06 yfz 450 problem

[supersour420]

I rode this yfz 3 time just bought it a few days ago. first two times had similar problems to some of the other posts, such as backfire, and stalling at the bottom of first and second when giving full throtle. the bike is stock except the spark arrestor has been pulled out. Yesterday the bike was running the best by far no bogging or stalling. Then I am wide open 5th gear on the rail road tracks in new york (70 degrees last night) when I start to loose power , down shift to fourth but it starts to cut out, I stop and then the bike stalled as if i ran out of gas. I still cant start the bike, dont know what happened. Today: put new plug in and tried to jump the battery. While trying to start the bike the starter will barley move for the most part. Then twice it started right up but then backfired louder than i have ever heard(louder than normal) and died. After it backfired the first time it started right up ran for 10 seconds and died. now nothing dont know where to begin. Any help would be greatly appreciated.

[yfzrider310]

I think your motor took a big poop. I would start tearing it down sounds like you need a new top end....maybe more. Also the wrist pin could have went out because thats pretty popular with 04-06 yfz because of oiling problems. Also check your gas line and make sure your petcock is not in the off position. I've done that a lot before. It sounds like its blown up or having fueling problems.

[Ride1Rob]

Before you tear anything down, buy a compression tester and test your compression.

[supersour420]

thank you you for the reply guys. I am not to mechanical but i will have a comression test done first. more than likely i will have to drop the bike off to someone or a dealer. I will let you know what happened as i can find out more. If anyone reading is near O.C. New York and would like to work on this bike that would be great too. if i have to drop off at the dealer then I wont see the bike for a month or more.

[yfzrider310]

I would not take it to the dealer for a couple reasons.

1. major rip off
2. most of the time don't know what there doing

I would go to a shop and not your dealer unless the quad is under a warranty.

[Ride1Rob]

Taking it to dealership to get a compression test done is no biggie. That's something simple. Not all dealerships are bad. There are also some shops that are terrible as well.

[Ride1Rob]

Taking it to a dealership to get a compression test done is no biggie. That's something simple. Not all dealerships are bad. There are also some private shops that are terrible as well. Check Thor300xRiders nightmare thread.

[yzhybrid450]

check your valves and your jetting

[xtullyx16]

ik this sounds dumb but check ur spark plug to see if its gapped haha

[raptoric]

hey supersour budz check your pms

[supersour420]

I was told that the piston was seized in two spots and the crank had tight spots. Not being very mechanical and the bike being so new to me i had no choice but to repair it. How is this possible in a two year old machine that was babied supposedly? I had a 2001 raptor 660 that i abused for three years and never had any engine problems what so ever, is that engine better than the five valve

(NEW)
-cylinder
-crank shaft assembly (I got shafted)
-gasket kit
-piston rig set
-piston
-circlip inner x 2
-pin
-bearing
-chain

I have put about 10 hours on the machine at about half throttle she feels and sounds great. No bogging or stalling so far. ready to change the oil and ride it harder. I bought synthetic and a filter a little worried about beating on this machine now($$$$$). Any suggestions would be great.

[squadie]

I had something similar happen to my 05. The crank bearings seized, and it was an expensive repair. I had changed the oil regularly. The recommendation I got from a nationally known motor builder was to change the oil very often, and use good oil. Mobil 1 and Schaefer's were suggested. Oil changes every few hours. Because these are high revving engines, they will require a lot more maintenance. Regular rebuilds are necessary -- depending on how hard it's ridden. If you want low maintenance go back to a Raptor or something besides a 450 machine. But after you've ridden a 450, how could you go back?!

I'm using the Schaefer's and it comes back out looking just like it did when it went in. Good luck.

[WOLFPACK]

Likely what happened is the bike wasn't rejetted after the baffle was removed and it ran lean. If you need help re-jetting it let me know. I'd be glad to help!

If anyone owns a pre-07 YFZ it is money well spent doing the oil mod. We machine the stock cases so you don't have to purchase a entire new one. Cheap insurance.

Shane

[echophreak]

What is the oil mod?

[WOLFPACK]

In 2007 Yamaha added a mod to better lubricate the crank/piston. To do the mod you either purchased a new side cover or you could have it machined. The have it machined is around $100. and they you add a nozzle and hi-flow oil pump.