Plan B; Mission Impossible

[throttlecable]

Plan A; take a supercharged 2009 Yamaha Nytro, and purpose build it for closed course hillclimb competition on the RMSHA circuit. Because the Nytro is a 600 class sled, the theory was to race in all (4) mod classes with enough horsepower to out muscle the 600 and 700 mods, and be right there with the 800 and open class mods.

The ISR monkey wrench; apparently there is some confusion concerning the grey area that involves boosted 4 strokes, and class elegibility. The ISR ruling , or lack thereof, may or may not limit a supercharged Nytro to open class status. After several attempts to get to the bottom of this, it was determined that even if I was allowed to compete in the lower classes at first, the possibility would exist for me to be limited to open class within the duration of the season. This scenario would be accelerated based on challenges and complaints from other racers. Additionally, there are solid rumors that within 2 years, all forms of boost incuding NOS will be limited to open mod class. This rule will apply to all makes and models, 2 strokes and 4 strokes.

PEER PRESSURE; my brother is a Polaris A-Team hillclimber, and so are some of my freinds. They have tried desperately to pursuade me to race the red sleds and give up the silly idea of building what can't be built. They would even settle for the idea of me racing yellow or green, but "NOT BLUE FOR CRYING OUT LOUD!" So I guess I'm stubborn,... I like to swim against the current, but the main reason I am doing this is because I was told it couldn't be done.

Plan B; Mission Impossible. Build a naturally aspirated Yamaha Nytro mod class race sled that will be competition eligible in all (4) classes. This sled will be narrow minded, and one dimentional. This sled will not be a good powder hound mountain sled. This sled will live with the sole purpose of attacking the shelled out junk/holes/rocks/stumps/mud/ice/trenches/ruts/jumps/bumps, and do it in dominating fashion.

The shopping list; these are the ingredients that will be used for this build. Some have already been purchased and installed, while others have yet to be ordered. Target goals are(1) a race ready wet weight under 500lbs (2) 160+ sea level HP and 100+ TQ (3) lower cg with centralized mass (4) under 8000.00$ for all upgrades.

-2009 Yamaha Nytro MTX 153"-
-EZ RYDE rear skid with dual rate titanium springs
-Zbroz 43"ctc A-arms
-17.5" FOX FLOAT EVOL R front shocks
-Simmons flexi skis w/ 6" carbides
-Diamond S chromo sub frame
-W.C.S light weight steering post
-RSI bars/riser/throttle/etc.
-Team tied secondary clutch kit w/ hollow jackshaft and SLP primary kit
-Aaen header/muffler exhaust system
-K&N intake system
-PC 3 fuel controler w/ mapping
-internal timing advance
-18/42 gearing w/ reverse delete
-tunnel cooler delete
-headlight assembly delete
-brake light and rear plastics delete
-custom rear bumper/tunnel modification
-race legal snowflap
-custom race legal clutch/brake guards
-custom venting on cowl/nose
-custom 3 wheel rear axle
-Better Boards
-custom tunnel bracing
-full length skid plate
-lightweight battery
-153" A-20 cut to 1.5" w/ ti hooks & screws
-XTX tunnel protectors
-delete all other unnecessary items
-relocate wieght for balanced CG

Here are the 1st pics of this project,...knee deep in the tear down, getting rid of the stock sub and ready for the new chromo sub from Diamond S. I didn't find this forum in time to get any before pics of the Nytro, but we all know what they look like anyway. I will do my best to document and photograph this one of a kind build,...stay tuned!

 

[AKSNOWRIDER]

Plan A; take a supercharged 2009 Yamaha Nytro, and purpose build it for closed course hillclimb competition on the RMSHA circuit. Because the Nytro is a 600 class sled, the theory was to race in all (4) mod classes with enough horsepower to out muscle the 600 and 700 mods, and be right there with the 800 and open class mods.

The ISR monkey wrench; apparently there is some confusion concerning the grey area that involves boosted 4 strokes, and class elegibility. The ISR ruling , or lack thereof, may or may not limit a supercharged Nytro to open class status. After several attempts to get to the bottom of this, it was determined that even if I was allowed to compete in the lower classes at first, the possibility would exist for me to be limited to open class within the duration of the season. This scenario would be accelerated based on challenges and complaints from other racers. Additionally, there are solid rumors that within 2 years, all forms of boost incuding NOS will be limited to open mod class. This rule will apply to all makes and models, 2 strokes and 4 strokes.

