2005 Yz450f misc questions....

Hello to all, just a few misc questions about a 2005 yz450f I just recently bought. Some back ground on myself--This is my first 4 stroke dirt bike I have bought. Previous experience was on all 2 strokes. Have not owned a bike in about 7 years. Took it out on a local trail system yesterday and experienced a few things that I did not care for and was wondering if there is a direction someone could point me to. First problem is we were running slow and tight trails for a good portion of the day and noticed it running warmer than I would like. Question is do I need to put fans on it or can I run some of the cooling additive/antifreeze instead. I do not believe I will be on that trail system again mainly just playing around from time to time. I am not a "hardcore rider" just want something run some river bottoms and pastures with. The engine was super strong and the power seems to be additive that is for sure. 2nd question is that this has the 4 speed tranny and 1st gears acts like 2nd gear on all of my previous bikes. Can some one recommend a gearing change to bring it down to what I am used to? I killed the bike about 10 times yesterday just trying to take off--looked like an idiot to my son! It does need a chain and sprockets so now would be the time to change ratio.Any information would be appreciated.

Edited by Arcticmat

I've got an '03 450. I changed my sprockets to 13 in the front and 50 for the rear. Big difference for me. In the woods, I couldn't keep it running. Sprocket change was the trick.

Put a 13 oz flywheel weight in it. Money very well spent! They run hot in slow conditions, just the nature of woods riding a MX bike. If it isn't puking antifreeze it's fine.

Regarding gearing, remember that this is a purpose built MX race bike, and has a close ratio 4 speed trans for that purpose.  Stock gearing was 14/51 (some turned up with 13/48 later in that year...stock on earlier models was 14/48, but those have a lower internal reduction ratio than the later bikes).  Check first to see if the previous owners raised the gearing to achieve more top speed. 


Additional flywheel weight is very beneficial to the engine, and is a low cost mod.

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