engine mods??

[renault_megane_dci]

Originally Posted by bschloop

Here's another thought. I could set up an egr system. Just tap into the muffler and pipe a small amount of exhaust gas through a copper pipe into the intake.question is how would this affect FE and performance?

On the paper that is a good one, it should reduce pumping loss at lower rpm, filling the vacuum of the throttle with inert gas.

But personally I would be worried with carb tuning.

[bschloop]

I kind of had figured that whatever I do, retuning the carb will be necessary.

[serialk11r]

I wouldn't add EGR on a bike because there's already so much overlap and poor combustion. Pumping loss reductions via lean burn and EGR are okay if the engine doesn't have any misfiring or rough idling. To decrease volumetric efficiency, I think moving the intake cam back a tooth (if that's not too much) would do the trick?

[renault_megane_dci]

I think the bike is SOHC so you can't dephase cam event unless you have it grinded.

But you can increase valve clearance on inlet to marginally reduce overlap.

[serialk11r]

If you don't care for the slight power loss, regrinds without weld process are really really cheap

[Grant-53]

Check the site motoIQ.com for their project scooter engine mods. There are several parameters to consider when retuning or modifying an engine. Consult an experienced engine builder and look at the spec. for industrial engines versus racing applications. We are looking for longer stroke, lower rpm, higher valve lift, and reduced overlap. Polishing, porting, coating components, timing, runner lengths, and jetting changes follow once the first four parameters are established. A longer stroke means a different crankshaft and higher lift, if piston clearance allows, means adding material to cam. A crank and cam from a similar engine of larger displacement might be reground to work. Look at the crankcase pumping method to minimize power loss.
With an air cooled engine alcohol injection is used to reduce pre-ignition when higher compression or turbocharging is used. An external water mist system in the air flow around the fins could help control temperature. Aircraft engines are often air cooled and literature on them may yield some ideas as well.

[renault_megane_dci]

I had a good read about a Honda RUCKUS but it was much more performance oriented that can be of use ...

More emphasis towards coatings maybe ?

[bschloop]

I just looked at Moto-IQ and it looked like they did a few things that we've been talking about. they did mill their head for higher CR. they also made use of the thermal barrier coatings. these two I will be definitely doing. I also want to look into WPC treatment. They claim it reduces friction quite a bit, and if that's the case then I might send in my trans and primary gears as well to see what kind of efficiency increase I can get. looks promising. I think I'll avoid any cam changes unless I can find another cam to play with. It will probably take a while for me to get started, because I'm moving this weekend. then I have to find a spot to work on the bike. we'll leave EGR on the back burner, but if the bike runs lean after putting it back together then it might be a good way to offset that effect without adding more fuel. otherwise I'll have to find a jet kit.

[renault_megane_dci]

Doing the gearbox in coating starts to make a fair amount of money.

If practical, a dry clutch conversion might be much more rewarding FE wise ...
I have seen a Honda CB400 twin with such a conversion, it's engine porn !

[bschloop]

Can a dry clutch conversion be done on a bike where the oil pump and clutch are side by side and sit in the same oil? The trans treatment might cost $100-150. On a related note, I may have found a parts bike. So I might be able todo a few of the more difficult mods.