85 Honda 250sx clunking noise

[Dustin96]

Hi everyone hope someone can help me with my issue. I just bought a 1985 Honda 250sx it ran and drove great for about 15mins but now I'm hearing a clunking sound in every gear besides neutral and reverse? If you got any ideas it would be greatly appreciated.

[Name Brand]

Mine made some popping noises before my differential broke. The 1985 SX is not sealed as well as other years and water will get in and do damage.
Open up the cap on the rear differential with a 17mm and check the fluid. Look for water intrusion, metallic particles mixed into the fluid and of course chunks of gear or bearing. It's probably best to drain that fluid and change it even if everything looks ok. Use a little magnet on a stick tool and see what you can pick up. If there's any chunks, then it's time for a rebuild. I believe their were a few members here do rebuilds if you can't locate a replacement differential. Once it's back together raise all those vent lines as high as possible on the machine.

[Dustin96]

Well I checked the fluid all seems good in there no water.Then I removed the swing arm and took the back cover/gear part off the "side gear" as I've seen people call it and all those gears look good to. But can hear the noise spinning the gear that's on the shaft that runs threw the motor so bad bearing in the side gear then??? Not sure if there's something else it could be since all gears work good just makes the bad clunking noise.

[Dustin96]

Anyone??? Sorry just trying to get this thing fixed.

[atc007]

Trace the power back from the engine. Do NOT pull the 90 degree output shaft out of the engine. Your universal joint may be bad , but good money is still on the pinion bearing being bad. Google search is your friend. There is tons of information about theses problems.

[Dustin96]

I have the swingarm removed and still hearing the sound it's for sure coming from something in the motor.

[Dustin96]

I'll post a video in just a little bit so you can hear the sound.

[Dustin96]

Here's a video of the noise. Sorry I didn't upload it directly here but Photobucket wasn't working so I had to use YouTube. https://youtu.be/pWmXru8QrXQ

[atc007]

Were you spinning the output shaft by hand there? Either way, you have some tearing to do :). My guess,,,would be someone pulled that shaft out and you have washers at least missing,maybe more. The one sound was really bad,but I couldn't make sense of what you were doing there.

[Dustin96]

Sorry had to hold my phone close to the output so you could hear it but yes I was spinning the output by hand.

[Dustin96]

Sucks it makes that nasty noise, got it on a great deal for my area ($150) and all the plastics are in great shape and everything works besides that nasty sound.

[Dustin96]

I did order a guaranteed usable condition complete output gear box, I seen some people say you can change that without splitting the cases if you push it out from the other side with a rod/pipe or similar diameter?

[atc007]

NO!! If you are going to pull it, you lay the bike on it's right side,kickstarter down. And pull straight up out, there WILL be washers left freefloating and they may fall. I have pulled the change off twice,one TRX and one SX. I have never seen an output fail,or make noise. Good luck !

[fabiodriven]

Ordering parts when you don't know what is wrong is not going to fix your bike. You can post and post and beg for the answers, but there is only so much we can do on this end. You have to dig into this and figure it out. I'm not saying the gearbox you ordered isn't going to fix it, but you're just guessing.

[Dustin96]

I'm not begging for the answers I was just posting to see if someone had a similar sound. Since when I googled other people's issues didn't sound the same as mine. Thank you atc007 for the help I really appreciate it.

[fabiodriven]

I understand your search for answers and help, it can be frustrating, but ultimately you have to dig into it to see what's going on.

[atc007]

Upon further thought.. I do suppose,if you pull the clutch cover,and have a dowel very close in diameter to the counter shaft, you could fish it through the kick starter and follow the CS out ,capturing all of the gears and washers . Either way,seems to be one i haven't run into... The worst noise in that vid halfway through,sounded like a bad rod.. But the rest , I couldn't make sense of. Keep us posted please.

[Dustin96]

I will keep your posted for sure, that different side gear comes in today so I'll try to get it installed without loosing parts in the case. If that don't work then guess I'm pulling the motor and digging in.

[Dustin96]

Well found the issue :( http://i1169.photobucket.com/albums/r507/mudmower16/Mobile%20Uploads/IMG_20170420_123124113_zpsellqnv7d.jpg (http://s1169.photobucket.com/user/mudmower16/media/Mobile%20Uploads/IMG_20170420_123124113_zpsellqnv7d.jpg.html). http://i1169.photobucket.com/albums/r507/mudmower16/Mobile%20Uploads/IMG_20170420_123129460_zpsneb81mkd.jpg (http://s1169.photobucket.com/user/mudmower16/media/Mobile%20Uploads/IMG_20170420_123129460_zpsneb81mkd.jpg.html)

[atc007]

Ouch........:(

[Dustin96]

Well going to try to sell one of my parts Yamaha tri Moto's so I can afford the parts to fix the good ol 250sx, is there any specialty tools I need to split the cases?

[fabiodriven]

Criminy! See what you can find with a little digging? I have a spare bottom end here that needs to go. Where do you live?

[Dustin96]

I live in southeast Iowa but pm me maybe we can figure something out.

[Dustin96]

Does anyone know if the transmission gears are the same between a 85 250sx and a 87 250sx?

[atc007]

Tope ends are the same if you sit your cylinder on up on the cases.

[Dustin96]

I found the gear set I need but it's from a 87 so wasn't sure if it would work in my 85 bottom end or not.

[Dustin96]

Well selling my parts Yamaha tri Moto, so should be ordering the parts for the 250sx tomorrow, I will update you guys as soon as I get them installed and tested.

[Dustin96]

Parts should be here the end of this week. So hopefully will have the ol girl going again by Monday or Tuesday :)

[Dustin96]

New gears in and everything's back together,as long as the rain holds off tomorrow I should be able to install it and fire her up :)

[Dustin96]

First try was a fail, but I got it together for the 2nd time and will try it again as soon as Iowa decides to stop being the tropical rain forest and raining every single day.

[Dustin96]

2nd attempt also a fail :( , but I'm not giving up yet I'll figure this damn thing out one way or another.

[Dirtcrasher]

Not sure where it is but I posted all about this issue a dozen years ago on the old board. I had bought an 85 250SX and it would jump out of 1st gear; Then I called him and he said he pulled those 3 bolts to fix a boot (Honda should have used a torxs screw there to help people think).

Anyhow, go to Partszilla make the gearshaft diagram big and print it out.

The 1st thing that goes in is the "1st gear thrust washer", thats what the guy had left in the bottom of the cases from the one I bought.

Use grease to hold things together whilst keeping it perfectly horizontal and just start assembling. Grease is key.

Make CERTAIN you line up all bushings with oil holes in them with the oil holes in the shaft itself. This is a great example of why everyone should use the free online service manual and read it while you take a poop everyday :lol:

To fish out the 1st gear thrust washer, I took my right cover off and poured gas in there to free it up and used a magnet. All that is done by removing the kickstarter shaft and a huge access hole opens up....

[Dustin96]

Well I got all gears again finally, now I'm just trying to track down a stupid ticking/chattery noise. I don't think the noise has anything to do with the gears because it doesn't change shifting threw the gears it only changes reving it up or down. I checked timing chain is tight, valves are to spec, tore the top end of and reinstalled it and the stupid noise is still there. But once I figure that out the ol girl should be ready to ride again.

[Dustin96]

Noise is fixed and all is great she's running and driving awesome thank you everyone.