Honda sh150i hp vs 125i hp with cylinder kit?

[nate22]

Ok according to my research the honda sh150i makes 15.56 HP (11.4 kW)) @ 8500 RPM. http://www.bikez.com/motorcycles/honda_ ... l_2011.php

And 12.35 rearwheel hp http://www.youtube.com/watch?v=udGMN-A1vJQ

Airsal makes a 58mm bore cylinder for the honda sh125i that according to their dyno produces 14.22hp/ Im assuming rearwheel.

airsal.jpeg

My question is this. How can the Honda sh125i with just a 58mm bore, create almost 2 more additonal hp, then a standard Honda sh150i?

Does the Airsal cylinder have a higher compreshion ratio?
Are the US model Honda 150i's resticted in any way?

The 150i models have bigger valves with more air flow, that inturn should prouduce more power.
Right?

[robber57]

I gues you asume the wrong thing...
I think its engine hp.
The 58 bore kit is just the 150 cc cilinder so you end up with a 125 cheaply converted to 150 with no 150cc head, vario, ecu etc etc so no 15.56 hp but somewhere in between a 125 and a 150.

Compression can be a bit higher with the airsal kit but just a thinner base gasket will already make that happen, i guess the cilinder is a ( cheap) clone of the original.
It is questionable if raising compression is the way to go, yes it will increase hp and torque a bit but it will also make the engine run much hotter.
The bbk from malossi has a bit higher compression and i guess 90 % of the thermal problems accociated with the kit are due to the higher compression ratio.

[nate22]

I thought the same thing but accourding to http://www.bikez.com/motorcycles/honda_ ... l_2011.php the Honda sh125i creates 13.00 HP (9.5 kW)) @ 9000 RPM at the crank.

So the chart provided from Airsal seems to be within line to 3hp being lost throughout the drive-train, for a stock Honda sh 125 that makes 9.79hp ( for the stock sh125 dyno anyways)

Now this is were it gets a bit confusing. When Airsal lists the same bike with their 58mm kit, it produces 14.44hp, almost 2 more additional hp from a stock sh150i. I believe this to be rear wheel hp because their listed hp curve of the sh125 is almost 3hp less then Honda's stated crank hp.

When the sh150i dynoed above it also was almost 3hp less then Honda's stated crank hp also.

So either Airsal is producing a great product, or they are inflating their 58mm bore dyno #s to gain sales.

What do you think?

[robber57]

What do you gues ?
Its just a cilinder and only this would raise hp almost to the level of a 150, without the head, ecu and all the other stuff.... I wouldnt take these dyno graphs to serious.
Its just a cilinder and unlike 2 stroke there is no magic in a 4 stroke cylinder.

[nate22]

Ya you are right. I guss my wishfull thinking just needed a reality check.

[waspmike]

Information I have accrued says the SH150i produces just over 16hp at 16.1. which agrees in part with bikz.com at 15.5.

So a 125 with a 150 barrel should have no problem getting 14.22. So playing with weights and adding an after market exhaust could get 16hp like it says.

SH 150 with J Costa gets 17hp. As has been said maybe it has larger valves?

Putting an exhaust on a PCX 125 netted 1.2hp increase so using same logic maybe an SH150 with exhaust could be nearer 18hp? Which would get 5kph over stock. Heady stuff?

There are 60mm kits also for 164cc. 150i can be taken out to 175 but the walls are a bit thin.