Author Topic: YZ 490 pipe on IT 490 motor  (Read 670 times)

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Offline storie585

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YZ 490 pipe on IT 490 motor
« on: January 10, 2019, 01:12:22 PM »
Anyone ever run a YZ pipe on an IT 490? What can I expect compared to the IT pipe?
Dave

Offline 4V5

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Re: YZ 490 pipe on IT 490 motor
« Reply #1 on: January 10, 2019, 08:16:40 PM »
you'll need the muffler to go with the pipe too as the IT muffler won't fit.

IT465x4 IT400C IT175F YZ465G YZ250C YZ250WR XJ650G RD350LC RD250LCx5 DT175Nx3 TW200x2 DT200L DT200R RT3 RX100G GT80F YZ80L PW50J KH250B1 KZ250D1 PE175C TS250ER TS185ER AG175B AG100

Offline storie585

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Re: YZ 490 pipe on IT 490 motor
« Reply #2 on: January 10, 2019, 10:57:40 PM »
Actually... I just picked up an 83 YZ 490. Building it for enduro / dual sport / cross country intentions. I have a rebuilt IT 490 engine I?m mounting in the frame. I?ll rebuild the YZ motor and put it aside. I?ll use the stock YZ exhaust. Any luck I will be able to get it road legal..
Dave

Offline storie585

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Re: YZ 490 pipe on IT 490 motor
« Reply #3 on: January 10, 2019, 10:59:24 PM »
Any performance differences?
Dave

Offline 4V5

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Re: YZ 490 pipe on IT 490 motor
« Reply #4 on: January 11, 2019, 06:03:09 PM »
honestly I'm not a good enough rider to pick the difference lol.

 ;D
IT465x4 IT400C IT175F YZ465G YZ250C YZ250WR XJ650G RD350LC RD250LCx5 DT175Nx3 TW200x2 DT200L DT200R RT3 RX100G GT80F YZ80L PW50J KH250B1 KZ250D1 PE175C TS250ER TS185ER AG175B AG100

Offline storie585

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Re: YZ 490 pipe on IT 490 motor
« Reply #5 on: January 11, 2019, 11:19:48 PM »
Then I won?t notice a difference either..
Dave

Offline fatterhatter

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Re: YZ 490 pipe on IT 490 motor
« Reply #6 on: January 12, 2019, 02:03:14 AM »

On a 2 stroke the exhaust is the camshaft. So the yz series pipe moves the power more suitable to MX.
If you are using an it barrel it wont work as well as a yz barrel.
(4 strokes race camshaft will change the power characteristics, with 2 strokes its the expansion exhaust that changes the power characteristics)

Offline T.RexRacing

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Re: YZ 490 pipe on IT 490 motor
« Reply #7 on: January 12, 2019, 03:03:34 AM »
Actually the pipe should compliment port timing. Port timing is equivalent to the camshaft on a two stroke. The pipe will work in the RPM range designed for and can make a slight change to delivery but if the timing and pipe are a total mismatch output will be low.

In the case of the OP the bike will lose a bit of low end response and power but will have a good mid-top end. According to DG my YZ465 National Pipe had a range from 3500-8000. A little high but in practice a big bore Yamaha should deliver plenty of low end. Won't be optimal but it'll be fine.
Whatever you do will be insignificant, but it is very important that you do it.
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Offline storie585

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Re: YZ 490 pipe on IT 490 motor
« Reply #8 on: January 12, 2019, 11:55:33 AM »
I figured it would change the power delivery at different rpm . If it moves it up and revs out a little more then perfect. I just didn?t want to have to buy an IT pipe for this project. I can?t imagine the low end grunt will suffer that much. I suppose I could raise the port height in the IT cylinder to better match the pipe but that engine is probably not going to stay in that bike.. who knows.. I change my mind like I change my underwear...
Dave

Offline Devondan

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Re: YZ 490 pipe on IT 490 motor
« Reply #9 on: January 13, 2019, 03:43:44 AM »
I figured it would change the power delivery at different rpm . If it moves it up and revs out a little more then perfect. I just didn?t want to have to buy an IT pipe for this project. I can?t imagine the low end grunt will suffer that much. I suppose I could raise the port height in the IT cylinder to better match the pipe but that engine is probably not going to stay in that bike.. who knows.. I change my mind like I change my underwear...

What, once a year?!
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Offline T.RexRacing

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Re: YZ 490 pipe on IT 490 motor
« Reply #10 on: January 14, 2019, 02:44:19 AM »
gee what did I miss?
Whatever you do will be insignificant, but it is very important that you do it.
- Mahatma Gandhi