Headers

[Horder]

What headers would you recommend for a 1340 with stage 1 cams and 40mm flatslides? Struggling to get the bhp it should have

[baldrick]

mine put out 174 bhp at the wheel with akrapovic system, a flowed head/cams and a set of fcr 39 keihins, if it helps.

[clivegto]

Hindle are good and our very own @gsxr884is a dealer for them. 

[wraith]

What system have you got on and what are you expecting to get RWBH ?

Take it with that size of big bore, you've put bigger valves in as well

Edited September 11, 2025 by wraith

[Horder]

1 hour ago, baldrick said:

mine put out 174 bhp at the wheel with akrapovic system, a flowed head/cams and a set of fcr 39 keihins, if it helps.

Mines about 20 behind that! 

[Horder]

32 minutes ago, wraith said:

What system have you got on and what are you expecting to get RWBH ?

Take it with that size of big bore, you've put bigger valves in as well

I don’t think the valves are bigger tbh. I can ask the question tho. cant remember what headers they are. I’ll try to find out 

[clivegto]

1340 really isn't going to work without larger inlet valves and a flowed head to get the best out of it. 

[Horder]

1 minute ago, clivegto said:

1340 really isn't going to work without larger inlet valves and a flowed head to get the best out of it. 

Definitely port and flowed

[Horder]

44 minutes ago, wraith said:

What system have you got on and what are you expecting to get RWBH ?

Take it with that size of big bore, you've put bigger valves in as well

Think that’s the headers I got 

[wraith]

29 minutes ago, Horder said:

Think that’s the headers I got 

There not a bad system, more for mid that full top end power, if you're just wanting top bhp on a graf get a V&H sidewinder.

But a @clivegtosays, with that big bore and if you haven't got bigger valves in the head, you're just pissing in the wind

[Horder]

4 minutes ago, wraith said:

There not a bad system, more for mid that full top end power, if you're just wanting top bhp on a graf get a V&H sidewinder.

But a @clivegtosays, with that big bore and if you haven't got bigger valves in the head, you're just pissing in the wind

Appreciate the reply mate. Not after pure top end. I like the bike to move about a bit underneath me while I’m riding. Had a quick action throttle on the 1216 and that made it much more fun for me. Not sure how well that would work with the 40mm flats tho?

[baldrick]

40mil flats are too big for a 1216 but should work well for top end on a 1340. 

As said bigger valves will make the most of the bigger bore, and a better exhaust like an akrapovic or Yoshi will help release the missing horses. The keihin fcrs carbs made a big difference on mine compared to mikuni rs 36 flats, was about 8bhp more if I remember correctly 

Edited September 11, 2025 by baldrick

[clivegto]

1 hour ago, clivegto said:

1340 really isn't going to work without larger inlet valves and a flowed head to get the best out of it. 

I could correct myself hear by saying you could fit an air squasher to the bike to get more fuel and air in there. I like big bore Turbo bike's  

Well some one had to mention a turbo 

[Duckndive]

2 hours ago, Horder said:

I don’t think the valves are bigger tbh. I can ask the question tho. cant remember what headers they are. I’ll try to find out 

How was the 1340 done ? thats a stock block 

[Horder]

50 minutes ago, Duckndive said:

How was the 1340 done ? thats a stock block 

Yea. Stock block. 

[Duckndive]

57 minutes ago, Horder said:

Yea. Stock block. 

OK try again how was the 1340 done then ? 

[Gixer1460]

9 hours ago, Duckndive said:

OK try again how was the 1340 done then ? 

 Where the F*** is the popcorn smiley ?

[Horder]

9 hours ago, Duckndive said:

OK try again how was the 1340 done then ? 

You’d have to ask the bloke who bored it out! It’s possible to to you know! 

[Duckndive]

2 minutes ago, Horder said:

You’d have to ask the bloke who bored it out! It’s possible to to you know! 

Yes but the way you posted it sounded like you acquired the bike done  

So may not be what its supposed to be  

If its a 1340 you should be able to see the liners near the studs looking through the block from the front 

[Dezza]

To what extent have you investigated the actual spec of your bike? It may be that for its spec, the output of the engine is entirely as expected because the previous owner may have been 'economical with the truth.' I have always been led to believe that really large big-bores aren't that practical as road bikes due to the huge increases in  heat they make so is this consistent with the bike in question?

[baldrick]

1 hour ago, Dezza said:

To what extent have you investigated the actual spec of your bike? It may be that for its spec, the output of the engine is entirely as expected because the previous owner may have been 'economical with the truth.' I have always been led to believe that really large big-bores aren't that practical as road bikes due to the huge increases in  heat they make so is this consistent with the bike in question?

think this is more usual with big blocks as they have less fins/ surface area for cooling, so might not be the case here