Online: Hilly

TC88 big bore kits/options

  • John.R
    John.R
    4 years ago
    Evening all,
    Anyone have experience or thoughts on the various big bore kits available for 88 cube motors? 

    Can stock cylinders be bored to 3.875, and suitable pistons found? What about 3.937? Or are aftermarket barrels necessary due to the liner (ans liner thickness)

    I note you can go to 97 without machining cases, however, would this be a good idea? Particularly for an engine that's likely to be flogged? 

    Basically trying to figure out if I can just bore the OEM cylinders to 95, or if i need to be going to a kit with stronger cylinders.
  • Soapbox2627
    Soapbox2627
    4 years ago
    My old Nightrain TC88 done a cam bearing and put metal through the engine, rebuild
    bored to a 103 new everything else, long stroke crank, pistons, cams all in the old shell, looked all the same but went like stink

    my nephew has it now, I gave him all the paperwork so cant say it in detail, so yes it can be done
  • speedzter
    speedzter
    4 years ago
    What are you hoping to achieve ?
    Balls out power or just middle of the road ?
    Me personally, I wouldn't opt for a 98" (3.938") overbore, but lots have done it with good success .
    I would stick with 95" , and there are plenty of decent pistons in all comp' ratio's easily available from HD to suit.
    You can use stock seasoned 88"/96" cylinders and overbore.
    S&S also have their 100" kit for around $1750.
  • John.R
    John.R
    4 years ago
    I just want a nice, reliable little motor that revs. 
    Reason I ask is initially I was going to bore OEM cylinders to 95, but can grab a 97in kit with pistons and barrels for $1300. The fact it was the largest size available before case boring scared me though, as I wasnt sure if this a reliable setup for something will be bounced off the limiter. 

    I'm not fussed bout the extra 2in capacity because i want to squeeze every last drop of power, just that its available so worth considering.
  • speedzter
    speedzter
    4 years ago
    Who is the kit from, and can you trust the cylinder to piston clearance ?
    You could get the pistons and bore your cylinders for around $800 if your want to save some money. 
  • Krash Kinkade
    Krash Kinkade
    4 years ago
    John, I would not go over 95 ( with stock stroke ) and think the 88" a good motor as thicker cylinder wall's, when you resize to 95 you have not got as much meat in the bore wall's to hold its round & seal as well. I had an 88" twin Cam & bored it to 95". it performed really well. but I could see they show the same type wear as the old 80" EVO in the bore.
  • fatbat
    fatbat
    4 years ago
    My understanding is the twin cams used the same cylinders but the earlier twin cam (88ci) used a shorter stroke than the 2006/7 onwards longer stroke twin cam. 
    So 88ci has the same cylinders as the longer stroke twin cam 96ci.  

    Ditto with 95ci to 103ci
    And 98ci to 107ci
    And now 100ci to 110ci

    Lots of 103 and 107 Ci longer stroke twin cams so can’t see why 95ci or 98ci would be much risk. I would have absolutely no hesitation going to 95ci.
  • crowster69
    crowster69
    4 years ago
    i got a 98 kit ready to be put in my fxdx.Will get it in this winter sometime.I had the same kit in another lowrider i had a few years ago and i did 50000ks on that before i sold it on and it is still going strong.Reliability is not a problem with these.Both kits i bought from dunne performance in the states including his heads.great street motor with 575 cyclerama cams.
  • Hoodeng
    Hoodeng
    4 years ago
    The biggest you can get over a 4" stroke is 98" the biggest you can get over 4.375" is 107" regardless if its 96" or 103" using the std OEM cylinder bored.
    I have never encountered a cylinder failure with 3.937"  i would also go with as big a cylinder or engine i could have for a given configuration.

    Cheers.
  • John.R
    John.R
    4 years ago
    Bit of any update, SE high comp 95in pistons, black OEM 88in barrels to be bored out, and SE 257 cams on the way.
  • Krash Kinkade
    Krash Kinkade
    4 years ago
    Quoting John.R on 14 Jul 2020 11:55 AMedited: 14 Jul 2020 10:31 PM

    Evening all,

    Anyone have experience or thoughts on the various big bore kits available for 88 cube motors? 

    Can stock cylinders be bored to 3.875, and suitable pistons found? What about 3.937? Or are aftermarket barrels necessary due to the liner (ans liner thickness)

    I note you can go to 97 without machining cases, however, would this be a good idea? Particularly for an engine that's likely to be flogged? 

