Tri z 490 a Monster is born

[Triz250]

My 86 Tri-z has been with me for 30+ years now and its time to preserve her, but I still need a rider...so I am building a Tri-z490. This past weekend I picked up the completly rebuilt engine and the powder coated parts/frame. I went with a gloss black and Chrome Look with a mirror finish. Definetly not polished chrome but does have a mirror finish an I have to say I am extremly happy. Check out the pics. I will post more pics soon as she is being put together. Can't wait to ride her

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[3 Wheel Drive]

That looks like fun! Check out Raffas 490z:

http://www.3wheelerworld.com/showthread.php/117381-The-490Z-the-saga-continues-Round-3!

[Triz250]

Yes, his bike has been my inspiration...can't wait to ride it.

[El Camexican]

Love it! Have you made any mods to the engine?

[fabiodriven]

Love it! Have you made any mods to the engine?

Hopefully in the quench/squish/dome department or something along those lines?

[El Camexican]

Hopefully in the quench/squish/dome department or something along those lines?

That’s what I was wondering. A friend of a friend participates in some sort of vintage events and has a stable of 490’s. Claims that he has them all figured out and that if I were to ever pick one up he’d share the mods needed to tame the mechanical demons said to plague these beasts.

Unlikely I’ll ever own one, but I’m always curious to hear what people have done to their engines, especially ones with reputations like this one has.

[big specht]

What pipe are you going to use ?

[Triz250]

Love it! Have you made any mods to the engine?
kept her stock for now. Plan on doing some head mods next top end, they say it helps to reduce detonation. The pipe, carb and reeds are aftermarket. The motor mounts I had custom made and the sprocket needed a 26/100's offset so had that made too. I heard from Raffa he runs stock sprockets so I can save some money in the future. The sprocket I had made is a work of art. I will try and get that up next pic. The motor really is a drop in like Yamaha planned on making a 490z.

[bkm]

I've always wanted to ride a big bore Yamaha 2 wheeler in IT form. They're pretty rare around here.

[fabiodriven]

I've always wanted to ride a big bore Yamaha 2 wheeler in IT form. They're pretty rare around here.

I had an 81 IT175. It handled like a Buick station wagon with four flat tires. You're not missing much.

Detonation, an already unreliable machine with an added extra-unreliable engine... At least it might look good!

[bkm]

I had an 81 IT175. It handled like a Buick station wagon with four flat tires. You're not missing much.

Detonation, an already unreliable machine with an added extra-unreliable engine... At least it might look good!Being that it's a Yamaha, I wasn't expecting much!

[fabiodriven]

Yeah the destruction of Raffa`s 490 was impressive............right down to the bent rod ........he never brought that one back !.........i think the next one was a 350 Tri-Z

Remember, that 490 had all the dome issues supposedly fixed by an expert as well.

I don't mean to be a naysayer or seem negative, I think this is a great project for someone other than myself. I've always had a thing with Tri-Z's being unreliable and everyone knows the history of the 490 engines. I wouldn't rest my foot on the kick starter of one unless it had been seriously worked over inside, but that's just me.

[Tri-Z 250]

We should be twins, maybe you can copy my Avatar too. Lol, my experance with the vintage Bigbore or any extreme overbores is keep the compression down, run pump non-E 86-92*. The Aircooled motors I found to be finicky to jetting hot/cool days. No more than a needle height adjustment, always believed it do to head temps to climate to cool fins. It's gonna rip, good luck. Welcome to the Glammy's Mentally deficient inflicted Yamaha group. Funny he's pointing out the tard's in the World and a fan of "been there done that" Duncan International....to end Duncan's quote, "and left it behind."

[fabiodriven]

Just so you know I do appreciate what you're doing. I give all the Yamaha guys a hard time, right Nico? [emoji23]

[yaegerb]

I would definitely run some numbers on that head before I cranked it up.

Static Comp (keep it around 175), UCCR (keep it around 12:1) and I would blend the dome angle from 90 to 30 degrees. Use the 40MM carb to feed the beast.

Those motors are known for detonation/destruction. As glamy said....just look at raffa's 490.

[Triz250]

Just so you know I do appreciate what you're doing. I give all the Yamaha guys a hard time, right Nico? [emoji23] Its all good. I love the site and the feedback. Can't wait to get you guys some video of this thing moving.

[El Camexican]

Here's one suggestion from the Internet. If you can find a place that has a reputation for fixing the detonation issues I'd send you head in. All in, all done including shipping shouldn't be over $200 bucks which is a lot less than a rod and piston and whatever else. Your call, but I wouldn't start it without at least a head mod and some big fat jets. If the timing is adjustable you may want to start off at full retard.

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[3 Wheel Drive]

https://www.youtube.com/watch?v=7K9zsiJMK68


If you look close you can see Glamy at the dunes!

[Triz250]

Here's one suggestion from the Internet. If you can find a place that has a reputation for fixing the detonation issues I'd send you head in. All in, all done including shipping shouldn't be over $200 bucks which is a lot less than a rod and piston and whatever else. Your call, but I wouldn't start it without at least a head mod and some big fat jets. If the timing is adjustable you may want to start off at full retard.

250085
I am looking into it. I have a couple of shops near me.

[fabiodriven]

You might also want to fire a compression release through the head while it's apart. They're pretty cheap and I think it's as easy as making hole in the head and threading it in.

[Shep1970]

Not your motor but check out this comp release, could it be be this easy? https://twistingthewick.wordpress.com/2013/02/15/ez-release-compression-release-by-wimmer/
Found it earlier thought i’d share
Shep

[yaegerb]

Not your motor but check out this comp release, could it be be this easy? https://twistingthewick.wordpress.com/2013/02/15/ez-release-compression-release-by-wimmer/
Found it earlier thought i’d share
Shep

I watched the vid.....So let me get this straight. If I install that on my cylinder a hot chick in a bikini shows up on my workbench? I don’t care if it works, I’ll take 10!!!!

[HondaRidr]

Awesome man! Last year I built a 84 atc480r. The big bore 2 strokes are something else!

Sent from my SM-G930T using Tapatalk

[fabiodriven]

Not your motor but check out this comp release, could it be be this easy? https://twistingthewick.wordpress.com/2013/02/15/ez-release-compression-release-by-wimmer/
Found it earlier thought i’d share
Shep

That's amazing!! I need to know more about that Wimmer unit! There's not much information about these that I've been able to find at all, but if it's that simple I need one of those. I was planning on drilling another hole in my cylinder head.

[Shep1970]

That's amazing!! I need to know more about that Wimmer unit! There's not much information about these that I've been able to find at all, but if it's that simple I need one of those. I was planning on drilling another hole in my cylinder head.

Well after some searching it looks like they discontinued them. I guess maybe it didn’t work so good, i should of searched before i posted- the item was a good thought but i guess to good to be true.

Shep

[jb2wheels]

.i like yami better then kawasuckme

blasphemy ;)

[3Z with Fangs!]

I had a '80 YZ465 for a handful of years up until recently when I sold it. 2 words... Straight Nasty!