Yamaha RD250 Reassembly. Will There Be Smoke?

[@martinowl]

Well done, must feel well chuffed with it. How frustrating & annoying that wrong thread must have been! Sounds great too.

[@RepairandRideout]

Couldn't believe it was the wrong thread, very fortunate I had another

[@davebracey2027]

Blimey 4th kick after a full rebuild! It was even trying on the 1st. Well done, thats extremely impressive. Looking forward to the 1st run 👍

[@RepairandRideout]

I did squirt a bit of fuel in first 😉

[@marcswinnen9100]

That sound gets my blood pumping😊

[@mikekilbride]

Fantastic well done. Patience always pays in the end. Sounds great

[@RepairandRideout]

Thank you

[@davestatham812]

I had an rd250e with small can allspeed exhausts, i idioticly sold it about 28yrs ago, which i still regret to this day, enjoy it, it looks and sounds awesome, top job 👍🏻

[@RepairandRideout]

I think we can all sympathize with that pang of regret. Pleased you enjoyed the video

[@paulstokes393]

I had allspeeds on my '82 X7. Liked the sound mpre than the Micron pipes. Like you, wish I still had it 😅

[@Honkawsuzyamal]

Hard cheese

[@georgemalkin6546]

Yes the strobe is definitely the way to check.

[@Scott-ph2yk]

Good job! Patience and attention to detail pay off nicely. Finish up your task list and you will be ready for a Spring ride. Break in the engine, check and recheck your bolts, and enjoy the fruits of your labor. Ride safe.😊

[@RepairandRideout]

Thank you, will do

[@bangersnmash4856]

Lovely sound, god bless two strokes

[@RepairandRideout]

2strokes are epic

[@motty1961]

That engine sounds really good. Well done

[@cbrider726]

What a sweet sound mate well done . The RD is one of my fave bikes . Great stuff 👍👍👍👍

[@RepairandRideout]

Cheers, really looking forward to getting it back on the road

[@stevecmason-rs6vf]

Sounds great. Hope all goes well from here on. Just love stink wheels!

[@RepairandRideout]

Cheers Steve

[@grahamhider3754]

Sounds sweet ❤

[@RepairandRideout]

Nothing sounds better

[@nobbybrown8056]

Oh that sound when you started it took me straight back to the 80's, there I was outside the chippy with all the lads just about to burn up the streets. I don't know if anyone has mentioned it but a plug chop at full thottle to check fuel mixture could save you from any problems in the future. Also as I'm sure you already know its a good idea to start with slightly too rich a mixture and work you way down, it cost a bit more in jets but saves a fortune in rebuilds. I keep listening to the start up and I realise now I NEED an RD in my drive soon!

[@RepairandRideout]

Delighted it brought back some great memories, I'd get an RD asap if I were you, just in time for the summer

[@Pokemongold88]

Great result bet your well chuffed 👍

[@RepairandRideout]

Very happy!

[@colinculverwell325]

Those replacement needle jets could well have been the route of all your issues. Stock mikuni ones should be O-8 and stamped on the jet. Stock needles were 5L3. The smaller needle jet could well have been the restriction that caused lean running. Stock main jets on those was 115 so I would have thought that the 140 mains would be big enough. You might well find it's too rich on the mains now but time will tell. I'm not a fan of pattern jet kits for the very reason you have discovered. I have a D model which runs a completely different jet set up to Stock but enables it to run as a stock bike if you see what I mean. It means I can run all genuine Mikuni jets. Allen's performance or Motocarb in UK for all jets.

[@RepairandRideout]

I was quite surprised when I compared the two tubes and I think you could be right. I have heard of Motocarb, I brought some jets from them last year. Just a few more setting up jobs to do!

[@paulgibson5326]

sounds lovely well done 👍

[@RepairandRideout]

Thank you

[@markaddy53]

sounds pretty sweet yhat lad bit ov fine fettling on carbs be spot on well done keep up the good work

[@RepairandRideout]

Cheers, will do

[@markleadbeatter6196]

As many have learned over the years, rebuild kits for these carburettors can be iffy. It is always best to buy genuine Mikuni if you can, with Cruzin Image parts probably the next best option. Keyster stuff can be good and bad in equal measure, so probably best avoided if possible. Glad you have her running again and you have learned lots of lessons over the course of this journey, that will be valuable for your next RD (and there will be a next once you get to really enjoy your 250) so I would suggest sampling a 400 next as they really are fun.

[@RepairandRideout]

I think that's right, take nothing at face value with buying parts for these older bikes. 400's are a bit out of my price range by the looks of things but I will look out for something 2stroke

[@Guzzi-SPORT]

Nicely done rebuild looks brand new great job

[@RepairandRideout]

Thanks 👍

[@raymondsteele4142]

Nice .

[@sidecarbod1441]

0.80mm squish is getting a little tight but should still be OK, I guess the head has been skimmed because a stock head would not have a squish clearance this tight, either that or the cylinders have been faced. Were the combustion chambers opened up? If not the CR will be pretty high, it might be worth buretting the heads in order to work out the CR, you do not want to be pushing it up too high with an old air cooled engine, I don't know what sort of fuel you have available but that also needs to be taken into account when messing about with the CR. Are you going to run an air lifter, the carbs don't seem to be connected to one. Any way it sounds great, a nice 'crackle' from those pipes!

[@RepairandRideout]

The heads and cylinders were only cleaned for a good fit, no combustion work carried out.. I am using quite a thin head gasket, 0.4mm from memory and I have other thicker ones. The thickness of the gaskets seems to vary by supplier

[@the_forbinproject2777]

sounds really beautiful ! so running some pre-mix with the pump , no worries but pre-mix weakens the fuel mixture but then again the larger jets will compensate for that ? did the emulsion tubes have a size stamp on them ? from what I remember there was one size just for the E model and one size for the rest of the 250 range . Same for needles and slot positions ( in other words the 250E was different !) another reat video and another milestone reached , cool , be ready for summer ( when ever it arrives ! )

[@colinculverwell325]

You remember right. The C/D models had O-8 needle jets the E O-6. The E also had different pilots, slide, needle and air corrector jet.

[@RepairandRideout]

Thanks, I'm not running the pump yet. I want to test its output by running it into a pair of cups. I can't fathom a reason why he feeds to each carb should be different, but as I've done everything else!

[@deedahinkent]

4th kick ! how good does that feel ?😅Well done looking forward to the test ride 👍

[@georgemalkin6546]

I notice when you set your timing you set it in the centre of the sensor, I have a powerdynamo ignition which is basically the same and my instructions say set the ignition on the leading edge, as the vape is just the same system have they changed the instructions?

[@RepairandRideout]

I've gone for the center as someone else advised it. I'll more than likely check it with a strobe light at some stage to see exactly where the firing position is

[@gk73man51]

It’s no good checking the squish in one place, the piston will rock in the bore giving a false reading. Ideally it should be taken at four places 90 degrees apart, or at worse 2 places 180 degrees apart. 0.8mm seems a bit tight for a standard engine on modern fuel.

[@bananabrooks3836]

Measures the squish then says 'l don't really know what is correct'🙄 Actually 0.8 is a good figure as Yamaha were a bit generous as stock.

[@RepairandRideout]

Thanks for the info, that's right, I didn't know what was the correct squish. Everyday is a school day

[@MeYou-yz2yz]

Something is wrong if it doesn't smoke.😂

[@davidparsons4625]

LOOK, I understand the desire to breed anticipation for your videos, but the stupid adage of "will it run?" is just annoying