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Author Topic: oil weight  (Read 1365 times)

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Offline cbr954

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oil weight
« on: January 09, 2015, 10:18:58 am »
Not another oil topic ::)   Not wanting to debate oil brands etc, I am wondering what you guys that race are using for weight of oil.  I am in the process of building two motors strictly for drag racing and I am wondering what weight of oil to run.  I have run 10-40 and 20-50 before in street motors with no issues in either case so looking for some input.
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03 CBR954RR, 72 750 chopper(970cc
F2 head), 2017 CRF450R, 2001 CR250R, 72 CB500, 79 XR250, 04 CRF50,70's soon to be rebuilt cb750 drag bike.

Offline 01Thomas

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Re: oil weight
« Reply #1 on: January 09, 2015, 01:57:08 pm »
These old-technology engines prefer thicker viscosity oils so I would stick with the 20W-50.
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1971 Honda CB750 Four K1 [Engine: CB750E-1113521 / Frame: CB750-1113838]
1977 Seeley Honda CB750F (F1) [Engine: CB750E-2551214 / Frame No: SH7-655F]

'96 Yamaha YZF750SP & '81 Moto Guzzi SP1000 & '80 Moto Guzzi 850 LeMans II & '82 Bimota KB-3 [Frame No 49] & '66 Ducati 50 SL/1 & '53 Miele K-50 & '38 Miele 98

Offline bear

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Re: oil weight
« Reply #2 on: January 09, 2015, 03:39:52 pm »
We run 50W in our competition motors.
Heat is a major issue.

Cheers,
Brian
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Offline jweeks

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Re: oil weight
« Reply #3 on: January 09, 2015, 07:15:40 pm »
     I tested a lot of oils on my Hondamatic drag bike. For bracket racing, I found the Yamalube 20W-40 worked the most consistently. It was discontinued/replaced by 20W-50. As a mineral based oil, too much heat in it will thin out the viscosity. That's why I run an external oil cooler and monitor oil temperatures. I don't have a clue what works with a clutch.
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Offline cbr954

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Re: oil weight
« Reply #4 on: January 11, 2015, 03:51:12 pm »
Thank you guys,  I will more than likely go the 20-50 route.  I've got a couple of cold months to think about it.
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03 CBR954RR, 72 750 chopper(970cc
F2 head), 2017 CRF450R, 2001 CR250R, 72 CB500, 79 XR250, 04 CRF50,70's soon to be rebuilt cb750 drag bike.

Offline POPS 911

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Re: oil weight
« Reply #5 on: January 17, 2015, 06:13:43 am »
A PRO-STOCK Suzuki motor runs -0 weight oil from V&H as you start the motor in the box = do a burnout = run 1320' at 190+ mph turn off motor and push back to trailer.
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Offline cb650

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Re: oil weight
« Reply #6 on: January 17, 2015, 09:20:15 am »
And it is required to tear down or replace every weekend.   
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Offline POPS 911

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Re: oil weight
« Reply #7 on: January 21, 2015, 09:19:43 am »
CB650 : You are right we had to tear that motor down every weekend = We won many races and PRO-STAR made the winner tear down. First time I put that -0 weight oil [ yellow in color ] in that small fill hole on that GS1150 Suzuki motor from V&H I shook my head and said to the owner " you sure this is right ? " must have been we won the PRO-STOCK Championship at PRO-STAR.
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