 0

 

[Nate Surveyor]

Well, on the Gray lines, it sounds like you have done a bit of searching, and found what you need to know.

Here is a general overview:

The following items should be cleaned.

Filter on bottom of fuel baffle.

Fuel select valve.

Water trap filter.

Carbs, and carb filters.

Check vent hose, to be sure it is un obstructed. Those gray fuel lines crudded up EVERYTHING on mine, so I replaced all of them. Vent lines, pulse line to fuel pump etc. Some folks don't replace the vent line, but I did, and really can not see a good reason to leave such a Trojan as disintegrating fuel lines ANYWHERE that it could get into the system again.

This has been an interesting thread. Amazing what some folks will doo, to GO FASTER! (they think).

And, a minor comment on the starter. If somebody has been cranking it with that HIGH compression, the starter may be partially burnt out, due to heat. It was not designed to crank it with that much compression.
But, I'd thoroughly clean all the bat cables, (both ends) and re assemble with a pat of grease, to keep out corrosion, first, and if it did not work right, there is a possibility of a starter problem. Also, it is OK to JUMP one of these, so long as it is done in a well ventilated area, AND the HOST motor is NOT running. You can mess up the mpem if it is running. A weak battery is a common problem. You can confirm that it is not the bat, with a jump, and good cables. BTW, don't waste you money on cheap jumper cables! Get good Mechanics grade cables. Four aught (0000) copper is good! But, I digress!

Nothing like a Sea Doo, for a ride around the lake.

Hope you find and fix everything!

Nate

 

[seadoosnipe]

And when you CC the combustion cambers on the heads, you do that with the head removed. Filling the cylinder with fuel will only cause your cases to have fuel puddle up because the rings are not designed to be liquid tight enough to trap the fluid to give you the proper reading. Now, if you put grease along the outter perimeter of the piston so the fuel won't leak past the rings then you could get a reading but the dimensions given for heads is typically by measuring on a bench, head removed and sealed up to compare to stock volume range. You could have measured your stock squish thickness with the head on but that'd only give you the thickness of the squish, not the volume of the dome itself.

Because you seem like a very good mechanic, I don't want to put you on the spot by when you say "you don't have the shop manual in front of you, that they need to know the spec" and "this is what I run", you go on to give a "this is how I do it" kinda way in the volume measurement. That procedure I quoted him came directly from the shop manual for volume measurement for that year, make and model. The required liquid is a 50/50 mix of oil and gas, which is sufficient to hold the liquid for the required amount of time to do the test. Fuel and oil puddling in the bottom of the casing (in my opinion) is not going to hurt anything. It's not like the ski sunk in water and your having to go through the procedure of getting all the water out (compared to a puddle of oil).

I've done the test by that procedure, just as the shop manual states (many, many times) and they have all worked well for me. Some have even allowed me to discover that a ring job was needed.

Your advice is sound but if you don't want people quoting something "how they do it verses what the shop manual so states", then you should not either.....:cheers:

BTW, with my old eyes, I still can't see any obvious difference in depth. I'd have to have it in front of me to see under my mag glass or measure it. Your talking mm's and my eyes are quickly nearing 50. But excellent pix!..........it seems the starter and other issues where answered with excellent advice....

 

[PWCdoc]

snip .... "you go on to give a "this is how I do it" kinda way in the volume measurement"... snip

No, CCing a head is done just as I stated. And I too have used the method you have outlined and if your cylinder is borderline worn out then it's going to leak past the rings. I say this from experience.

We don't need to try and split hairs on how different people do this or that when they both seem to use proper techniques. What we do need to do is to stay on topic and help this guy figure out what is going on with his ski. He has some scuffing in the #2 cylinder, obvious carb issues, possibly a detonation issue...which could be old from running lower octane fuel than required for that compression due to the obviously reworked head. With that much pressure he should have been running fuel with an octane rating over 105 which would certainly cause problems by just running pump gas.

 

[seadoosnipe]

Exactly right.....

Your exactly right. This is about his motor. But, to give false information or information that is inconsistant, doesn't do this member or any other member good.

Your method is quoted in none of the 30 or so manuals I've read thru in the last year and a half I've been reading them. My skills in rebuilding engines, 2 stroke and 4 stroke are greater than 35 years. I'm not hear to bump heads with no one. But, I am here to give advice, not based on "how I set something up" verses what the manual says, unless I state it so.

If you have a shop manual, please quote me the one you used for this volume measurement test and chapter. I'll verify this and humble myself to you that I was wrong.

As long as I have been in engines, I have an opinion and idea from principle or theory on how I think it will run better......but, unless I state that it is what I am doing, the members here, jr. and premium, dont' get any guesses from me. They get information that I research directly from the shop manual. Most of the times, it's summarized for compressing, to keep from typing a 5 page procedure. But it's the procedure none the less.

The idea of doing the test while on the machine is to see that the liquid will stand for several seconds to ensure there isn't a leak between the piston and cylinder walls. How can you know what the measurement is, from it laying on it's back, exposing a dimension of a few inches to deterimine from which side it's going to run to. You'd have to have a table perfectly level and an eye that can see that it's perfectly flush across the top. A couple CC's isn't very much.