    Basically trying to figure out if I can just bore the OEM cylinders to 95, or if i need to be going to a kit with stronger cylinders.

    John I had no trouble with my tc88 bored to 95 but guy who resized barrels had a good set up & torque plate, I did 100,000 on it , but somewhere along the line the stock flywheels slipped, put the crank out, I did not know straight away as was only drag racing the bike at that time ( recovering from injury ) I just noticed the ET & trap speed was taking longer & going slower in the traps, but though I was riding the same. so pulled the heads, was surprised as could Harley turn the motor in the cases. took out the oil pump that's on the shaft , but the S&S Gear drive cams I used no damage. picked up near new stock tc88 flywheels checked trueness & had pin welded that was a while back but motor still going strong. & I was doing 7,200 RPM through speed trap in 4th gear at Sydney Drags and best time 11.2 with me riding it trap speed 121.5 MPH 4th gear. the stock barrels bored to 95" looked fine, just showed the normal wear marks like the old EVO 80" normally show, the thicker tc88 bore would hold it's true better. but I never tried, I just went 95".
    sorry for long reply.
    Your builds looking really nice!!
  • beaglebasher
    beaglebasher
    4 years ago
    Great reply KK.  Even I can understand that.. Sort of.
    What is a torque plate?
  • John.R
    John.R
    4 years ago
    Yeah the plan will be to get it bored with torque plates. There is/was a bloke local in Queanbeyan, so will hit him up when they arrive, otherwise I'll send them somewhere.

    Beaglebasher, a torque plate is tool that is basically some chunks of steel that let you torque the cylinders to spec before boring it out. It means (in theory) you're perfectly cylindrical when bolted onto the bike, rather then boring with no load, and then cylinders are slightly tweaked when bolted on. 

    Theres lots of back and forth about whether its necessary or not, I think the premise and idea makes sense, but im not an engineer. Call 10 machine shops and they'll all say they can bore the cylinders, then see how many of em have torque plates for Harleys and maybe 1 or two will. 

  • Baloffski
    Baloffski
    4 years ago
    Not an expert of any means, but, in saying that I was going to pump my 2006 88 out. Did a lotta homewok, decision was a 95 absolutely. With Christmas tree boobles, little extra stuff. Wish I'd stuck with it, as I think as a keyboard hero at the moment, would be a wise choice.
  • fatbat
    fatbat
    4 years ago
    Quoting John.R on 03 Aug 2020 12:06 PM

    Yeah the plan will be to get it bored with torque plates. There is/was a bloke local in Queanbeyan, so will hit him up when they arrive, otherwise I'll send them somewhere.

    Beaglebasher, a torque plate is tool that is basically some chunks of steel that let you torque the cylinders to spec before boring it out. It means (in theory) you're perfectly cylindrical when bolted onto the bike, rather then boring with no load, and then cylinders are slightly tweaked when bolted on. 

    Theres lots of back and forth about whether its necessary or not, I think the premise and idea makes sense, but im not an engineer. Call 10 machine shops and they'll all say they can bore the cylinders, then see how many of em have torque plates for Harleys and maybe 1 or two will. 

    John, who in Queanbeyan are you considering using? My harley engine guy uses graham silk racing enterprises in Queanbeyan so might be worth checking out 
  • John.R
    John.R
    4 years ago
    Thanks for the heads up Fatbat. Do they have torque plates for TCs?
    The only one I knew of that has them and I've used is Chris Douglas aka Dougo
  • John.R
    John.R
    4 years ago
    Arrived today.

  • fatbat
    fatbat
    4 years ago
    Nice work John I didn’t realise you were buying new cylinders. Thought you would doing a bore out job. 
    In relation to a couple of messages up I can’t be sure that Graham silk has Torque plates to suit harley cylinders 

    Good luck with your project 
  • John.R
    John.R
    4 years ago
    That was the original plan fatbat, but these cylinders where included in the price ($350 for pistons and cylinders) and they're the cooler looking ones, as i was gonna paint the donk black anyway. 

    I'll try and call GSRE again tomorrow to check, otherwise I know Dougo has em, or theres a heap of options in Syd.
    Out of curiousity, who builds your motors here? Im not real familiar with everyone in the ACT scene, still learning shit as I get more and more into it.
  • fatbat
    fatbat
    4 years ago
    I used to use Peter Pulford in Mitchell but he retired and sold all his workshop stuff. 
    I now use Bestway Customs and Choppers in Conder. Jason is an s&s dealer and is very meticulous with his work. And he knows his evos very well like the back of his hand.