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Tired of my weak TBI 350

efi or not

This is the way I put mine together having a very similar goal. I searched till I found a factory 4blt main roller vortec block in good shape(100) tore it down and put the factory crand and rods with 10:1 trw piston and a .020 overbore. Balanced the lower end,Put an lt1 cam in due to its good low end torque and midrange power had the heads shaved just enough to add a little extra compression, then topped it off with factory roller lifters, dual springs and cranes gold series full roller rockers. Most of the parts where out of the junk yards (core engines) If you know what you are looking for it isn't that expensive. Cost me 800-900 including machine work and am pushing rite at 310 with the factory TBI. The modified TBI claims to be able to get me another 20-25 hp.?
 
dirtwarrior17 said:
I can understand you defending carbs because you run one but what are you trying to prove? YOur buddy runs a carb on his boat... whats your point? EFI is better hands down...more expensive but better.

Dirtbikes have been coming out with 4 strokes for the last 5 years(in motorcross) and they have an unfair advantage from the extra cc's. for example 125's run with 250 4 strokes.... thats double the cc. Then you look at 250 2 strokes vz 450 4 strokes... If it was really fair they would need to apply the same rulz as the 125 class and double the cc's of the 2 stroke. That is the WHOLE reason the 250 two strokes are still kicking the 4 strokes asses and the 125 two strokes are getting their asses kicked(even thought the last championship was won on a 125.... just because stewart was riding it tho.) But that has nothing to do with efi. Dirtbikes already cost 6 grand new... they run carbs for the cost, not because they prefer them.

Carbs have been around for decades and there are a lot of people that know their way around em becuase of that.

A narrowband o2 only means the level of gauging is limited it has nothing to do with accuracy. a wideband might measure 10.0 to 18.0 and a narrow might measure 12-16 but they are both equally accurate when the readings are in the band.

If you ask me, you are the one that has a lot to learn about efi...not trying to start **** just my opinion.

the boat thing is towards "thunder" and no one else.

If you knew how an engine work. You would know the difference between the power a two stroke makes and a four stroke. That is why a four stroke needs a "larger" engine to compete with a two stroke. It maybe due to one engine having more power strokes then the other. And btw, four stroke dirtbikes have been around way longer then 5 years. I am refering to EPA rules of stopping production of two stroke motorcycles all together. You dont see two stroke street bikes no longer in production. They were quick as hell.


for the oxygen sensor. heres a website with the graph i was refering too.
http://www.turbosaturns.net/articles/oxygen%20sensors.htm

notice they mention "accuracy"

I can quote you about not knowing how to diagnose efi. Something about resetting a tps by pressing the gas pedal. :crazy:
http://coloradok5.com/forums/showthread.php?p=1149078#post1149078


People with the fast boats are nuts. Might be as much as the top fuel guys. I have seen too many vids of guys in the boats hitting a wave and the boats go flipping in the air. Then they come crashing down like a RC airplane made out of balsa wood.
 
1991 GMCk2500 4x4pu. Has anyone here swapped over to 4 bbl from tbi? This seems the best way to go for the best and cheapest hp gains. This is what I have in mind to get to 300hp from the stock 200. Vortec heads ($500), intake ($250), 600 cfm 4bbl ($300ish), an rv type cam ($200). Just looking to hear from someone who has done it before I go it alone. I also think that my truck cant get much worse gas mi than it doeas now--11mpg. It is all orig w 98K and runs beautifully. thanks

***************Post hijack mode off ********************

I am going back to the orginal posters question.

First I am going to say its not cheap HP as you think
Besides the things you listed for the conversion you will also need:

An old style HEI dist. TBI dist wont work without a computer. New performance HEI dists are $250 +?

A fuel pressure regulator with return line 50.00+

Linkage/adapter for your TV cable so you will be able to keep the TV cable in adjustment. And dont fry your 700R4 transmission (if so equipped). $50-$100

Dont expect a carb to give you better milage. You wont get much of a carb for 300. Unless you plan on just doing light wheeling or street. You will need a Holley truck avenger or a Qudrajet carb for best offroad performance. Thats closer too $400, if you buy new performance. You said you only get 11MPG? There is something wrong. I get 14-15mpg Average city and hiway driving 18 on the highway. With a mild built TBI 350 33s 3.73 GR. I have a buddy with a Sock TBI 350 K2500 It gets 16 on the highway.


