Red Hot Exhaust - SV650.org

03-01-05, 07:35 PM

Need help! My son was in a minor accident with his 2001 SV650S. Most damage was to fairing, speedo and lights. I've replaced all damaged parts and need some help. I started the bike up last week for the first time in 2 months. I noticed that when I rev the bike to around 3000 RPMs that the exhaust down-tubes off the front cylinder gets red hot. I don't remember this happening before. What could the problem be?? The bike seems to be running fine but don't want to damage anything until I get this fixed if needed.

03-01-05, 07:46 PM

Sorry - stupid question here:

When you say "red hot" do you mean this literally?

It is perfectly normal (as you know) for downpipes to get hot - they will be the hottest external part of the engine/exhaust. But getting "red hot", i.e. glowing, is not

03-01-05, 08:20 PM

Don't worry about it! There is no airflow when the bike is standing still. I've had mine glowing cherry red in the garage.

03-01-05, 08:31 PM

They all do this. Tis no biggy. Like scoobs says the lack of airflow means they don't cool as usual.

If you ever get the chance to watch a bike run on a dyno they can get fairly warm

Whilst were on this subject, dont run your bike too long on choke if you have a bellypan fitted. My old man had a Tl1000S in the garage once, and due to the overly close fitting of the bellypan and the hot front downpipe, there was a slightly soft bellypan

. Just something to be aware of.

Dan

03-01-05, 08:48 PM

Quote:

Originally Posted by Dan_SV

Whilst were on this subject, dont run your bike too long on choke if you have a bellypan fitted. My old man had a Tl1000S in the garage once, and due to the overly close fitting of the bellypan and the hot front downpipe, there was a slightly soft bellypan

. Just something to be aware of.

Noooo! I didn't do that either!

03-01-05, 08:49 PM

03-01-05, 09:08 PM

When I say "Red Hot", it gets to glowing red/orange". The radiator has been replaced along with other non-engine parts. I've checked for vacuum leaks around the carbs and re-checked the exhaust flanges. It doesn't do it at idle, only when I increase the revs. Choke is shut down right after starting. I'm going to have my mechanic check things out but I thought I'd start here to see if there were any suggestions.

Scoobs, does yours do it at idle or when revs are increased??

03-01-05, 09:11 PM

Um, I'm not a mechanic, and won't claim to be competent in this regard, but isn't it a sign of running lean when your downpipes get red hot so easily?

03-01-05, 09:29 PM

Er really guys this is normal. Mine does it when the revs are held at about 3000 for a while. The TL was similar too.

I can vouch that my bike isnt running lean, as im the son of a mechanic. I know that doesn't necessarily qualify me but I do have a fair idea. When I have pulled the plugs for servicing they are a nice healthy colour. The bike also runs a treat.

Also the TL couldnt run lean as it was completely standard and also in top notch nick.

You could take your bike to a mechanic but you would be chasing your tail.

I had never noticed it until one night I had left the bike on choke on fast idle before I went out, and then had to mess about inside for a bit. Anyway cut a story short, came out in the dark and the front pipe was glowing. Upon closer inspection so was the rear. I had never noticed it before until it was dark.

If anyone wants to say theres something wrong with their bikes go and start them, let them warm up then hold the revs at about 3-4 grand for a short while. Cherry downpipes for all.

As a final note though, if you do think there is something wrong, it will probably be incurable. So give me a ring and il be more than happy to take the salvage away for you............. :P

Dan

embee · 03-01-05, 11:49 PM

Yes, just to confirm what everyone else says, mine's a SK1 and it does it.

One of the reasons it's so noticeable on the SV is that the downpipes are very thin material, so the outside surface is nearly as hot as the inside. Many bikes used to have double skinned downpipes which is why they didn't discolour like more modern bikes' do.

Also it's partly down to relatively retarded (or at least not very advanced) ignition timing at these speeds and loads. Later ignition timing = higher exhaust gas temp.

Yours is probably OK.

