ktm/husky 300. whos spent time making more power?

[portgrinder]

You know the old saying, no replacement for displacement. I think a 300 would be a downgrade from your 500 since you already have modern ergos with the AF. If you are looking for a more nimble feel maybe the answer lies in the a new back half of your bike. The new narrow rail Yeti might be up your alley.

M5

Ya you’re 100% on that. It’s never going to be a 500. They are just an absolute hoot to ride though. Like jumping on a 125 after riding a 450 on dirt. Ya you’re not going quite as fast but it’s way more fun.

Narrow rail might be an answer. But narrow track seems like a bust to me. They just don’t chew near as good.

 

[eric82930]

Portgrinder, It sounds like you may have had a 500? Just curious, If so what is the reason you are thinking of trying to get more power from a smaller bike?

Vibration, hard starting and narrow power are the reason I couldn't justify keeping my 500 I was really glad to see it go. Hopefully the brc might fix the first two issues. Iv'e been dabbling in ktm 360's and 380's lately and raising the exhaust port about an inch seems to be what they like to be a good snowbike.

And I don't agree with the "no replacement for displacement" in the field of snowbikes. If it was true why isn't the panthera in every snowbike out there by now....??? Every 450 made in the last 5 years makes more power than the 500's and they have half the power strokes. Its about airflow in this case which probably needs to be the main topic of this discussion on the 300's.

I'm not an engineer by any means and kinda sloppy in my approach to tuning but I ride snow 2-3 days a week oct - july and have tons field trial and error experience to see what works on the snow. My conclusion is stock mx bikes always do best because the factories tune them for peak hp. The big bores never seem worth it because they trade hp for torque because the peak airflow is choked off somewhere in the system. Big bores also vibrate more, start harder and are less reliable. High comp is almost always better for high altitude as long as it will still start.....

I'm super biased to 2 strokes and 1st choice would probably be a 60hp GP tuned counterbalanced 300. If the brc can make reliable 70hp it will probably be my 2nd choice until ktm starts building the 2 stroke 500SBS "snow bike special". It will come with the tires in a separate box with a warning label that says "INSTALATION MAY RESULT IN BODILY HARM OR DEATH"

 

[portgrinder]

See above.

500 not for sale any time soon. Mine is dialed.

 

[byeatts]

Portgrinder, It sounds like you may have had a 500? Just curious, If so what is the reason you are thinking of trying to get more power from a smaller bike?

Vibration, hard starting and narrow power are the reason I couldn't justify keeping my 500 I was really glad to see it go. Hopefully the brc might fix the first two issues. Iv'e been dabbling in ktm 360's and 380's lately and raising the exhaust port about an inch seems to be what they like to be a good snowbike.

And I don't agree with the "no replacement for displacement" in the field of snowbikes. If it was true why isn't the panthera in every snowbike out there by now....??? Every 450 made in the last 5 years makes more power than the 500's and they have half the power strokes. Its about airflow in this case which probably needs to be the main topic of this discussion on the 300's.

I'm not an engineer by any means and kinda sloppy in my approach to tuning but I ride snow 2-3 days a week oct - july and have tons field trial and error experience to see what works on the snow. My conclusion is stock mx bikes always do best because the factories tune them for peak hp. The big bores never seem worth it because they trade hp for torque because the peak airflow is choked off somewhere in the system. Big bores also vibrate more, start harder and are less reliable. High comp is almost always better for high altitude as long as it will still start.....

I'm super biased to 2 strokes and 1st choice would probably be a 60hp GP tuned counterbalanced 300. If the brc can make reliable 70hp it will probably be my 2nd choice until ktm starts building the 2 stroke 500SBS "snow bike special". It will come with the tires in a separate box with a warning label that says "INSTALATION MAY RESULT IN BODILY HARM OR DEATH"

I also have a xcw 500 with ECU with a yeti here and it will not climb anything like the 450, They have torque however torque is great to tractor around however the high rev 450 motocross bike will spin the track so much faster while climbing . They have incredible over rev capacity , The 500,s always craps out hitting rev limiter when pushed and they are much heavier.

 

[eric82930]

See above.

500 not for sale any time soon. Mine is dialed.

What did it take to get it dialed? Porting? pipe? head? How would you compare the power curve to stock and can it over rev any better?

Its funny just today my buddy with a really good running beta 300 I tuned, lectron & head, Said he would rather have the top end power of my other buddies 250sx (also tuned). I never said a word about it, it was all his idea. I though I was the only one....

 

[powdermuncher]

You guys -- by now we all should have come to the conclusion that the 2 stroke with a carb has gone as far as they can--FI will allow that next step in the evolution. Precise metering of fuel where you need it -- in the combustion chamber.

I just got one and will be working on making power in the dirt first and after that on snow. With a tun-able ECU and most of the groundwork already there -- We should have something to work with.

 

[eric82930]

You guys -- by now we all should have come to the conclusion that the 2 stroke with a carb has gone as far as they can--FI will allow that next step in the evolution. Precise metering of fuel where you need it -- in the combustion chamber.

I just got one and will be working on making power in the dirt first and after that on snow. With a tun-able ECU and most of the groundwork already there -- We should have something to work with.

Are you talking about the 300 tpi? I just learned about the standalone ecu you can change timing too. Still probably needs more air flow at high rpm.

 

[powdermuncher]

Yes 300 tpi there is the Get ECU or the JD tuner

Any of us that turbo charged sleds over the Years will be very familiar with the controllers and concepts involved.

