2003 750 Katana Hot Exhaust Issue

[kaptainkid]

Hey Everyone,

So over the past weekend I took off my fairing and discovered a few problems with my 2003 Katana 750.
8600 miles, 2003 750 Katana everything is stock California model.

Can anyone check your back fender and let me know if you have the same problem. Honestly I would had never noticed the problem because the back fender is always hidden under body fairings. Most people don't ever look under there.


1st I attached a off switch to the electric fan since I heard only the California emission Katana's have a fan.
I usually run with the fan off, since I've read it prevents vapor lock on the bike. I suspect it does more than that.

1st problem I noticed I was losing power driving on the highway. Full tank so I know it's not low on gas.
Noticed the rubber fuel line was twisted and super rubbery. As if the heat was breaking down the rubber fuel line. I replaced the fuel line with a new rubber hose. Running fine now.
2nd I noticed the front fender closest to the exhausted was melted badly. So badly that the fender was melted and warp. The paint was bubbled. I do not have any exhaust leaks so I'm guessing it's strictly heat from the exhaust. I spoke to a few motorcycle riders and mechanics. 1 person had gixxer and changed out the exhaust and it started to melt his fender. Mechanic say it's common problem showing on older bikes with 40k and it's sign of age and shouldn't start on a bike with 8600 miles. Honestly he wasn't a Suzuki mechanic but should be informed. I ride the bike in warm weather and I'm in a lot of Los Angeles stop and go traffic.

Has anyone else has problems with melted fender and fuel line?

[steves]

if the fender got hot enough to melt/bubble, you had something going on for sure, just not sure what.

You could be running too lean, or sitting at idle too long in stopped traffic.

The carb fans will do nothing for this....

[92xjunker]

+1 for sure.

[kaptainkid]

Here is some photos.. It doesn't look too bad but still a surprise.

What do you guys think? Am I'm over reacting too much?

[92xjunker]

What temps are you riding in. 100+ will do that, been there. A jet kit helped as did the advancer.

[kaptainkid]

I don't ride in 100+ temps that often but the previous owner might have. He lived in the valley and I know it's 100+ there easily all summer long. I put on the last 2500 mile but I do find my self 100+ once in while during stop and go traffic some days.

[maniac1886]

I thought the advancer leaned out the mixture.... thus more heat.... maybe im wrong. But from my understanding, the california models do run lean and therefore hotter. If I were you, I'd bypass the california emissions crap, jet it, adjust the fuel air mixtures screws to richen it up a bit.

Also, letting it sit and idle for a long time generates tremendous amounts of heat. Keep that baby moving, or shut the engine off.

[kaptainkid]

We'll I not sure if I want to pull the emission stuff off just yet. I know it really doesn't sever any purpose except for gas fumes and carbon canister crap. I know hose goes back to the tank some how. I've taken the Emission stuff off my klr but that only had 1 carb and I don't want 4 carbs out of tune.. Sounds like huge headache to me. I might want to rich up the fuel mix. 1/2 a turn each i'm guessing?

I thought the advancer leaned out the mixture.... thus more heat.... maybe im wrong. But from my understanding, the california models do run lean and therefore hotter. If I were you, I'd bypass the california emissions crap, jet it, adjust the fuel air mixtures screws to richen it up a bit.

Also, letting it sit and idle for a long time generates tremendous amounts of heat. Keep that baby moving, or shut the engine off.

[steves]

Advancing the timing may slightly increase the cylinder temps, however the bikes in the rest of the world (including canada I think) already run with the 2* advance from the factory. Retarding it in the US market was for emissions.

The purpose of the PAIR system is to draw unburnt fuel vapors from the exhaust and direct them back into the airbox where they have another chance to get ignited and burned off.

The fans on the carbs are designed to help cool the carbs off after running. What I mean to say is- the carb fans shouldn't be running during normal operation. They are designed to reduce the amount of fuel vaporizing when a hot bike is turned off. I heard from anecdotal evidence that a 60's mustang is a worse polluter sitting in a parking lot on a hot day with the fuel burning out of it's carb then when it was running.

