To provide some input from a seat of the pants perspective, both the 590 and 625 cams have very good low-end torque. I've had both in my 103 engine.

But just like Drago said, the 625 also pulls harder than the 590 in the mid and higher rpm range. I do enjoy racing another bike from time to time and do agree that the 625 smokes in the mid and high ranges.

I'm still considering going to a 107 by boring my OEM cylinders (sitting in a box somewhere) and a new set of domed pistons so I can use them with my SE 110+ heads. My heads have never been cc'd, but SE shows them to have 95cc combustion chambers.

Drago, what high dome pistons would you recommend for my configuration. I will be staying with the 625 cam and want to keep a 10.5 to 1 mechanical CR.

Jim

 

Was able to talk with Frank @ Dragos and even though I will probably not purchase from him he was very helpful and knowledgeable.Made some good points on cams and power,torque.....A very no nonsense kinda guy....seems to be a straight shooter.Frank I'll keep you posted as the build unfolds in a couple weeks....Thanks....Dave

 

I've been running a TR-590 for about 4 wks and it seems strong, it's in a 107. Stick with the stage II heads. TR's have 1.90 intakes which is about as big as you want to go in a 95-98 ci. His next bump up is 2.0 intakes which will hurt your torque. I think I would take his advice and go with the 555's. Alot of the noise in high lift cams comes from the pushrods hitting the inside of the pushrod covers. There are things that can be done to alleviate it, but why put yourself there if you don't need to and in the range you're looking for power you don't have to. Good luck with your build and have fun!

 

I've been working with a set of 110 heads and there's not much options with domed pistons with this head. most 107" come as flat tops and with the 95cc 110 head you will have a very low compression about 9:1 ........The domed pistons that are availible for the 107" do not have the 110 chamber shape or correct valve pockets and still wont give desirable comp.
Your best bet is Harley makes a 103" piston for that head (not for long as it's scheduled to go obsolete). you can pick it up from LSH for 225.00. The other option is go BIG 124" with a flat top will bring the comp up to the 10.5:1 range. Or you could go with a total custom piston for a 107" Good luck with that on too.

Hope this helps
Jim

 

Jim,

It does help a bunch. I'm assuming you know what you are talking about. My issue is, I've been discussing this matter with three of the main engine builders two of whom hang out here and I've NEVER been told they simply do not make a compatible high-dome piston for my head, for a 107 bore. On the other hand, I've never been told a piston, other than a flat-top, exists either.

I need confirmation on this so I can stop thinking about going from my 103 build to a 107 with my same SE 110+ heads. Please, will one of the engine builders confirm this?

Thanks,
Jim

 

Jim, going the 625 route myself when TR gets his new batch in on the 5th

 

Garcou, have you dynoed your bike since you installed the EMS? If so, could you post your chart? I'm really curious because I'm running a similar set-up.

 

I myself went with the TMan 662-2 Cams and am going with the 11:1 103" pistons for the SE 110 heads


HardyHarHarley: I tell you the truth. If you want the 110 heads and High Comp you will have to go 103 with the SE Pistons Part#21928-08 11:1 comp and part#22137-08B for the 10.5:1 you can get the 11:1 from LSH for about 225.00 and I was told these are not being produced anymore, all that is left is whats on the shelves. The .010 overbore of the 103 (3-7/8" Bore, +.010) are already gone.
Or you could build a 124 flat top and that would bring the comp up to a good 10:1. To run a flat top you have to bring the cubes up at least to a 117"
No amount of milling the head will bring the comp up with out a domed piston on a 107. Not only that even if you could then the head would then be useless on a future 124 or larger build as it would bump the comp up way to high.
Those heads have huge 2.120 intakes with 1.63 exhaust valves even most of the flat tops may need new valve reliefs cut in for the larger valves.


Jim

 

HardyHarHarley: You will also want to get bronze guides in those heads before slapping them on a motor. They are known for guide issues. That why there was recalls on these heads.
You will also have to change springs as your 96" heads have 7mm valves and the 110 heads have 5/16 valves here is the SE part# 18281-02A for the Race valve springs that come in the new 120R motors and can be had from LSH for 129.00 shipped

Jim

 

Your probably better off having a stock set of 96 heads worked up