PEER PRESSURE; my brother is a Polaris A-Team hillclimber, and so are some of my freinds. They have tried desperately to pusuade me to race the red sleds and give up the silly idea of building what can't be built. They would even settle for the idea of me racing yellow or green, but "NOT BLUE FOR CRYING OUT LOUD!" So I guess I'm stubborn,... I like to swim against the current, but the main reason I am doing this is because I was told it couldn't be done.

Plan B; Mission Impossible. Build a naturally aspirated Yamaha Nytro mod class race sled that will be competition eligible in all (4) classes. This sled will be narrow minded, and one dimentional. This sled will not be a good powder hound mountain sled. This sled will live with the sole purpose of attacking the shelled out junk/holes/rocks/stumps/mud/ice/trenches/ruts/jumps/bumps, and do it in dominating fashion.

The shopping list; these are the ingredients that will be used for this build. Some have already been purchased and installed, while others have yet to be ordered. Target goals are(1) a race ready wet weight under 500lbs (2) 160+ sea level HP and 100+ TQ (3) lower cg with centralized mass (4) under 8000.00$ for all upgrades.

-2009 Yamaha Nytro MTX 153"-
-EZ RYDE rear skid with dual rate titanium springs
-Zbroz 43"ctc A-arms
-17.5" FOX FLOAT EVOL R front shocks
-Simmons flexi skis w/ 6" carbides
-Diamond S chromo sub frame
-W.C.S light weight steering post
-RSI bars/riser/throttle/etc.
-Team tied secondary clutch kit w/ hollow jackshaft and SLP primary kit
-Aaen header/muffler exhaust system
-K&N intake system
-PC 3 fuel controler w/ mapping
-internal timing advance
-18/42 gearing w/ reverse delete
-tunnel cooler delete
-headlight assembly delete
-brake light and rear plastics delete
-custom rear bumper/tunnel modification
-race legal snowflap
-custom race legal clutch/brake guards
-custom venting on cowl/nose
-custom 3 wheel rear axle
-Better Boards
-custom tunnel bracing
-full length skid plate
-lightweight battery
-153" A-20 cut to 1.5" w/ ti hooks & screws
-XTX tunnel protectors
-delete all other unnecessary items
-relocate wieght for balanced CG

Here are the 1st pics of this project,...knee deep in the tear down, getting rid of the stock sub and ready for the new chromo sub from Diamond S. I didn't find this forum in time to get any before pics of the Nytro, but we all know what they look like anyway. I will do my best to document and photograph this one of a kind build,...stay tuned!

what can you legally do to the motor?..old trick for a 4 stroke to make more power...spin it more rpm...open up the breathing, really good porting(as in welding if needed), all titanium valvetrain, big roller cam, complete intake and exhaust tuning...short stroke/big bore makes topend HP.. as does longer rod ratios....all billet pistons titanium rods...I used to race big V-8 race motors..I competed with a 427 chevy punched .125(440 cubic inches)...against motors as big as 640 cubic inches...and I beat them regularly...but I out rpmed them by a bunch..and I left no stone unturned in the motor...

 

[throttlecable]

Those are good points. As long as bore and stroke remain the same, anything goes for internal modification. I think the factory snocross motors utilize alot of that tech, but my budget may limit what I can do right now. Thanks for the info.

 

[Snow Duck]

loads of work

looks like you just opened a can of whoop a-- to show how something can be done...nice Throttlecable looks to be a interesting build..

 

[ruffryder]

AWESOME!!! We need more N/A builds!! You mention an ignition advance, you can buy a module for the power commander that does this as well, but gives you the ability to adjust it for different RPM/s and throttle openings. Something to think about.

 

[throttlecable]

Thanks for the support Duck and Ruff! As far as the timing advance, my freind is a factory Yamaha rep who has done the internal key adjustment before, and he stands behind the results. I do appreciate new ideas and information,...keep it coming!

 

[ruffryder]

As far as the timing advance, my freind is a factory Yamaha rep who has done the internal key adjustment before, and he stands behind the results.

So spill the details already!!!

Pretty please?

 

[throttlecable]

You would have to waterboard him for the details,...all he will tell me is that there is significant gains to be had with internal timing advance, and that the factory doesn't even get close to the ceiling when it comes to the capabilities of production motor state of tune.

 

[ruffryder]

You would have to waterboard him for the details,...all he will tell me is that there is significant gains to be had with internal timing advance, and the factory doesn't even get close the ceiling when it comes to the capabilities of production motor state of tune.

