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-   -   TSP head mod - 2018 EC250 (http://www.gasgasrider.org/forum/showthread.php?t=23716)

memphis2857 08-01-2018 11:51 AM

Quote:

Originally Posted by AZRickD (Post 184608)
Is there anything wrong with just going for the $150 rechambering?



Why is this better than the Millenium service?



RK-Tek for Gas Gas:



https://www.2strokeheads.com/index.p...formance-heads







https://www.2strokeheads.com/images/...%20CHEAT-1.jpg



The re-chambering offered by RK Tek is what I was talking about. They cut your head to accept an insert.

I had an RB head on my 05 and S3 heads on my 11’ and 15’. The RB head doesn’t offer much of a performance boost. It just smooths out power delivery and makes the bike easier to jet. The S3 gives some extra bottom end by increasing the compression. The RK head changes everything. Also it gives you the option of having multiple inserts cut. Say you want to run race gas normally but sometimes only run pump gas, you could have an insert cut for both. Or maybe you ride and different altitudes. I know the majority of us would never change heads for these scenarios but the option is there. Guess my point is, it offers more tuning options.
Most guys don’t bat an eye at spending $250 on a FMF gnarly pipe to gain a tiny bit of bottom end. Why not drop $150 or even $300 on something that offers far more performance?


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AZRickD 08-01-2018 01:14 PM

I don?t want increased compression. I want a good squish set to Arizona?s crappy 91-Octane pump gas.

That means cutting the head while opening up the combustion chamber to maintain a specific compression.

memphis2857 08-01-2018 07:51 PM

Quote:

Originally Posted by AZRickD (Post 184622)
I don?t want increased compression. I want a good squish set to Arizona?s crappy 91-Octane pump gas.



That means cutting the head while opening up the combustion chamber to maintain a specific compression.



That’s the glory of an RK Tek. Just call him and tell him what you’re after performance wise, what fuel you run, and what altitude you’re at. He will cut an insert specifically for you. It’s not some canned head that is setting on a shelf. He doesn’t have any inserts pre-made, he will cut your after he talks to you.


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AZRickD 08-01-2018 08:05 PM

So $150 for the machined head and insert?

How do they want the squish measured? Rosin core solder impression?

What about the supposed difference between the XC and EC piston (something about a different dome shape).

Gibnut 08-01-2018 08:38 PM

Quote:

Originally Posted by AZRickD (Post 184649)
So $150 for the machined head and insert?

How do they want the squish measured? Rosin core solder impression?

What about the supposed difference between the XC and EC piston (something about a different dome shape).

Rick, after my dramas with crown height I would recommend whipping the barrel off so you can mic up the piston & get an accurate measurement there as well as negative deck height.

FWIW, Dave Macarthy at Two Stroke Performance here in Australia reckons the comp is too high, period, on the 2018 300. He lowered it on gassernate?s bike (not sure to what) which is now running quieter & stronger than ever. Dave also said my bowl shape & compression (stock - 13.5/1) should see the bike able to run well on 91RON. I will test it one day, but currently run 98.

I had an S3 head on a Beta RR250 a few years ago & getting the head set up specifically for my bike has yielded much better results than bolting on one of 3 inserts.

AZRickD 08-01-2018 08:45 PM

Wow. Compression too high ??

Even with a sad 2mm squish or would that be if the combustion chamber wasn?t more aggressively opened up?

I was hoping to just do a rosin core measurement a la RB-Designs, but I?ll do what I must.

Gibnut 08-01-2018 09:50 PM

I?m referring to the EC250 only. EC300 has a flat top piston, afaik.

It is weird - totally counter-intuitive to think lowering compression will give smoother & sometimes stronger power.

We would need a dyno to confirm the results, but we are talking about inefficient combustion compared with very efficient combustion. Even this is surely enough to cancel out the drop in bottom end when lowering compression.

It is far easier to buy a solution off the shelf and fit it up & I’m certainly not saying S3, RK-Tek, etc don’t do exceptional work. I have gone 180 degrees on this - from bolting on stuff to understanding why you get the gains from setting up your motor for YOU & your specific requirements.

AZRickD 08-01-2018 10:28 PM

I would prefer simple: reshape the stock head and be done with it.

I have done this three times in the past ? KDX220, and two GG250s.

All to good effect.

SS109 08-01-2018 11:14 PM

Quote:

Originally Posted by AZRickD (Post 184660)
I would prefer simple: reshape the stock head and be done with it.

I have done this three times in the past ? KDX220, and two GG250s.

All to good effect.

Same here. I've had great results with RB's mod on two KDX's and my previous GG EC250. Simple but they all made better power and were easier to jet.

AZRickD 08-02-2018 08:31 AM

So, which one for Simple?

Millenium or RT-Tek?


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