99 Vmax P200TLRX lack of power/surging issue

[Smallie_Hawgin]

Alright folks, I had asked Skeeterstew some questions on a separate thread. He did a great job helping me out with timing/carb sync issues etc. Well, I still have "the surging problem" I had earlier and really need some help. The 200 Vmax is mounted on a hydraulic jack plate, on a 2001 X19. Best I got out of her was 4200 rpm, 32 mph, turning a 23" Solas Scorpion

• Compression is 115-120 all cylinders
• Gone through the entire fuel and fuel delivery - Cleaned carbs, replaced fuel separator filter, removed extra ball valve. Pressure good under load etc.
• Synced carbs and timing advance per Skeeterstew's post.
• Checked ohm readings on coils and caps - Coils 4.5 ohm, caps varied so I replaced all six. Total resistance with the combos = 9.5 ohms
• Replaced and gaped plugs
• All ignition circuit wiring seems good.
• Rectifier charges effectively
• Stator circuit seems good - no burnt connections or other issues.

After doing all the above is when I was able to get some smooth running and the 4200 RPM.. Oddly, in reverse I could get better rpm??? Then, all of a sudden, it was doing the same crap as it was earlier. Lack of full power, surging between 2000 and 3000 RPM. A few videos of it running can be found here: https://photos.app.goo.gl/YQdjtHkNaFxu7YHW9 Other potential diagnostics? Other suggestions? I mean two strokes are pretty simple right? Fuel, air, spark... LOL

And yes, I am bald, otherwise I would have pulled my hair out by now...

[Smallie_Hawgin]

TTT...
Update, replaced coils, solved some of the lack of power issue, however, still surging and won't hold steady rpm above 2000...
Leaning towards stator. Other suggestions or rule outs?? Thanks in advance.

[DLAB]

I would start by replacing the fuel lines to ethanol resistant if they haven’t already been changed. The old lines delaminate from the inside and can cause blockage issues. Other than that with a carb motor, if the carbs are good she should run fine.

another overlooked item is the bulb. Just change it out first. Sometimes that’s the most obvious/not obvious easy fix

[Smallie_Hawgin]

I would start by replacing the fuel lines to ethanol resistant if they haven’t already been changed. The old lines delaminate from the inside and can cause blockage issues. Other than that with a carb motor, if the carbs are good she should run fine.

another overlooked item is the bulb. Just change it out first. Sometimes that’s the most obvious/not obvious easy fix

Yeah, unfortunately, been there, already done that... :( Went through the carbs, jets, floats, fuel lines, filters and yep, the bulbs too. It seriously is like a rev limiter or something. It feel more like it is actually shifting gears, it's that instantaneous... Both ramping up and down. Grrrrr

[Cphil]

Let us know what you find. I was having surging issues with my carbed Vmax 150 and I replaced a few of the same components you have. Every inch of fuel line, bulb, water separator, filters, pick-up tube in the tank and cleaned carbs. Spark plugs, wires...etc...
After all that I ran my boat on a separate remote 3 gallon tank with 93 Octane and an entire bottle of seafoam added. I ran hard up and down the lake until that tank was empty. Then I ran the rest of the day, making a lot of stops to fish, with the 93 octane in the boat’s tank. By the end of the day the surging had stopped and it is no running extremely smooth. Unfortunately I can’t say what actually did it because I did it all at the same time. This boat sat a lot before I bought it so I did a lot of this maintenance for piece of mind. So now that it runs and starts great I still have an issue that has been there since before I did anything to this motor. And it’s a head scratcher!! No matter what prop pitch I run and no matter what my prop to pad is, I cannot get over 5100-5200 RPM...it’s smooth all the way there but I cannot figure out why I can’t reach 5500 or max no matter what I try? Sorry if I jacked your thread but you mentioned your 4200 seems to be max so I wonder if we both need the same fix and what that fix might be!!??? I have not messed with timing advance as you did? Maybe timing and sync?? Thanks

[bassinman215]

Check the anti-siphon valve on your fuel tank.

Had an issue with my 150 hp VMAX where it would get on plane and then lose power. Tried a bunch of different things, turned out that the valve was sticking.

If its easy to get too, its a cheap fix.

[Cphil]

I have, and I believe the OP has too, removed the anti-siphon valve or any/all ball valves between the tank and motor. Good idea though.

[Smallie_Hawgin]

Well, tore the front end off again... Looking a little deeper this time. Found a Reed valve block (for cylinders 5 and 6) had some rust on it. The motor was bought on auction from FL. How it got rust, I have no idea... possibly residual water dripped down in that area during shipment?? Maybe had a head gasket leak in the past?? In either case, it has barely enough steel to cause rust (valve block is aluminum coated with rubberized deal, reeds are stainless, restrictor plates chromed, screws chromed??).
Upon initial inspection, it didn't look so bad. After closer look, the seal material that coats the Reed block base had become delaminated and bubbled. There was also a tear in one portion. So basically, my thought is it would seal, then not seal or get compression, then not. I have a replacement assembly on the way. Hope to have it running by next weekend.������
IMG_20200515_200454_01.jpg

[Smallie_Hawgin]

Just a minor update. Needless to say, with the way things are in our country these days, shipping of parts has been delayed.... A lot! Ordered a reed block new on May 15.... Hasn't arrived yet. (Jun 5 now), supposed to arrive tomorrow. Well, checked with dealers and thay all said there was one, yep one, in a GA warehouse... And 10 in Japan!! In any case, I got impatient and found a good used one that should be arriving today for quite a bit less. In the mean time, I thought, heck, might as well freshen up the reeds and see what mods I might be able to do. Looked around a bit and found Chris Carson Marine... Custom reeds and stuffers for us old school carb guys So, will be installing the fiberglass reeds to replace the stock and old stainless variety and adding the stuffer kit to give it a little extra compression.... I will report back when all is up and running. Thankfully, this is a project rig, we have been fishing out of my River-Pro... but, looking forward to having the X19 with the Yamaha Vmax 200 done soon!

[Texas Larry]

Sounds like this has been an ordeal! Hope the new reeds fix it. You probably have, but have you tried pumping the bulb while it is surging? Just a thought.

[Smallie_Hawgin]

Got the project Xpress X19 with the Yamaha 200 back together and was able to test it Sunday... Got great response, power and top end went up considerably.. Yeah, this was a series of learning lessons. Good and bad of course. Addressed fuel supply issues, spark issues, and found out the one reed valve block was rusted. I was able to find that used block and swapped the high performance reeds in there and added the stuffer plates. She definetly runs now!! Still don't feel we are getting all of what she has yet. 54 MPH, 5900 RPM, 23 Solas scorpion, 3/4 tank full, two people no real gear on board to speak of... I want to try some other props, but, at this point, happy she's running well!!!