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SRAD 725 Project

25K views 66 replies 17 participants last post by  TwistedMister 
#1 ·
I got the top end tore down this weekend and fitted some parts just to make sure they fit. My main concern was making sure the Srad 750 block fit the 600 cases and they did. I've been burned before on a ZX10/11 project when the 11 block didnt fit the !0 cases after being told they would. In order to use 750 pistons I got some from an 00-03 K model 750 and they fit the 600 rods no problem. Side by side the 750 piston pin is slightly taller...maybe 1/4 mm but the 600 piston dome is actually taller so they will be the height at TDC. Ive done several big bore projects before but was amazed at how much bigger the 750 pistons are next to the 600. Still deciding on a 3 or 4 layer head gasket just to be safe. Can someone tell me if SRAD 750 cams are that much more aggressive than the 600 ? I might as well sort that out while I have everything apart.
 

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#7 ·
Have you not considerd a rod upgrade? By all means i dont know everything but an extra 150cc is going to put alot of stress on those rods, if your planning on using the 600 head id suggest stronger springs and hard weld cam, the last thing you want after doing a build like this is valve bounce
 
#8 ·
Got everything bolted back together and she fired right up. Cant ride it because of 14 inches of snow. I ended up using the 600 intake and 750 exhaust cam combo with the stock carbs and BMC race. Sounds damn good but there is a small coolant leak between the head and block between # 3 and #4 cylinder. I used a new 74mm Cometic head gasket to try and lower the compression a little but I'll either have to go with a stock head gasket or try and re-torque the cometic a little higher...maybe 36-40 ft. lbs.
 
#10 ·
Today I got the coolant leak fixed and even though its in the low 30's I couldnt resist testing it out. On my street there is a 2 block stretch that is snow free but thats all I needed to know that this thing has some balls now. Cracking the throttle open in 1st from low rpm results in the tire spinning on the damp pavement until it hooks up and wheelies you down the block.It reminds me a little of my old R1 the way it comes up at will. I see that the 600 is geared a little shorter than the 750 so I might changed the rear sprocket to make it more sane and less squidly.
 
#13 ·
Nice, I had a 97 600 and grenaded the engine at mosport. Did an engine swap from a wrecked 98 750 for about $1600 about 12 years ago.

Nice thing was I was paying 600 insurance rates for essentially a 750 lol. Was a real sleeper too, cause the badges were still 600 so other riders were real confused when I pulled away from them so strong.

Didn't upgrade the swing arm either so it wasn't a dead giveaway. Hahahahaha.


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#14 ·
Hello i have 98 gsxr 600 with duplix yoshirmura headers carbs done by ccm im new to the forum but im real intrested in this 725 good job i have found 2001 750 pistons i havnt bought yet because they want 132.00 for them and i still got to match 750 cyclinder my 600 your concern not matching is what im worried about what year 750 cylinder work on 600 and does the 750 camshaft have to be certain year i plan on using the duplex headers and the can is also yoshimura but ccm did some tunning to it im going to use 600 carb that he built for me just making sure having right cylinder and camshaft is my main concern and you seem to solve it.I also like to know what grimlins im going to run into.I havnt even done my profile yet so i could ask you for any help would be appreciated
 
#15 · (Edited)
I emailed dood that does the 750 crank, rods, pistons and barrels into the 600 cases using the head, he said its a straight swap but you have some cam work, dial em in a I think? so you would need an adjustable sprocket.

I think you also have a few cam options as well forget which cams he used if he even mentioned it but he said with carb work he got 125 hp at the wheel, I think he said with a lightened and balanced crank you could eek out a little more?

I want to do it, that would set the SRAD up very respectable as he says he no longer has to down shift when passing.. :)
 
#19 ·
I emailed dood that does the 750 crank, rods, pistons and barrels into the 600 cases using the head, he said its a straight swap but you have some can work, dial em in a I think? so you would need an adjustable sprocket.

I think you also have a few cam options as well forget which cams he used if he even mentioned it but he said with carb work he got 125 hp at the wheel, I think he said with a lightened and balanced crank you could eek out a little more?

I want to do it, that would set the SRAD up very respectable as he says he no longer has to down shift when passing.. :)
Thank you response but I'm not changing crank or rod off 750 yet I'm just use bottom end of 600 basically put 750 top so I need to know what year 750 pistons will work I posted question more in detail what I was asking.I'm going run yoshimura duplex headers and carb done by ccm the bike is lowered has double clicker rear shock stretch just a little
 
#16 ·
Arh the 725 mod,yes i remember doing one of those , ended up with a great engine.
Heres what ended up with;

1999 750 barrels/pistons(balanced)/crank(lightened)
1998 600 head (i ported and skimmed)
1999 750 head gasket(thin)
Race 600 cams with Adj. cam sprockets( A MUST imo)
1998 600 carbs
K&N + AKRO full system
Gearing 15 front and 46 rear

Dyno'd at 124.8hp ATW . Happy days.
 
