97 Speedster Smoking (1 engine only)

[Domino]

97 Speedster Smoking (only 1 of 2 engines)

Greetings all,

Recent purchase of a '97 speedster has been a blast so far. Project boat that simply needs some TLC. I am looking for the forum opinion on only 1 engine smoking.

Here are the details:
* Port side engine smoking (blue) at low RPM's to the point where it nearly chokes itself to a stall. (NO PROBLEMS WITH STARBOARD ENGINE)
* Automatic Oil system still in place.
* Hesitates as RPM's increase to get the boat on plane, but then runs smooth once boat is past mid throttle to top end.
* New plugs in both engines which temporarily helped until 2nd start when engine again had excessive blue smoke.


I am not familiar with the automatic oil system. I do expect blue smoke from 2 cycle engines, but expect it to be consistent between the two engines. Is it possible to be mixing at different rates for both engines? Any other comments/ suggestions?

 

[seadoosnipe]

Rave valves!

I think I can give you an answer to one of your problems. My boat, using the 787 Rotax engine, was doing the same thing when trying to plane out. When I gave it the throttle, it would seem like the power just wasn't there, but as I slowly gained speed, it was like a passing gear kicking in. I later found out it was the RAVE valves. These valves are designed to change the flow rate of your exhaust gases to give you more low end torque (closed position) and top end speed (open position).
It's recommended to clean them of deposits annually. It's very simple to do. Two allen head bolts hold each one on and once you take them out, they clean easily with Carb. cleaner. Adjustment recommended by ROTAX is the red plastic cap be flush with the edge of the black plastic cover. I've seen posting's though where others have found a difference in power if adjusted in other ways. I hope this helps a little.
BTW, there are postings through-out the forum on the RAVE valves. You might like to read what others have found out.
Welcome to the forum Domino!.......

 

[Domino]

Excellent! I will give this a shot and report back. Likely over the weekend!

 

[seadoosnipe]

Seals!

If your having a problem with excessive smoking, then it's possible your injecting to much oil into your cylinders. But it's also possible that your seals in your engine, that provide a minimal amount of oil to flow pass them and into your combustion chamber are going bad.
One thing you can do to find out. There has been a lot of debate about the oil injection system in craft that are putting on the years. It seems that in general, as the Rotax engine ages, the oil system becomes less dependable. It seems that engines have been totally blown due to a faulty oil injection system. The consensus of forum members seem to believe in premix after an engine is 5 years or older.
To change over to premix, you'll need to add the 2-cycle oil to your gas at a ratio of 40 or 50:1. You can order a injection pump block off kit from places like ebay. You can't remove the oil tank though, because the bottom end of your engine is oil submersed. If you choose this route, then you'll be able to telll if your oil injection system is the cause of your engine smoking. If not, then it's the seals.
You can read through the forums and see how other members have tackled this. I'd say to ask them how it came out for them. How they like it.
:hat:

 

[Domino]

720 Engine..W/o Rave Valve?

The 97 Speedster is the 720 engine right? I looked tonight and did not see the red/black caps on top of the exhaust. I compared it to the 787 and see it on that engine, but difinitley not on the 720. Are they located in a different spot on this engine?

 

[seadoosnipe]

717....sorry!

Sorry Domino.....
The speedster does have the 717 engine, that was my mistake. Your correct, there is no RAVE valves on that engine. So now it seems that we're going to be looking at the carbs..........
Once again, sorry. I should have looked the speedster up. I'm finding the more and more reading I do on so many questions asked of me, I'm making some mistakes in my answers. I'm reading about the Mercury M2, the 951 DI and RFI, the 787, which is my favorite, the 717....which I haven't read much about lately and the 500's.............once again, I'm sorry for misleading you. I wasn't intentional.
I will go in and look at the trouble shooting guide for you and see if I can find any more leads for you!.........

 

[Domino]

On to the Carbs

ABSOLUTELY NO PROBLEM...Completely understandable. I just appreciate the help and and quick response.

On to the carbs then. I do have the shop and owner's manual. Any insight is appreciated. Any simple adjustments or cleaning to start with?

 

[seadoosnipe]

Carbs...

I just went into the manual so that I could give you something better to work with. I think there is a really good possibility your having some carb issues. First, your plugs, should be the NGK BR8ES and the gap set at .021". The next thing you can look at before thinking of a rebuild is to check the adjustments. The low speed screw should be set at 1 turn, +/- 1/2 turn, the high speed should be 1 and 1/4. The slow response time could also come from the carbs linkage not being synchronized. You said you have the manual, look up the syncro section in the carbs because there is a pix in there that will help you determine where the marks are to do this. After you do, and if you start it just to hear it, don't run but for just a minute. Any changes to the carbs linkage means you need to check the linkage to your oil injection pump. There is a chapter and pix on how to do this in your "Lubrication" chapter. The chapter you read on your carbs will also point this out.
I hope I've been of some help to you and once again, sorry to mislead you earlier.............
Holler back at me, let me know what you find out......or if you have more questions! :cheers:

BTW, your fuel filter should also be high on your list. There is also a small strainer in your carbs. It's really small, meant to catch anything that got by your main strainer. If you get to that point on the carbs, read up on it in your manual......it will definitely be of interest in the hesitation too!