Help with re-jetting

[Spoon]

When I get some free time (i.e. when the mrs takes herself and the kids to the inlaws) I'm going to be fitting some new bits to the bike (650 k2), i.e.:

WRP titanium full system
BMC RS filter
Chewys tanks spacers
K3 cam swap

At the same time I'll be re-jetting using a JHS stage 2 DJ kit. Unfortunately haven't got the money to get it set up properly on a dyno so whilst I understand that its going to need a bit of tweaking I'm looking for some good baseline settings. After a bit of research I was thinking of:

1. We already have 17.5 pilot jets in the UK so no need to touch those
2. DJ needles 3rd clip from the top
3. 170(DJ) main jets
4. 2.5 turns of the A/F screws
5. Drilling the slide holes

Can anyone with a comparable setup let me know what you're running to see if I'm in the right ballpark or not? Cheers!

[northwind]

That's exactly what I have, down to the spacers :D I used a DJ stage 1&3 kit and added the bigger jets to suit. Unfortunately, I don't know exactly what's in it now, I've lost track- it's either 180 or 185 mains, which is bigger than I expected to need, and I think 2 and a quarter turns on the idle mix screws. No idea of the needle slot though, I think I have a half-step shim in though. I can check that out, though, I'll probably be in there over teh weekend checking out something else so I can easily drop the back needle out.

Now, how close to right it is I'm not sure- it's pretty close, but maybe not perfect, I ran it on the dyno then made 2 small tweaks (up a main jet, down on the idle turns) which we reckoned would get it right, but I've never done the final run to check as I'm thinking of changing end can. I reckon it's in the same margin of error as standard though, from the overall response.

Oh yeah, and it does have drilled slides, I did that previously with the Renegade airkit... And also still has the Renegade intake stacks fitted, though I have no idea if they're beneficial or not.

[Spoon]

Cool - thanks :D

If you do get a chance to take a look I'd be grateful for any more info. I'll try it with the 170 mains (the biggest that come in the DJ kit - I was assured would be sufficient) but it looks like I might have to go bigger then...

[northwind]

I started with 155s or thereabouts :rolleyes: When I phoned PDQ for the big ones, the guy said "Tuning a Firestorm I take it?" :D

[Jase22]

If you're in need of a set of 180s or indeed 185s I've got some in my DJ stage 1&3 kit which I won't use.

[Spoon]

Thanks Jase - a set of 180s would be good just in case I need to go that big - I'll send you PM

[northwind]

Right, just had a look- and before I tell you the answer, I'm going to tell you how much trouble you just caused, so you can be suitably grateful :D Took the back off the rear carb, nice and easy. Stupidly decided to remove the needle assembly by pushing the needle back instead of pulling out the retainer- retainer and spring pinged off across the garage. But that's OK, I heard them land in the lawnmower grass bin, so I took that out to check. Not in there. OK then, I'll take out the lawnmowers and look around there and CRASH! The handle of the lawnmower knocked over 2 big boxes of nails, which showered down over the mowers and barbeque. When people as me what I did at the weekend, I think I might miss this part out :smt120

Anyway! It has 180s, and the needle (standard dynojet) is set at the 4th slot up from the tapered end. Ever so slightly surprised by that, I thought it was on 3 and a half or 3, but I remember I tweaked it when I went up to the 180s, so that's probably why. I have to say, I'm slightly unconvinced by that setting, it doesn't make an awful lot of sense, so I would approach it with caution... I need to get this thing back on the dyno to be sure. I might try and get that sorted for the next couple of weeks tho.

[Dangerous Dave]

Good choice, but if you are going with the BMC RS and JHS stage 2 DJ kit I would opt for the JHS cams over the K3 cams any day!

[northwind]

I wouldn't, the price penalty doesn't justify it IMO.

[Spoon]

Cheers Northwind - sorry about the nails.

Things like that do my head in - my wife says its all down to karma and I'm being repaid for things I did in the past (before we met obviously ;)).

[Spoon]

Dave - agreed - but I'm trying to do this on a budget. I probably wouldn't have gone for the WRP system either as there seems to be very little info on it (apart from Northwind saying its OK), but I got the K3 intakes for ?50 and the WRP system for just over ?100 so the decision was easy :D

[northwind]

Yeah, that's why I chose the WRP too :) Both of mine cost less than a typical slipon. They do work decently enough though.

[TheStudent]

What sort of gains would this work give?

Tom

[northwind]

Mine was just under 80bhp when it was last run (on a racebuilder's dyno, not a flattering dealership one :mrgreen:), with the bigger mains it might just have tipped over the 80. 68 on that same machine was my stock figure. It also revs out more strongly, ie doesn't drop off in power as hard after peak. It's not massive- it never really feels like anything other than a stronger SV, and you're never going to think "Ooh, that's incredibly powerful". But compare it back to back with stock and it's very noticable in pure rideability stakes.

[yorkie_chris]

How much difference is there between the intake cam swap, and the K3 cam swap?

Dave, I'm sure the JHS cams are better, but not at that price!