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dwillouby

YZF450 wont start

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Hello, New to site. Working on a YZF450. refuses to start. Customer states motor was built with big bore kit, ported head, hotcams. Has hour meter showing 5 hours. Atv has many high end chassis parts and does look well built. Managed to start when first brought in but couldn't idle.  Had stripped threads in exhaust cam holder. Made repairs now wont fire at all Occasional pop. Checked cam timing , Good leak down, new plug, carb clean but haven't verified tune. Acts like no compression. Decompressor seems to work correctly Will not fire even by spraying starting fluid in carb. Have noted while cranking starter seems to slip. Don't know how fast it must spin to overcome decompressor? Contacted Hot Cams to get info but no response at all. Been working on bikes 30+ years but am stumped don't want to just throw parts at it.

Any ideas

Thanks

David

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