1984 It490?

[Yamatrike400]

How are these bikes? I have a chance to get one for cheap/or free. Guy has it stored in his garage for years and isnt in shape to ride it. Its been crashed once by him but rebuilt. Are they reliable? Hows the power? thanks. There may be a trike conversion in the future!

[deathman53]

I've heard that the 490's aren't so great. Vibrate alot, spottly jetting and hard to tune. My friend had a wr500(very similar to yz/it490) excpet for tranny and stator. I didn't like it, fast as hell, but vibrated alot and the jetting was a nightmare and can detonate easy. There is alot of reports about how to make it run right, you need to have the dome re-cut and then you can jet it, so that it doesn't run like crap or great, but top end won't last long. That guy rick has the 490's listed as one of the worst bikes ever made. Honda atc's are on there too, but his report on the 490's, is really close to my friends wr500. If you can get it for free, do so, don't pay any real money for it.

[Yamatrike400]

Well i can get it for 200. Needs a clutch lever and kicker return spring otherwise it runs.

[erectordale]

the 490 is what Raffa built his drag Z out of and it ripS he did detonate it in his basement was the last i heard

[Blown 331]

I had a TRI-Z with a YZ465 and it was pathetic. It ran good just not that much power for a 465 2-stroke. It had an extended swing arm, wheelie bar and solid bar in place of the rear shock. My cousins modded 426EX freakin smoked that thing.

[Yamatrike400]

You sure it was running good? I hear they are absolute beasts.

[Blown 331]

You sure it was running good? I hear they are absolute beasts.

It wasn't miss-firing or anything and it opened up just fine. I got it from Rockthunder (on here). I never talked to him about it so I have no idea what he thought about it but i think it freakin sucked! lol. Maybe he will chime in.

[Yamatrike400]

Ive read the things will do 90 and will power wheelie at 70+. Maybe the 490's have alot more power?

[PLJ.]

Beast's they are but not in a good way. I had an IT465 for awhile and have ridden many YZ490's over the years. Power yes, but very short, blubbery and abrupt without much on top. For a drag motor only I think that it could be modified and made usefull. An uncle of my wifes tried to tune/ride/race an 87 490 for over ten years he spent tons of time and money on the head mods, ignition timing, compression ratios, port timings and could never get it to really run right, when the 400F came out it 98 and he bought one his troubles were over!! Its to bad Yamaha couldnt make this motor run any better, because I love the IT chassis. One of my favorite bikes of all time is the 85/86 IT200. Good suspension, excellent turning, lights, guards, etc. a really great bike. Honestly, when I had the IT200 I wished for a 490 but that was well before I rode any!! Heck, for $200.00 give it a whirl, its a good expirence to own at least a few open class monsters in your lifetime, good stories for the kids and grandkids.

[Yamatrike400]

I picked one up..i may be getting another on Tuesday for 50 bucks!

What a BEOTCH to start! I mean i read these were hard starting but jeez....You have to just jump on that kicker to get that bigga$$ piston to move. After many, many kicks, i got it to run- temporarily.This thing vibrates like...INSANE. It also sounds like a F'ing firebreathing demon straight out of hell. I will admit, i am a bit scared to ride it...I just need to get it running good tommorow, because its late and the thing wakes the dead....

[Yamatrike400]

Carb was very gummed up,and the filter was deteriorated. so hopefully it will run good tomorrow when i get it all back together.

Heres a pic.

[hancadam]

The YZ490's are not that bad. I have had two and loved them both. I got rid of them because they scared the piss out of me. I sold one to JD here on the boards. They have more power then what would ever be necessary. Total beast, and not for sane people.

[Yamatrike400]

Well i got it going. The vibrations at idle are like my 250r at WOT, and well, when you hit the throttle, the front end INSTANTLY goes up...and i really cant emphasize online how much it vibrates..lets just say i couldn't control my hands. Its very fast also.Honestly I think im going to sell it, its just to f@cking violent, and i know the bike is just way too much for me to handle. I dont know why yamaha didnt put a counterbalancer in such a bigass engine...if it didnt vibrate so much it would be alot better to ride.

[tecat-z]

None of the open class 2 strokes in bikes had counterbalancers. The big yamaha engines were not very refined compared to the 86 up Honda and Kawasaki engines. Without water cooling, and consistent temps, finding a good all-around jetting set up was always a compromise. These engines ran so hot on certain days that detonation was iminant. Generally, running more fuel will cool an engine a bit, but it will be overall rich most of the time. And jetting on the lean side will make an already hostile engine even more so, and risk seisure due to extreme heat. Without a variable exhaust to smooth things out it was again a big compromise. They are simple in design, but difficult to keep running properly if that was even ever possible. If i has one, i'd lower compression with a rechambered head, run a 38mm carb, lighten fly a bit, and run a stock pipe, with a big quiet silencer. It would tame it considerably. Have good response and a big thick middle. I'd gladly sacfifice the top end h.p.

[Yamatrike400]

Yeah i could do that, and it does have a 38, but the bike just vibrates to the point where its ridiculous. I dont really know how to explain it, but After letting off the gas it will get into some tune of vibration that just kills my hands and fingers.These had lower compression than the yz's and a smaller carb, but it still is terrible.The bike also weighs as much as my 250r,and i just dont think its worth keeping. I have too many toys as it is.