GT550 + Higgspeed: crud vs sealing the cylinder to exhaust

[jabcb]

I’m getting black crud at the GT550 Higgspeed to cylinder fitting. Have a GT380 with Higgspeed exhaust without problems.

Higgspeed uses the same headers for the GT380 & GT550. The header matches up nicely with the GT380 exhaust gasket & it was easy to get clean results.

The header doesn’t match up as well to the GT550 exhaust gasket. I used silicon seal as recommended. (Or perhaps more accurately as I thought was recommended.)
Am getting black crud. Any suggestions?

[Alan H]

Sounds like they don't nip up properly. Have you tried thicker sealing gaskets? Use genuine not after market seals.
I use ordinary silicone sealer for the slip joints on my 550A spannies and apply to both parts of the joint and let it go off before running the bike.

[jabcb]

Pics of the exhaust header. Header with the GT380 exhaust gasket is on the left. Header with the GT550 exhaust gasket is on the right. Both gaskets are genuine Suzuki parts.

I also emailed Higgspeed. They recommended putting more silicone seal around it. Will give it a try, but it's not confidence inspiring for an amateur mechanic.

GT-ExhaustHeader by jabcb, on Flickr

[daxman]

I wonder what would happen in you tried the (smaller) 380 gasket on the 550? Would it 'fall into' the exhaust port? Or how about a 'cut and shut' on the 550 gasket to make it slightly smaller in diameter, or trawl ebay for an intermediate size. Strikes me the crud/goo is leaking through a gap from using the small gasket.

[jabcb]

The GT380 exhaust gasket matches the lip in the GT380 exhaust port. Same for the GT550.
A smaller exhaust gasket on the GT550 would just make my problems worse.

The problem could be solved by welding a ring to the GT550 header so that the OD matches the GT550 exhaust gasket.
I don’t know much about welding, but I presume that I would need to tell a welder exactly what type of metal it’s made out of.
I told Higgspeed that they should consider doing this. I would have gladly paid an extra $50 for that to have been done.

[Willsy69]

Could they have sent you the wrong ones?

[jabcb]

The headers are correct. I emailed Higgspeed about it. From their explanation, they work fine if you properly apply enough silicon seal.

I had used red high-temperature silicon seal. It doesn’t seem to be very forgiving about filling a large gap between the header & cylinder.
Probably will try the clear regular silicon seal which is a lot more forgiving.

Alternatively, I think I can get them to make a set of headers that match up to the exhaust gaskets.

[Willsy69]

For the price they’re asking it seems like a bodge rather than them making the inner ring a larger diameter. I wouldn’t be expecting to start having to use gasket sealant on something this expensive.

[jabcb]

I totally agree.

But I understand their perspective. As a small business they went with a product/inventory simplification to have fewer header variations than exhaust variations.
Hopefully my inquiry will cause them to rethink this decision.


I do prefer Higgspeed’s use of short headers + springs over the bolted-up designs. It allows you to remove the exhaust without disturbing the header bolts/studs, which have a tendency to break way too easily.

[Willsy69]

I agree they do look good and it does get over the problem of any leaks between the header and expansion chamber on the two piece systems.
Hope you manage to get it sorted

[Alan H]

That's why I had slip on Abbeyspeeds made specifically for my bike and used standard pipes with (knackered) standard silencers cut off. https://www.kettleclinic.co.uk/kcforum/ ... &start=130 - since ceramic coated and still look good 5 years on - and page 22, same thread for ceramic coated pics and details where.
Personally, I don't like higgies. To me they aren't pretty with the 2 'corners' in each pipe, and just sound loud without the performance. (They sound fast though......)
There again, everyone likes something and whatever floats your boat.

[Macmenace]

If it’s one pipe flange leaking maybe excess pressure on the exhaust. Oily baffling? Something restrictive on that one pipe. Not sure if you can pull out baffles and check.