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simple question
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Posted by: barkbuster350r

Just want to make sure of this before I order parts. I'm rebuilding my 86 trx, and want to go long rod. I have an 88 cylinder that has national porting by paul turner. So can I just order an 88 crank, rod, and piston. Just wanted to make sure that a 88 crank would work in a 86 cases.

Thanks

Posted by: stever250r

That will work if thats what you choose to do.

The difference is in the wrist pin location on the piston.

Personally, I would run the 86 piston, with the 88 crank rod assy and use a spacer plate under the cylinder.

I think most do this because the 86 pistons have more oversize options which will allow you a few more bores on your cylinder when needed.

If my info is incorrect, someone please correct me.

But yes, the 88 crank will work in the 86 cases.

Posted by: Dave83

Steve you are correct.Supposedly the long rod with the 86 piston and spacer plate adds to the bottom end power by increasing the crankcsae volume.Barkbuster,I see you are located close to me.I have a spacer plate that is for the above setup.PM me your address and you can have it.

Posted by: barkbuster350r

Call me dense, but i'm having a hard time understanding. If I'm right, you build more low end power with an 88 crank rod and an 86 cylinder piston together than I would with an 88 cylinder and an 88 piston together?

Posted by: barkbuster350r

I would really like to use the 88 cylinder that I have because it's already been ported and it's in great shape. The 86 cylinder that I have hasn't been ported and I am on a tight budget.

Posted by: stever250r

You can use the 88 cylinder. Just have the bore measured and match it up with the appropriate size 86 piston and use a spacer plate to make up the difference in the wrist pin location so you dont bump the head.

Again the 86 piston comes in larger bore sizes.... this will give you longer life on your 88 cylinder... you will get 2-3 more bores on the 88 cylinder by using an 86 style piston...

Posted by: robyone

you can use what ever cylinder you want. if you use the long rod crank with the 86 piston, you need the spacer plate, you use the 88 piston, you don't need the plate. the difference is in the pistons. I'm pretty sure you need longer studs to use the spacer plate also.

Posted by: Dave83

All the cylinders are the same as far as the height.Roby 's info is dead on.The rod/piston combo doesnt really add anything to your power.The 86 piston has the wrist pin located 5mm lower than the 87-89 piston.The rod lengths are diff to make the stroke the same.When using the long rod and 86 piston,the spacer raises the deck height to allow for the 5mm increase caused by wrist pin location.This doesnt change the stroke because the spacer takes 5mm from the downstroke and moves it to the upstroke for clearance.Kind of a redneck way to explain it but that is a simple way to say it.The spacer allows more volume in the bottom end.This helps the bottom end power.If you want the spacer,I also have the longer studs to make it work.Let me know.

Posted by: barkbuster350r

I assumed that the sleeve was thinner in an 87-89 cylinder than it is in an 86. But thats not the case, if I understand. If I go to a 86 piston I could boar this 88 to 120 thousands is that right. It is 50 thou over now and looks good, planned to boar 60 thou just to make sure.

Posted by: Dave83

Correct

Posted by: barkbuster350r

Thanks guys you been a huge help.

Posted by: sandspanker

If you want to use a 88 crank in the 86 bottom end.with the 86 clutch assembly, the end of the cranks are different.If you want a long rod crank just have a long rod put on your existing crank. dont want you to spend any unnessary $$$ buying a crank and then buying a clutch hub. hope that helps.

Posted by: barkbuster350r

Well i've allready ordered a 87-89 hotrod crank. Is it true that my 86 clutch hub will not fit the newer crank, if so what all has to be changed to make it work.

thanks