had this on montesa... a worn piston skirt makes a kind of dry clanging noise, more noticable to spectator than rider. got steadlily worse over 4 months of abuse
piston skirt to bore clearance should be around 2 thou new, about 4 thou at max wear.
check bore for deep scoring, replate if worn through nikasil coating
couldnt workout why my airbox kept filling with dust particles and water, even after 2 new air filters and a new filter cover.
found out that the platic had cracked on the seam where the lugs for the mudguard support brackets are, the split only became apparent when you aplied force to the bracket.
sealed it up with some super sticky silicone, problem solved.
also fitted some of those boyesen reeds, (thanks ff) what a difference, super strong midrange now and revs to infinity and beyond, no noticable change at low revs.
have had my 2003 315r for about a month now after having a 1996 gg jtr 270 for years.
suspension is silky smooth and manuovering the bike is effortless compared to the gg thanks to lightweight ally frame, superb brakes, and balanced handling.
have still got some work to do to get the engine to run as smooth as the gasgas, probably thicker base gasket or different needle. plenty of power but not as linear yet.
generally i found i never really need more than 1st and 2nd gear as the engine revs out so well.
am in the final stages of rebuilding the engine on my 1996 jtr 270. noticed alot of corrosion in the crank case, kind of brown mud looking substance but very gritty, may of been the cause of the engine wear.
has corroded max 2mm deep in places, mostly at the bottom, not in any structural places or bearing/sealing faces
am told this is the result of fuel oil corrsion?
i have always used fully synthetic 2t oil and decent fuel (not 6 month old lawnmower fuel) the longest the bike has stood still is 3-4 months.
are you supposed to flush out crank case or leave the drain plug out, when you leave the bike for long periods?
should the crank case be painted? if so with what?
so far i have bead blasted most of the corrosion out, and am waiting for my crank to have new rod fitted.
after i got used to the intial extra poke compared to my old gasgas, i was very pleased with the bike, engine is silky smooth and found grip everywhere. brakes are super sharp and bike seems very flickable/ agile
the tyre fell off the rear rim though (michellin tubeless), towards the end of the day, think i was running to soft or got puncture?
questions 1. what causes the tubless tyres fall off rim... i.e what pressure?
question 2. how the fk do you get it back onto the rim?
question 3. what is main advantage of tubeless? apart for pinch punctures
my gasgas runs an inner tube, thinking of sticking one in montesa for convinience.. do i need tyre clamps?
thanks for the input, i think i am 90% in favour of the montesa route. the bike must last me more than two years i am not worried about the extra 3 kilos
(doesnt seem to bother dougie).
i love hondas have had numerous cars, worked on numerous honda racing cars, so i suppose am a honda fan?
have got at least 4 to look at this weekend, quick before this cash burns a hole in my pocket.
thanks for all the input
am new to this forum and didnt realise how popular it is... keep up the good work admin's
would like some advice on wheather to by a Montesa 315r or a 290 sherco
i have max 2000 to spend
i am upgrading from 96 gasgas jtr 270.
will be using it for kentish trials (i.e mud and logs) novice/inter and lots of practicing / jumping and larking around
would like a lighter more modern bike
i love the fact that the Montesa has a honda engine (i had a crm 250 and was over the moon with engine).
have ridden the sherco and liked the light feel and buckets of power (if a little too much) am worried about reliability especially if im buying second hand, if previous owner hasnt change oil/filters etc.
not too keen on doing shed loads of maintenance every week and want total confidence in the machine.
my jtr 270 96 started to make a knocking noise during running has been slowley getting worse, and is getting noticably down on power. (especially compared to mates 04 290 sherco)
sounds is something between a deisel car and a small air compressor.
some of the nikasil has worn off the cylinder around the exhaust port, rings are still in one piece.... have not split case yet
also seems smokey but that may of been me running 50:1
Looking At A Bike... Engine Noise Normal?
in Sherco
Posted
sounds like it could be piston slap.....
had this on montesa... a worn piston skirt makes a kind of dry clanging noise, more noticable to spectator than rider. got steadlily worse over 4 months of abuse
piston skirt to bore clearance should be around 2 thou new, about 4 thou at max wear.
check bore for deep scoring, replate if worn through nikasil coating
also as mentioned check crankshaft play
then check con rod big end and little end.