Stock Flame Arrestor vs Aftermarket Air Filters/Cooling Question

[ChrisSJ]

I just picked up my second Superjet, my first Superjet with mods. It's got an R&D head, B Pipe (with single cooling), aftermarket stainless prop, ride plate, etc. As I am from Michigan, I plan on doing "surf" riding on Lake Michigan, which lead me to question the aftermarket air filters it has. A previous owner put Riva Racing air filters on the carbs, without the waterproof mesh that goes over to keep water out. It looks like the ski was originally built as a rec/mild buoy racer, so the odds of it being upside down are lower than that in wave riding. I was looking for a second opinion on whether to keep the aftermarket air filters and buy the mesh coverings that supposedly keeps water out, or just switch back to the stock flame arrestor. I understand that there is still a chance of water getting in the stock air box, however it seems lower than that of air filters based off of the design.

Now onto the cooling, I've done some research on single cooling for a b pipe, and found some diagrams of it, and my cooling routing does not seem to match any that I have seen so far. I rode the ski a few days ago on a nicer day (for Michigan at this time- 40 degree air, ~40 degree water) for about 10 minutes just to shake down the ski, and make sure there were not any huge issues that needed to be addressed this winter. I never really rode it hard, as I was slightly paranoid about a cold seize, and colder air resulting in a leaner mixture, but got it to as high of an operating temperature as it would achieve with around 1/4-1/2 throttle maximum. Based off the temperature of stream coming out pisser, the water was warm, but not normal operating temperature as to be expected without restricting flow for cold water temperatures. From a glance, it looks like the water goes from the intake on the pump to the exhaust manifold(only one fitting-not set up for dual cooling), then from the bottom of the head pipe to the head, but the weird thing is there is a T fitting on the feed from the head pipe to both fittings on the head, then a line runs from the top of the head pipe with a T fitting to the end of the expansion chamber and the pisser. Based off of diagrams I've found from other posts on this forum it looks like I should run a line from the forwardmost fitting on the head to the top of the head pipe, then run a line from the bottom of the head pipe to a T fitting that splits to the pisser and end of the expansion chamber. I am wondering if you all think I should change my cooling routing, wait to see if it runs hot in normal operating conditions, or if my current cooling routing is fine. Below is an attachment of my engine bay and current routing.

Any input on either of these topics would be greatly appreciated. Thanks in advance!

 

[mn_reeds]

What do you have for water evacuation? single/dual bilge pump, scupper, factory siphon? As long as you keep the splashing water down inside the engine compartment those FAs will likely be fine. You can always make a turf splash guard or fancy tupperware box setup that is floating around here somewhere. If you switch back to stock you might have to adjust jets depending on how many screens you run.

The water line routing is also setup properly since you only have single input cooling. The aftermarket head has dual outlets so you can either plug one or tee it like pictured. To restrict water flow for cold riding a short length fuel line will slip right inside the cooling before the pisser and probably get close. There are also plenty of other options that all cost more money.

What compression do you have with that head? Just make sure to run the right octane before holding her open for long periods of time.

 

[kevbo]

Your cooling arrangement looks fine. I would install a stock flame arrestor because even the slightest amount of water in the hull will splash right into the carbs when its rolled to the right. The most important aspects of tuning is figuring the minimum octane requirement and making sure its not over propped. That means checking the compression and ignition timing. Stock timing and up to 180 PSI is considered safe provided the carbs are set a little rich of peak rpm. Use a tach and check top speed rpm, you can set the top mixture screws at the same time. With a stock cylinder you want to see at least 6700 rpm and set the top screws at least 20 rpm rich of peak . If it turns slower, bore the nozzle then repitch the impeller.

 

[ChrisSJ]

What do you have for water evacuation? single/dual bilge pump, scupper, factory siphon? As long as you keep the splashing water down inside the engine compartment those FAs will likely be fine. You can always make a turf splash guard or fancy tupperware box setup that is floating around here somewhere. If you switch back to stock you might have to adjust jets depending on how many screens you run.

The water line routing is also setup properly since you only have single input cooling. The aftermarket head has dual outlets so you can either plug one or tee it like pictured. To restrict water flow for cold riding a short length fuel line will slip right inside the cooling before the pisser and probably get close. There are also plenty of other options that all cost more money.

What compression do you have with that head? Just make sure to run the right octane before holding her open for long periods of time.

Thanks, I'm running a single bilge with the factory siphon as well. I think I may just switch back to the stock FA's, and I appreciate your input on my cooling. The engine is running around 180 PSI of compression in each hole, so based on what I've found on various forums it looks like 93 should work, and I won't need to mix with 110.

 

[ChrisSJ]

Your cooling arrangement looks fine. I would install a stock flame arrestor because even the slightest amount of water in the hull will splash right into the carbs when its rolled to the right. The most important aspects of tuning is figuring the minimum octane requirement and making sure its not over propped. That means checking the compression and ignition timing. Stock timing and up to 180 PSI is considered safe provided the carbs are set a little rich of peak rpm. Use a tach and check top speed rpm, you can set the top mixture screws at the same time. With a stock cylinder you want to see at least 6700 rpm and set the top screws at least 20 rpm rich of peak . If it turns slower, bore the nozzle then repitch the impeller.

Thanks for your advice on tuning. It does not have the msd enhancer, and as far as I know I am at stock timing. Based off my short ride the other day I think I'm going to repitch the prop as it didn't have the low end hit I want to achieve. I've done some tuning on cars/other toys and it did not seem rich down low. That being said I don't think I ever got to a high enough rpm to get up on the pipe, so not a ton was learned from that test. Once the water warms back up I plan on doing more with pipe tuning and carb tuning. I appreciate your input!

 

[SexPanther]

Stock flame arrestor works super well for surf.