Reliability of Hi Comp drop in Pistal Pistons Kits?

[Rango]

Reliability of Hi Comp drop in Pistal Pistons Kits?

I'm considering a used '08 Hyper I found on CL that has this drop in kit. I'm gun shy about any used bike that the motors been into...usually that's because there's been an "issue". Anybody here have experience with that kit?

The 1100 isn't enough!?

How many miles should one expect from one of these motor before needing to do a top end? I sort of used to my 4 stroke motocross bikes, my CRF 250 took a piston every 15 - 20 hours.

[08hyper]

The "drop in" HC Pistal 98mm pistons will raise compresion not size, and will last as long a stock piston, but with better performance.

A "big bore" 100mm HC pistal piston =(1123cc) vs (1078cc stock) might not be as reliable as stock because the cylinder liners are on the thin side, & may get out of round easier, I have a "big bore" engine & I'm now starting to use a little oil, I have aprox 12,000mi on this engine. For most people I would recommend the stock size HC piston because of this possible issue. Aloha Alex

[Ben710]

Alex, how was the performance increase with the 100mm bore? Do you have before and after dyno charts?

[disgo duc]

have ncr hi comp pistons and never had an issue but only 4500 miles since build...but i dont ride it as hard as alex does..he does more track days than i do..

[08hyper]

Originally Posted by Ben710

Alex, how was the performance increase with the 100mm bore? Do you have before and after dyno charts?

I'll try to post them, but since all dynos are slightly different, & the Euro dynos read TQ differently, numbers sometimes do not apply, what is important is the increase from stock, run on the same dyno & operator, in my case my Hyper went from stock 81HP to 106HP with a heavily modded motor.

The "big bore" engine will add more TQ to the motor, rather than all out HP. Aloha Alex

[el tardo]

life of any motor will be less with high compression pistons as there is more stress over stock, thats plain and simple.look at racing the faster you get the sooner it needs a rebuild,no matter what parts you use.

now Reliability as in if it will break sooner is a different question and alex has the most experience with hyper builds.

i can speak on car motors if you go hi comp pistons you'll want better rods over stock.

and about the used hyper,you need to be more worried about rings and con rod bearings over the top end as thats where all the stress is at.

[Chouch]

Originally Posted by el tardo

now Reliability as in if it will break sooner is a different question and alex has the most experience with hyper builds.

He sure does.
Motor Of Death I died
Motor Of Death II is burning oil
I'm sure he's thinking about MOD III when he goes to bed

Originally Posted by disgo duc

have ncr hi comp pistons and never had an issue but only 4500 miles since build...but i dont ride it as hard as alex does..he does more track days than i do..

Is it the 1900$ big bore kit from NCR you have ?
Did you have their rods and crank installed aswell ?

[08hyper]

Originally Posted by Ben710

Alex, how was the performance increase with the 100mm bore? Do you have before and after dyno charts?

1. Dyno of my stone stock Hyper
2. Dyno of my Motor of Death I & II

Stock.... 81.83 HP 68.03 TQ
MOD I. 102.03 HP 76.21 TQ
MOD II 106.57 HP 78.91 TQ

Aloha Alex

[Ben710]

What is the overall spec of MOD2 and 3?
Sorry for being so nosey.

[Decreasing Dave]

Originally Posted by Ben710

What is the overall spec of MOD2 and 3?
Sorry for being so nosey.

Bigger squirrel.

Must be, because his bike has more nuts now than it did.

Dave