Tell me more tell me more!!! I have a nytro, if you couldn't tell.

So does it require you to run premium or race gas? How hard is it to do?

More more more!! ha ha. Dang, lots more available on the table? I take it you have to spin the motor up higher to get the goods?

 

[throttlecable]

Honestly Ruff, I dont exactly know, and it hasn't been done yet. What I do know is that it requires a special timing key, and it will be able to run premium at 6000 to 8000 ft. I will try and get more info from him when he does this so I can pass it on...

 

[X2Freeride]

Honestly Ruff, I dont exactly know, and it hasn't been done yet. What I do know is that it requires a special timing key, and it will be able to run premium at 6000 to 8000 ft. I will try and get more info from him when he does this so I can pass it on...

Wow thats impressive.

 

[Angermangement890]

Honestly Ruff, I dont exactly know, and it hasn't been done yet. What I do know is that it requires a special timing key, and it will be able to run premium at 6000 to 8000 ft. I will try and get more info from him when he does this so I can pass it on...

Do you mean a computer program or some other external adjustment to the timming system? Like adjustable cam gears? Or advancing the timing interanlly in the computer at specific RPM points?

 

[ruffryder]

Do you mean a computer program or some other external adjustment to the timming system? Like adjustable cam gears? Or advancing the timing interanlly in the computer at specific RPM points?

A timing key changes the flywheel orientation with respect to the crankshaft position. Though, the nytro uses a crank sensor for determining crank position, and I think it is what the computer uses for determining spark and fuel injection events. I don't know for certain though.

 

[throttlecable]

cutt'n and screw'n

Here is the latest progress:
Cutting the A-20 down to size and installing some worn out practice screws,(I'll save the sharp ones for the races). 2LBS of cut rubber off sets 2LBS of screws. Some close up shots of the dual rate ti spring and the 3 wheel axle on the EZ Ryde, and the custom rear tunnel/bumper/race flap. The exhaust pic shows the Aaen muffler with custom fit Trinity Racing end cap.

 

[throttlecable]

GOING ALL THE WAY

Budget concerns had these plans on the back burner when I started this thread, but the further along I get, the more I realize that you can not pull any puches when racing, and I don't like doing things halfa$$ed, so here we go! Today we removed the motor from the chassi, and the head was then taken off and shipped to Wisconsin for some extensive porting. High compression Wiseco pistons, and delaminated head gaskets will give me a ratio of 14:1, additionally, the counter weights will be removed from the balance shaft, and the internal timing advance will achieve 4 degrees on the flywheel. According to my sources, these changes combined with the free flowing intake, and exhaust components, and tuned with additional fueling should produce 182-187HP at sea level when measured at the crank.

 

[throttlecable]

Timing Advance

So here is the scoop on the internal timing advance,... previously this seemed to be classified information, but now that the cat's outa the bag, it doesn't appear to be that big of a deal. The factory key stock which syncs the crank to the flywheel, is cut on one side .004, this effectively advances 4 degrees of rotation in relation to the flywheel passing the crank position sensor. The stock can also be turned around or reversed so as to retard the timing for different applications. Apparently the Yamaha techs have played with this enough to determine that there is a small window right at .004 which does produce 4-6 additional HP throughout the powerband, while .002 or 2 degrees of advance produced no gain, and .006 or 6 degrees actually lost power. These results were achieved on pump gas, and below the 9200 rpm rev limit. Knowing that Yamaha is aware that there is more power available, I asked why they don't tune them this way from the factory, and the answer is because of the popularity of adding boost to these engines would make these changes counter productive for a large percentage of Nytro consumers,...there ya go.

Here are some pics of the tunnel cooler delete. Dropped 6-7 lbs...

 

[Snow Duck]

Nice!!!!!!!!

This lil racer is going great for ya...i like all the info you are providing for all us sled heads here...thanks throttlecable...

 

[throttlecable]

Back at it.

Finally got the motor back from the performance guru, and had it installed back in the frame within a couple hrs...also bolted on the Diamond S chromo sub, and mocked in the Zbroz front end along with West Coast light weight steering post. These pics are of the recent progress, and a close up shot of the titanium post kit which adds strength to the high load area of the sub.

 

[SSWIM]

Looks great Cable. Tell Brozina he's looking OLD. HAHAHA.

Sam

 

[xtrememotorworks]

Nice build man! Looks killer. We will be offering CNC ported big valve head for the Nytro here soon for our turbo stuff, would be cool to see it on a high compression all motor build. Keep the pics coming!