KTM 300 TPI icing?

summitag163 · Mar 18, 2018

Considering a snowbike build with the 300 TPI once/if they come to Canada. I am looking for opinions if it would have the same freezing issues as carb versions. I have been running Avid heated APT carbs for years, when heat is turned down the slide freezes. With so little engine heat from 2-strokes am wondering if throttle body will stick/freeze with TPI without Avid or something.

heliwrench · Mar 18, 2018

Shouldn't be a problem. I think most of the carb icing issues are due to the venturi in the carb. Throttle body is straight through with a butterfly in it instead of a slide.

wwillf01 · Mar 18, 2018

Yep

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M5- · Mar 19, 2018

That's a really good question.

If you've ever looked inside a 2 stoke carb once it has really frozen up badly the entire bell gets coated in ice which eventually binds the slide. I would think a butterfly would be better but I'm not sure the throttle body would be immune to freezing in the right atmospheric conditions. You are just moving so much more air than with a 4T plus 4ts run a lot hotter than 2Ts. You would want ensure that you keep the engine temps up at all times with Tstats, shrouding and all that crap in order to give it a chance of keeping ahead of icing. Doing that would cost a little bit of power but no big deal really.

M5

summitag163 · Mar 19, 2018

Yes, can run all day sometimes without carb heat and not long other days when foggy or humid. I can see how the lack of Venturi will help but guess the butterfly may not be immune on those certain days. Thanks for the opinions.

CATSLEDMAN1 · Mar 19, 2018

carb vs fuelie

on the 4 stroke KTM and Yam, the jump from carb to fuel injection just eliminates the carb icing issue. When 2 stroke sleds went from carb to fuelie in the mid 90's, same, no more carb icing. We ran a lot of fabric hoods back in the day on the sleds and it was not unusual to ice your carb with cold underhood temps. Then when the fuelies came along, nada, I don't recall any true icing issues.

I am guessing that a fuelie KTM 300 with minimal shrouding around engine and fuel injection unit will be trouble free.

coryf89 · Mar 20, 2018

A&E racing in brooks already has a TPI or two 300xcw. $10,500 fair price too. . I’d be waiting for the 2nd or 3 rd year out with tpi at least.

teal_210 · Mar 20, 2018

A buddy of mine has a 250 TPI. He used it as a snowbike for one day, was a deep powder day - bike ran good all day with no icing issues. He said he couldn't get on it though, the EGT's would spike. Most of the expansion chamber was bright blue, can't say I've seen that on a 2-stroke!

Sheetmetalfab · Mar 20, 2018

teal_210 said:
A buddy of mine has a 250 TPI. He used it as a snowbike for one day, was a deep powder day - bike ran good all day with no icing issues. He said he couldn't get on it though, the EGT's would spike. Most of the expansion chamber was bright blue, can't say I've seen that on a 2-stroke!

Interesting.
Sounds lean.
Wonder if the air intake temp sensor was somehow blocked.

teal_210 · Mar 20, 2018

Sheetmetalfab said:
Interesting.
Sounds lean.
Wonder if the air intake temp sensor was somehow blocked.

I'm thinking they just were not designed to run wide open with such an extreme load on them. It definitely runs lean!

It'll be interesting to see what aftermarket fueling options are available for them.

portgrinder · Mar 20, 2018

this is gonna be the problem with FI 2 strokes. too lean on the top end.

why?...because you cant load up a bike like you can a snowbike, so they wont be programmed to need as much fuel. the tire just spins, or you let off to grab a gear. you cant work them hard for two minutes straight like a snowbike. the factory bike settings are just plain and simple going to be too lean.

That's good. all you guys with big cash go buy the new fancy setup, and then buy fuel controllers to fix it when it doesnt work.

i'll stick with carbs.

coryf89 · Mar 20, 2018

Why not just stick with 4 stroke and then also get instant torque too??

Robster · Mar 25, 2018

300 TPI

My riding buddy had a -17 exc 300 with Tedesled kit last year and it needed carb heating and insulation of the carb to work good in pow and in really cold temps.

The -18 exc 300 TPI that he has put +50 hours on this year has not once had problems with carb icing and that is without insulation and heating. It just flat out rips!

Northwestguy · Mar 29, 2018

How did it do hooked up to that Yeti? Overall, that is.......

M5- · Mar 30, 2018

coryf89 said:
Why not just stick with 4 stroke and then also get instant torque too??

Big 2 strokes make torque. Lots of torque. I don't know about a 300 but my CR500 makes more torque and horsepower and pulls way harder than my 4 stroke GYTR CNC ported race cammed 450 YZ. 4 strokes are forgiving and very easy to ride the 2 stroke is a bit more interactive but I really prefer the 2 stroke for hard riding and the 4 stroke for casual exploring.

M5

chumbilly1 · Mar 31, 2018

coryf89 said:
Why not just stick with 4 stroke and then also get instant torque too??

Because the 4 stroke feels 100#s heavier, rings my ears, is slower from tree well to tree well, and has a lot of expen$ive moving parts in the motor. Thats just me though. I have both and cant wait to sell the 450 next fall. Gonna keep my 300sx 129SS, sell the 137, and by an 850 for the deep. If the OEM produces a powerful well built unit I will go that route, but that sprobably gonna be a minute.

chumbilly1 · Mar 31, 2018

And most likely the 300sx will be a BRC500sx by fall. As long as I can see the thing on the snow this spring! Hint BRC Hint

jackbombay · Mar 31, 2018

teal_210 said:
I'm thinking they just were not designed to run wide open with such an extreme load on them. It definitely runs lean!

It'll be interesting to see what aftermarket fueling options are available for them.

JD (James Dean) is working on, or already has a fuel controller for sale for the TPI KTMs.

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KTM 300 TPI icing?

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