GS500EL backfire

[Diseasedfern]

Hey all this is my first post! I just bought a 1990 GS500EL off of craigslist I'm doing a total rebuild everything except for the engine. Just seeing if anyone knows why I'm back firing. It has a yoshi slip on and individual air filter pods. As for carbs I'm gonna start cleaning them out but I'm not sure if the person before me jetted them. I am planning on using a K&N dual flange air filter and changing out the gear ratio to more of a canyon riding setup and jetting the carbs to a stage 3. Let me know if you have any guesses on the backfiring. Am I running too lean?

[Huff1371]

Uh....what's a "EL" its probably just a "E". Not trying to sound like a duck. Welcome to the forum.

[Higgins13]

Hey all this is my first post! I just bought a 1990 GS500EL off of craigslist I'm doing a total rebuild everything except for the engine. Just seeing if anyone knows why I'm back firing. It has a yoshi slip on and individual air filter pods. As for carbs I'm gonna start cleaning them out but I'm not sure if the person before me jetted them. I am planning on using a K&N dual flange air filter and changing out the gear ratio to more of a canyon riding setup and jetting the carbs to a stage 3. Let me know if you have any guesses on the backfiring. Am I running too lean?

What do you consider a canyon riding gearing? more power or more fuel economy?

[Funderb]

most importantly: Define backfiring.
in the carbs or in the pipe (muffler)

[weedahoe]

My vote are the carbs. Pull, drain, clean throughly and tune them........and change the plugs

[Dizzledan]

REEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE jet

Welcome to the forums!

[Diseasedfern]

Thanks guys for the input. Btw Huff according to the Haynes service & repair manual I have an EL model since it was produced in 1990. Anywho I went though the carbs today and found a couple things that might have been the problem. First off there was tons of rust in the float bowl area, secondly one of the springs had broken in half, and lastly the person who owned the bike before me jimmy rigged the jet needle w some washers that were cracked. So once I get it up and running I'll figure out if i fixed the problem. I can upload some pics soon of what I got going on. Now I've run into another problem does anyone know about installing a digital speedometer using a hall sensor?

Thanks again I really like how helpful this forum is. 

[007brendan]

It's probably running lean.  Cleaning out the junk in the carbs and adjusting the mixture screws should help that.  Also, it should definitely be rejetted if it's go the K&N air filter and slipon.

Also, don't use the dynojet kit; I've heard they're a pain to tune and you have to drill your carbs.  Just get the larger jets from Buddha.

[Huff1371]

I'd say carbs . Talk to Buddha,  he's the guy who could probably use his GS mind-control fix ability to set you up good.

[bombsquad83]

I can hook you up with a new spring for the slide.  PM me if you are interested.

[jestercinti]

The above posts have covered the basics.  I'd also check the exhaust bolts and gaskets.  If not tight/a good seal, it will backfire.  However, most likely carbs.  Just be careful...exhaust HOT.

[mchollan]

If there was a bunch of rust in the carb bowl there is a good chance the tank is rusting on the inside.  If it is you can drain it and use something like http://www.amazon.com/Evapo-Rust-ER012-1-Gallon/dp/B001BO1DGY/ref=sr_1_2?ie=UTF8&qid=1348886291&sr=8-2&keywords=motorcycle+rust+remover

[Huff1371]

If there was a bunch of rust in the carb bowl there is a good chance the tank is rusting on the inside.  If it is you can drain it and use something like http://www.amazon.com/Evapo-Rust-ER012-1-Gallon/dp/B001BO1DGY/ref=sr_1_2?ie=UTF8&qid=1348886291&sr=8-2&keywords=motorcycle+rust+remover

Be VERY VERY Careful with evapo-rust. It reacts into a sludge that can be a PITA to get out. And if ANY remains it will destroy every gasket ans seal it touches (petcock seal, float bowl gasket, needle valve, cap vent seal, etc.) It does work good on getting rid of rust but then you have a nice bare metal surface ready for rust. There are better ways.

[mchollan]

If there was a bunch of rust in the carb bowl there is a good chance the tank is rusting on the inside.  If it is you can drain it and use something like http://www.amazon.com/Evapo-Rust-ER012-1-Gallon/dp/B001BO1DGY/ref=sr_1_2?ie=UTF8&qid=1348886291&sr=8-2&keywords=motorcycle+rust+remover

Be VERY VERY Careful with evapo-rust. It reacts into a sludge that can be a PITA to get out. And if ANY remains it will destroy every gasket ans seal it touches (petcock seal, float bowl gasket, needle valve, cap vent seal, etc.) It does work good on getting rid of rust but then you have a nice bare metal surface ready for rust. There are better ways.

Very good points.  Once you clean out the rust you are back down to bare metal.  You shoould coat it after that.

You can also use the "rock tumbler method".  Thats where you fill the tank with bits of broken chain, or rocks, or some other abrasive and rotate the tank around slowly for a while.  The idea is that the scratch and score the rust out from inside of the tank.  I have never done this because I'm terrified of getting something stuck in there, a friend of mine did it to a Ducati he traded for and it worked great.  He had much bigger holes in it from where he removed the fill cap and fuel pump though.

[BockinBboy]

I've heard of folks putting nuts in the tank for this 'method' ... Ended up with dents from the inside out.  Read a similar story on the forum even... It can work decently well.  Just don't get carried away with what you put in it.

- Bboy

[Huff1371]

I'm a fan of the electrolysis method. It can sound intimidating but it's not hard and it works really good. Yet again,  make sure you coat the inside afterwards.

[RossLH]

Uh....what's a "EL" its probably just a "E". Not trying to sound like a duck. Welcome to the forum.

'E' is the generation code, 'L' is the year code. '89-'00 were EK-EY respectively (EO, EQ, and EU were not used). '01-'08 are K1-K8 respectively, with FK5-FK8 being the F models from '05-08.

[Huff1371]

Yes, I am aware. Not really pertinent info considering the rev changes year to year.

[RossLH]

You asked what an EL was....I answered.

[Huff1371]

I was a little confused. Was hoping I didn't miss a model only available "not here". Then realizing the not so common use of year code, didn't worry about it but did not edit my post. My sincere apologies    (end flippant @$$hole rant)