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Author Topic: yz465h. no torque like i remember!  (Read 11807 times)

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Offline Kane Mcguire

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yz465h. no torque like i remember!
« on: November 02, 2007, 07:48:03 pm »
i have a really good 465 with dg pipe and boysen reeds. it revs well up top and has good power up there,  but before that it has no pull. it has torque like a 250 i would guess but not at all like i remember 20 years ago. it will not pull torquey wheel stands through the gears,  only if its well up in the revs. it seems to run ok jetting wise and compression, reeds, etc seem ok. please help! thanks.
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Offline Freakshow

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Re: yz465h. no torque like i remember!
« Reply #1 on: November 02, 2007, 10:33:42 pm »
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74 Yamaha YZ's - 75 Yamaha YZ's
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BONEHEAD

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Re: yz465h. no torque like i remember!
« Reply #2 on: November 03, 2007, 09:41:52 am »
good advise freakshow you cant go wrong there, anyway your concern could be related to a number of things such as, jetting incorrect(possible blocked jets), not getting full throttle,exhaust blocked,gearing incorrect,compression and ignition timing,blocked air filter,rear brake lever jamming(on the clutch cover), air leaks at manifold, fuel mixture(eg 20:1), spark plug incorrect,hope this will help CHEERS BONEHEAD
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Offline YZ250H

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Re: yz465h. no torque like i remember!
« Reply #3 on: May 06, 2009, 07:44:34 pm »
Hi guys,

I am now the very proud owner of this beasty.  Obviously Kane has sorted the thing out as it went like stink when I first got it home 8).

Slight problem now though  :-\  It started to blubber and has got progressively worse over the last couple of rides - now it is really bad  :o.  Starts well and runs crisply on the pilot jet, but as soon as I give it some throttle it turns to crap.
I have bought a new iridium plug, tried fresh fuel, checked float level, cleaned carb, but all to no avail :(.
The only thing I haven't done is clean the air filter (I've bought a new one but haven't tried it yet) - would that do it ??  Doesn't look to be overly gummed up (but that's probably not an indication).  I haven't been riding it in dusty conditions.
I did not take note of the jet sizes while I had the carby apart, but based on the fact that it went VERY nicely when I first got it I thought maybe jetting was not it.  Will do so on the week-end.

Ideas ???
Otherwise I will ride it around blubbering (the bike and probably me too  ;D) at CD6 until someone feels sorry for me and helps  ;) :D
 
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Looking for YZ250C parts NOS if possible

"My inability to use emoticins in the right context is really getting me down :)
Quote from: GMC on May 03, 2014, 10:35:22 am
The only triple jumps he would have been doing are the hop, skip & jump.

DR

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Re: yz465h. no torque like i remember!
« Reply #4 on: May 06, 2009, 07:52:51 pm »
check all your wiring conections, cdi, HT coil mounts and the grounding wires if any YZ, the description could describe an earth going bad through corrossion at a mounting point or a loose terminal. Could be something entirely different but it doesn't cost anything to double check ;)
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DR

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Re: yz465h. no torque like i remember!
« Reply #5 on: May 06, 2009, 07:53:40 pm »
what the heck am I doing in the yamaha camp!!! :o ahhhhhhhhhh! runaway!!
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Offline holeshot buddy

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Re: yz465h. no torque like i remember!
« Reply #6 on: May 06, 2009, 07:56:33 pm »
throw the iridium plug as far as you can
they are shite
put in a standard b8es  ngk
run it on 40 to 1 synthetic
with bp ultimate
oil and fit new air filter
set mixture screw to 1 and three quarters out
change plug cap (they are only cheap)
run it if it is still crap check plug colour
if its oily pull off carb
tell me what jets you have and check your needle jet and needle
are not worn
its one of those things a process of elimination
could be top coil stator timing broken wire etc etc
do what i said first and see how you go

cheers rusty ;D
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Offline YZ250H

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Re: yz465h. no torque like i remember!
« Reply #7 on: May 06, 2009, 08:00:48 pm »
You are a legend Rusty 8).  Once I get it going you can show me how to ride it ;)
I will try this on the week-end and report back.
Shall also check electrical connections Doc - now get back over to the Yellow Peril room  ;D ;D
Cheers
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Looking for YZ250C parts NOS if possible

"My inability to use emoticins in the right context is really getting me down :)
Quote from: GMC on May 03, 2014, 10:35:22 am
The only triple jumps he would have been doing are the hop, skip & jump.

Offline VMX Andrew

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Re: yz465h. no torque like i remember!
« Reply #8 on: May 06, 2009, 08:02:07 pm »
my YZ250h use to do the same thing
started ok allright down low but when you open her up it blubbers like shit...
replaced the inlet manifold....bang .... hey presto different bike... :)
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Offline YZ250H

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Re: yz465h. no torque like i remember!
« Reply #9 on: May 06, 2009, 08:10:17 pm »
Do you suspect was an air leak Andrew ??

There was a suspicious fuel mark on the side of the barrel where the model number / capacity is.
That is now gone - Is a pin hole there a possibility ?  Would be very odd wouldn't it (?) That would not make it progressively worse either.  I will have a closer look at the manifold (with my glasses on ::))
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Looking for YZ250C parts NOS if possible

"My inability to use emoticins in the right context is really getting me down :)
Quote from: GMC on May 03, 2014, 10:35:22 am
The only triple jumps he would have been doing are the hop, skip & jump.

Offline holeshot buddy

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Re: yz465h. no torque like i remember!
« Reply #10 on: May 06, 2009, 08:13:17 pm »
if it had a air leak it would do opposite
and lean and rev out ;D
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Offline VMX Andrew

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Re: yz465h. no torque like i remember!
« Reply #11 on: May 06, 2009, 08:16:59 pm »
i forgot something... i also replaced the reeds with new ones at the same time i
replaced the manifold...
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Offline YZ250H

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Re: yz465h. no torque like i remember!
« Reply #12 on: May 06, 2009, 08:20:34 pm »
DOH! forgot one critical thing.  When I turn the fuel off and run it out it goes well again very briefly when running out.
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Looking for YZ250C parts NOS if possible

"My inability to use emoticins in the right context is really getting me down :)
Quote from: GMC on May 03, 2014, 10:35:22 am
The only triple jumps he would have been doing are the hop, skip & jump.

Offline VMX Andrew

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Re: yz465h. no torque like i remember!
« Reply #13 on: May 06, 2009, 08:23:28 pm »
Quote from: holeshot buddy on May 06, 2009, 08:13:17 pm
if it had a air leak it would do opposite
and lean and rev out ;D
you are right there holeshot buddy..mine was reving out almost like missing a gear
but it sounded like it was running toooooo rich....
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DR

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Re: yz465h. no torque like i remember!
« Reply #14 on: May 06, 2009, 10:42:30 pm »
mmm..does sound like a fuel issue. Most bikes go really hard just as they run out of fuel as the mixture leans right out. If it revs well during this period then ignition is not the problem. I can only assume your airfilter is okay and yes, fit the new one if you have to eliminate this item :P ;D ok ok..back to the yellow men ::)
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