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Yz 465

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I just picked up a 1980 yz 465. Going to be my vintage racer for next year. I'm also restoring an 83 it490.

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Enjoy the 465. I've had one since the last century. Still a 3 kick starter and until the brakes fade hangs with 4 strokes. In fact it pulls hills better than my CRF450R. Take your time and jet it right. Makes it easier to ride.

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Yea Thanks. I'm excited. It brought a smile to my old man's face he was an old open class racer from back in the day.

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Nice bikes. The 80 YZ465 had more power than the 81 did.Yamaha detuned the 81 to try to make it more ridable. lol.

 

FYI. If you kick start levers ever rotates to far forward (into the case) your kick start shaft is cracked. I just replaced my IT465 kickstart shaft with one out of a 87 YZ490. When doing this you need the kickstart lever as well as the splines are a different size. They changed the shafts after the 85 model year so it can happen to your It490 as well.

 

Here are a few good write ups with mods for the YZ465.

 

http://www.yz465.info/motor/

 

http://www.advrider.com/forums/showthread.php?t=772033

Original 465 shaft use a pressed on piece. Newer ones are billet one piece.jpg

Edited by Zrt1200

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Thank you! I went through everything on the it, gear box was perfect in it and amazingly it is on the stock bore still after all these years. I'm going to do the same on the yz is in pretty good shape for what it is I should have a good platform to build a bike on.

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Thank you! I went through everything on the it, gear box was perfect in it and amazingly it is on the stock bore still after all these years. I'm going to do the same on the yz is in pretty good shape for what it is I should have a good platform to build a bike on.

Post some pics when you can :thumbsup:

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Make sure you check all the suspension bearings as well as wheel bearings and steering head bearings. My one IT200 drove me nuts till I figured out it was missing 4 rollers in the bottom triple clamp bearings. Check it at home and all was tight. Take it to the woods and it would be loose. Check it again at home and all was tight. I thought I was loosing it for a while then I tore it a part and found 4 rollers missing from the bearing as the cage had broke.

 

I agree with (ITS CHOOKEN) We need lots of Pics.

 

 

FYI Also. There is a head mod to stop the Spark knock on these big bore Yamaha's. Its called the Eric Gore mod. I have posted in the forums some where before so I will have to see if I can find the link for you. What it is.... Is a 30 degree angle cut at the end of the squish band going into the combustion chamber. If I recall correctly its like 8mm long but dont quote me on that. Let me see if i can find the link.

 

Remember when your YZ465 was built we could still buy 100 octane lead fuel at the pump. It was called Sunoco 360. If you need any info on your IT490 the best place is the Yamaha IT Forum.

 

http://www.yamahait.com.au/forum/index.php

 

On the IT490. If you need plastic's I have herd a lot of Bad with DC plastics but I also heard they changed there mold to make them fit correctly???

 

On the IT forum after you have enough post you will see where you can buy hand laid fiberglass parts.

 

 

UPDATE, this is not the post I made but its the same head mod. A lot of guys do it on the YZ465 as well. I think it was post number 6 in the link. If you need it done let me know as I am a machinist by trade.

 

http://www.thumpertalk.com/topic/1055324-best-yz-490-mods/?hl=%2Byz490+%2Bhead+%2Bmod#entry11169375

Edited by Zrt1200

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Oh yea the it has new bearings in every place you can stick a bearing. And yea I already had my experience with dc plastics. I bought the front plate for it because mine has a crack.... Not even close, won't give them another dime. I will get out in the garage after work in the morning and take a bunch of pictures. Thank you for all the info.

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I was going to mention that 490 head mod too.  It makes it easier to live with.  It will run cooler, ping less- or none, It will be easier to jet and easier to start.

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Very NICE. :thumbsup:  I am curious to what front end is on the IT490 as stock that came with drum brakes up front. May be a 86 IT200 front end with disk brake??

 

Also here is some good info about needing reed spacers and why. Its the 4th post down.

 

http://www.yamahait.com.au/forum/index.php/topic,18214.0.html

 

And if you want to make life easier starting the bike take a look at this. I am going to do this to my IT465. At 54yrs old I dont have the strength I once did. lol

 

http://www.yamahait.com.au/forum/index.php/topic,16459.0.html

Edited by Zrt1200

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Good eye. The front end is off of a 98 xr400r. My dad gave me the idea of doing that. The forks and the wheel slid right in the stock triple clamps and everything lined up like it was meant to be.

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In my IT465  use the Two head gaskets, NGK BR8EIX Sparkplug.

 

It starts up on the third kick cold.

 

Pre mix Lucas two stoke oil at 20-1

 

I did the swing arm zerk fitting mod so that I don't have to pull the swing arm every 300 miles.

 

 

 

 

 

 

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In my IT465  use the Two head gaskets, NGK BR8EIX Sparkplug.

 

It starts up on the third kick cold.

 

Pre mix Lucas two stoke oil at 20-1

 

I did the swing arm zerk fitting mod so that I don't have to pull the swing arm every 300 miles.

 

I have to get the Zerks in the swing arm yet but that is a must IMO. The NGK Iridium is a very good plug. Right now I am just running a BR8ES. I run 32-1 Klotz in all my bikes and snowmobiles. I am not a big fan of doubling up on head gaskets but I understand why you did it. The head mod takes the Ping away and makes it run better on the crappy fuel we have now days.

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I am doing the 510cc mod to it.

 

I got a YZ490 barrel bored to 2mm over and a Wiesco piston of Ebay.

 

Sending over to Eric Gorr for a The head mod and porting.

 

Double head gasket works fine no leaks,

 

I have been running all my two stroke bikes and cars for the last 43 years on 20-1.

 

http://www.bridgestonemotorcycle.com/documents/oilpremix6.pdf

 

 

 

 

 

 

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The head mod is not needed on the 465. I've run pump premium but it's happiest running VP U4.4 @ 32:1 BelRay H1R. Check the squish and correct to 1 MM for best results.

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The head mod is not needed on the 465. I've run pump premium but it's happiest running VP U4.4 @ 32:1 BelRay H1R. Check the squish and correct to 1 MM for best results.

True -  maybe the only reason you'd have the head mod done is if the ONLY fuel available for you is poor but you have no choice.

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The main contributing factor to the 490's pinging problem is the chamber design made the MSV too high. Cutting the head per Gore slows the MSV and in turn slows the burn. It was the burn rate not cylinder pressure that caused the detonation issue on the 490's. I can set my 465 up to run regular pump gas and lose no measurable output. Response will be a bit soft but it'll still rip right along.

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