ok... i was riding.. started loosing power... check compression 90lbs. after talking to the dealer they assured me it was probably just the rings even though the old ones looked fine. put it back together... 90lbs compression.

head/valves are fine, rings are fine... i put it together correct, timimg is good...
did a leakdown test an hour ago, held all the pressure we gave it... looked great... did another compression test at the dealer and they got between 65 - 80 on 2 different testers.

what is wrong? decompression seems to be working good...
dealer is lost... they gonna call yamaha tomorrow but we all know how smart they are...

help me!!!
and i am serious on the 20$ thing...

 

What do you mean loosing power? Is it bogging down?? Will it rev in nuetral? It maybe in the carbs. Did you check the air filter all the way to the head?

 

it ran smooth... just didnt have the power it didnt b4 (and yes i know this for a fact, its not just me)
how would carbs effect compression? either way all that stuff is fine.

 

Just to take a guess and my friend has a 450. I have read that the stator (i think) in these things are pretty crappy or the battery I am not for sure, but if it is the stator or something to do with your spark you will get a bog down. This was the problem with my friends LT250R, his coil was only firing when it felt like it, and would bog down like it was loosing power.

Also I noticed you have a HMF, do you have the quiet core/spark arrestor in, if not try and put that in to help you out on back pressure.

These are just guesses from what I have read, or experienced.

 

it doesnt bog down... runs and revs smooth... just no power... the low compression explains that i think...
back pressure isnt an issue... that doesnt matter with a compression test.
thanks for the suggestions tho.

 

I would be willing to say 1 of 3 things.....

#1 a bent valve

#2 crack in the cyl wall

#3 crack in the dome

 

So, what is the compression supposed to be?

 

stock blaster compression is like 135 and with the 240 mine is like 160. now put that up against a 450. just to give you an idea cuz idk the stock yfz pressure

 

Check the valve train for a broken valve spring,valve adjustment.burned seats. Cut your oil filter apart and check for metal flakes .

 

He has done all of that guys......this man has tried everything obvious, you have to search deep in your heads to help him......Its not something obvious, something that hasn't happened before on a yfz.......

I think the compression should be around 130ish.....




Hozed, if worst came to worst you could just fire up the preddy(or put that motor in it)[img]i/expressions/face-icon-small-happy.gif[/img] j/k hozed.....I hope you figure it out......this sucks....