still struggling with this. vm34,220 main, 30 pilot jet,jet needle 6DH4 and needle jet 150o0 with 1.5 needle and seat is what i'm trying but sled is very boggy and is flooding at idle with a few bubbles coming out the over flow tube. Any help would be great. Thanks.
matty k
New member
Monte, bubbles from the overflow could indicate that the float level is too high. Try lowering the float level by 2-3 mm. Are you running an air filter?
I am wondering if the original equipment Keihin fuel pump will work with the 34mm Mikuni carb or should I just order something different? THX for all the info offered here.
you have to mount another fuel pump as most of those had the fuel pump built onto the carb from all the ones i have seen.
Track
Sounds good. One more question... As I recall from when I ran a sled like this (last time was 1971 B.A. [before army]), the rear end had some bounce to it. This sled's track end has no up and down movement at all. I am ordering a new gas shock along with everything else mentioned in this thread in hopes that I'll get some cushion back in this thing. At $83 I hope I'm not wasting my money on this. Are there any tips I might benefit from for installing new shock? Thanks again Mr. Maim for the help...
Sounds good. One more question... As I recall from when I ran a sled like this (last time was 1971 B.A. [before army]), the rear end had some bounce to it. This sled's track end has no up and down movement at all. I am ordering a new gas shock along with everything else mentioned in this thread in hopes that I'll get some cushion back in this thing. At $83 I hope I'm not wasting my money on this. Are there any tips I might benefit from for installing new shock? Thanks again Mr. Maim for the help...
sounds like it could use the shock for sure but it is sounding like you need to pull the suspension out. most likely the shafts are sezied in the tubes for the suspension. my grandmothers 79 gs 340 has this problem and it was stored in a garage its entire life. once freed up, i would do the mod i did to betsy (et410) witch was i welded 1/8" steel pipe couplings to every tube. i then drilled through the tube and put grease nipples in the couplings. never gets stiff now as i grease it all the time.
Pulled suspension and installed new gas shock, cleaned tubes and greased shafts. unfortunately still no suspending going on no matter where I set the track tension bolts. Any suggestion? I'm thinking of calling in an old-timer who may know what to look for.
Pulled suspension and installed new gas shock, cleaned tubes and greased shafts. unfortunately still no suspending going on no matter where I set the track tension bolts. Any suggestion? I'm thinking of calling in an old-timer who may know what to look for. Maybe the limiter strap is too tight...
how much suspension are you expecting from this sled? they only had 4" of travel at most. check where the torsion springs are set. they should be in middle hole for factory setting. for stiffest setting, in the top hole (300lb rider). for a light rider, they can go in the lowest hole. limiter strap on that sled just stops wheelies and spearing the track with the slide rails.
BornYamaha
Member
Has anyone tried to use the oil injection with a split cable? I think maybe the pull length of the throttle could be an issue. I would think if you just adjusted it to be at maximum oil delivery at wide open throttle it may not be so bad to not have it return fully at idle position. Maybe play with the adjustment from there a little bit. I had a split cable on a "90" Phazer back in the day with dual flat 38s and a cable going to the oil injection as well. A kit from Reichard Yamaha. Always ran fine. I just don't remember how the oil cable travel worked. I doubt it had full travel. I have a 250 that I need to do the 34 Mic upgrade to. I would like to retain the oil injection if at all possible.
jjmoneysauce
Member
You can use I believe a vmax 540 oil cable. I have the part # somewhere.
OK, I'll get the new slides on which may affect it a bit, then I'll add some tension on the torsion spring and get the track tension bolts adjusted and see if that gets the suspension back up. I'll be hoping to get anything close to 4 inches. THX Maim
Pulling/plugging oil pump
I would like to pull the oil pump off while I have nice access to it. I see earlier in this thread that some guys just plug the lines. I think one guy mentioned he pulled it. Could you tell me what I will need to plug if I yank the oil pump?
I would like to pull the oil pump off while I have nice access to it. I see earlier in this thread that some guys just plug the lines. I think one guy mentioned he pulled it. Could you tell me what I will need to plug if I yank the oil pump?
golf t comes to mind. i have used screws, bolts and tree branches.
Chazm107
New member
I just want to say how great this thread is, I just had a 1978 ET250 given to me and it’s my first vintage sled, I plan to do this carb swap once I have some other things sorted out on this sled. Not to Hyjack this thread at all but if someone could post where the best place to source new points and condenser that would be great.
that sled does not have points and condensor according to port yamaha's site. the one my dad had would brake the input wire off of the coil and we had to re ground the engine to the chassis to make it run right. the enticers also would break the wires where they came through the fan/engine housing.
I have two 78 ET 250's with the stock carb. Work great all the time, I don't know why people want to change it out and lose the oil injection while at it.
Of note, I've had a couple come to over the years after the owners installed a rebuild kit and the sled won't start. The problem is that the rebuild kits are not correct in that the layers of gasket don't have the holes there that feed the choke circuit. So they have to be added to correct that problem.
If you insist on a round slide, you will need the need jet to be on the smaller side, like in the O-series, or possibly a P-0 or P-2 at the most. Remember these sleds do not have an expansion chamber exhaust.
Of note, I've had a couple come to over the years after the owners installed a rebuild kit and the sled won't start. The problem is that the rebuild kits are not correct in that the layers of gasket don't have the holes there that feed the choke circuit. So they have to be added to correct that problem.
If you insist on a round slide, you will need the need jet to be on the smaller side, like in the O-series, or possibly a P-0 or P-2 at the most. Remember these sleds do not have an expansion chamber exhaust.
Chazm107
New member
My sled absolutely has points and condenser as I have the stator plate assembly sitting on my bench right now. I did manage to find an original Yamaha points and condenser set online so whenever those ship I’ll get them installed. Thanks for the tip on the wiring, I checked the wires in the spot you mentioned and they check good with my meter.
Correct. 77-79 250's had points. 80-81 had CDI
BornYamaha
Member
Did the conversion to 34 slide Mikuni. Saw why oil injection removal may not be mandatory but would be a major pain to get right. Setting it properly could have an expensive learning curve. Used provided part # and specs. Runs like a top. Actually starts on the first pull after sitting for a week. (40* garage). Thanks to everybody that contributed info over the years. Another one saved 