carbureator adjustment??? timing issue???

[seasoned]

I just bought a 1997 spx used obviously. At first the previous owner did not tell me that the gas was 5 months old... so I went ahead and used it; however, that should not be the problem, as I have used it and filled it up several times over the last few days with high octane.

The first few days I couldn't even get the speed up to top speed because I couldn't hang on. Then, I began having a problem starting the ski. It would start, but as soon as I gave it gas, it would die. After finally getting started, it would run well.

Marine mechanic replaced the spark plugs and fooled around with the carbureator screws; however, he claims he put them back to what they were set to before. After replacing the spark plugs -- there seems to be some confusion from local service dealerships what the proper gap for spark plugs are... so teh most reliable was .032.. gapped spark plugs and installed, cleaned wires. Never seemed to go as fast. However ski seems to be running rich because spark plugs have excessive build up.

Replacing the spark plugs got rid of the starting problem; however, dealership recommended adding a fuel additive in order to make sure build up of old gas in carbureators was not a problem -- added fuel additive (maybe too much accidentally) and let sit overnight.

Put jetski in the water today, started right up, however, would not get high revs. Appears to be missing at high rpms. No water is coming into the ski that I can tell -- nothing appears wet. There is no corrosion.

I ran it around for like a half an hour and still no avail. Marine mechanic started engine and pulled out plugs one by one.. each time the ski died. Every once in a while the engine back fires and dies on startup and continues to rev on it's own occasionally.

It's my opinion that the carbs need to be adjusted.. what would be a reasonable cost for this from a dealership? I don't trust epowersports or jetski connection here because of false diagnosis of what they called a starter problem when it actually was a wire with the insulation wore off (WHICH I HAPPENED TO POINT OUT IN FRONT OF THEM AND THEY DENIED!!!!!)

Anyone have an opinion of what this problem could be related to? What could I expect the dealership to say. My dealership tends to look at the most expensive thing first..a nd right now I'm unemployed.

HELLLLLLLLLLP.

[Bryan Glynn]

First, the proper gap for your plugs is 0.020" - 0.024", no more. Second, mo matter what you put in your gas to try to clean the carbs (this only works well on car carbs BTW), if you let gas sit in it for 5 months, it's waaay past it's shelf life. Not only is it's octane level way below the safe level for running, it's already formed a nice varnish in your carbs and started deteriorating your diaphrams. You need to get a couple rebuild kits (we sell them for $30 each for your carbs, Mikuni Super BN) and rebuild your carbs. Third, until you do this and reset your mixture screws, you will not be able to accurately diagnose the problem. Any problem in a carb will mask other problems, and create new ones - you'll just drive yourself crazy or blow your engine trying to [img]smile.gif[/img]

I don't have the book in front of me, but I believe the stock screw settings for a SD 800 is around 1 1/4 low, and 0 high. Someone please correct me if that's wrong - otherwise I'll double check Monday morning when I get into the office.

From what you said, it sounds like the carbs are mixing rich...what are your settings at right now?

Costs from a dealer tuning carbs on a twin can range anywhere between $50 and $300, depending on their location, and rates.

[seasoned]

Unfortunately I don't feel handy enough to work on carbs. I do well with network engineering.. however, that would probably be over my head.

If tuning carbs costs that much.. does that include a rebuild/cleaning or just to tune?

Is there any reliable service shop you could recommend in the Miami FL area.

[Bryan Glynn]

Don't sell yourself short! We've provided step-by step instructions for rebuilding carbs - there is a detailed guide available for download in the Technical section. Pick that one up for the Mikuni SBN, and also pickup the Installation guide for the Sea-Doo 800, to show you how to take your carbs off - it's easy to do! As for tuning, if your ski is stock, all you'll need to do is turn your screws back to the original setting. :D

If you still need a good dealer recommendation, I can give you one of Monday when I get back to the office.

[ March 03, 2001: Message edited by: Bryan Glynn - SBT Webmaster ]

[seasoned]

Everytime I click on that link or any other link for that matter on the technical installation instructions page on your web site, it causes my computer to just hang.

If you could email them when you get a chance I would greatly appreciate it.

jnord24@telocity.com

And yes.. I would still like you to recommend someone when you return to the office on Monday -- hopefull reasonably priced with reasonably skilled and experienced technicians.

Thanks.

[seasoned]

Sorry about that.. it seems to work when I right click and save as. I will check them out tonight.

I have been using the ski almost everyday for several days now.. and it appears to run great. So I'm wondering if gapping the spark plugs properly and adjusting the screws on teh carbureator will fix it.

Are instructions for adjusting the carbureators available?