The detonation was probably caused by the lower chamber volume and high compression. That, it seems we agree on. So, with the engine together and running, that problem will probably disappear.

It's nice to have a good mechanic in the forum. We have several. Your in the top of your class. But remember, there are more than one.:cheers:

 

[PWCdoc]

Here is one I found online for you to peruse: http://www.compcams.com/Technical/Instructions/Files/130.pdf

As techs, we will almost all have different methods for arriving at the correct outcome. I know from my 20+ years what works best for me. IT was obvious to me the head was reworked and his compression was way way way too high. That info alone would be sufficient to replace the head and get it back to stock.

We'll get it figured out I'm certain of it. He'll have his compression back down and on the road to running properly soon.

 

[yama0918]

Maybe you guys missed my post on 1-7-09 at 6:45pm. I installed the new head and that resolved my compression issue. Now I'm trying to decide on a replacement battery. It has no trouble starting my other ski's but barely cranks this one. Even after a full charge, it has trouble. Any recommendations on a good battery without breaking the bank?

 

[timmyboy76]

yama quote....Maybe you guys missed my post on 1-7-09 at 6:45pm. I installed the new head and that resolved my compression issue.

No offense, Snipe/PWC, BUT....that's funny...
Believe "Nate" mentioned, if jump'n it and she fires up, then prob "may" lay in battery, but if still trouble to turn, then I'd take gander at starter..

 

[seadoosnipe]

Resolution.....

Your very right. This issue was solved because the new head arrived, so now compression is back to normal. But, in a thread, when we start out with advice, we have to make sure that members, especially jr. members, who don't have access to the BRP shop manuals get the approved advice by Seadoo manuals, as moderators, that's our job.

The above link that was quoted is for 4 Stroke engines and does not apply to the 2 stroke Rotax. The procedure I quoted in my post for volume measurement, is exact from the procedure for rebuilding the Rotax from the BRP shop manual, therefore, should supercede any other procedure. Especially one that is used in a 4 stroke engine (note in the procedure it mentions valves and alcohol and water).

The reason for this obvious hi-jacking is because of our search engine. If someone in the future comes in looking for information to do this procedure, I cannot let them be misled into a procedure that is not BRP approved.

I said I'd humble myself if I were wrong. I wasn't. Please, if you need to test your engine for proper volume measurement in the Rotax engines (outside of the 4-TEC), then use the BRP approved procedure I quoted above.

Now, timmboy's information on the issue with the battery sounds very sound. :cheers:

 

[yama0918]

I really wish I had a spare starter so I could swap it to see if that is my problem. Since they cost too much I will probably buy a new battery first. I could always use the battery anyway.

But first I will remove the carbs (to clean and rebuild) and starter. Someone here suggested to check the starter for worn or dirty parts.

Unfortunately it is little too cold to work outside for long.

 

[seadoosnipe]

Load test.....

You can take the battery for a load test at Autozone or Advanced auto parts. They can tell you if the battery holds the necessary amps as rated. It may hold the volts but not the amps.

You can also, connect a set of jumper cables to your car battery and give it a try. This can only be done if the vehicle you are jumping from is not running. Because the electronics could be damaged from the charging system of another vehicle. If you jump and it works fine, then the torque in the starter is fine. You just need a new battery. If the starter barely turns over but spins freely with the plugs out, then the starter's torque is shot and it can't deliver enough to overcome the compression of your cylinders.:cheers:

 

[seadoosnipe]

24 members.....

There have been 24 members who have read and contributed to this post. With no doubt, read the "head bumping" that PWCdoc and I have had.

I have PM'd PWCdoc several times and he's replied. What I take away from this is, there is more than one way to skin a rabbit. I know that as well as anyone else. But, I think it very important that in the forum, we stick to a procedure unless we quote or say, I have information from another source. Most who have read my threads, know that when I do research or make a statement, I quote (cite) where this info is coming from. If I don't, you can bet I read it from the BRP manual and summarized it for a post or thread. Procedures can become rather lengthy and time consuming to type.

In closing, I'd like to say, that I have also PM'd yama0918 on his battery issue along with the post. I think he will be able to find a solution now from my post along with others who have made good replies to his problems. I'd also like to say that in communicating with PWCdoc in PM's, I do know he's a highly skilled mechanic in the PWC engines and works a lot like me, by understanding the theory of how an internal combustion engine works. That means, sometimes, we don't need a manual.

Please forgive my hi-jacking and I hope this puts to rest the issues in procedural tests in this thread, or in the forum for that matter.:cheers:

 

[yama0918]

Today I was able to connect my portable battery pack to the battery terminals and crank the engine fast with the plugs in. So obviously I need a new battery. Before I changed the head which lowered my compression from 200 to 148, I did this same exact thing with the battery pack and even with jumpers to my truck battery and it would not crank. I wonder if it ever started before I bought it.

I removed one gray fuel line and did not see any deterioration. I am going to replace all of them anyway. Now I'm in the process of removing the carbs to clean or rebuild those.

 

[kustomkarl]

You usually won't see any obvious damage in the fuel lines...it all accumulates in the carb filters over time.

Karl