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Bryan Bosch

Video: KTM'S CARB VS TPI (TRANSFER PORT INJECTION)

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TPI! It's short for transfer port injection and it's KTM's response to increasingly tough European emission laws. TPI is often promoted as the latest and greatest innovation for two strokes, but in reality it's being forced on manufacturers by demands for less emissions so no more carbs or carburetors. So it's a mixed bag of good and not so good features. Yes TPI is better for the environment. So up ahead is Pete on his 250. It's all he will buy and he often tells us we will sell our 300s and get 250s when we learn how to ride properly. Of course we tell him he is a skirt wearing nancy boy who will sell his princess pony 250 when he mans up and grows a pair.

So how do they compare? Well two strokes have come a long way recently, and especially the 250s. Way less smoke and better fuel economy. Performance? The more honest dirt bike reviews say it's not a startling difference and some riders may not even notice the differences. But generally the reports are the bikes run a bit better at low revs, they are less snappy and the power is a bit more linear. Of course there's no jetting required with TPI, and the system automatically adjusts if you do big altitude changes. TPI is a complex system but the good news is it doesn't make top end rebuilds any harder... good for the home mechanic. The Europeans are really getting some serious low down grunt from the little smokers, which has narrowed the difference considerably with the bigger 300s. But the 250 is still a favourite for guys who like a lively engine, and like to rev more without killing themselves. The smaller engine revs up faster, usually a bit higher, and despite having less lowdown power in most brands the 250s are putting out the same top end power as the 300s.

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Not so good part of transfer port injection? The fuel pump, oil pump and sensor add a whopping 3kg to the bike. In Australia it also adds a whopping $1000 to the price. The TPI fuel pump knocks a litre off the fuel tank capacity, although this should be offset by better fuel economy. And of course the added complexity of transfer port injection means more things that can go wrong, and harder to fix than a carburetor when on the trail. So how reliable is TPI? For less experienced riders the 250 will probably be safer and less tiring too. The milder power in the low to midrange revs will keep you out of trouble, and if you adjust your power valve you can soften that hit of power you usually get with the 250s at higher revs. Transfer port injection was not so good in the first year. Oil tanks splitting, and many reported issues with starting, idling and running lean. But apparently most of this has been resolved now and reliability has been improved a lot. There are certainly a lot of happy TPI riders out there. If you live in a country where you can choose TPI or the carburetor models, you may need to test ride both to see which you'd prefer. Let us know what you think of transfer port injection.

Courtesy of http://www.crosstrainingenduro.com and http://tractionerag.com

176957_KTM-EXC-TPI-Engine-MY-2018-studio.jpg

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The problems with TPI bikes are still going on.

Good point about the smaller tank. The mileage is about the same as an XC bike. My 19 XC gets 28-30 MPG. The TPI is about the same but with a smaller gas tank and less range. LoL.

TPI was never built with performance in mind. Instead it were developed out of emissions, which has robbed horse power and torque traditionally in the past.

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2 hours ago, Bryan Bosch said:

 

TPI! It's short for transfer port injection and it's KTM's response to increasingly tough European emission laws. TPI is often promoted as the latest and greatest innovation for two strokes, but in reality it's being forced on manufacturers by demands for less emissions so no more carbs or carburetors. So it's a mixed bag of good and not so good features. Yes TPI is better for the environment. So up ahead is Pete on his 250. It's all he will buy and he often tells us we will sell our 300s and get 250s when we learn how to ride properly. Of course we tell him he is a skirt wearing nancy boy who will sell his princess pony 250 when he mans up and grows a pair.

So how do they compare? Well two strokes have come a long way recently, and especially the 250s. Way less smoke and better fuel economy. Performance? The more honest dirt bike reviews say it's not a startling difference and some riders may not even notice the differences. But generally the reports are the bikes run a bit better at low revs, they are less snappy and the power is a bit more linear. Of course there's no jetting required with TPI, and the system automatically adjusts if you do big altitude changes. TPI is a complex system but the good news is it doesn't make top end rebuilds any harder... good for the home mechanic. The Europeans are really getting some serious low down grunt from the little smokers, which has narrowed the difference considerably with the bigger 300s. But the 250 is still a favourite for guys who like a lively engine, and like to rev more without killing themselves. The smaller engine revs up faster, usually a bit higher, and despite having less lowdown power in most brands the 250s are putting out the same top end power as the 300s.

Not so good part of transfer port injection? The fuel pump, oil pump and sensor add a whopping 3kg to the bike. In Australia it also adds a whopping $1000 to the price. The TPI fuel pump knocks a litre off the fuel tank capacity, although this should be offset by better fuel economy. And of course the added complexity of transfer port injection means more things that can go wrong, and harder to fix than a carburetor when on the trail. So how reliable is TPI? For less experienced riders the 250 will probably be safer and less tiring too. The milder power in the low to midrange revs will keep you out of trouble, and if you adjust your power valve you can soften that hit of power you usually get with the 250s at higher revs. Transfer port injection was not so good in the first year. Oil tanks splitting, and many reported issues with starting, idling and running lean. But apparently most of this has been resolved now and reliability has been improved a lot. There are certainly a lot of happy TPI riders out there. If you live in a country where you can choose TPI or the carburetor models, you may need to test ride both to see which you'd prefer. Let us know what you think of transfer port injection.

Courtesy ofhttp://www.crosstrainingenduro.com and http://tractionerag.com

From what others have said around here, it doesn't automatically adjust. You have to reset it by stopping and starting the engine a couple times. Now if you're on nasty trails while doing elevation you are already stopping and starting so it does have a chance to reset.