You can easily get around 300 HP staying with TBI and spend about the same. By adding heads, cam, intake, and a chip. For a little more put on a bigger throttle body.
You will end up with a better running more dependable truck for all around use if you stay with the TBI system. You wil also learn something about Fuel Injection. It is really not that difficult to understand. TBI is a very simple system. You can get a lot of help here.
But
If you want a carbed rig sell yours and buy an older truck. That seems like the easist route to go. But that is just my opinnion.:grin:

**************Hijack in progress****************


BTW when I say "Fast boat" this is what I am talking about.......
Style.jpg

Dragon2049B.jpg


No Carbs here! ........Drool.......
 
Fierospeeder said:
the boat thing is towards "thunder" and no one else.

If you knew how an engine work. You would know the difference between the power a two stroke makes and a four stroke. That is why a four stroke needs a "larger" engine to compete with a two stroke. It maybe due to one engine having more power strokes then the other. And btw, four stroke dirtbikes have been around way longer then 5 years. I am refering to EPA rules of stopping production of two stroke motorcycles all together. You dont see two stroke street bikes no longer in production. They were quick as hell.


for the oxygen sensor. heres a website with the graph i was refering too.
http://www.turbosaturns.net/articles/oxygen%20sensors.htm

notice they mention "accuracy"

I can quote you about not knowing how to diagnose efi. Something about resetting a tps by pressing the gas pedal. :crazy:
http://coloradok5.com/forums/showthread.php?p=1149078#post1149078


People with the fast boats are nuts. Might be as much as the top fuel guys. I have seen too many vids of guys in the boats hitting a wave and the boats go flipping in the air. Then they come crashing down like a RC airplane made out of balsa wood.

Ok dude your missing the point. i said four strokes in MOTORCROSS... and if your gonna sit there and say i don't know the difference between a four stroke and a two stroke you didn't see the posts where i said i rebuilt my 125. A two strokes is firing twice as fast and doesn't have cams or valves.... it has power valves but thats it.

Once again your proving you don't know anything about efi.... to "reset" the tps after you disconnect power to the ecu you should always turn the ignition on(not turn it over) and depress the throttle to wide open 1 or 2 times... you can do the research on that one.

Actually you can still find 500cc two stroke street bikes that are fuel injected coming from europe but they are still around. two strokes will always be around, on tracks at least.

[email protected]

back to the original poster....

if you look at my earlier post you'll see that a carb over efi at 300 hp is only about 50 bucks cheaper if you find some deals. EFI is the way to go

Fierospeeder.... we are about to get warned.

that email link isn't for decoration...

peace.
 
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those are organ donor boats


Europe can do anything they like. They are not regulated by the united states to uphold EPA and saftey regulations. I have ridden two stroke motorcycles in europe, motor guzzis. Nothing high performance just single cylinder two stroke motorcycles.

You were mentioning how it is unfair for one dirtbike to have a larger volume then the other. But if you knew how the engines worked, they are putting out almost identical in power, and not argued it is unfair.


Why would the TPS need to be "set". There are either adjustable or non adjustable TPS sensors. You set the minumum voltage on the adjustable ones. I have hundreds of EFI manuals and i have never seen one mention to press the pedal. And i have been replacing TPS sensors for years.

On 2.5l engine, the TPS is not adjustable. The ECM uses the reading at idle for the zero reading, so no adjustment is necessary
I would think my service manual would tell me to press the gas pedal?

Only reason you would press a gas pedal down is on a carb vehicle with a choke.
 
I was saying the 125 class is unfair.....

125 two strokes run with 250 four strokes 125x2=250 (125 class:four strokes are double the cc's of the two strokes)

250two strokes run with 450 four strokes 250x2=500(250 class:four strokes aren't double the cc's of the two strokes)

see what i'm saying? one of the classes needs to be changed.

