The Yamaha Road Star Warrior Forum

I recently had high compression pistons and a taller fifth gear installed. Now my top end seems to be less! Is it because the speedometer reads slower with the taller 5th? Now I can barely make it to 180 Kms/hr where as before I had hit 200.

 Also, when going with the High Comp Pistons, should I also have a high lift cam to get the most benefit from them? What kind of performance change should I expect with just the High Comp Pistons without the cam?

I have Cobra 2-1'a, Dyno Jet Power Commander 3, K&N open air 

Thanks,

Captain Bob aka: popeye

popeyes-world@hotmail.com

The taller 5th gear would throw the speedo off a little. I have a 31t pully so it thows mine off in the other direction. Not sure how much you would be able to tell the difference in the seat. Just keep looking ahead and ignore the speedo.

Your speedo is off by 5% so you still run the same speed.If you still have the same ecu the fuel should start to shut down at 125 mph.speed star ecu lets it run another 600 rpm.On my bike I run minimum 103 octane to get the benefits of the hc pistons

 Thanks for that! I think I still have the same ecu but are not sure! Some of the mods were done before I got the bike. The highest octane I've seen here in British Columbia, Canada, is 94 tho! 

Seems weird that my top end is 180 kms then as 5% more would still only bring me up to a little less than 190 when before it hit 200

The taller gearing in fifth does cause a slower top speed.  The Warrior can't pull redline with the R* fifth gear.

TaiwanJohn :

The taller gearing in fifth does cause a slower top speed.  The Warrior can't pull redline with the R* fifth gear.

Probably a true statement with a stock engine.  I have the RS 5th gear set, HC pistons, V-BAK and big shots.  I can hit redline in 5th.  And believe me, fuel does not shut down at 125 or even 135.

 Installation of a higher duration cam and some tighter valve springs will give a huge bump in power. I've made up to 75 horsepower on a small block chevy by adding a cam and adjusting the timing accordingly. On a warrior I'd bet you could net another 10 hp at least with the cams in conjunction with hc pistons and valve springs. Not to mention it makes no sense to me to go into my engine to swap pistons and NOT change the cams and valve springs...Definitely run high octane fuel. So if I'm understanding you right, you swapped out to a roadie 5th gear for better cruising rpms and swapped out to HC pistons...I will almost guarantee you that what your experiencing is speedo discrepancy's. The mile per hour or KMH difference is progressive, it's not a set rate..so where your experiencing a 5% change at 80mph it could be as high as 8 or even 10% at higher speeds and rpms. Motorcycle speedo's are notoriously incorrect after certain speeds depending on the rider's set-up and the manufacturer's programming. I once had a Yamaha 600R that read it was doing 187mph and I highly doubt that I was going that fast...especially when a guy passes me on a busa in a wheelie...see what I'm sayin? I was realistically doin 150 maybe 160...

OldMan:

TaiwanJohn :

The taller gearing in fifth does cause a slower top speed.  The Warrior can't pull redline with the R* fifth gear.

Probably a true statement with a stock engine.  I have the RS 5th gear set, HC pistons, V-BAK and big shots.  I can hit redline in 5th.  And believe me, fuel does not shut down at 125 or even 135.

Jack do you have any dyno numbers on your bike? I'm thinking of your same set up only minus the roadie 5th gear and I want to do cams and springs and I'm curious what I might see. According to my dyno guy I'm at 86 hp and 101 tq right now...and that was before I switched to a 2-1 exhaust.

 As stated previously the Road Star 5th gear conversion will slow your speedometer reading. In actuality you were reading high with the stock gearing, now you are reading closer to the actual speed. If you install a 240 you'll read even lower. I blow past everyone on the highway @ 75 when most cars are travelling at 75mph.

I have never hit redline in 5th gear after installing the 240.

Terry:

Jack do you have any dyno numbers on your bike? I'm thinking of your same set up only minus the roadie 5th gear and I want to do cams and springs and I'm curious what I might see. According to my dyno guy I'm at 86 hp and 101 tq right now...and that was before I switched to a 2-1 exhaust.

I started out with one of the lower stock HP and torque bikes.  I have the HC pistons and Big Shots and you are only 3 HP and 9 lb ft  behind me.  That dyno run was before I put on the V-BAK though and no custom map.  You throw in cams n springs along with the pistons and it should move right along!

BTW, with HC pistons you don't need to go any higher on octane than what your local station sells.  91 works just fine. 

+1.  The tach will flash and fuel will be controlled but it won't shut down completely.  This feature is rpm-sensitive not mph sensitive.

OldMan:

I have the RS 5th gear set, HC pistons, V-BAK and big shots.  I can hit redline in 5th.  And believe me, fuel does not shut down at 125 or even 135.

See what happens after a break-in period for the new piston rings.  If the mod work was correctly done your top-end speed should be slightly higher and the speedo error should be somewhat corrected by the gear swap to a more-accurate MPH reading.  The R* gear swap causes the Warrior to cruise at slightly lower rpm's and the 5krpm redline remains the same (5500rpm for S* ECU).

Remember that regional seasonal gasoline blends will change performance.  HC pistons generally like 91+ octane fuel although if you have PR 108ci HC pistons they are 10.25:1 and seem to like regular octance unleaded in many cases around the USA.  The octane rating methods vary in other countries.

The addition of HC pistons doesn't change the top end, it just makes the bike get to the top end much faster!  Its the gear-swap that improves the top-end MPH slightly, although it won't make it exceed the 5krpm redline ECU parameter.

If you add injectors and cams, you'll get to the 5krpm redline even faster!

Its possible the HC pistons will benefit from a new dynotune to get the top end MPH back.

exetrite:

I recently had high compression pistons and a taller fifth gear installed. Now my top end seems to be less! Is it because the speedometer reads slower with the taller 5th? Now I can barely make it to 180 Kms/hr where as before I had hit 200.

 Also, when going with the High Comp Pistons, should I also have a high lift cam to get the most benefit from them? What kind of performance change should I expect with just the High Comp Pistons without the cam?

I have Cobra 2-1'a, Dyno Jet Power Commander 3, K&N open air 

 

Thanks,

Captain Bob aka: popeye

popeyes-world@hotmail.com