Exhaust and gas leaks

[Parrydise7]

I just bought a 1986 250R that hasn't had much maintenance in awhile. I did a search but didn't find anything helpful. I've got two problems: 1. an exhaust leak and a gas leak.
I can't get the exhaust pipe to seat square on the exhaust flange. I've pulled the exhaust several times. I attached the flange to the head and then attached the exhaust. That didn't work, so I attached the flange to the exhaust and then bolted it to the head. That didn't work either and each time the exhaust ends up cocked on the flange and I have a leak. The flange and the exhaust are probably worn, so I'm assuming I have to replace one or both. Do I need that billet aluminum flange, (it's cheaper than an oem flange) or, can I use high-temp RTV?
The second problem is that gas seems to be leaking out of the overflow tube when the trike is sitting flat on the garage floor. Any recommendations?
Thanks!

[Red Rider]

The billet exhaust flanges with o-rings work great! It sounds like your flange is a stock one. Is it missing the expandable, spring steel ring that seals against the inside of the pipe? The stock flanges don't leak that much if installed properly. To install it properly, the ring gap needs to at the top when you slide the pipe over it. As for your gas leak, it could be that your floats are out of adjustment, or most likely, something is just causing the float seat to not seat properly, which is allowing too much fuel into the float bowl, which then has no place to go except the overflow tube. It could be a worn float seat, or most likely, a grain of sand that's causing it to not seat properly. An inline fuel filter will prevent any further sand particles from entering the carb.

[Parrydise7]

Dear Red,

The flange is stock. I bought a replacement spring steel ring, and new gasket, but I've probably got the spring steel ring installed improperly. I will pull it and put the gap at the top.

I will also check the float. By the way, how do I do that?

Thanks, again.

[Red Rider]

First off, I assume we're dealing with a Keihin carburetor, am I correct? To accurately check the float level, it takes a special Keihin carburetor tool that's calibrated for the carburetor. Before automatically suspecting the float level, try this first.

1.) Turn the fuel tank petcock to OFF.
2.) Remove the float bowl drain plug on the bottom of the carburetor's float bowl.
3.) If there is a lot of sediment inside the plug, I would suspect that there is some debris that is interfering with the float seat. (An inline fuel filter should cure your problem)
4.) When reinstalling the float bowl drain plug, just cinch it up until it stops turning. It has an o-ring that will seal the drain nicely without excessive torque. Tightening it too much will definitely strip the threads on the plug or the carburetor.

[Parrydise7]

Dear Red,

Yes, it is a Keihin.

Thanks for the info, I will give it a try.

Is Clymer the best repair manual? (Sorry to be a pest, I'm new to this).

Thanks.

[Dirtcrasher]

OEM copy is the best repair manual. A carb rebuilt kit (moose) will most likely fix the gas problem along with a thorough cleanign after removing all the jets.

Is it possible that the exhaust is either bent or using the wrong mounts somewhere which isn't keeping it parallel to the flange whn bolted up??

[Red Rider]

I've never looked through an OEM Honda repair manual, and I'm sure they probably have more technical info than a Clymer manual, but my Clymer manual has served me quite nicely for 18+ years, guiding me through 2 complete teardowns & rebuilds of the frame, as well as splitting of the cases and going through the transmission.

Dirtcrasher brought up an interesting possibility on why your pipe isn't mating to the flange correctly. It could definitely be incorrect, or improperly mounted, expansion chamber mounts. Even the mounts on the silencer/spark arrestor can affect the angle of the expansion chamber. Is the expansion chamber/silencer stock or aftermarket?

[Parrydise7]

I just went outside to see if anything looks bent. Not that I can tell and replacing the gasket and piston ring like thing reduced (but did not eliminate) the amount of blow by. And, I did not have the piston ring thing with the gap at 12:00 (right?) so I'm going to go outside and try that now to see if it helps.

It has a Paul Turner exhaust on it (is that the expansion chamber?). Is that factory original?

BTW, I greatly appreciate your help. I just got it about a month ago.

[Dirtcrasher]

No, PT is a nice Aftermarket pipe.

Take off that flange, mount the pipe solid to the frame mounts. If you measure from the pipe flange to the cylinder all the way around it should be even. I'm willing to bet it's tipped just a bit, one way or the other and it should also be fairly centered without the flange pulling it in.

Lots of times aftermarket exhausts don't mount up just right and people make there own brackets or spacers but regardless, it has to get that flange in the right spot.

[Red Rider]

I did not have the piston ring thing with the gap at 12:00 (right?) so I'm going to go outside and try that now to see if it helps.

That's correct. The ring gap should be at the 12:00 position. If the pipe is not sliding all the way onto the flange squarely, more than likely it will leak gooey oil gunk, which by the way is the scientific term for what you are experiencing. You're welcome for all the help. I'm an original 250R owner for 21+ years, so I've seen a lot of the things you're going through & will go through. Good luck.

[Parrydise7]

I checked with Helm and the factory shop manuals are not available, so Clymer it is.

I pulled the gasket (it looks like lead covered brass or copper) and the ring. Isn't the ring supposed to go in second after the gasket? For some reason the gasket was on top (I had to pull it out first) and then the ring. The gasket is pretty beat up so I'm going to put a new one in and then try what you've recommended above.

I pulled the drain plug from the float chamber and did not notice any sediment. Since the bike has been sitting for some time, I guess it is time for a carb rebuild.

Okey dokey Red and Dirt. I appreciate your help. I hope my bike looks as good as yours one of these days. Thanks, again.