Date: Fri, 24 Sep 1999 14:57:15 -0400
Subject: Re: 97 GasGas 270 engine knock
From: Chris L Johnson 

Sorry for the late response.  If air cleaner is kept clean, and if you
never suck water/slime through the engine, you should never have to break
i nto the head.  Surprising but true!

To most likely eliminate the knock, pull the slide out of the carb and
raise the jet needle one groove (lower the clip position).  If beteer,
but not gone, try two grooves.  If bike blubbers under load off idle to
mid range, go back  one groove.

Chris Johnson
Scorpa 250 EZ Fun/Gas-Gas 160/Fantic 305/Yamaha Virago 1,100/XV920RH Euro
and now vintage `74 TY 250
chris "at" college-park.com as Director of Engineering at College Park
see www.college-park.com and papazit "at" juno.com (personal address)


On Fri, 17 Sep 1999 01:06:21 CDT "Weston _"  writes:
> I own a 97 GasGas 270 and have had no previous problems.  Recently I 
> was 
> riding casually, for about 30 minutes and began to hear a distinct 
> knock in 
> the engine under acceleration/deceleration.  The knock can only be 
> heard at 
> higher RPM's, nothing heard at idle.  I checked for vibration of 
> loose 
> equipment and found none.  The engine still starts easily and runs 
> clean.  
> Gas has always been mixed at 100:1 with synthetic oil.  General 
> maintainence 
> has been kept up routinely.  Checked spark plug, had some carbon 
> otherwise 
> was fine.  Air filter is clean.
> 
> I am fairly new to trials motorcycles and am unfamiliar with 
> frequency of 
> engine maintainence, such as piston/ring/rod/bearing replacement 
> (how 
> often?).  This bike has never been apart, all parts still original 
> and no 
> tuning adjustments have been tampered with.  I realize it's hard to 
> determine problems w/o hearing the bike, but any suggestions on 
> where to 
> begin would be greatly appreciated.  I have already learned a great 
> deal by 
> reading past letters, thanks and keep up the good work!
> 
> Wes
> 
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