Yam RD "Blue Dream"- Ride,Maintain,Tune

[Ply318ci]

Re: Yam RD "Blue Dream"- Ride,Maintain,Tune

Looks good man. As for the main I run stock pipes and pod filters (UNI brand) and have a 200 main to start with. After all that work I would think you should start at least at that and go down would suck to seize that beautiful motor first time out. But my RD isn't running so hot so what the hell do I know. In my defense this is what JPMobius recommended for me and he has forgotten more about RDs then I will ever learn.


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[2_DONE_THE_TON]

Re: Yam RD "Blue Dream"- Ride,Maintain,Tune

Thanks ply!theres only one thing to know....there are different nomenklatures for vm jets....iirc i have hexagonal head jets...i will check with my mikuni dealer...
How do i feel that the motor runs too rich or lean?is there a rule of thumb?
Mobius always recommends testing WOT, but how do I feel if the bike leans out or is too rich?

 

[2_DONE_THE_TON]

Re: Yam RD "Blue Dream"- Ride,Maintain,Tune

Here are some pics from the process of restoring my cylinders and heads
Blasted and painted,baked then took a belt sander with 240 grit to the fins...came out good!!!!!

 

[Shoeman]

Very impressive. So that's a 350 crank in 400 cases with what was once upon a time called "crank stuffers" to eliminate the extra volume the 400 cases have over the 250/350 cases?

 

[2_DONE_THE_TON]

Very impressive. So that's a 350 crank in 400 cases with what was once upon a time called "crank stuffers" to eliminate the extra volume the 400 cases have over the 250/350 cases?

Thanks man!

no actually its my original RD 250 F bottom case, with 250 crank (same stroke as the 350), 400 gearing (clutch and primary and oil pump gear)-->the 400 gearing is the same as the 350...

I still have a shimmed out 400 case for a 350 crank,but didnt use it,too knackered...

 

[2_DONE_THE_TON]

Just found this:

http://www.hvccycle.com/carburetor-jetting.html

can anyone verify this as a guideline to jetting my RD350 with y boot and DG pipes?

 

[Tune-A-Fish]

I have been in the shop several times and bought parts from them... good people and been in Lincoln Nebraska a while now so I would not have a reason to think they would steer anyone wrong. But I know another parts guy in Lincoln that is a complete asshole and has been around even longer so??

If you start wet and work your way to dry with plug chops and looking at the drool for consistency, listen for pinging you will lear what to listen for and how the power reacts to changes... go to the track(s) find someone who has a dirty ole trailer with sweet smokers inside and pick brain... Just take most of what you hear with caution.

I used to blow holes in pistons a lot just because I premixed by color Ha HA!

 

[2_DONE_THE_TON]

Re: Yam RD "Blue Dream"- Ride,Maintain,Tune

I have been in the shop several times and bought parts from them... good people and been in Lincoln Nebraska a while now so I would not have a reason to think they would steer anyone wrong. But I know another parts guy in Lincoln that is a complete asshole and has been around even longer so??

If you start wet and work your way to dry with plug chops and looking at the drool for consistency, listen for pinging you will lear what to listen for and how the power reacts to changes... go to the track(s) find someone who has a dirty ole trailer with sweet smokers inside and pick brain... Just take most of what you hear with caution.

I used to blow holes in pistons a lot just because I premixed by color Ha HA!

Thanks man!

I guess i will start from 230 and make my down!
I will have an assortement of jets ranging from 115 to 230!

 

[der_nanno]

OMG is my hair really that thin already on the back of my head?

That said a #220 is plenty... I'll check which jets I have at hand in my shop and we can just work our way down until we hole a piston and then roughly up it one or two sizes. How does that sounds for a plan, my good man?

Cheers,
Greg

 

[Tune-A-Fish]

What a drag it is... getting old :-X

 

[jpmobius]

I'd probably start with the #230's. You have to lean on the engine pretty hard to burn through a piston crown. The problem is, very often the engine will be running EXCEPTIONALLY well right when it fails. This actually makes sense because you can't actually run a perfect air/fuel ratio. The stoichiometrically correct ratio ends up being too lean not because it is actually lean, but simply because you need the excess fuel to cool the engine. Engines are PRIMARILY cooled by the fuel they use. This happens because the fuel has to make a phase change from a liquid to a gas in order to be used. You have to heat the liquid fuel until it turns into a gas and that heat comes from the engine. Dial down the fuel to air ratio to chemically correct and you get optimal efficiency and in theory power, but you get more heat as a result also and without any extra fuel to vaporize and cool things off you get a very rapid spiral of overheating right when the thing really starts to sing.

So as long as you don't overdo your test drives, you should be safe. I get in the range just riding the bike. If it bogs out like it runs out of gas - won't take full throttle - likely it is lean so increase main jet until it revs out. If it motorboats, runs blubbery, 4 strokes, etc it usually is rich so decrease main jets until it smooths out. Err on the rich side, and start doing plug chops or dyno runs.

I'd expect the #230's to not be far off, but there is no telling. For reference, the black motorcycle I posted here a few months ago ended up with #280's in it. That motor had stock port timing and original carbs. The modifications were all very mild. Stock "y" boot with a big K&N filter. Ended up altering the mid range circuit in the carbs like an R-5 (same mod as your carbs with the new needle, emulsion tube and main air jet - ran slightly better on this engine). 9mm spacers under the reed block and YZ 125 reeds. None of this has much effect on main size. The big changes were the pipes (Moto- Carrera, pipes and altered cylinder heads set to .040" squish clearance. That's a pretty mild, basically stock engine with pipes and air cleaner pretty much like yours. So don't be convinced that #230's will necessarily be rich - #280's are a long way from there!

 

[CarbsAndCylinders]

Kids are different today

 

[CarbsAndCylinders]

I remember one time I was at the front desk of a hotel and I could see the top of a man's balding head in the security TV. Then I noticed that every time I moved my head, so did the man on the screen. It was quite a let down.

This has been a good reminder to me that if cleaning carbs, EVERY THING!

 

[redwillissuperman]

Re: Yam RD "Blue Dream"- Ride,Maintain,Tune

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Today is the day I clean the workbench off

 

[2_DONE_THE_TON]

Re: Yam RD "Blue Dream"- Ride,Maintain,Tune

Thanks mobius for your precious insight!
Don't feed the trolls!

Waiting out winter then i will dig into the 2 stroke fun 350 is reassembled and ready to go back into frame!

 

[Tune-A-Fish]

Ready for Launch... Begin Countdown.... :'(

 

[CarbsAndCylinders]

I like the way you finished the engine paint and polish.

 

[jpmobius]

laughing hysterically.

 

[2_DONE_THE_TON]

Re: Yam RD "Blue Dream"- Ride,Maintain,Tune

Ran into a little problem yesterday when I reassembled the motor.
Realised that the plugs reach depper into the 350 heads than the 250 ones...guess i have to try short threaded plugs...since one of the heads has been helicoiled i guess this was the issue that caused this...

 

[Ply318ci]

Re: Yam RD "Blue Dream"- Ride,Maintain,Tune

Looking good.


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