DF15 wrong carb?

[JMauly]

Thought I'd give an update. I put on the new Solas 8 pitch prop. The hardware is very confusing and Solas's documentation is very poor. It appears my old Suzuki prop does not use a thrust washer nor does the Solas, which is contrary to what Solas says. The Suzuki prop had a spacer on the nut side but that spacer won't fit the Solas prop. This info just confused Solas's support guy.

I installed the Solas prop without either thrust washer or spacer and it fits but the castle nut is at the bottom of the threads and the cotter pin barely touches the castle nut slots. But there is no play and it spins freely.

Now I'm up to 5100 RPM at WOT with just me in the boat. Still about 800 RPM less than ideal. There is a lot of vibration at WOT. When I spin the prop it doesn't appear to be off but I'll have to check the prop shaft with a dial indicator.

BTW, Lowes carries non-ethanol gas $20/gal. I must run that through this carb at the end of the season or I will have to rebuild the carb in the spring.

I'm getting really tired of this motor. I think I'll look for a used Yami.

[JMauly]

I have a question on the CDI maybe someone out there can answer. The spark advance in this motor is apparently controlled by the CDI which has an embeded CPU. The Service Manual simply says to replace the $400+ CDI if the timing is off. When I search Google I mostly get info about Suzuki Motorcycles and they generally say a bad CDI just won't fire. Has anyone ever had a CDI failure that caused, say, ignition timing to be wrong or not advancing with speed? If there no way to mechanically set the initial advance in this motor?

[JMauly]

So I made some careful measurements. The distance between the hull bottom and the motor mount top of the transom is 21". The distance from the anti-vibration (or anti-ventilation) plate to the motor mount top is also 21" give or take about 1/4". So I think we ruled that out.
In the next couple days I'll check the timing, change the prop and, if it still is not right, try a Doel-Fin. I'll report my progress then.

Thanx again for all your great suggestions.
Jeff

[Moonlighter]

Engine sounds like its set far too deep. Maybe in the process of removing the motor from the boat to work on it, if that happened, and puttingnit back on, it went on too low. Many people with smaller motors set them so the clamp sits hard down on the top of the transom thinking that this is how they have to go, but not the case.

That anti-ventilation plate (the large one immediately above the prop) should be close to or just skimming the surface when planing along at cruise speed, thats how we try to set them on larger motors and I dont think the smaller ones would be any different. (See the sticky thread at the top of this forum on props and engine height for more info)

So I would suggest lifting the motor higher on the transom first before changing the prop or doing anything else. Likely to pick up quite a bit of revs and performance by lifting it to the correct height, and its so quick and easy to lift a small motor like a 15.

[JMauly]

Thank you Jim and Art. I did follow up on your suggestions. First - I know there is a mixture adjustment under an anti-tamper (Welsh) plug nut I believe that is only 'idle' mixture and the motor idles good and does not hesitate so I didn't drill out the plug. Re the carb part number, I can't find a part number anywhere on the carb. It just says 'Suzuki Japan' and the part number on the box is the right part number. But who knows if the carb that came is the box belongs to that box.
Prop size - I ordered an 8 pitch prop, down from the 10 that is currently on it. I'll try that before taking the carb apart.
Re the linkage - there is a boss on the carb that stops the butterfly from opening beyond full throttle and I verified that the shaft is contacting the boss at WOT.

I'm trying to borrow a timing light. I understand that timing is electronically controlled by the CDI and that may have failed.

Lastly, I'm looking at the depth of the prop. The anti-cav plate (I know that's not what it's called but I've calling it that all my life) is just below the bottom of my hull which is about 6" in under the surface when running on plane. Is that too deep? Would one of those fins on the plate help?
Thanx again guys

[artdf175]

Well I didn;t find the invoice but I have the old carb and the box the new one came in. According to the box the part number is 13200-93E50 which is supposed to be the carb for my motor (DF15ESK1). I looked all over the old carb and don't see a part number anywhere. So I'm still hoping someone can tell be how to identify the difference between a DF9.9 and a DF15

when you find the part off the parts page, if I am remembering correctly, you then click on the part number and it will take you to a page that shows all the engines that part number is compatable with

prop size ?? this will effect rpm

Art

[Murray]

That's good input, Jim. Not sure where I could find that info and I was hoping to avoid taking the new carb apart but you just pointed out it 's possible the new carb could have a wrong or misdrilled jet so it's worth the effort to compare jets, etc between the old and new carb. BTW, I'm using the boat on the Atlantic so I'm at sea level.

Thanx

Jeff

You would assume that the carb would be “plug and play”. I like Jim’s idea, check the carburetors jet settings vs with the manual. You could also compare the old vs the service manual.

[jHydroman]

Attached is link for the Service Manual for your motor. I would make sure that the throttle linkage in provide full travel of the carburetor butterfly.

https://www.maritimepropulsion.com/files/pdf/1001408
Jim

[jHydroman]

I'm assuming that your carburetor is a fixed jet, not an adjustable one.

Jim

[JMauly]

That's good input, Jim. Not sure where I could find that info and I was hoping to avoid taking the new carb apart but you just pointed out it 's possible the new carb could have a wrong or misdrilled jet so it's worth the effort to compare jets, etc between the old and new carb. BTW, I'm using the boat on the Atlantic so I'm at sea level.

Thanx

Jeff

[jHydroman]

It could be that the new carbureted is not jetted properly for your altitude. Might check what high seed jet is correct for your application.

Jim

[JMauly]

This boat didn't have a tach before now, but I have a finely tuned ear with 55 years of experience with small outboards. It was considerably faster before, both the revs and the boat.

When I say before I mean when I had the opportunity to ride several times with the previous owner, and much may have changed. I got this boat from another fellow, a friend, and I had to change the carb just to get it running. The previous owner also went through several props. This thing would tear out the rubber bushings, perhaps every 2 years. Unfortunately, all the old props are gone and it's possible that the current prop was not the same pitch as the original. But it's obviously not my only problem as I'll not gain 1000 RPM WOT with a prop change. I gained about 120 RPM by tilting the motor back and lifting the bow. I've ordered an 8 pitch prop to replace the 10 but I've been told to expect only about 200 RPM improvement. I'm going to try bypassing the 10-micron fuel filter but I suspect if it were fuel starved it would break up at WOT. I don't know what else to try.

I'd buy another carb but they are so expensive. The carb is similar to that on my 12 HP lawnmower and a new carb for that cost me $50. Suzuki wants $325.

[jHydroman]

What was you RPM with the old carburetor?

Jim

[JMauly]

Well I didn;t find the invoice but I have the old carb and the box the new one came in. According to the box the part number is 13200-93E50 which is supposed to be the carb for my motor (DF15ESK1). I looked all over the old carb and don't see a part number anywhere. So I'm still hoping someone can tell be how to identify the difference between a DF9.9 and a DF15 carb.

But if I have the right carb, what else might I look for that could be causing the motor to run without misfiring and yet be power starved (or rev. limited)?

Thanx for all your help

[Murray]

Where is the old carburetor?