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Old 06-29-2012, 02:25 PM   #16
FJ_Kevin
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Quote:
Originally Posted by mudmantra View Post
A few idea's I've been thinking about. #1 is the crankshaft heavier in the IT465 motor? The crankshaft in the IT490 looks a lot heavier, but I can't tell with the IT465. #2 has anyone here installed a crankshaft from an IT465/490, and did it work? If I could just slow the power band hit a little, I think it would help a lot. Right now when it hits, it's instant wheel spinning, fun, but not very useful. Any other idea's on how to smooth out the power band would be good too.

Hi,

To me it sounds like your bike could use some rejetting. I think they generally came jetted too rich on the bottom. So the hit you get is rather sudden as you move into an rpm range where your jetting is better.

I recently completed my 465 and purposely jetted rich to start off with. It ran poor and no grunt off the bottom. Fortunately, there are some well established recipes that often work well so long as the rest of your bike is in good shape (so make sure no air leaks!).


Here is a setup that worked extremely well on my YZ465 and my IT490. These are for the stock 38mm carb.

MJ=380 (a 370 made my IT490 ping when hot)
PJ=40 (IT490), 45 (YZ465)
Slide cut away is modified from 3.0 to 3.5 setting
Needle Jet RO (247 series) for IT490 and Q8 for YZ465 (I think the RO would work fine in the 465 also)
Needle 6DH4 (both IT and YZ)
A 6DH3 is similar to 6DH4 and would also be OK I think. I tried a 6F8 needle and it did not run as clean.

Both my bikes have DG pipes but are otherwise stock.

The slide modification and replacing the needle made a big different in low end through mid-range. I cannot say this enough!

In both cases, I modified my existing slide by hand using a file. I first marked out the arc I wanted to follow using a felt tip pen. The dimensions are from this drawing...


You know you have filed enough of the arc away when you can pass a 7/32" drill through the cut away when the slide is held against a flat surface (bottom down).

Others have fly cut their slides in a milling machine.



The slide modification photos came from the yahoo yz490 group (a good bunch).

A gearing change may also hep. My IT490 came with a 44 tooth sprocket. I dropped this to a 50 tooth for tighter trails. You may have a 48 tooth sprocket on your 465 as I think that is the stock gearing.

With the carb modifications you should have no trouble woods riding your 465.

BTW, these guys have great prices on Mikuni jets!

http://www.psep.biz/store/mikuni_carburetor_part.htm

Good Luck,
Kevin
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Old 06-29-2012, 09:54 PM   #17
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Awesome! Thanks for the details Kevin. I have some parts on order and well start working on it as soon as they come in. I just got the new chain and new sprockets. Stock this bike was 14/46. I'm going to try 14/48 and see how that works out. If I get the jetting sorted out, I think it well be good. Lots of things to do to get this bike the way I want it, but so far it's been a blast.
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Old 06-30-2012, 05:50 AM   #18
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As far as gearing. Well the IT465 or IT490 gears work in the YZ's. From what I understand the IT gear set has a lower first and a higher 5th. I don't really need the higher 5th, but a lower 1st might be good thing. I also have a 1982 YZ490 motor in pretty bad shape. I wonder if an IT465/490 5 speed would work in it?
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Old 06-30-2012, 06:16 AM   #19
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Are the 247 series needle jets used on both the IT490 and the YZ465 stock carburetors? My list has the 247-Q-8 and 247-R-0, next to each other, so I'm guessing they are pretty close to the same size. Maybe the 247-Q-8 is slightly smaller/leaner? Maybe I'll get a jetting chart, so I can understand a little more of what I'm doing.
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Old 06-30-2012, 06:41 AM   #20
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Cool thread. I have an '84 CR500 that I'll be setting up for the woods when I get a couple other projects out of the way.
Do you have any pics of your bike you could post up? I always thought the YZ/IT 465 and 490s were good looking bikes.
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Old 06-30-2012, 05:30 PM   #21
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Originally Posted by mudmantra View Post
Also, I forgot to ask. Are you using the stock YZ465 carburetor? I'm thinking it might be a good idea for me to replace the needle jet and needle on my 1980 YZ465 carburetor.

Yes,stock VM Mikuni.
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Old 06-30-2012, 09:58 PM   #22
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Cool thread. I have an '84 CR500 that I'll be setting up for the woods when I get a couple other projects out of the way.
Do you have any pics of your bike you could post up? I always thought the YZ/IT 465 and 490s were good looking bikes.
Setting up a CR500 for the woods sounds cool. I never really thought too much about taking a big 2 stroke through the woods, but now I'm hooked. I have a TT500 4 stroke for woods riding and it's a blast too. But I've got the TT500 apart for some major work. So the YZ465 is now my woods bike, and it's been a lot more fun than I expected. I'll take some pictures of the YZ465 and post them here.
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Old 07-01-2012, 05:49 AM   #23
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A tip. Check the timing and run it at the advanced edge of the range. Then jet to suit.


A tired old image of my 465.



They handle well with the tubes up in the trees too.

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Old 07-01-2012, 11:02 AM   #24
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Nice YZ465. It's in better shape than my YZ right now. Mine has no decal on the tank too. I checked into a decal and the decal company said they might bubble or fall off plastic gas tanks. They said to empty the tank after every ride. I don't think I would do that. So I'm with out a decal right now. Good idea with the forks. I'll try that with mine too. A little quicker steering might be a good thing in the woods. Plus I like the idea of a lower seat height.
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Old 07-11-2012, 09:46 PM   #25
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I got a few rides in. Hard to start but lots of power. Then I got some parts together to fix a few things. I pulled the exhaust off, so I could paint it. I then inspected the piston through the exhaust port. It looked real bad. I pulled the cylinder off and it's going to need a new piston and cylinder needs to be bored over sized again. Already 1mm over stock. Who makes good pistons for these motors? A picture on a short ride. On the bright side, it well have even more power when I get it right.
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Old 07-12-2012, 05:42 AM   #26
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Wiseco is your only hope other than a resleeve.
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Old 07-12-2012, 12:54 PM   #27
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Your bike looks way better than my CR500, that's for sure.

You have a PM.
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Old 07-12-2012, 09:16 PM   #28
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Your bike looks way better than my CR500, that's for sure.

You have a PM.
I like the way the YZ465's look. I'm going to get some decals and freshen the looks up a little. The Honda CR500's are cool. I just talked to someone who had a CR500 with motor that's beyond repair. I don't know what he's going to do with it. I could check into it. Right now, I'm doing the math on the parts and work I need to do to get the YZ running good. I'm lucky that I just my dirt only XT500 running. At least I can get out in the woods, while I fix the YZ.
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Old 07-12-2012, 09:20 PM   #29
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Wiseco is your only hope other than a resleeve.
Yes I think I'm going to go with wiseco. Wossner also makes a yz465 piston. I don't know as much about them, though.
http://www.wossnerpistons.com/produc...iston-8265d150
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Old 07-13-2012, 05:49 AM   #30
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I've had issues with Wossner pistons in a twin. The weight between the pair was 15 grams different. Just one instance but it did cure me of ever considering them again. Never seen that with Wiseco,ProX and OEM (ART).
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