#18 ·
Not sure about cam on this mod I was told 750 exhaust cam use 600 intake is that right I know I have to get 98 750 cylinder but another issue is piston being 2001 k1 750 pistons suppose to have same size wrist pin is there any other years that work or just 2001 now I plan using 600 rods and crank so I need to make sure 750 pistons interchange with 98 600 rods I look on eBay for 2001 pistons but always 2001-2003 I ask seller what year size wrist pin don't get Reply will 2002,2003 work is it same size wrist pin anybody knows and on that exhaust 750 cam are you suppose to use with 600 intake cam?and do I use the 600 timing chain?Can anybody help or any information will be helpful I ask question few days ago I see some reply thank you everybody that reply like I said in my first post I'm new to this just found d this post again I have to learn also to use this forum I'm outdated not good on computer but trying to learn don't even know how to do profile I know it sad but I have buddy here on this forum monolith that help me a lot and ccm been great already bought some nice stuff from ccm and he jetted and build carbs for me.
 
#21 ·
I found set 2001 750 piston got them measure wristpin it the same as 600 i have 98 750 sleeve i hope i can get still talking to them about condition but im going to use 2001 750 piston looks in good shape and if sleeve good ill purchase that i already have carb set up by ccm i got the (MJN) yoshimura kit and it mean and he got me those duplex yoshimura stainless headers tune the can dying to put on 725 but i have to figure out cam i had few people tell me diffrent things so i need to know what can i go with?also i have big problem whare big tube stick out one side broken and i have to take that bolt out first you can see threads it bolt onto sleeve.so that my two main thing bolt,cam i here adjustable cam not sure what that is but i was told just use 750 exhaust cam 600 on rest is that correct anybody?
 
#23 ·
I emailed the dood that built the SRAD67 over in the UK somewhere, he is sympathetic to the distance and emailed me a short email explaining the basics, I'm sure as you go along he would be willing to help out, my guess is you can use either cam but you need to dial them in?

thats when you are using the 600 cases, 750 crank, rods, pistons, 600 head

they most likely need to be dialed in due to the crank difference or crank cam gear?

you are doing something entirely different,

600 cases, 600 crank, 600 rods, 750 barrels, 750 pistons and 600 head? is that correct? then you want to know which cams are usable?

list the precise build parts you are using or want to use I guess would be the best place to start, you jumped around a little bit, what do you mean by "big bore"

I think I read you can use the 750 exhaust on the 600 intake? I thought I read something about certain 1000 cams somewhere as well?
 
#24 ·
I'm using a 600 intake and 750 exhaust cam. When I measured the lobe height on the 600 and 750 intake they were both the same but the 750 exhaust cam was taller. If my son gets here in time tomorrow I'll throw on a new rear tire and swap some jets and let the dyno operator take it to the limiter this time. I'm sure there is another 6 or 7 horsepower to be found which would bring it into the 115 rwhp range. I'll take that especially since I'm using 600 carbs.
 
#26 ·
OK little update on 725 I was able to find k1 pistons I have ccm getting 750 sleeve and cams for me and he ordering all parts for me rings,gaskets,new bolts etc I seen original post he did for 150.00 I'm already in 620.00 just in parts and that saving a lot if it wasn't for ccm I would spend lot more he have found all kind of deals for me now mind you I'm not using to many use parts just cylinder,pistons,cams.all gasket rings wrist pin etc new ccm cleaning prepping sleeve for me just to help out giving me lot of help so now just waiting for all parts come in to do project nothing wrong with my 600 I hate to take apart running so good but I hop up much I could so I will see what 125 extra cc will do and if everything goes well see what it will do. Now I'm just changing top half not messing with crank going to put k1 piston right on stock 600 rods I know it easier just put 750 in be done with it but to have something different you put together take a chance if it going to work is what I'm looking for long as it run stronger than I have now good enough because trying to be the fastest is out of my price range there always someone faster and has the money.I will update when I receive everything get started
 
#27 ·
I'm sorry when I said ccm 150.00 for build I didn't mean he did build someone else did he helping me get everything together to build but where still having problem on the cam issue I know you can run both 750 cam on 600 heads but I need to know for sure do I just run exhaust side run 600 on intake side I have new rings to file to make sure have complete fit if anybody know anything on this subject can you give me some info any will be appreciated I have perfectly running 98 600 monolith help me lot on it has all the goodies from ccm I'm willing to take apart to make 725 and I'm on very small budget and I already have 620.00 roughly just for conversion that I already paid so I am dedicated to the project no turning back(so is there anybody knows or have input on this project)thank you
 
#34 ·
:)

Ccm did some checking on that for me to he new a guy with just stock 600 stuff on 725 it still produce 120hp to rear tire that not bad but your right i am going to put 750exhaust cam on it see what that will do with all the upgrades I gotten from ccm I know carb,exhaust,got to give me some more power that yoshimura MJN carb no joke and they say the yoshimura duplex headers suppose to be real good not to mention he did trick out my can on my 600 you can tell big difference .Now ccm friend was just talking about basic 725 I think has some bad ass motors that built up he went down to crank I don't know what that one producing I bet it strong and he using yoshimura cam and adjuster
 
#32 ·
Ccm when you said you was going to touch up you wasn't kidding I like I can't wait to see the other goodies now I got to make you proud and build it when you send it thanks for pic I'm suppose to get monolith help me post pic on forum I know it a shame I don't know how but I will learn
 
#35 ·
I'm putting new piston rings and file to fit each cylinder I notice in book the gap are different for type of motor if you have v,w or x and y all have different gaps so that the next thing I have to find out I just sent message to find out I will post later hopefully more in detail and explain more fully with correct information don't want to give out wrong information if anybody now I would sure be interested
 
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