As far as the tps.... I don't have a 2.5l in my blazer so why would i be talkin about one? I was refering to 5.7's. 87-91.


two stroke street bikes are street legal in some states. A 500cc in a street bike is something new to me so i don't know if it was single or multiple cyclinder.

you run a carb right? why do you have an efi manual?
 
two strokes make the same amount of power to a four stroke with twice the size.

My redneck friend who plays with dirtbikes all day long knows this.



Go find me a quote from someplace that states how to reset your TPS sensor on your truck. Im too lazy to go pull out my mitchell manuals now.


The only way two strokes can be legal is if it in production before the federal law making two strokes illegal.


Actually, i have a manual for almost every single car. Something you need when you work on cars, plus more then 10,000 dollars worth of tools.
 
I'm holdin a dirtrider magazine with dyno specs in my hand right now... 450's make more torque and more hp than 250's but weigh another 20 lbs. same with 125's and 250's. your buddy doesn't know as much as you think he does.

How do you explain 2 stroke jet skis and outboards?


here ya go...

91GMCSuburban said:
I do agree with this and would do and have done the same thing. But since I've been there, I now what's coming.

Check vacuum lines, clean tbi (maybe even rebuild) and clean the injectors.

Also (and this is not likely because it would be a free fix), reset the TPS. Unhook the battery to reset the computer, once reset, turn the key to "ON" and then press the thottle pedal from zero to full throttle 2 or 3 times. If it had been replaced and not reset like this... you may get lucky.
 
well, with outboards. you mix a certain ratio of oil to gas. you pour it in the gas tank.
Same thing with jet skis.


Wheres the numbers to prove one makes more hp then the other? And at what rpm?

And the quote from a service manual about setting a tps sensor?
 
http://www.dirtrider.com/141_0401_250/

you can see that the four strokes are more powerful hands down from the bottom of the rpms to the top.... they are just heavier. go down to where it says opinions and click on the dyno sheet.

this was a 2004 test from dirtrider.

wrong on the mixing gas. my unlces 95 yamaha is a 750 two stroke which is oil injected. You have a lot to learn about two and four strokes...its better to just leave it alone.

HOw is me saying this is a quote from a manual gonna make you beleive me?
 
otherwise, i dont believe you if you cant back it up with a source. Even, find a link to it on the internet.
How many years have you been a professional mechanic?

Adding oil to gas or oil injected. Two strokes still work on the same principles.

How about a 1920 firestone outboard is that oil injected? My friend has about 5 of those. Just because a manufac has a different way of doing things doesn't change the aspects of how an engine works.


Havn't looked at your link. But if you go by my article. the 125 is making more HP. Each has pros and cons. But both bikes have very close torque and hp numbers. Which argues to you about how an engine twice the size is making twice as much power :rolleyes:
 
well, with outboards. you mix a certain ratio of oil to gas. you pour it in the gas tank.
Same thing with jet skis.

why did you say this then? to me it looked like you thought all 2 stroke jet skis and outboards need to mix oil with the gas.

I never said anything about oil injection changing the way a two stroke works... you suggested that it does.


origianally posted by dirtwarrior17: How do you explain 2 stroke jet skis and outboards?





originally posted by fierospeeder:
well, with outboards. you mix a certain ratio of oil to gas. you pour it in the gas tank.
Same thing with jet skis.






I am not trying to embarrass you... just educate you. dirtbikes have been working towards 4 strokes in motorcross for a long time. Its just recently that the 250's have surpassed the 125's in power. that is why the entire 125 class is now four strokes. The cc's thing i was saying about doubling the cc's is the reason two strokes are still king of the pile in the 250 class.

the link i posted is a dyno test not an article and it is recent... i'd bet money the article you posted was done earlier. my 99 yz 125 could kill my buddy's klx 300 because it was a 2002. the 04 and 05 four stroke 250's would be bar to bar with me the whole time(more like beat me but i would never admit it).

click on that link.... i don't feel like doing this.

professional mechanic.... dude i posted the thread where i got this info. I even quoted it. don't argue with me about being a professional mechanic. go back one page and you'll see what im talkin about.


