Jump to content
Sign in to follow this  

74 MT 250 elsinore Diesieling? HIGH RPM

Recommended Posts

ok where to start, i bought a honda elsinore MT250, it didnt run all that well so i bought a carb rebuild kit. so i rebuilt the carb and it will not run without the choke on, it seems not to responde to needle changes as well. i rode it around the block to try and clean it out. it statred really smoky. after about a 1/4mile ride when i returned the throttle back to closed position the motor didnt seem to wind down instantly, so it seems that it is running too lean. I went back to the garage started the bike after 10 min of kicking it finally fired ran for 10 -15 sec the the motor rpm's shot up super high. i mean crazy high so i turned the kill switch, nothing pulled the spark plug wire, nothing still running (this is my first experience w a motor running with no plug wire so i am freaking out.) finally i pull the fuel line after 20 sec it dies. whew. I noticed this morning that the trans has no more oil in it, is there a possibility that some of the smoke commig out of the motor was trans oil due to bad crank seals?

Share this post

Link to post
Share on other sites

I had a similar experience with my friend's MT250 when I ran the carb dry before putting the bike away. The carb had been running really rich and the idle speed screw was set high, and after idling for a few minutes the rpm shot up to redline and stayed there. Luckily, the kill switch worked OK.

If you ever have that dieseling experience again, I'd jump on the bike, shift it into 2nd, and let out the clutch with the front brake on; better a little clutch wear than the motor turning 12 grand. :thumbsup: It can be kind of hard to remember what to do when all hell's breaking loose, though.

Try refilling the gearbox and see if you get smoke. If not, something probably went wrong during the carb rebuild; plugged jet(s), incorrect float level, leaking gasket/manifold, etc. I'd replace the LH crank seal too.

If you DO get smoke which goes away when you lean the bike way over to the left, that's almost certainly a bad RH crank seal, and a big repair job.


Share this post

Link to post
Share on other sites
I noticed this morning that the trans has no more oil in it, is there a possibility that some of the smoke commig out of the motor was trans oil due to bad crank seals?

explains all of your issues.

massive air leak and its burning the trans oil.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

  • Similar Content

    • By SNORE125
      Anyone else have 130 main and 38 pilot jets already in the carb I took the wifes ttr 230 carb apart to add the bigger jets and this bike from 05 that I bought new already had them in it? I was reading that they came with a 125 main and a 36 pilot.
    • By Charles Joseph Miron
      Hello all.  Need a helping hand here..  
      I bought an older TT225 and am not about to spend almost $600 on a new carburetor for it. So I'm hoping someone can help me out with an idea of what (other than original carburetor) style, type and brand I should go with..  I'm also having a bit of trouble finding info on this bike.  It's a 1986 Yamaha TT225.  
      Thank you in advanced
    • By Br0ck
      Hey guys, I went on vacation all summer and let my bike sit (2002 CR250). When I got back I ripped it apart and cleaned carburetor and put it back together and it started fine and ran alright, but idled really high. I adjusted the idle screw and realized it was a ridiculous amount of turns out. I can't remember exactly how many but id say 6+ turns out. My killswitch was a POS and didn't work anymore so I replaced it with an oem replacement. My last ride I crashed the bike pretty bad and I was off the bike for 2 weeks. I can't get the bike to start ever since I got installed the new killswitch. I think I wired it right I just replaced one wire at a time and it looked pretty straight forward. I verified it by testing spark while holding it in I was getting no spark but with it in running position it would spark. 
      Anyway I am just looking for some base settings for the Mikuni TMX to get my bike running again, my carburetor has a 35 Pilot and 380 Main jet which appear to be stock. I am located in Edmonton, AB, Canada which is about 2500ft and usually ride between 10-25 celcius.
      Thanks for any replies. 
    • By Goon Rides
      Hey guys... so I have a problem... I took the bike at Cal City, broke it in, and while I was doing so, the bike was bogging in first gear (Yes, first gear). Also it doesn't idle at all. I have to keep blipping it otherwise it'll stall. So I adjusted the screw circled in image 1. Well I was listening to the sound of the of the bike, yet the rpm's weren't increasing, and it was still stalling. So then, I unscrewed the screw in image 2, well I found out that it was fully twisted to the right. So then, I twisted it to the left, still nothing; it was still stalling... where's the idle screw? I am sure that the screw in image 1 is for the air/fuel mixture screw, and the screw in image 2 is the idle screw, just broken? I don't know, any and every help would be appreciated.

    • By Zach7018
      So Ive decided its time to pull apart my favorite machine and freshen it up, and I'm looking to make some improvements in the process. I already have a 3x3 mod and a JD jet kit done and it seemed to have changed the world. The stock bike just plain sucked and now its a lot better. I never expect 450 race bike power here but I know there is a little more and I'm wondering if the juice is worth the squeeze. I already plan to add a header and exhaust, an FCR39 carb and stage 1 hotcams. After some research it really seems like those places are where the gains actually come from, so would it be worth it to throw a 434 big bore kit at this bike or just stick with what I already mentioned and a new stock bore top end??? Also my rides are often solo and pretty isolated,how much of a reliability headache can I expect with these mods?