Rebuilding YFZ 450 engine

[gundi]

The quad has low hours but over heated. 2005 YFZ 450 has intake exhaust cams by hot cams, Factory four complete exhaust, rev box , power now fuel inlet and an air intake system. The motor currently sits in a box.

What would it cost me to take it to a shop to get the motor rebuilt and does a rebuilt motor necessarily mean less reliable?

[co pilot mclovin]

that question is very open. what do you mean rebuilt losses reliability. are you trying to pump more out of the motor? replacing the piston with a stock piston? not enough info

[amr126]

If the motor is rebuilt correctly(I did the same motor just last month), then there should be a increase in reliability for the given part in general. This is because someone who actually knows how to build a motor (vs. just putting one together) will carefully check all clearances and measurements-something factory doesn't have time for. The factory has close enough tolerances to get away with this, but mistakes happen and the elusive 'lemon' comes into existance. A higher compression piston will require race gas and will wear the motor quicker.

[CRAWLR]

Check out CT Racing. They really know how to make reliable power. My YFZ puts out over 50 HP on the dyno with stock compression and it will literally run all day long. Not a single motor problem all year in the Best in the Desert series, and Yamahas don't have the best reputation for endurance. Thats over a thousand desert racing miles with nothing but an oil change between each race. I'm very impressed!

Very informative web site with tuning tips and price lists and they are great to deal with, and they are in so-cal.

http://www.ctracing.com/

[cosmo]

Call Alan McDonald, Al Tech. He's just past lawrence Welks off the 15. Does my motors. 760 751 0971.

[gundi]

that question is very open. what do you mean rebuilt losses reliability. are you trying to pump more out of the motor? replacing the piston with a stock piston? not enough info

When I say reliability... I'm under the impression that more mods you do on a motor, the less reliable and more touchy. As far as rebuilding a motor to stock, is there any risk even though your not boring it out or doing anything crazy?

[co pilot mclovin]

no you are making it more reliable. pison and rings wear the fastest ona motor. you replace the piston with a same compression piston you will just be making it the way it was when it was new. not sure what the best piston for a yfz. you can run a better air filter and exhaust and it will make it run better with no harm. you start getting into reliability issues when you change out cams, port and polish, deck the head. stuff of that nature. you should be fine. ask around what the best piston is. i know for a honda it is a stock honda piston. for a yfz maybe its a cp or ct has them too. call around.

[Nick Sexton]

I have Allen Fox in Alpine build my motors. allen does a great job of rebuilding motors for maximum performance and reliability, he is very detailed in his work, he has never let me down. he is also known for building some of the motors that are in race winning quads and bikes that race district 38. he is located in alpine give him a call 1.619.445.1415

[co pilot mclovin]

yeah nick you are right. for a lot of years allan did every motor that won in baja with the two strokes. he has my honda motor right now.