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The TPI bike is a great bike though. If it’s for trail riding , it could be faster on the trails vrs the XC for most intermediate riders. A very linear power curve. A light feel. On the other hand, if your craving is for insane mid range power that blows your socks off, then the XC line is most definitely your choice imo. :-)

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Especially with the red power valve spring I should have added to the above post.

With the yellow spring turned in a bit can actually give a rider the feel of a super light, zippy bike. I set my 19XC that way when experimenting in the tuning process. It was cool and everything but the bike came alive imo using the provided red spring the XC’s come with.

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These systems are of dubious quality when new, heaven help you if plan to keep a bike 5-10 years.

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On 1/15/2019 at 9:51 PM, 2strokenut said:

What part is of dubious quality?

The oil injection design stinks.  Plastic hose running down to a fitting on the intake.  Bikes were showing up with the oil tank cracked.  The pump can lose its prime without warning, especially on a tip over.  

Edited by redrider144
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9 hours ago, redrider144 said:

The oil injection design stinks.  Plastic hose running down to a barbed fitting on the cylinder.  Bikes were showing up with the oil tank cracked.  The pump can lose its prime without warning, especially on a tip over.  

The oil pump is actually a quality made Japanese part. A guy in our facebook tpi forum took one apart. I've launched my TPI off cliffs nonstop since I've bought it and I haven't had an issue, neither has my buddy who rents TPIs out on the regular to extreme enduro riders visiting AZ. The oil tank in the 19s were changed to a different type of plastic (PP instead of PE). The pump and injection are from the 4Ts and they are very reliable. So I think it's just conjecture from TPI haters :D

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14 minutes ago, 2strokenut said:

The oil pump is actually a quality made Japanese part. A guy in our facebook tpi forum took one apart. I've launched my TPI off cliffs nonstop since I've bought it and I haven't had an issue, neither has my buddy who rents TPIs out on the regular to extreme enduro riders visiting AZ. The oil tank in the 19s were changed to a different type of plastic (PP instead of PE). The pump and injection are from the 4Ts and they are very reliable. So I think it's just conjecture from TPI haters :D

+1, would also like to add that the oil is injected just in front of the throttle body plate, the barbed fitting on the back of the cylinder is for the MAP sensor.

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21 minutes ago, 2strokenut said:

The oil pump is actually a quality made Japanese part. A guy in our facebook tpi forum took one apart. I've launched my TPI off cliffs nonstop since I've bought it and I haven't had an issue, neither has my buddy who rents TPIs out on the regular to extreme enduro riders visiting AZ. The oil tank in the 19s were changed to a different type of plastic (PP instead of PE). The pump and injection are from the 4Ts and they are very reliable. So I think it's just conjecture from TPI haters :D

So the people that had their pumps lose the prime and smoked their cylinders were just imagining it?  Riiiiiight.

You're apparently one of those guys that thinks because your bike hasn't had an issue, there's no issue.

4 minutes ago, zig06 said:

+1, would also like to add that the oil is injected just in front of the throttle body plate, the barbed fitting on the back of the cylinder is for the MAP sensor.

Oh well by all means that changes everything.  Not.  Way to focus on the most inconsequential and insignificant part of my statement and completely miss the point.   

No no no, the tassels and tutu Zig was wearing weren't purple, they were fuscia!   I was totally wrong!

Edited by redrider144
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2 minutes ago, redrider144 said:

So the people that had their pumps lose the prime and smoked their cylinders were just imagining it?  Riiiiiight.

You're apparently one of those guys that thinks because your bike hasn't had an issue, there's no issue.

Oh well by all means that changes everything.  Not.

If your going to hate, you should at least have your facts straight.

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1 minute ago, zig06 said:

If your going to hate, you should at least have your facts straight.

You're right, like I said.   I was totally wrong when I said I saw you in a purple tutu.  It was fuscia.

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20 minutes ago, redrider144 said:

You're right, like I said.   I was totally wrong when I said I saw you in a purple tutu.  It was fuscia.

Why not just share a thread with example problems or references. The sarcasm doesn't further the conversation or help your point, it just makes you sound like a dick.

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14 minutes ago, redrider144 said:

So the people that had their pumps lose the prime and smoked their cylinders were just imagining it?  Riiiiiight.

You're apparently one of those guys that thinks because your bike hasn't had an issue, there's no issue.

Oh well by all means that changes everything.  Not.  Way to focus on the most inconsequential and insignificant part of my statement and completely miss the point.   

No no no, the tassels and tutu Zig was wearing weren't purple, they were fuscia!   I was totally wrong!

I'm not saying they didn't have an issue, I'm saying it's overblown by people don't have a TPI. My good buddies went and raced Romaniacs last year. 50% of riders are on TPI bikes, maybe more. I asked them if they spoke to the local guys about any issues with the TPIs (this was before I bought a TPI) and they said "yeah, riders have zero issues with the bikes". I asked them about pump failure. Couldn't find a single person with a problem. Oil pump going out? No one had a problem.

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On 1/15/2019 at 10:46 PM, Zuminazx said:

These systems are of dubious quality when new, heaven help you if plan to keep a bike 5-10 years.

 

The oil injection is simple and reliable, no major issues out there. I can actually HEAR the insecurity of tpi haters out there talking about “dubious quality”. Get real.

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I liek how it was next to impossible to even see a TPI at the showroom floor 6 months ago. Now they're sitting collecting dust. :P

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1 minute ago, 240ZDAN said:

I liek how it was next to impossible to even see a TPI at the showroom floor 6 months ago. Now they're sitting collecting dust. 😛

You probably can get a pretty good deal on one then, right? Ditch that stupid carb and join the future of all two strokes.

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