Taller 5th.. any known drop ins?

[rerb]

Busy winter ahead... extending and bracing a spare swingarm 6 inches over, going efi, and putting better internals in. All to run 200+ mph at a LSR event in July. 

Unfortunately I don't have Carillo money, and the rods I bought (maxpeeding rods) are only rated for 9k rpms. Not a big issue since power peaks at 8300 or so especially with long gearing. But I've calculated that with a 17/40 sprocket setup (which seems to be the tallest I can reasonably install given parts availability and chain clearance to the swingarm pivot) I need to spin the motor at 9200 to barely reach 200. Sure it'll work for now, but once I do 200 maybe I'll want 225 next. 

I know hayabusas have some tall ratio gears for sale but haven't seen any for a bandit. I have a spare gearbox sitting around and will get measurements and start looking around, but wanted to know if anyone was aware of a drop in 5th gear set from another suzuki that fits the forks/shaft diameter/spacing 

Thanks.

[peter1127]

I have 17/40 too on a gsxr with hayabusa swingarm. A bit of a pig from standstill so taller 5th would be interesting for me too! Cant find it either. 

Regarding the maxspeeding rods, I'm about to install those too. Carillo's indeed crazy expensive. Big money to protect the engine, which is only expensive due to the .......rods.  They used to have a cheaper version which were not H beam but seems they dont make those anymore.

Dont really understand the rpm rating of the maxpeeding rods. A rating lower than oem makes no sense since everybody installing those rods will go to/over the limit....... Must be a mistake right. I put the rpm limit to 10K but that is more to protect the crank, and turbo engines dont benefit much from overrevving other than topspeed.

[Arttu]

I would simply forget about that 9000 rpm spec for the rods. They seem to have that for pretty much all their rods, including GSX-R1000 ones which are routinely revved up to 12000+ without issues...

[rerb]

Good to know! I just wanted to be as safe as possible to avoid an engine lockup holding max power on the big end of the mile and a half. 

I did a lot of reading on gear manufacting and design instead of studying and I'm going to ask my campuses manufacturing center if they have the ability to mill 4340. They've worked with me before on engine parts for our SAE car, If so I might try and CAD up a gear and see what the cost would be to machine a billet and harden it. I know they have the tools for it but not sure what they'd charge me. Might be over my head on that, but that's why I have 2 spare motors haha. They're more business focused than indivual, if there's any interest from bandit owners in the concept of a taller 5th set works out I might be able to promote it as a prototype for a commercial product and get the senior engineers to help out with design.

On a side note, the MTC pistons are over a grand for the kit. As I'm running hayabusa OEMs right now with a shaved head, I was considering ordering a set of wiseco stock cr forged busa pistons and just running those instead, aiming for 9.5 or so CR. They're half the cost but I haven't been able to find much info on what power level they're rated for. I know oem busa pistons are probably good for very low 300s, so I'm assuming a set of forged should be good for the 350 or so I'm shooting for. 

Anyone gone this route? Otherwise I'll have to remachine my spare stock jugs for 81mm and I'm looking to save as much money as possible (college student) 

[Arttu]

I think stock Busa pistons are used for over 500hp. I wouldn't worry about their strength as long as you can keep the tuning right. So replacing them with aftermarket pistons at the same compression sounds like wasted money... Instead I would concentrate getting the deck height and squish gap correct. Using Busa rods could be a good choice for that.

[rerb]

1 hour ago, Arttu said:

I think stock Busa pistons are used for over 500hp. I wouldn't worry about their strength as long as you can keep the tuning right. So replacing them with aftermarket pistons at the same compression sounds like wasted money... Instead I would concentrate getting the deck height and squish gap correct. Using Busa rods could be a good choice for that.

Oh, good to know! I'm at 9ish :1 cr right now with a mm shaved off the head. I'll use water to find the exact ratio and then a piece of solder to find squish band (that's how you do it right?) To make sure it's fine. I like higher compression which is why I'm going efi to run e85. 

As far as bottom end bracing goes ill be using APE hardware. After that and stiffer valve springs I think that's all the weak parts of the motor addressed

[Arttu]

Yes, definitely a good idea to first measure what compression ration and squish band you have now. Then you can work out what you need to do. And yes, solder wire or clay is one way to measure the squish gap. Or you can measure piston to deck height and head gasket thickness, should be the same. I would aim somewhere between 1.0-1.5mm, preferably to the smaller end if possible. For E85 10-11:1 compression should be good.