Thumper Club Forum
Technical => Bike Problems/Questions => Topic started by: CHRIS211083 on October 03, 2009, 12:49:47 AM
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hi, has anyone ordered parts from them??? they have a srx 686 big bore kit??? im after tunning but would this be a reliable srx600??? any info would be great?chris.
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Hi Chris, someone else may correct me, but in my (racing) experience, above 640cc (for the srx) tends to be a hand grenade waiting to go off!
More or less anything bigger than std. is generally going to be (on average) less reliable, (in my opinion)
Having said that! I, myself, ran a tuned srx620cc on the race track for about 12 years, & never had the engine apart!
Other opinions will differ from mine I'm sure! but that's my twopence worth...........
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Agreed John,
Bigger bore without liquid cooling and reduced piston skirt/cylinder wall interface = GRIEF! >:(
Different rates of expansion and lack of support for the cylinder liner from the cylinder casting + hotspots at the back of the cam chain tunnel on the left hand side. Not clever. ???
The 634cc plenty big enough and prone to 'slap'! ???
Regards, Bill.
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Seen it done, seen same bike after 3 laps at snetterton.....head and barrel made a good effort of punching their way through the frame top tube and tank...not reccommended (mind you they were 3 very quick laps ;D )
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690 bore on an aircooled motor will tend to lift the barrel, it cracks round the base flange.
The watercooled motor has thru-bolts which prevent this.
I think 640 is probably as big as you want to go, even then, it may be a bit of a pig as a roadbike.
(plus you'll want a cam, carbs, exhaust, etc etc....)
As John said, 620 is good tho!
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