slingy1157

I didn’t weld mine. Just a machined press fit is fine. There is no load on it essentially and the hardness of the 2 materials is very similar so the expansion rates should be close so the press fit resistance should be the same regardless of temperature. Plus if you want to change the missing tooth spacing to aid starting or anything, you can.

My short stroke build thread is on here somewhere. Wiseco listed the largest pistons for these engines with a rebore at 76mm. So I ended up finding ZX10 pistons. Think mine were 05 model. These are factory forged flat topped pistons but I think 17mm wrist pin. So like you stated I got the rods bronze bushed to suit that pin size. Deck height was pretty good but very slightly low. This combined with the flat top and larger valve pockets gave about an 8-1 cr. The block could be skimmed to perfect deck height and run one layer of the multy layer steel head gasket would help get it back to 8.5-1. being 76mm means you can run a 1052cc head gasket too which is helpful. This gives an 813cc engine with turbo friendly CR and forged pistons. Mine were $40 with the rods, combined with $150 for the rod sleeving and then a rebore, so pretty good value for money. I think the rods will be fine for 200hp. Studs is the problem. You can use 1052 ARP studs which are too long. But there is room in the head and around the cams to machine up very thick washers to make them work. Tip- replace the studs when your cases are apart getting the rods sleeved so when the old ones snap off in the cases it’s easier to get them fixed lol

Yep. Mine was stock shortstroke, bored to 76mm. Stock rods sleave to 17mm? I think. 04 zx10 pistons. Deck height was mere perfect from memory and used a stock 1052 head gasket. The big problem was CR. This was about 7.5-1, low even for turbo use, and this was already with a dot head obviously. CR would improve with a longer stroke a bit but I doubt a head skim would gain enough for NA running

Mine was a short stroke 750 slingshot. Didnt have much luck with the carbs (just me) so went efi, then did ny own 813cc big bore with zx10 pistons. Only made about 130bhp at the rear wheel on 10psi, mainly because the zx10 pistons dropped the the cr too much so that would have dropped the na power starting point. Even though, SO much fun to ride, like a giant 2 stroke, without being silly power so could still wind it on and have some fun. Also here in Oz on ASF site, Latheboy has a longstroke (same as your engine basically) slingshot running blow through carb, t25 on 10 psi i think, stock motor, 1100 clutch and making the 150bhp ish by memory. He does work in a dyno shop so it has had endless dyno time to dial it in perfect. Pretty sure its running different jets in each carb to even fueling to air delivery by plenum etc. But still pretty impressive for a stock motor. I think he blew a motor up at the drags, but was back running again quick as, cause 750 motors are ten a penny and no prepping other than n clutch needed lol

Is that a FBM kit? Looks really good by the way

Hi dave. The 750 went 1052, then 1157 then sold so i no longer have it. But definitely get back to yours and get it sorted. Efi rocks and ironically was the one element that always worked ok on all 3 engines lol

Got my gsxr750 short stroke rods bronze sleeved to fit zx10 pistons. No dramas woth it

I never had problems with oem style gaskets

Yep. Datalogs will tell you everything you need to answer this. What does the map sensor read when static? And what map sensor do you have and is the right one selected to suit in the software. If a gm style map sensor, alot advertised as 3 bar aren't. You need to google the part number and check. 1 , 2 and 3 bar gm map sensor all look the same so be carefull.

I worked with a guy here in oz, and he built a cheap drag car with a 4 cylinder motor, mechanical FI and a huge turbo. He actually filled the block and head water passages with resin to stiffen the block. And as has been said, i do remember him saying there was no over heating problems because of the methanol . Mmmmmm........Resin filled methanol WP running big boost?

On a normally aspirated bike you could probably go really ghetto and use the tach out of the oem ignition module as the input reference to the mS. Then use the tach out from the mS to run the tacho again for fuel only. Save trying to diode and resistor a clean tach signal off the coil negatives. I wonder if you could use this as a crank signal and by adding a cam sensor then use the Ms for fuel and spark with the stock trigger wheel? Interesting......... .

Good work. If the fuel height is about the same as gravity i dont you should lower the float height for the moment. Just do what your talking about and change one or 2 things at a time.

That is actually a really good idea. Theres no reason why it couldnt be a like a 36-6 wheel and have 6 missing teeth really. As long the first tooth after the gap is still 5 teeth or more before TDC so it can work out the timing nicely for 1 and 4 it dosnt really matter. I still like the 36 tooth wheels as it keeps the math all nice and easy with 10deg per tooth and all that and gives really good timing reference to the ecu. And as one of the main issues is sync durring cranking with these then why not make the gap bigger so absolutely unmistakable at cranking. You can set it to whatever you want in TS so thats no drama as long as the teeth on the wheel are all the same size and evenly spaced to begin with it dosnt matter how many teeth get removed qithin reason to make the gap.

Ok so to throw another slight spanner in the works here with the gravity test. The gravity pressure at the floatvalve is directly proportional to the height of the fuel not the volume. So an 8mm pipe with the end held 1metre above carbs and then filled with fuel will give the same pressure as a 5 litre fuel tank full of fuel with the fuel level 1metre above the carbs. So the key point here when doing a gravity test is that whatever fuel tank you are using, the fuel level needs to be about where it would be if it were in the oem tank on the bike. So if using a temporary tank, it would be better hung from the bars or similar to better replicate the oem setup. If you have it hung too high you might get a couple of psi of gravity pressure anyway. Which is not what this test is about. Its about trying to get an oem base line setting so you know what to adjust to compensate for the pressure.

Yeah mine looked fine but didnt stop flooding untill i replaced all 4. An expensive exercise on the old bst36 carbs as you had to buy the whole plastic float and frame assembly to get them . Carbs really do need to be in 100% as new condition, not just clean. ANY wear seems to be greatly exaggerated by the fuel pressure and boost.