Cylinder head profiling etc etc - worth it???

[alanscottj]

Ok, so I have got my engine finished and had it dynoe'd by Jerome at Readspeed, power in 3rd was 15.9 hp and torque 13 ft-lbf. My question is, would it be worth me having some porting done on the engine, cylinder head profiled etc. What am I likely to gain in terms of power etc? Is it worth it? and what are your thoughts on adding a reedvalve?

Thanks in advance

[olliewtf]

what top end is it?
I think really you know the answer, which is yes.
It's all about harmony.
Power is what we all want at first, but with it comes the need for a safety margin for reliability. So its always a trade off between the two.
If its a good top end you should assume that the porting and cylinder head is in the right ballpark, you can check this by mapping your cylinder, checking your squish and measuring your CR. You'll gain more power if the porting or head are way off and you correct it, plus a far better, rideable engine. having said that this is in conjunction with gearing choice, ignition and exhaust, plus carburation.

In terms of reedvalve, you get better fuel consumption, and if your inlet is overtuned, it can alleviate this. This equates to essentially perfect inlet timing, as the vacuum of the cylinder dictates the exact amount of fuel drawn from the carb; at least that's how ive understood it. The question is what impact this could have with relation to your other timings, and the rest of your set up.

2 stroke engines are simple. But theyre also quite complex. This is what ive found out over time.

[alanscottj]

what top end is it?
I think really you know the answer, which is yes.
It's all about harmony.
Power is what we all want at first, but with it comes the need for a safety margin for reliability. So its always a trade off between the two.
If its a good top end you should assume that the porting and cylinder head is in the right ballpark, you can check this by mapping your cylinder, checking your squish and measuring your CR. You'll gain more power if the porting or head are way off and you correct it, plus a far better, rideable engine. having said that this is in conjunction with gearing choice, ignition and exhaust, plus carburation.

In terms of reedvalve, you get better fuel consumption, and if your inlet is overtuned, it can alleviate this. This equates to essentially perfect inlet timing, as the vacuum of the cylinder dictates the exact amount of fuel drawn from the carb; at least that's how ive understood it. The question is what impact this could have with relation to your other timings, and the rest of your set up.

2 stroke engines are simple. But theyre also quite complex. This is what ive found out over time.

Nice one olliewtf,

my top end is a Mugello 198 Ulitimate, straight out of the box, had nothing done to it or my casing.

[olliewtf]

i would start by checking your squish.if the kit included a piston then the head should be machined right. MB's tech pages criticizes some of the older mugello port timings, but they wont be the same as yours. you could always measure them and ask on here if they sound okay, but chances are they will be as its not exactly a cheap kit. if you noticed a great overlap between the transfer passages between barrel and casing you could address this if you want the best out of your set up...
what spec are you running elsewhere?
Most fit reedvalves for easier starting as if an inlet is quite large and your running a filtered carb, the spitback can gather in the hose of the filter and cause starting problems.
For more power I would look more to your choice of exhaust and carb... if your running a 22m with clubman for example, you could gain alot more by runnng a larger carb and expansion.
Either way, ride the bluddy thing and enjoy it, thats the main thing, and if you feel it has more to give then think about the rest!