Convert a 9.9 yamaha 2 stroke to 15hp (1996 and newer only)
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- Опубликовано: 2 окт 2024
- The only difference between a (1996+) 9.9hp Yamaha 2stroke and a 15hp is the reed valve assembly. The 9.9 limits airflow and torque which limits horsepower. This is for US models- may or may not apply to international models- like ENDUROS or Vmax. Check local laws.
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Thank you for the reply I bought the whole reed valve assembly for a 15 hp and brought to Greece with me last week. I got the mechanics that were servicing my outboard to install it. At first they said it didn't work and that hey needed to reinstall the old one. But after I insisted they try harder the got online and figured it out. I think they had to adjust something in the carburetor but I'm not really sure what they did. They mechanic doesn't speak English! Anyway, now the motor works great and is a much needed improvement! Now my family of 4 can plain out now problem in a 12' Caribe dinghy. I just wish I'd known it so easy 10 years ago! Thanks again.
This is true. Bought a 2006 9.9 off a widow who said her husband had converted to a 15hp. "Something about reeds" she said. Didnt run very well though. Took off the carb and cleaned still dint run very well. Pulled brass plug from pilot screw hole and cleaned and reset. Purrs like a kitten now. Even called the local Yamaha dealer and he confirmed that only diff is the reed stops. This engine is a Japanese made model and this video applies to this motor too.
Good vid here and thanks.
Very surprised that the dealer confirmed the reeds as the only difference. Most would tell you " no way !" Most dealers here are total A holes and would rather walk over broken glass than mess with a small outboard. That's good for me though.
+bsrktm1 what about prop did you chabge pitch?
A prop change may or may not be needed. As long as the motor isn't massively under propped(prop pitch too small) it should be ok. I prefer a slightly small pitch to a larger pitch simply because if the boat is heavily loaded, the smaller prop will work better. Some testing- with a tachometer- will be of benefit. Max rpm is 5500 on these motors I believe. Somewhere close to that is ideal.
Ok thanks, i just converted mine happy with the results but i think im going to go to a 10 pitch from the 9 that came with the motor.
I am trying to order the correct parts to take to my boat which is in Greece. My outboard is a 1997 Yamaha 9.9MSHV. Do I just need to order replacement reeds from Boyesen.com AND would i order the 2 pedal or 3 pedal reeds from them? Or do I need to order the entire reed valve assembly for a 15HP 15MSHV and install it on my 9.9? What gaskets do I need to take with me? I have trouble getting parts over there. Thank you so much!
Hello, and whether in addition to this part you still need to replace or adjust the carburetor to get 15 hp from the 9.9hp engine
Carbs are the exact same part number and are identical in every way. Minor adjustments might be needed.
@@bsrktm1 I understand that we are talking about minor corrections in the carburetor settings
Hello, I'm from Poland I have a yamahe 9.9 D 682C 2 stroke so it is on the plate I have a question whether tom yamahe can also be converted to 15hp by replacing these organs from the 15hp model or something else needs to be replaced in the carburetor or just adjust the carburettor after replacement thank you in advance
Hello ! I have a 9,9FMH 2000, what is the parts number of the reed valve of 15 HP ?
Bedankt maat! Na al die jaren nog steeds bruikbaar deze video
If I bend only the valve stopers,? Now is 1,3 mm, and for 15hp Reed valve gap is 6mm, According to the service manual, or must change the Reed valves? Did this the only difference according to the service manual, thanks.
The reeds are exactly the same. It’s only the valve stops that’s different. I wouldn’t bend a 9.9 set to a 15 as they need to be uniform.
bsrktm1 i have a 2005 yamaha .9.9 and i want to adjust the reed stops would you have the new setting for the reed stops thanks
Ye got it done thanks for the video
Does a 2007 work ?
Instead of removing the whole valve, is it possible to twist the valve to get a more open flow ?
Yes you can! It worked for me, there’s specs in te manual for the exact distances
hello, did you need to change the carburetor jet?
watch the video for the answer- its there.
Thanks!
I got a 2004 Yamaha 9.9 2 stroke. Are the carbs still the same all the way up to a 2004? Thanks
All years 1996 and later are interchangeable. Some model years have a sealed idle mixture (pilot) screw. This plug over the screw can be removed, if needed, to gain access to the mixture adjustment. (Sometimes a slight adjustment to the idle mixture might be required when converting a 9.9hp to a 15hp) Otherwise, all jetting and venturi sizes remain the same- for both 9.9 and 15.
Awesome thanks a lot! 👍🏻
Can you also convert a 1987 model 9.9 hp flatop to a 15 using this method?
Read my reply to Mr Jokkoma
@@bsrktm1 thank you...I will try it out..
Intheresting! I have a Mariner 9,9 from early 80's.
As I have understood Mariner is a yamaha made on license. It,s made in japan and looks identic whit the Yamaha.
Probably same thing here whit other reedwalve and carburator jettings.