Just messing about with the tpi bike on the first open hill climb around here revealed some interesting stuff.

First of all the bike feels less powerfull with the linear power delivery , does not like to lift the wheel the same as the carb bike --- but going in a gear high it pulls the hill where I have to shift down with the carb Bike go figure. Clean solid pull at mid RPM. This should work out well for the snowbike.

 

[portgrinder]

Interesting to see how you make out. i like old school for many reasons.

cooler piston
cooler crankcase
lighter
cheaper bike
cheaper to tune

I don't like the idea of spending a bunch of extra cash for an FI bike and then getting all fired up about spending more money to be able to tune it.

anyhow. getting off topic. i'm going to cut a few different heads, make a few pipes and see what we can learn. if anyone has a lectron 40mm+ near Edmonton I would sure like to borrow it for a few runs.

 

[powdermuncher]

I hear where you are coming from , but just look at 2 stroke turbos 200+ HP out of 800 CC reliable all day long on pump gas. Just a few Years earlier the carb turbos was a blow up fest could not keep them in one piece for any length of time.
It took EFI and all it's drawbacks to make it work. I have many thousands of reliable miles on FI 2 stroke sleds with all the above drawbacks. They just work and last 2 times longer than the carbureted sleds before them.
There will no doubt be some issues to deal with, but the positives are hard to ignore. I will keep watching on where your builds take you -- no doubt the same mods that work for you with a carb will be a great starting point and work even better once we have a efi system dialled for them.

 

[eric82930]

i'm going to cut a few different heads, make a few pipes and see what we can learn. if anyone has a lectron 40mm+ near Edmonton I would sure like to borrow it for a few runs.

Thats awesome you can make your own pipes. Keep us posted. My 300 mod was my favorite build so far until just a few weeks ago it would wax the 360 and the 380 and hang with any 450 as long as I wasn't lazy. I'm finally getting better power with the 360. The 450's have to follow my tracks now to keep up in the deep. Not wanting to grind the exhaust port (irreversible) I just kept raising the cyl each ride and cutting down the head to see where the bike would start to loose bottom end. It never did. Now I'm at 2.5mm above stock! Its crazy that I can't feel any loss in low end yet. It just keeps making more and more peak power mostly beyond the range where it used to fall off on top. Now the power band is crazy wide like my 300. The piston is no where near the deck at tdc. My head is flat now with just a hemi dome in the center. there is no lip to drop to the squish pad and I started cutting into the water jacket around the rim right below the outlet spigot so I had to stop there and epoxy it a bit so the water doesn't short cut around the head. The Comp Ratio is just slightly more than stock and running fatty pipe on the retarded ignition mark. I just got a programmable cdi with no base maps. But Its running so Awesome I'm afraid I will make it worse or blow it up.

 

[eric82930]

Can anyone confirm if the brand new 300 sub ex ports are still lower than the main port? They started doing that in 04 on the 300's. All the older cylinders have higher sub ports and the new 250' still have higher sub ports. I spent some time with turners software years back and it seemed having the subs at the same height as the main was key to best peak numbers.

 

[portgrinder]

Computer may tell you that but the old boys I talk to say you want the subs just a smidge lower than the main.

Raising the whole cylinder will help, but blowdown is important too. If you lower the transfers I bet you will see huge gains. Tough to do without removing aluminum. Might be able to jam some epoxy in the roofs of the transfers.

 

[NEWDUCK]

A bit off topic but has anyone tried a different head on the 250 sx? Seems all I hear about is changing heads on the xc, xcw models.

 

[portgrinder]

i'm going to cut some stockers and i'll let you know when we run them. I looked at what fancy heads were worth. forget that. bought a couple stockers and will slice them up myself.

 

[eric82930]

The sx heads are pretty good stock but for high altitude ive seen good results with slightly more comp. Took off .015 with std base Gasket and did one at .030 with the thickest bg. About the same perf

 

[simbatheking]

Carb turbo

I turboed my tx300. The guys who say carb turbos don’t work have no idea what they are talking about and should not spout off ignorance. I have 6000km on a turbo xp carb at 10psi with a full rebuild at 5k for preventative maintenance. It’s all in the tune and it doesn’t matter if it’s efi or carb. My tx300 weighs the same as a 4 stroke but power comes on faster and way more of it. I literally ran circles yesterday around my friend on his 4 stroke and it took him 8 attempts poaching my track to make a climb I did first try. I don’t have any more pic room on this weak site but reference my other threads where I posted a utube vid if u want to see. My biggest beef by far is that it floods upside down badly. If anyone has a remedy roll over valve I would really appreciate that

 

[simbatheking]

Also nearly all the sled hp records were 2 stroke carb turbo. Google Gus bohne for reference at dyno tech research.

 

[eric82930]

I have to agree with simba that 2 strokes with carbs are fine in my book. fi has some minor advantages when tuned properly (that's the key) like not flooding when upside down and fine tuning for air density. ive also built boosted xp's that run as good as the etechs. most fi systems I see in the power sports world are not tuned well from the factory and anything with a piggy back tuner is usually much worse than stock unless the owner knew how to jet a carb prior to geting fi.....

the 4 strokes though have benefited big time from fi.they can run 46mm throttle bodies without any low rpm bog and the starting has also improved from fi especially after tipping over.

 

[Fwd55]

Trying to keep up with all the 300 FI tuning info

Do you see any reason why a 300 tpi would not be able to perform in a bottom less snow condition at sea level ?

Sound to me that the FI provide a better control of the fuel flow that would be a great benefit for Long period of WOT in bottom less