[Bryan Glynn]

You need to update your Acrobat installation - you probably only have v. 3.01 installed, and you need 4.0. Click on the Get Acrobat button on the front page, or the Guides page to update. They are quite large and most email servers would not accept attatchments that large. You should have no problem viewing them after updating.

As far as instructions for adjusting your mixture screws, they are very simple. On your ski, there are two screws - one is the high-speed one is the low. The one higest ont he carb is the high-speed. To determine where you are set right now, turn the screws in just until they seat lightly, counting the exact number of turns. I'll get you the stock settings, and then you can turn them out to exactly where they are supposed to be. As for fine tuning them, that guide is being worked on and will be available next week. It is very possible that your over gapped plugs and mixture setting (if they are too far out - rich) could be causing your problems - but your carbs still need to be rebuilt if the gas was 5 months old.

I will get you some dealer contacts on Monday.

[ March 03, 2001: Message edited by: Bryan Glynn - SBT Webmaster ]

[seasoned]

I can't seem to find the second screw. Do I have to remove something in order to find it. The one I can see is outside the flame arrestor on the carb. Is there another one somewhere where i can't see it.

By the way.. the mag wire.. is that the one in the front or the back

[seasoned]

I hate to say this but I think my plug wires were criss crossed on the wrong cylinders. According to the rear electrical diagram, on ronnie's site...the second wire goes to the MAG (which according to the instructions for installing the engine on your site is the cylinder closest to the front).

I really think the jet ski place criss crossed these in order to get me to come back. Because everytime we have been workign on it, we pull them one at a time and replace then put right back on and move on to the next.

What type of behavior would this cause on the jetski. I just flip flopped the wires, and started and it appears fine now. Would this cause any serious damage. I know if you do this on a car it won't start at all.

[Bryan Glynn]

The second screw may have a T-handle on it, or it may have a plastic cap covering it, which you have to remove - you'll have to look and see. The screws are always ont he opposite sides of the carbs from one another.

The term MAG refers to the flywheel side of the engine (front) and the term PTO refers to the rear of the engine. On a twin cylinder, it makes zero difference which wire you plug in to a plug. You can swap all day long and it won't make any difference. Both wires spark at the same times, and both spark every 180 deg (twice per revolution).

[seasoned]

Are there two screws for each carb or just one set that controls both? I know the lower screw is very tricky to get to behind everything.... any tricks of the trade?

No hurry on that response...

[Bryan Glynn]

Two screws per carb, yes. The trick is to find a good small screwdriver [img]smile.gif[/img]

[Joe St. Louis]

You must rebuild your carbs. Any craft that has been sitting for 5 months with gas in it definitely needs a carb rebuild. You may get it to run "OK" but you will never realize the full potential of your craft until you rebuild the carbs. Once the carbs are rebuilt then you can diagnose any other problem without the carbs being a factor.

[seasoned]

I adjusted the top screws all the way in.. according to another post over on seadoo.net after what I said below. The problem with the adjuster screw being on opposite ends is that would be the bottom of the seadoo which I cannot see under. I tried one of my handy dandy computer tools with a mirror on it.. and still couldn't find anything similar. Life sucks. At any rate... it seems to be fine after all my fiddling.

After gapping the spark plugs properly, and swapping the wires back the ski flies like never before. I had on my scuba full footies and was still barely able to hang on. My arms are really sore today. I took it out on the water alll day yesterday and didn't have any problems. The only time it died was when I ran out of gas 50 yards out from the boat ramp (had to be towed in). Apparently my fuel guage doesn't quite work well. It kept showing a half a tank and then bounced to empty... great. I guess I'll just check it manually next time.

I don't think all the gas that was in the ski was that old.. I think less than a gallon was actually 5 months old, from further conversations with him. Plus when I filled it, I put in around 6 gallons and it's only a 9 gallon tank.

I do have another question though.. I noticed yesterday after my hard ride that there seemed to be black oil coming from second (what I believe to be - black and red in color with a funny clamp and a spring that flies like no tomorrow -- that was hard to find) rave valve -- is this normal/semi normal. It's not much oil, but I was concerened.

If I have further problems I fully intend to have the carbs rebuilt. Thanks for all your help.

[Bryan Glynn]

First of all, the gas in the the tank has nothing to do with why you have to rebuild your carbs - it's the gas that was in the CARBS that causes the problems, so it doesn't matter how much was in there. 5 month old gas in your carbs means certain gunk and varnish buildup.

Second, no, blow-by out of the RAVE valves is not normal. You are either getting blow-by from the base of the valve, between the cylinder and the housing, or out the bellows. When you removed the top cap, did you notice if any of the rubber was rolled off the green cap, or if the retension spring around it was loose? Can you see a pattern of where it is exiting?