[Mel Wainwright]

It could be that the front suspension has sagged with age bringing the fender into close contact with the exhaust header causing the melting. Hold the front brake on and rock the bike forward and check the clearance between the header and fender (you might need to have a friend help you do this)

[kaptainkid]

Look what I found on CL....

http://palmsprings.craigslist.org/mcy/4980891670.html

[92xjunker]

Should I say it or let someone else say it...

[kaptainkid]

Are you replacing the Kat? I totally want 2006 GSXR but since it would cost more I would take it out less. Honestly, I really don't care too much about the Kat and I can leave it anywhere and no one ever takes a second look at it or wants to steal it. That's up side of Sport tourer tea cup. My bitch is "ugly black betty" and it's great for work commuter and little twisty on the weekend.

[kaptainkid]

Here is interesting information I just found about the heat issue with my engine and exhaust.

1st let's start off when my bike was built and for where?
A. It's California model with smog emissions
B. It was designed to run on 100% gasoline with no/ethanol mix.
2003 750 Katana
2nd Ethanol is proven to break down faster and dissolve plastics and rubber.
A. My rubber fuel line became very rubbery and couldn't hold solid form. It so rubbery the bike died on the highway at speed.
3rd I thought the heat from the engine was breaking down the rubber hoses. I've read through other forums ie: Hot rods, Boats, classic cars were all having problems with Ethanol wreaking havoc in engines.
4th I just replaced my fuel line with heavy duty fuel injector 1/4 inch line because it was last longer.
5th My petcock was just rebuilt this past weekend and I noticed all the rubber in the petcock was gone. I just replaced my petcock on my 2001 KLR too. Both California models 16k on klr and 8600 katana. It was an eye opener how bad this problem is. I wonder if my 2002 Pathfinder is having rubber line issues too? I guessing ethanol is breaking down rubber around 10-12 year mark.

Conclusion was my engine running hotter stock? Was anything wrong with my factory set up? No with regular gas in some states; Yes in California Ethanol mix. Out come bad fuel lines, hotter exhaust and lost of power and poor gas mileage. I was getting 25 mpg city driving and 45-50 highway. This seems very low compare to other kat riders from other states.

My next project is to pull the emission stuff off and rich up the fuel mix. It's the cheapest and correct solution for this stupid ethanol problem...

Honestly I hope this helps out other riders who might have the same problem and who is scratching their heads about there similar issues.

[dnelli]

Here is interesting information I just found about the heat issue with my engine and exhaust.

1st let's start off when my bike was built and for where?
A. It's California model with smog emissions
B. It was designed to run on 100% gasoline with no/ethanol mix.
2003 750 Katana
2nd Ethanol is proven to break down faster and dissolve plastics and rubber.
A. My rubber fuel line became very rubbery and couldn't hold solid form. It so rubbery the bike died on the highway at speed.
3rd I thought the heat from the engine was breaking down the rubber hoses. I've read through other forums ie: Hot rods, Boats, classic cars were all having problems with Ethanol wreaking havoc in engines.
4th I just replaced my fuel line with heavy duty fuel injector 1/4 inch line because it was last longer.
5th My petcock was just rebuilt this past weekend and I noticed all the rubber in the petcock was gone. I just replaced my petcock on my 2001 KLR too. Both California models 16k on klr and 8600 katana. It was an eye opener how bad this problem is. I wonder if my 2002 Pathfinder is having rubber line issues too? I guessing ethanol is breaking down rubber around 10-12 year mark.

Conclusion was my engine running hotter stock? Was anything wrong with my factory set up? No with regular gas in some states; Yes in California Ethanol mix. Out come bad fuel lines, hotter exhaust and lost of power and poor gas mileage. I was getting 25 mpg city driving and 45-50 highway. This seems very low compare to other kat riders from other states.

My next project is to pull the emission stuff off and rich up the fuel mix. It's the cheapest and correct solution for this stupid ethanol problem...

Honestly I hope this helps out other riders who might have the same problem and who is scratching their heads about there similar issues.

Sounds like you need to move outta Cali bro...