still working out bugs on tri-z power band???

[johnnytri-z]

so ive finally gotten to a point to where i have time to ride and most of the kinks have been worked out on my 85 1/2 tri-z. anyone got an idea why it would start off really slow through the power band then all of the sudden hits hard? will be riding along 1/2 throttle in 2nd or 3rd gear then without really having increased throttle it will lift the front tire...thanks

[RIDE-RED 250r]

That's called "gettin on the pipe"!! Enjoy!!

[Bryan Raffa]

did you try the purple band?

[volfan537240]

could be a jetting problem , air leak or a number of things. how does it idle?

[wisconsinite]

Tri z's have a lightswtch power band, pretty normal.

[atc007]

And while you're being ribbed lol. No such thing as a 85 1/2 Tri Z,just a black or yellow 85. If your carb is clean,and fuel pump is working good.No air leaks and good spark/timing. All is probably the way it is supposed to be.

[ATC-Eric]

Tri z's have a lightswtch power band, pretty normal.

What he said /\

They do not come on smooth like the 250r.

[wisconsinite]

Yep, gotta pay attention or they'll getcha :lol:

[zepol]

Thats what u call the powerband

[zzmegad]

the way you worded that post it sounds like it's the first "racing" 2 stroke you have ripped, if that's the case... Hell yeah!! sweet aint it

[Bryan Raffa]

this is where reed spacer work on Tri-Z's ... it smooth's that hit out....

[tommerp]

I like the hit.. puts you back in the seat a little.. makes you really want to grab on and keep twisting!

[johnnytri-z]

been a few days. but here we go.first IM NOT A MORON.2nd lets just all forget the phrase powerr band exists. i appreciate all of the legitimate answers. i have owned several bikes, trikes and sleds with two stroke engines. from my first to my first dirtbike. a 1983 ds80 to my first two stroke trike a 1983 tri-moto 175 all the way to my 2008 arctic cat m1000. the problem is ive never had a two stroke that has had a ton of machine work done to it {before i bought it} the whole bike was beat to hel.i had alaska drag bike tear down the engine to see if the work was done professionally and replace all wear parts/bearings. he said whoever did the machine work did a very nice job he also said he had never seen an engine carbon fouled as mine ever. now here is where i am at a loss. the head has been milled, intake and exhaust enlarged, runs a 490it rod, boyeson reed kit and a k&n air filter. ADB did not touch the carb or timing settings. the carb is stock.all that said no 2 stroke ive ever straddled has ever behaved like this one. idles great runs through the gears great. the only issue/question i have is why when the throttle is set at a constant, would the bike on a whim create more power and rpm without increasing the throttle.

[ktmcrasher]

My ktm does a similar thing, when I'm trying to go along at a constant speed like at 50mph on the road the bike won't run at a constant rpm. It sounds like its spluttering and the revs change up and down. I don't have problems at lower revs, is that similar to what you're talking about?

[barnett468]

Hello


Since these bikes are apparently “pipey” modifying one will typically exacerbate the problem.


[Quote] he said whoever did the machine work did a very nice job he also said he had never seen an engine carbon fouled as mine ever. [Quote]

Running rich oil mix, running old school castor bean oil and/or jetting too rich for your particular set up or a fuel pump leak.

1. Install plastic lines on all vacuum lines on fuel pump. Start and ride bike and If there is fuel in the clear line then pump is leaking fuel into the engine creating rich condition and possible erratic rpm at steady throttle, cool huh?

2. If pump was leaking then after it has been repaired and oil/gas ratio been determined [commonly 32:1] install new plug, ride moderately fast AND slow for 30 minutes then check plug color. Lite tan is good dark brown is slightly rich, dry black is too rich. Jet accordingly.

xxxxx

[Quote] why when the throttle is set at a constant, would the bike on a whim create more power and rpm without increasing the throttle. [Quote]

1. Bad fuel pump randomly leaking fuel into the engine.

2. Jetting to rich [typically won’t cause erratic rpm at steady throttle].

3. Excessively worn carb slide/body [typically causes biggest problems at idle though] .


[Quote] the head has been milled[Quote]

Do a compression test with gas off, carb bowl empty and throttle wide open and post results.

Xxxxx

What octane are you using?

Did you run it on 93 octane and if so did it ping/detonate under load?

[barnett468]

been a few days. but here we go.first IM NOT A MORON.2nd lets just all forget the phrase powerr band exists. i appreciate all of the legitimate answers. i have owned several bikes, trikes and sleds with two stroke engines. from my first to my first dirtbike. a 1983 ds80 to my first two stroke trike a 1983 tri-moto 175 all the way to my 2008 arctic cat m1000. the problem is ive never had a two stroke that has had a ton of machine work done to it {before i bought it} the whole bike was beat to hel.i had alaska drag bike tear down the engine to see if the work was done professionally and replace all wear parts/bearings. he said whoever did the machine work did a very nice job he also said he had never seen an engine carbon fouled as mine ever. now here is where i am at a loss. the head has been milled, intake and exhaust enlarged, runs a 490it rod, boyeson reed kit and a k&n air filter. ADB did not touch the carb or timing settings. the carb is stock.all that said no 2 stroke ive ever straddled has ever behaved like this one. idles great runs through the gears great. the only issue/question i have is why when the throttle is set at a constant, would the bike on a whim create more power and rpm without increasing the throttle.

