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| Change heads to Thunderstorm https://www.ukbeg.com/forum/viewtopic.php?f=7&t=24362 |
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| Author: | ogri211 [ 04 May 2020 11:16 ] |
| Post subject: | Change heads to Thunderstorm |
I have been gradualy as recomended by various people on this site been upgrading my 1996 S1 Lightning. I fitted a Mukuni HRS 42 and the bike runs lovely with it for the very small shot I have had during lockdown, My question is has anyone done a straight swap of heads and pistons from standard to Thunderstorm, and if so what is the difference in performance? I knows these heads are like hobby horse poo , but they do come around from time to time, is the upgrade worth the expence and how much would you be expecting to spend to do it? I belive the cams in my model are similar or the same as the X1 and the WL, but my bike has a very low milage and runs great so would I be best just leaving my top end as is. Also what other heads and pistons have people been using? Thanks in advance. |
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| Author: | ursus americanus [ 04 May 2020 11:43 ] |
| Post subject: | Re: Change heads to Thunderstorm |
You can't rely on me for technical guidance but, as someone who was selling the S1 Lightning and then the S1W White Lightning with Thunderstorm heads when it was introduced, there was a claimed increase of 10 BHP. Seat of the pants dyno agreed with this so when I had the opportunity to buy an ex-demo S1 or S1W there was no question. Still have the old girl now and she's acquired a few more ponies since. The Mikuni didn't add much in terms of power but great rideability straight out of the box. Steve |
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| Author: | 03 [ 04 May 2020 12:09 ] |
| Post subject: | Re: Change heads to Thunderstorm |
OP - You may find XB heads** perhaps easier to come across? They are considered possibly the best XL Sportster cyclinder head as stock. Also, they work just fine with the flat top pistons in a standard S1 motor. There's a few folks around who've done this swap. If you wish to do a little more research, Hammer Performance have a page plotting the history of XL Sportster/Buell heads from 1991 onwards. ** >04 to 07 XL Sportster heads are similar but black with highlighted fins. I used them on my '97 M2. One day soon, I hope to get it running again. HTH. |
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| Author: | ogri211 [ 04 May 2020 12:31 ] |
| Post subject: | Re: Change heads to Thunderstorm |
03 wrote: OP - You may find XB heads** perhaps easier to come across? They are considered possibly the best XL Sportster cyclinder head as stock. Also, they work just fine with the flat top pistons in a standard S1 motor. There's a few folks around who've done this swap. If you wish to do a little more research, Hammer Performance have a page plotting the history of XL Sportster/Buell heads from 1991 onwards. ** >04 to 07 XL Sportster heads are similar but black with highlighted fins. I used them on my '97 M2. One day soon, I hope to get it running again. HTH. Thanks is that from an XB 1200 there seems to be a few about I take it they have the larger valves but retain the original volume? |
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| Author: | 03 [ 04 May 2020 12:39 ] |
| Post subject: | Re: Change heads to Thunderstorm |
ogri211 wrote: 03 wrote: OP - You may find XB heads** perhaps easier to come across? They are considered possibly the best XL Sportster cyclinder head as stock. Also, they work just fine with the flat top pistons in a standard S1 motor. There's a few folks around who've done this swap. If you wish to do a little more research, Hammer Performance have a page plotting the history of XL Sportster/Buell heads from 1991 onwards. ** >04 to 07 XL Sportster heads are similar but black with highlighted fins. I used them on my '97 M2. One day soon, I hope to get it running again. HTH. Thanks is that from an XB 1200 there seems to be a few about I take it they have the larger valves but retain the original volume? XB9 + XB12 heads are the same thing. Worth a read - http://hammerperf.com/ttxlheads.shtml |
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| Author: | ogri211 [ 04 May 2020 12:43 ] |
| Post subject: | Re: Change heads to Thunderstorm |
Very interesting read it would appear that the most suitable heads are the XB which would only require the breather carb mount holes to be drilled and tapped, Thanks again for the info. |
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| Author: | 03 [ 04 May 2020 12:47 ] |
| Post subject: | Re: Change heads to Thunderstorm |
ogri211 wrote: Very interesting read it would appear that the most suitable heads are the XB which would only require the breather carb mount holes to be drilled and tapped, Thanks again for the info. Correct. Recommended to use XB rocker box covers/breathers. The deck height is lower on the XB heads but that's not an issue really. Also, one of the front motor mount bolts is moved inwards by around 1/4". Not an issue if you get the recommended billet front mount made. |
