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| 73 billet crank question https://vintagedirtbikeforums.alp-sys.com/viewtopic.php?f=21&t=2094 |
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| Author: | woosh [ Tue Dec 02, 2008 11:12 am ] |
| Post subject: | 73 billet crank question |
Honda used the billet crank in some of the 73 cr250's it had the two holes one on each side of the rod and less cut away. What I wanted to know is did they use them for the mt250 in 73? I have two cranks one is the normal crank with a ton of cutaway but the other in pretty round with two holes one on each side of the rod. Is there any benefit to a billet crank? |
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| Author: | woosh [ Tue Dec 02, 2008 11:18 am ] |
| Post subject: | Re: 73 billet crank question |
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| Author: | dogger315 [ Tue Dec 02, 2008 12:00 pm ] |
| Post subject: | Re: 73 billet crank question |
In terms of strength and durability, billet is superior to cast. Replacing a cast iron crankshaft with a forged billet crank is ususally one of the first orders of business when building a high performance engine. Most if not all of Honda's works bikes have billet cranks. In the case of Honda, The '73 CR250M was the company's first high performance two stroke, having been involved only in road racing (four stroke) up to that point. I don't know if the billet cranks were used because of concerns over reliability or due to expediency to get the new bikes to market. It takes less time to forge a billet piece initially then it does to tool up to produce castings. Once the tooling is done, it takes less time and is far less expensive to produce cast parts in mass. dogger |
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| Author: | ktm450exc [ Fri Dec 12, 2008 6:44 pm ] |
| Post subject: | Re: 73 billet crank question |
I've got a extra crank (not billet) that has a copperish color to castings?? You guys got any info on it? |
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| Author: | g-ride2 [ Mon Dec 22, 2008 9:04 am ] |
| Post subject: | Re: 73 billet crank question |
From what I understand, Honda put the billet crank in the first thousand or so engines they built for the 73 cr250m. I have a few myself and they do have numbers scribed into them. They are hard to read. I'll try to post pics of them soon. |
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