Hello

I think that if you had posted this along with your original question you might have gotten more serious and helpful comments. In my opinion you set yourself up perfectly for a bit of hazing in your original post. Based upon the type and minimal amount of information it contained I don't how anyone really could of replied much differently, do you?

[christph]

I got my Z with a stock engine and have since modded it significantly, Sprock head, pipe, carb. etc., and at no point would I have called it a "light switch" powerband. In fact, I've got two old magazines with reviews of the 86 Z (DirtWheels and 3-Wheeling) and they describe the power as smooth and linear. Sure, all two strokes have that moment when they are "on the pipe," so to speak, but it sounds like something more than that, perhaps your mods, a jetting issue, etc. I know my 84 Tecate has a light switch powerband. Such engines are a lot of fun so long as you can keep the revs up and don't lug them.

[barnett468]

I know my 84 Tecate has a light switch powerband. Such engines are a lot of fun so long as you can keep the revs up and don't lug them.


Yeah, now you're talkin!

[TimSr]

Really sounds to me like the classic text book case of TriZ way too rich, but no one can say without actually hearing it. Have you done any spark plug test readings? What does the plug look like in general? What size main jet is in it? What gas/oil mix are you running?

Conventional internet wisdom says that every time you change a fender or the color of your grips you need to jet richer and most of them out there running stock carbs are way too rich because of it. Then when it won't run right because its jetted way too rich, the practical solution is to give up, and run a Keihin carb.


If your plug is black and oily, and your main jet is 470 or larger, and your gas/oil mix is 32:1 or leaner, start dropping main jet sizes. Don't fool with the needle until your main is dialed in. Your air screw is adjusted for best throttle response off of idle while sitting still adjusted in 1/4 turn increments/decrements - should end up somewhere between 1 and two turns out, and does not affect how it runs once the throttle slide moves of of closed position.

The 85 especially does indeed have a light switch powerband, but that does not mean it needs to bog off the bottom, it means from idle to scream with no pause in between.

[johnnytri-z]

thank you barnett you are the man! fuel pump was leaking bythe problem. i ran the vaccumm line test.FAIL!!! i appreciate you sharing your tricks of the trade. everything seemed good with the carb. but i couldnt see inside the fuel pump....thanks johnnmy

[barnett468]

thank you barnett you are the man! fuel pump was leaking bythe problem. i ran the vaccumm line test.FAIL!!! i appreciate you sharing your tricks of the trade. everything seemed good with the carb. but i couldnt see inside the fuel pump....thanks johnnmy


Hello


Great, glad to hear it, now where's my set of free steak knives? I had no suggestions until I saw your latest post. Information is king. When you said it was eraatic at STEADY throttle I figuI have no idea but until someone else comes along that knows, this is how it works. If a tri z has a jetting problem the fuel pump has ALWAYS been bad it seems, lol.

[barnett468]

thank you barnett you are the man! fuel pump was leaking bythe problem. i ran the vaccumm line test.FAIL!!! i appreciate you sharing your tricks of the trade. everything seemed good with the carb. but i couldnt see inside the fuel pump....thanks johnnmy


Hello


forgot to mention if you need a pump rebuild kit they are available for around $24.00. Try cmsnl.com, partzilla, bike bandit. rocky mountain atv parts etc.

[Rigaman]

I am very interested in hearing how it runs after the fuel pump problem is fixed. Keep us posted.

[tri-Z ripper]

first guess is the reeds are worn and opening at the wrong time! try replacing reed petals, sorry disregard my post just read all the way through.

[johnnytri-z]

well i bought a rebuild kit from A.S.S [alaska snowmobile salvage] i gotta tell ya THIS THING IS SCARY FAST NOW. And to answer Tim sr. the main jet that was in it when i bought it was a 560 get this i called the guy i bought it from when i started the tear down and said "why the hell is there a 560 main jet in the carb. his response "Because there was an air leak" ha. it has a 510 in it now. ive chop tested the plug several times it always looks good running 40:1 AMZoil 50-50 87/100ll gas. that was the problem it ran great and everything appeard fine. but i would just get random power bursts kinda like when a 2 stroke is running out of gas you'll get a few surges. my next guess was going to be retard the timing a little, but it didnt make sense.

[barnett468]

Hello johnnytri-z

Great glad to hear it "steak knives"?

[RIDE-RED 250r]

Love it... Addressing an air leak with richer jetting... :rolleyes:

Glad you got it sorted out though! :beer

And I'm sorry for being the first to give you a smart-alec reply... I really thought you were new to these machine by the way your OP was worded..

Anyway, BRAAPP ON!! :D