Old Mariners ARE usually Yamahas. Pre 1996 Yamahas have a different set up. THE VIDEO ONLY APPLIES TO 1996 and LATER!! Old 9.9s have a 4 petal reed vs a 6 petal reed on the 15. Also the carb venturi on a 9.9 is a little smaller- maybe 1/8" or so. Timing specs MAY be slightly different too but I don't have the manual in front of me right now. Anyway, its a more involved conversion than the newer motors. Also, Check your reed 1st. MANY MANY of these old motors have been converted previously. If it were mine, I'd just put a 6 petal 15 reed in it and try it out. The reed limits air flow more than the carb does- at least on these motors. good luck.
+bsrktm1 Thank you I'l check this whit the reeds up. The engine sure runs great, I however could use a little extra torque to get the boat in level from the start whit a few passengers inside.
Can you also convert a 1995 or older 9.9 Yamaha to a 15hp? thanks
Yes. The the above reply regarding the old Mariner applies to Yamahas.
Did you change the gasket as well or is it ok to go with the old one?
There is no gasket for the reed- it is rubber coated.
@@bsrktm1 Ok, thanks!
Can this be done to four stroke Yamaha 9.9?
Some 9.9 4strokes can be converted to 15hp. If the 9.9 has the same cc (displacement) as the 15, the 9.9 can be made into a 15. Usually by changing to a 15 carburetor and possibly other things. Many 9.9s share blocks with the 8hp though. You can't do anything with those. Boats.net has good parts break downs.
4 strokes as no reed valve
I converted a 9.9c by swapping the reed valve from a 15D, the spark plugs from BH7 to BH7-10 and the propeller. The fuel consumption went up from 6.6 to 7.3LPH. And pushed my boat from 17kts to 21.
Do not adjust the carb or plug gaps (1mm) and be sure to renew the gaskets either side of the reed valve and it’s good to go. The 9.9c reed assembly has no deflector under the valves (like the one in this video). The 15d does. Either fit the other.
A reed valve with a deflector has 3 bolts along the bottom.. one without only has 2 (You can tell whilst it’s bolted to the power head). If it has 3, don’t touch the middle bolt when taking it off- it’s not a mounting bolt. It’s holding the rubber deflector to the plate inside. It will spin it round.
does it works for older 95 9.9 motor ?
Steph Miami yes it will
Do dis work on a mercury 8hp 2stroke
No, but your engine can likely be upgraded to 9,9hp. Probably not worth the trouble unless you can get the parts cheap or free and can do the work yourself.
What slows down the spees on a 8 compr to a 15 cus its the same block en what parts do i need then
@@bsrktm1 and you also have bodsey power reeds for a 8hp 2stroke do you think these work
@@tijslust8081 Although the block appears the same, 8hp and 15hp Mercs have different displacement (cc). The 15 is about 50cc larger (bigger bore with the same stroke). The 15 carburetor has a much larger venturi (bore size) and a tuned exhaust. The 8hp and some 9.9s have the same displacement but the 9.9 carb has a bigger venturi and tuned exhaust in order to gain the extra 1.9Hp. Some 9.9s (later models) have the same displacement as a 15, but use a small bore carb and no tuned exhaust to lower the Hp to 9.9. So, as stated, you can't make an 8 into a 15. But, it can be made into a 9.9 if you acquire the correct 9.9 carb and exhaust. Some people claim to have good results by only changing to the proper (larger venturi) 9.9 carburetor. Changing just the jets wont work- its gotta be the correct 9.9 carb. good luck.
@@bsrktm1 tank you but if you only do jetting will it get to much gas ?
do I need to buy whole Reed valve body
No. You can buy an aftermarket reed valve like Boyeson. You can't buy just the reed stops from Yamaha- that's the only difference between the 9.9 and 15 but the Boyeson eliminates the reed stops all together. The Boyeson reeds probably won't last as long as the stock reed but it is cheaper.
@@bsrktm1 boyesen
The carb is also bigger on the 15 hp
NO it isnt!. 1995 and older yes. 1996 and newer use the exact same carburetor. same jetting. same venturi size. exact same part number 63v-14301-00-00 or 63v-14301-10-00 depending on the year. And, the only difference between these 2 part numbers is the tamper proof mixture screw on the -10.
1995 and older, the carbs are exactly the same. The 9.9c has 2 breathers going to the crankcase. The 15d does not.
@@jasonjoyce4487 So how to convert 95 older 9.9 to 15HP ?
Steph Miami take off the carb. Remove the 9.9 Reed valve assembly and replace with the 15hp one. Refit carb- do not adjust it. Change the spark plugs as mentioned below and change the prop. Reed valve assembly, plugs and prop is all you need to change. Carb settings remain the same.
I was wrong about the breathers. Both are the same the difference between 9.9 and 15 Reed valves, the 15 valves open slightly further.
@@jasonjoyce4487 Dude, thanks for your answer.
I have 4 petals reed valve on my 9.9 so I will put an 6 petals valve from a 15hp.
If I only change the reed valve and not the prop may It works too ?
Thanks guy !