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| Author: | ogri211 [ 04 May 2020 12:57 ] |
| Post subject: | Re: Change heads to Thunderstorm |
Thanks, I think I will look out for heads, I allready have the billet mount but Im sure I could either modify it or someone from here could use it if I have to get a new one. |
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| Author: | x1glider [ 04 May 2020 15:32 ] |
| Post subject: | Re: Change heads to Thunderstorm |
That would be the only thing that would add much cost. The billet mount adapting to the XB heads can be costly be it is pretty. Other than that, you'll need a new ignition map. The original S1 from 96-97 had the same heads and camshafts as a S2 I had, N4 IIRC. On a Dynojet 150 inertia dyno, the S2 dyno'd at 72 RWHP. A Screaming Chicken ignition module set to map 4 brought that up to 81 RWHP immediately. Lightning heads were a little better as has been said. My stock X1 with basically the same cams as the N4 dyno'd at 89 RWHP, so the Lightning heads added about 8 RWHP but I'm sure some of that had to do with the fuel injection and a better map. And I've seen graphs of XB heads bringing another 3 RWHP over what other mods were done to a bike. But XB heads alone may lose something somewhere without a better set of cams and the right map. But everyone else is right that XB heads will be easier to find than Lightning heads. New old stock ran out 3 or 4 years ago and guys like Hammer Performance couldn't source them anymore. |
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| Author: | ogri211 [ 04 May 2020 17:20 ] |
| Post subject: | Re: Change heads to Thunderstorm |
Thanks , you are saying that the cams in my 96 are different from the X1 I thought all the S1's had the same cams, the ones similar to the N4, if that was the case and the XB heads were better that the TS ones that would leave just the ignition map, as there is no fuel injection, my question then has anyone stuck a set of XB heads on an early S1 and if so how good was it. |
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| Author: | x1glider [ 04 May 2020 18:55 ] |
| Post subject: | Re: Change heads to Thunderstorm |
When I say original S1, I meant the tube frame not the fuel in frame XB-S. XB cams are different...more lift and narrower lobe timing for EPA but reducing valve overlap. Being taller and narrower, I hear clatter at higher rpms if you play there. The S1 cam should be the same as an X1. When I got my 1st X1, it was a 2000 and the cam was a different part number than 1999. But I think the lift is similar but I don't know for sure if any of the profile and timing is any different. I've never seen a spec sheet on the cam. I've always used the SE536 in my bikes mainly because I built a Pro-Thunder spec bike once and liked how they felt. The Thunderstorm heads were built with using these in mind for the Pro-Thunder race series, so, it really wakes up the engine. |
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| Author: | 03 [ 05 May 2020 01:17 ] |
| Post subject: | Re: Change heads to Thunderstorm |
ogri211 wrote: Thanks , you are saying that the cams in my 96 are different from the X1 I thought all the S1's had the same cams, the ones similar to the N4, if that was the case and the XB heads were better that the TS ones that would leave just the ignition map, as there is no fuel injection, my question then has anyone stuck a set of XB heads on an early S1 and if so how good was it. Don't worry, they're a bolt on addition. No need to do anything with camshafts or ignition. |
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| Author: | ogri211 [ 05 May 2020 08:27 ] |
| Post subject: | Re: Change heads to Thunderstorm |
03 wrote: ogri211 wrote: Thanks , you are saying that the cams in my 96 are different from the X1 I thought all the S1's had the same cams, the ones similar to the N4, if that was the case and the XB heads were better that the TS ones that would leave just the ignition map, as there is no fuel injection, my question then has anyone stuck a set of XB heads on an early S1 and if so how good was it. Don't worry, they're a bolt on addition. No need to do anything with camshafts or ignition. Thanks Thats what I want to hear sometimes on these forums you get to much info. |
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| Author: | ogri211 [ 05 May 2020 09:25 ] |
| Post subject: | Re: Change heads to Thunderstorm |
There seems to be a lot of rear heads for sale is there a reason why there are more of them about? |
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| Author: | TOPGUMM [ 05 May 2020 09:46 ] |
| Post subject: | Re: Change heads to Thunderstorm |
If you have a crash, the engine mount rips the bolt out of the front head. Bolt can work loose and feck it that way too. |
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