I just looked at it and it is 2002. I rest my case. If you want to continue this email me otherwise we are about to get slapped on the wrist.

[email protected]
 
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so where is the oil being injected to? Or is oil serving another purpose then a typical two stroke motor that has a mixed fuel?


Even your article, which i clicked because i got broadband. All of the dyno sheets have very close numbers. And a lot of them all flow together. If one bike accelerates slow, the tech just needs to change the sprockets.


Your main point of the dirtbike thing is one motorcycle has an unfair advantage because the motor size differs. You still need to provide real info that one motorcycle has such an unfair advantage. It isn't like comparing a four cylinder to a v8.
What if kawasaki 125cc was making 5hp more then a yamaha 125cc. Will you state the race is unfair now? Or during motorcross day, team A has a better mechanic then team B?
You even said, the two strokes are beating 4 strokes on the track.

So how many years have you been a professional mechanic? Because then you can back up the TPS sensor. Or not needed to bring your moms vehicle to the mechanic.
 
edited to be nice

If you think the 2 and 4 strokes were real close you need to look at the dyno sheet better. all the ones on the top were fs and all the ones below them were two strokes.

wrong again.... my main point was that 250 four strokes have an advantage over 125 two strokes compared to the 250 two strokes vz the 450 four strokes.

125cc X 2 is 250

250 X 2 is 500

if both the classes are going to apply the same rulz the 250cc 2 strokes should be running with 500cc 4 strokes not 450cc 4 strokes.

My mom wouldn't let me work on it. period. I wanted to do it and she wouldn't let because she thought the mechanic would get it done faster. I did my swap with no help besides the occasional post asking about tuning or knock sensor. I am more than capable of takin off a head and replacing the gaskets.

do you have a dirtbike? what year? have you ever rebuilt one? the difference between a 125 and a 250 fs is less than 3 hp and they allow it because they weight more. the difference between the two and four strokes are huge. 5 hp in the 250 class and they make tons more torque right from go. you still aren't getting it. you are acting like you are a master mechanic at a local bike shop but all the info you've giving about them is way off.

I am done with this thread.

sorry to the original poster for the hijack... i posted on the subject twice then vierred off. next time i will leave my email and stay on subject.

[email protected]
 
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i use to have a dirtbike, and i will be getting another one again. I tear motors with my friend all the time. Hes a redneck so he plays with two strokes all day long. your lucky you dont live next to him, i wouldn't want too. Outboards, snowmobiles, dirtbikes etc... reving all day long.

I got bored one day and rebuilt my 2 stroke concrete saw. a lot better then an air cutting wheel. i can chop a car up in no time. :grin:


I do have 2 1/2 street bikes. But the theories of those are same as cars. I can take the test for master mechanic, but ill wait for that. But i know none of the certification tests say to reset the tps pedal by pressing the gas pedal.
 
Originally Posted by 91GMCSuburban


Also (and this is not likely because it would be a free fix), reset the TPS. Unhook the battery to reset the computer, once reset, turn the key to "ON" and then press the thottle pedal from zero to full throttle 2 or 3 times. If it had been replaced and not reset like this... you may get lucky.

I consider this site to be as good as the manual and sometimes better.

I guess im like your redneck friend... i've had the cops called on me plenty of times for dirtbikes and my nitro powered 2 stroke rc truck.
 
i wouldn't go by that quote.


I have seen so much stuff people say about EFI systems it isn't true.

It isn't like playing "contra" Press up 5 times press down 4 times right 3 times press A 5 times press B 2 times and earn 500 extra lives.


My buddy talks to the cops a lot. They pretty much dont care anymore. Only major time he got busted is when he had one of those stupid gasoline scooters. Someone called the cops on him for that.
 
Fierospeeder and Dirtwarrior17,

Take it to email or IM. These hi-jacks and bickering are no longer going to be tolerated. stick to the subject at hand, or start your very own thread, or argue with each other endlessly somewhere else. :mad:

Rene
 

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