Oilyspanner Posted February 19, 2019 Posted February 19, 2019 Nick at Suzuki Performance Spares got back to me about Wossner pistons' weight, he has a batch coming in on Weds and will weigh them for me - which is good of him, he could've just said' it doesn't say the weight on the spec sheet'. I'll post the weight on here when I get the e-mail, it'll be well worth considering a lighter big bore piston if you use high revs a lot. - a good forged piston is always going to be strong, so a lighter forged piston will be better for pick-up, reducing stress on rods, g.pin, bearings and crank - If the Wossner pistons are near std weight they must be worth trying - I'll use a set in the next engine I work on if they are, would be smoother at cruise speeds too.... probably find out they weigh the same as all the rest Quote
clivegto Posted February 19, 2019 Posted February 19, 2019 So which pistons have you weighed & what weight were they ? Quote
Oilyspanner Posted March 14, 2019 Author Posted March 14, 2019 Wiseco 80mm and 81mm 12:1 seem to be much the same avg. 315.6 incl. gudgeon pin (78g) + rings 15.4 g = 331g ….. bare piston 237.6g avg. - haven't got retainer clip weight. Std 78mm 10:1 pistons with rings and g.pin (71g) = 299.8g avg incl one g.pin clip. Bare piston 213g. JE pistons - from their figures - bare piston both 80mm and 81mm 234g - listed as 13:1 comp. ratio …..their 82mm piston is listed as 238g (1246cc kit) Unfortunately Nick Pepper hasn't replied yet, said he had another batch coming in a couple of weeks ago and he'd weigh one and get back to me - I've been in touch since, but nothing, could've been good for Wossner if they were 15/20g lighter than the American pistons, that would be a big reduction in force at high revs. So sorry this thread's landed on it's ass ! thought it'd be useful info for anyone going through their top-end - if anything happens I'll update this thread Quote
clivegto Posted March 14, 2019 Posted March 14, 2019 (edited) Mk1 Hayabusa 81mm piston with pin & rings = 310g. Edited March 14, 2019 by clivegto Quote
clivegto Posted March 14, 2019 Posted March 14, 2019 (edited) JE 79mm turbo piston with pin & rings = 344g. Edited March 15, 2019 by clivegto Quote
clivegto Posted March 14, 2019 Posted March 14, 2019 Gsxr 1127L piston pin rings & clips = 300g. 1 Quote
jonny1bump Posted March 14, 2019 Posted March 14, 2019 Aftermarket been heavier makes sense, why they more robust. I bet the 13.1 JE's give far more compression then that. Quote
Oilyspanner Posted March 15, 2019 Author Posted March 15, 2019 Cheers Clive ! go info. I think it's just the time/money it would take to lighten the forged pistons - forged pistons are stronger than cast ones and can be made to be lighter/ of the extra strength - 10 % extra weight over standard is a lot, it'll eat into the safety margin built in by Suzuki - I know it's just the way Iam, but it just grates on me knowing the pistons could be made to add no extra stress on rods/bearings and crank, instead they'll remove a chunk of safety margin at peak revs, then you have to spend more money on upgrading your crank to get some margin back... Here's the photo of the Wossner pistons that got me interested. Quote
Gixer1460 Posted March 15, 2019 Posted March 15, 2019 13 hours ago, clivegto said: JE 79mm turbo piston with pin & rings = 355g. Unless my melon has turned to mush overnight (possible) that scale says 344g not 355 ! Quote
clivegto Posted March 15, 2019 Posted March 15, 2019 48 minutes ago, Gixer1460 said: Unless my melon has turned to mush overnight (possible) that scale says 344g not 355 ! So it does was drinking Guinness at the time lol. Quote
Ted M Posted March 15, 2019 Posted March 15, 2019 I weighed mine a while ago and the weights are the same as posted here 298 g for Blandit 1200 pistons, rings, circlip and pin and 344 g for Wiseco 81mm 12:1 pistons complete with pins, rings and circlip. I am wondering about the rev limit for the engine as like @Oilyspanner says it's quite a bit of extra mass in the engine. Quote
jonny1bump Posted March 15, 2019 Posted March 15, 2019 Once you have machined pistons for correct compression there has not been a huge amount of ally to go carving I have found. Ok depending on pistons your looking at, I'm specifically looking at the 13.1 pistons. Quote
Gixer1460 Posted March 16, 2019 Posted March 16, 2019 Logically my head says if the pistons are actually heavier then surely this unbalances the crank and should have some weight added to return the 'status quo'? Not easy to do - have seen tungsten slugs added to V8 cranks to achieve this but its not usual. I guess Bike OEM pistons are just 'pretty good' in regard weight vs use to start with! Quote
Duckndive Posted March 18, 2019 Posted March 18, 2019 On 3/16/2019 at 9:16 AM, Gixer1460 said: Not easy to do - have seen tungsten slugs added to V8 cranks to achieve this but its not usual. We used to get the cranks' for the Hemi done at Basset Down Engineering Modern TF Nitro engines often run a different C/R on some pairs of cylinders.... Quote
dupersunc Posted March 18, 2019 Posted March 18, 2019 (edited) 1 hour ago, Duckndive said: We used to get the cranks' for the Hemi done at Basset Down Engineering Modern TF Nitro engines often run a different C/R on some pairs of cylinders.... The alter the cr between runs depending on how they are running. They have a selection if different length rods to alter the cr. If the big end bearing is being squeezed out the side of the rod, fit a shorter rod. If the big end bearing is hardly marked, fit a longer rod. When engines are torn down between each run, adjusting the cr to tune the motor is simpler than changing the fuelling. Edited March 18, 2019 by dupersunc Quote
Duckndive Posted March 18, 2019 Posted March 18, 2019 9 minutes ago, dupersunc said: The alter the cr between runs depending on how they are running. They have a selection if different length rods to alter the cr. If the big end bearing is being squeezed out the side of the rod, fit a shorter rod. If the big end bearing is hardly marked, fit a longer rod. When engines are torn down between each run, adjusting the cr to tune the motor is simpler than changing the fuelling. Rods are normally same length just the pin hole is different position Top bearing is replaced every run bottom may go a 2nd time ... Its my understanding the different c/r in different holes is due to the way the fuel is forced by the blower Quote
Gixer1460 Posted March 18, 2019 Posted March 18, 2019 2 hours ago, Duckndive said: Modern TF Nitro engines often run a different C/R on some pairs of cylinders.... Reminds me of a story about a very well known bike racer who got to end of the year having blown most of his shit up and couldn't afford new, so bored a set of barrels with one cylinder @ 1327 size, 0ne @ 1550 size and two @ 1427 size - vibrated a bit but held together for the whole meeting! With desperation anything is possible! Quote
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