I'm going to the dyno

[Capz85]

Right, as I've got sm wheels on and I'm pretty much guessing with the jetting setup I think it's probably best to just take it to a dyno, I'm doing a piston change this weekend and I have a fresco big one pipe to put on, I'm thinking of trying a selection of needles or a jd kit,if anybody has some needle recommendations, I'm using n3cj i like it so may try some other variation of the n3

Also need to make a decision on base gasket thickness

 

[roverhybrids]

If I was going to a dyno I would, along with the new top end, have my head machined to correct the squish band and compression.

 

[gassergrant]

Personally I would do the piston change and break it in so it's nice and fresh

 

[Capz85]

I will put a few miles on it before I take it

I would like to do the head mod but I haven't got a clue who would do it in the UK

 

[(F5)]

I googled and found quite a few but clearly you will have to call to see if the have templates / records for your bike head else they will need to measure on engine. Search my head thread.

Don't assume aftermarket pipe will be better just because it cost money. Test old then new. Get good at swapping mains by rotation of carb on bike.
Don't be upset when dyno figures seem pathetic compared to claimed HP.

Check if dyno operator is confident with testing needles. Wide open runs are easy to get consistent but only test mainjet is right at full throttle with that needle. I've never been good enough to test part throttle on the dyno. Your guy might be.

Add your bike to your signature so we have a clue.

 

[Capz85]

I will do some checking on the head mod

I didn't really buy the new pipe expecting a huge difference it was more the fact that the old standard one is looking a bit worse for wear, I'm pretty happy with the way the bike goes but I'm just looking to get it set up, the guy at the dyno seems pretty keen to help

 

[Capz85]

I found a place that will machine the head but I will have to give them the measurement of what I need taking off

 

[jimjim]

How about alittle porting on your jug?

 

[Capz85]

If I end up getting the head machined I will ask about porting

Has anyone here had any porting work done?
Also I've seen a s3 cylinder and head for sale, is there any different with the s3 cylinder ?

 

[jimjim]

I had my 300 ported,have not ran it yet as in the process of resto.The shop that did the work said I should get 13-15 hp bump.I think the s3 jug is just a flowed and ported jug.

 

[(F5)]

That's like a 40% increase in power. Extraordinary claim. Would make it totally unusable as a dirt bike and require road race pipe. Bless them I think they got a bit carried away with the claims.

 

[jimjim]

That's like a 40% increase in power. Extraordinary claim. Would make it totally unusable as a dirt bike and require road race pipe. Bless them I think they got a bit carried away with the claims.

Its a gasgas 300 quad.I was tired of getting beat by 450s so I had them do a "drag port" which is supposed to be very agressive,combined with a Lectron,custom drag pipe and a major diet it should scoot good in the sand.As soon as its done I plan on taking it back to have it dyno tuned.

 

[(F5)]

OK then, that I'd believe, but not that useful to our man here.

 

[Capz85]

Sounds like a hell of an increase

Finally got a piston last night and put it in will squish test it tonight and see what's what, had a quick trail fit of the fresco pipe seems a half decent fit should bolt up with too much drama( hope I didn't speak too soon)

 

[(F5)]

Looks flash. Has to be pretty thick solder or it just won't touch.

 

[Elvis74]

I've seen a dyno chart from a bike for the German championship. This bike had about 46PS (I don't know he HP, I know it's different) on the rear wheel. It is not very much, but the graph was like drawn with a ruler.


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[Capz85]

Yeah I found that out last night, got to grab some later from a plumber friend

Also on bdc I have a few mm of piston visible on the exhaust port, whats acceptable or should it be fully clear?

 

[(F5)]

The bottom of the port is not the important part of the equation, although it is theoretically a waste I wouldn't compromise the closing timing (top) for any reason.

As a dirt bike I'd leave it where it is. As a sm or open track bike a couple of heads allowing for some experiments on the dyno with more duration (base gaskets) could be worthwhile for more top end. Possibly. Don't want to get transfers too high and the pipe will become a mismatch pretty quickly varying too far from std.

 

[Capz85]

I'm currently watching a 2013 s3 cylinder and head that's pretty cheap, might possibly get it, and have some work done to that, I did measure the squish earlier and it was 2.2 mm, the machine shop I was going to use let me down so I've put it back together for now, wayy more compression and no piston slap pretty pleased

 

[(F5)]

Did you ever read my thread ?


http://www.gasgasrider.org/forum/showthread.php?t=16560

The head is steeply angled so could be 2.2mm at the edge and 3 closer in.

But just getting the squish right will make compression wayyyy too high, needs to be done in conjunction with chamber reshape as well.