As you read this thread bear in mind it is intended to pertain to specifically 1983-1986 TT600s & 1984-1989 XT600s.



I am in the process of building a motor for my 86 XT600. I currently have an 85 TT600 motor with a bottom end going out and a good top end installed in the bike. I also have the XT's original motor with a good bottom end & a bad top end. I am thinking that I will use the good TT600 top end on the good XT600 bottom end. If I go this route I am trying to decide if I want to use the TT cam or the XT cam. If I don't go this route I will rebuild my XT top end & use the good XT bottom end. If I rebuild my XT top end then I am wondering if I should go with the TT cam or the XT cam. Either way I will be using the XT bottom end as it is good & because I want the lower first gear that XT transmissions have compared to the TT transmissions.

I have been trying to find out the differences in 83-86 TT600 vs 84-89 XT600 cams. I have searched the net & around this forum & all I have been able to find out is that the TT is supposed to be a more performance cam. I also read the the performance boost of the TT cam is in the lower rpms & there is a trade off of power loss in the upper rpms. I do not know if this is correct however. As far as I know it may all be a load of rubbish.

I have been trying to find out the differences in 83-86 TT600 vs 84-89 XT600 cylinders. All I can find out is that the XT has a cast iron cylinder & the TT has a Nikasil cylinder. As I understand it the Nikasil is a slicker surface that allows for higher rpms with lower engine temperatures due to decreased friction. What I am wondering though is what actual performance differences there are if any between the two cylinder linings.

I am also wondering if there are any carb differences between the XT & TT carbs besides jetting & needles. While I have been researching finding info on cams & cylinders on the TT & XT 00s I ran into some info that claimed the TT600 has a larger secondary carburetor throat. I know the TT & XT have different needles & jets but I am unsure of the throat diameters being different. I am wondering if anyone can shed some light onto whether these carbs have different throat bodies or if this too was just rubbish.

As far as the cam & cylinder choices I may choose I am considering all of the following:

XT cylinder with XT cam
XT cylinder with TT cam
TT cylinder with XT cam
TT cylinder with TT cam

Regardless of which cylinder & cam I choose I will be running the heavier XT rotor/flywheel & the XT ignition to run street legal lighting. I actually have the XT rotor, stator, pulse pickup in the TT motor that is what is currently installed in my XT at this moment. So I know that all these parts are compatible but what I am wondering is whether or not the heavier rotor & ignition choice is gonna have an effect on which cylinder & cam I should choose.

What I am hoping comes out in this thread is for someone that really knows these motors to offer the following:

1 A true & valid explanation of the physical differences of the two cams

2 What each cam provides in regards to performance

3 When the performance is higher for each cam in regards to rpm range

4 When the performance is lower for each cam in regards to rpm range

5 Besides Nikasil being a slicker surface what difference in performance is there between a Nikasil vs a cast Iron cylinder

6 As far as cylinder & cam choice when it comes to the performance of various options is one setup best for road, one set up best for dirt, one set up best for both?

7 Does the use of the XT's heavier rotor/flywheel &/or ignition have an effect on which cam & cylinder should be chosen?

8 Did the 84-89 XT600s & 83-86 TT600s have different sized carbs?

Even if you don't have all the answers on please share what you know. I would really appreciate any info that anyone has. No doubt if this thread gets to the truth in all this the info will invaluable for many people like myself trying to get all his sorted. Thanks.