V&H Chrome Megaphone... do i really need to rejet?

[lehrin]

I just got a stock '82gs1100e, its 9/82 so it's actually an ED, black motor etc. First I have to take care of the bad compression issues :? psi: 120-70-90-120... rings may be stuck, I'm trying some Marvel Mystery Oil for now but will tear apart the engine if I need to. It only has 16k miles on it, and it's gorgeous. Anyway, I want to get a header. It's mostly a commuter bike, I'm a student, but i like the 4-1 sound and weight loss, so I'm just thinking I'll get the V&H Chrome megaphone, and I want to know how much of an issue rejetting will be, if I make no other mods? DennisKirk says "rejetting recommended for maximum performance."
Thanks,
-Lehrin

[lhanscom]

You can try not rejetting, but be prepared to need too. I expect you'll need to put a stage 1 in it, I would probably just buy the kit (@ $35 you can't lose). It's easy to put in, and will probably make your life easier.

[Jeff Tate]

I agree with the above. Just make sure you get ALL other engine issues sorted (tune-up) out before doing any carb work or you may end up chasing your tail.

[Anonymous]

Dennis kirk recommends rejetting for all aftermarket exhausts. I went to a 4 int 1 and didn't have to jet, but I used a mac system. (close to stock replacement). V n H is usually geared toward performance, and jetting will be necessary for a performance system. If you're looking to go lighter with a better sound, and not jet, kerker and mac both make systems that shouldnt require a jet kit, I think jardine makes one too. Good luck, Dominick.....

[Anonymous]

I always recommend a check about mixture whenever something is modified on a bike. Most common if u replace an exhaust and/ or put in another filter is that the engine runs leaner than before. Maybe not always an issue but who knows? If the bike runs too lean, as a friends GS1100 did, that can result in different types of problems. As in my friends case, he runs a -83 GS1100 that had a Megaphone and KN-Filter. At 48000 miles the engine needed a rebuild. So he bought a cylinder with 1135cc Wiseco pistons, a set of Mikuni Smoothbores and was planning on sending away the cylinderhead for change of valveguides and bigger valves+ portingjob when he was at it. But the firm who was supposed to do the job checked the head and said that it wasn?t anything to do since the head was full of small cracks between the sparkplugholes and the valveseats, cracks that?s about 1cm deep. With a fat chanse that the valveseats could fall off resulting in total damage.
All this because the carbs had original Main-jets.
So he had to get another head instead since that was cheaper than welding and rework the old one. So don?t just think that a KN and a 4-1 works as bolt-on, it needs adjusting in most cases. Not always, but who wants to take the chance? Not me anyway......

[lehrin]

You can try not rejetting, but be prepared to need too. I expect you'll need to put a stage 1 in it, I would probably just buy the kit (@ $35 you can't lose). It's easy to put in, and will probably make your life easier.

Where do I find one? All the ones I can find are $100+ on DennisKirk, BikeBandit, etc.

[lhanscom]

https://secure.oc-net.com/ecomm/kn/jf.cfm

[Pillage]

Thanks!

Thanks for the information Guys,
I just ordered the V&H Mega and the K&N jet kit. I can't wait to get them installed and dialed in! I'm thinking about getting pod style air filters as well; any thoughts? 81 GS1000GLX

[lehrin]

As for the K&N jet kit, I just ordered a replacement polyurethane foam air filter from JC Whitney, not K&N... will this make a difference? Should I return it and spend the extra few $ on the K&N filter?

[Anonymous]

Rejetting YES Carb Sync YES Valve Adjust YES

Make sure you do the valves and carb sync FIRST and like the others say, "get it sorted out or else chase your tail."

These bikes respond really well to carb rejetting with a nice pipe.

You will be very happy with the results.

good luck.

Patrick