Engine dies when I give it gas

[dogshoe21]

Hello Everyone,

I have a 1979 Honda trail bike called the XL185S. I'm new with bikes and decided to buy this as a project bike to work on. The stock exhaust was REALLY restrictive and there was rust inside the muffler and pipes so I got some 1" steel pipe and made an exhaust pipe that goes to a shorty 12" muffler and bolted that on.

Next I took it out for a ride and seemed to be ok but if I gave it too much gas, the engine would bog down. I then took it home and removed the stock intake thinking it was starving for air. So now its just an open intake tube that connects to my carburettor. So I'm currently looking for the right size of K & N style filter, but right now with no intake restriction or exhaust restriction, the bike will turn over and start but if I give it any gas, it just dies. Is this too much air flowing in? Do you think I need more fuel? If so, do I need to rejet or can I just mess with the air fuel ratio? Thanks for you help!

 

[IndyMX]

Hey Rich, got a live one here... :whoa:



Dude, there is so much wrong with what you just said..

Did you make a pipe that is the exact same dimensions as the old one?

As for the intake, you are going to trash the motor without a filter.

Once you get the proper filter, then you can think about jetting. Not until then.

Do you have too much air flow, I'd say it's very likely.

Are there a million other possible problems, sure. It's an old bike.

How fresh is the topend? Are the crank seals good? Are there cracks in the boot between the carb & the intake?

You need to sort out all of the mechanical's before you even attempt to get it jetted right.

 

[2strokerfun]

Are the crank seals good?

Indy: Isn't that a 4 stroke??
Take carb apart and clean very very good. Check valve clearance. Is your gas fresh? New plug?

 

[IndyMX]

Indy: Isn't that a 4 stroke??
Take carb apart and clean very very good. Check valve clearance. Is your gas fresh? New plug?

Errr.. so it is..

Still, even a brand new carb and fresh gas isn't going to make this bike run..

He's got all kinds of other issues to deal with first.

 

[dogshoe21]

to update my post, the bike ran flawlessly before and still starts on the first kick, but since I started making these changes it obviously has been running differently. The motor only has 3K miles on it, the carbs have been cleaned and the engine and everything else works fine. I rode this to work for several weeks with no issues. Now with the exhaust and intake changes of course its not going to run right, I only ran the bike for 3 minutes without the air filter on just to see if it still would run without all the intake restrictions. My question is can I modify the air/fuel mixture to have more fuel or do I need to jet up or both? So assuming a good running bike in good condition gets more air in the intake and more free-flow on the exhaust side, what else needs to be done?

 

[_JOE_]

It's not like that. If flow was all we needed from exhaust we would just take the pipe off completely. As you now know, just randomly whipping up a pipe will make the bike run WORSE.

 

[dogshoe21]

Anyone else have any other opinions, so far I'm not getting any substantial help, mostly demeaning conversation rather than advice...

Thanks,

 

[whenfoxforks-ruled]

You may need a blower, joking, a little! Attempt jetting?

 

[Ol'89r]

to update my post, the bike ran flawlessly before and still starts on the first kick, but since I started making these changes it obviously has been running differently. ?

You just answered your own question.

These guys have answered your question also. Maybe it was not the answer you wanted to hear? Nobody has demeaned you.

My advice is to buy a stock or aftermarket exhaust for your bike and quit trying to screw with something you obviously don't understand. Your intake and exhaust is 'tuned'. That means it is designed at a certain length and diameter to take advantage to the pressure impulses that your engine produces. If you change that length and diameter, you also change the way those pressure impulses react and you have changed the way the bike runs. If you can't find a new pipe for your bike then, duplicate the old exhaust system EXACTLY the same.

Now, if you want to be demeaned, we'll call Rich. :yikes:

 

[fatcat216]

[quote='89r]if you want to be de-meaned[/quote]
ol'8Niner-Is that anything like being de-loused? :whoa:

Dogshoe- you are asking for help on something hand made. I doubt you'll find exact answers- like raise the clip, blah blah blah....I know you want a recipe card. Don't we all.

There are some good sources of info on flow, pipes and jetting....if you really want to be creative about this. However, you really need to start with controlling the changes you made at the outset. You have too many variables to start with and a potential disaster on your hands.

Try searching the words pipes, flow, intake, and jetting. (Not necessarily together.) There are lots lots lots of unrelated threads that may help you brainstorm, and give you a good education (if you don't have it already) on how things relate to eachother. I started to put some out there for you, but they were pretty random. I was not sure that they addressed the gaps in your knowledge you were seeking to fill.

There are others who are better able to point you in the right direction on what you aren't grasping about your pipe/intake.

 

[zoommx]

Bottom line-the fuel delivery system is now way too lean. To correct this, the exhaust needs to be fabricated correctly and the intake needs to be corrected. Then the carburator will need rejetted. I would recommend a supertrapp exhaust and using as close to stock intake as possible. Those stock exhausts were sky high on the price back in the day and I'm sure if you could even find one now it'd still be very expensive. I had an 80 model, and it was not quite as cool of a bike as my friends XR.

 

[Circleburner]

Everything that has been said sounds good, but if your problem is money take a different route. Raise the needle as far as it will go, change the main jet at least five sizes and see how it responds. I'd leave the slow speed alone as it starts good and idles. If it runs better, keep going bigger on the main till it doesn't, then back up. If it runs on the main jet but stumbles in the mid range you will have to find a richer needle.
This isn't the right way to do it, it's just the cheap way......Good Luck