03-01-05, 07:35 PM	#1
marshms Guest Posts: n/a	Red Hot Exhaust Need help! My son was in a minor accident with his 2001 SV650S. Most damage was to fairing, speedo and lights. I've replaced all damaged parts and need some help. I started the bike up last week for the first time in 2 months. I noticed that when I rev the bike to around 3000 RPMs that the exhaust down-tubes off the front cylinder gets red hot. I don't remember this happening before. What could the problem be?? The bike seems to be running fine but don't want to damage anything until I get this fixed if needed.

03-01-05, 09:08 PM	#7
marshms Guest Posts: n/a	Red Hot Exhaust When I say "Red Hot", it gets to glowing red/orange". The radiator has been replaced along with other non-engine parts. I've checked for vacuum leaks around the carbs and re-checked the exhaust flanges. It doesn't do it at idle, only when I increase the revs. Choke is shut down right after starting. I'm going to have my mechanic check things out but I thought I'd start here to see if there were any suggestions. Scoobs, does yours do it at idle or when revs are increased??

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03-01-05, 07:46 PM	#2
Jabba Guest Posts: n/a	Sorry - stupid question here: When you say "red hot" do you mean this literally? It is perfectly normal (as you know) for downpipes to get hot - they will be the hottest external part of the engine/exhaust. But getting "red hot", i.e. glowing, is not

03-01-05, 08:20 PM	#3
Scoobs Guest Posts: n/a	Don't worry about it! There is no airflow when the bike is standing still. I've had mine glowing cherry red in the garage.

03-01-05, 08:31 PM	#4
Dan_SV Guest Posts: n/a	They all do this. Tis no biggy. Like scoobs says the lack of airflow means they don't cool as usual. If you ever get the chance to watch a bike run on a dyno they can get fairly warm Whilst were on this subject, dont run your bike too long on choke if you have a bellypan fitted. My old man had a Tl1000S in the garage once, and due to the overly close fitting of the bellypan and the hot front downpipe, there was a slightly soft bellypan . Just something to be aware of. Dan

03-01-05, 09:11 PM	#8
Carsick Guest Posts: n/a	Um, I'm not a mechanic, and won't claim to be competent in this regard, but isn't it a sign of running lean when your downpipes get red hot so easily?

03-01-05, 09:29 PM	#9
Dan_SV Guest Posts: n/a	Er really guys this is normal. Mine does it when the revs are held at about 3000 for a while. The TL was similar too. I can vouch that my bike isnt running lean, as im the son of a mechanic. I know that doesn't necessarily qualify me but I do have a fair idea. When I have pulled the plugs for servicing they are a nice healthy colour. The bike also runs a treat. Also the TL couldnt run lean as it was completely standard and also in top notch nick. You could take your bike to a mechanic but you would be chasing your tail. I had never noticed it until one night I had left the bike on choke on fast idle before I went out, and then had to mess about inside for a bit. Anyway cut a story short, came out in the dark and the front pipe was glowing. Upon closer inspection so was the rear. I had never noticed it before until it was dark. If anyone wants to say theres something wrong with their bikes go and start them, let them warm up then hold the revs at about 3-4 grand for a short while. Cherry downpipes for all. As a final note though, if you do think there is something wrong, it will probably be incurable. So give me a ring and il be more than happy to take the salvage away for you............. :P Dan

03-01-05, 11:49 PM	#10
embee Member Mega Poster Join Date: Jul 2003 Location: Warwickshire Posts: 2,804	Yes, just to confirm what everyone else says, mine's a SK1 and it does it. One of the reasons it's so noticeable on the SV is that the downpipes are very thin material, so the outside surface is nearly as hot as the inside. Many bikes used to have double skinned downpipes which is why they didn't discolour like more modern bikes' do. Also it's partly down to relatively retarded (or at least not very advanced) ignition timing at these speeds and loads. Later ignition timing = higher exhaust gas temp. Yours is probably OK.