BIG MISTAKE: RD250 Build By A Newbie *Help Me Grow Up!*

Thanks everyone for the advice and support

Status Update: I had someone come over and give it a once over. It turns out that I fouled the plugs and flooded the engine, since I left the Peacock in the on position. It starts up and runs awesome now.

I do run premix at 40:1 right now (any suggestions on ratio?) because the oil injector or "yamalube" isn't hooked up.

Will start degreasing and cleaning everything tomorrow.

He also freaked out when he found out the bike was originally bought at Malcolm Smith's dealership and saw the license plate. I don't even know the significance of that but will look it up.
 
For what it's worth, oil isn't usually a cause of fouling in two strokes; it's running rich with too much fueling. The combustion chamber will run hot enough to burn out any of the oil unless you jet it too rich on fuel. That's when things start to go badly.

If you rev the bike a lot, you will want to use a higher concentration of oil. If you ride balls to the wall 24/7, then you can go down to as low as 10:1 though empirical tests have shown maximum power is right around 18:1 - 22:1. However, if you run with a ratio in that range and don't push the bike hard enough, you're just wasting oil.
 
Sonreir said:
For what it's worth, oil isn't usually a cause of fouling in two strokes; it's running rich with too much fueling. The combustion chamber will run hot enough to burn out any of the oil unless you jet it too rich on fuel. That's when things start to go badly.

If you rev the bike a lot, you will want to use a higher concentration of oil. If you ride balls to the wall 24/7, then you can go down to as low as 10:1 though empirical tests have shown maximum power is right around 18:1 - 22:1. However, if you run with a ratio in that range and don't push the bike hard enough, you're just wasting oil.
Click to expand...

That's good info, cheers :)
(and I don't even have a stroker!)
 
Sonreir said:
For what it's worth, oil isn't usually a cause of fouling in two strokes; it's running rich with too much fueling. The combustion chamber will run hot enough to burn out any of the oil unless you jet it too rich on fuel. That's when things start to go badly.

If you rev the bike a lot, you will want to use a higher concentration of oil. If you ride balls to the wall 24/7, then you can go down to as low as 10:1 though empirical tests have shown maximum power is right around 18:1 - 22:1. However, if you run with a ratio in that range and don't push the bike hard enough, you're just wasting oil.
Click to expand...


Excellent info... I learned something. 10:1 I would have never tried... Though, I new about 2 strokes never being too rich because of oil. Only jetting... Thanks!
 
congratulations on your rd.

I'm sure you have probably already discovered but there are a few 2 stroke specific forums that deal mainly in rd's

http://www.2strokeworld.com/forum/index.php
http://www.usa2strokers.com/default.asp

there is allot if valuable information to be found on that site.
 
If you absolutely must use pre-mix, get an Accu-mix jug from Accu-products.com. Best way to mix fuel in the whole universe.

32 - 40 is fine. My kart buddies run 12:1 or richer and that works well at 14,000 rpm. On the street, use the stock autolube pump. Clean it, check it and then just add oil to the oil tank. Different oil pre-mix versus injector BTW
 
Great to hear, I will reduce my ratio down to 32:1 for now and see how that goes.

Update:

I've decided to hold off doing anything cosmetic or not related to the engine until I am sure it is running well. It seems to be really finicky and inconsistent about starting. It was alright starting two days ago..took about three kicks. Yesterday, I was pretty happy when it started right up with one kick. Today was a nightmare getting it started...took me about a half an hour.

Here is a brief video, does it sound normal? I can kind of hear some knocking, but maybe it's just my imagination as I am not used to these older bikes.

http://youtu.be/kgI7pv4tF_U

Also, I believe I have some leaks, here is a link to that post: http://www.dotheton.com/forum/index.php?topic=38413.msg417950;boardseen#new

Apparently the off position for the petcock is in the middle (in the other post)? What's happening when I leave it on the other position?
 
JiveTalkinRobot said:
Apparently the off position for the peacock is in the middle (in the other post)? What's happening when I leave it on the other position?
Click to expand...

Depends on the type of petcock. Some don't actually have an off position and will instead have "Prime". It's important to know which type you have as they behave differently.

If the type you have is on/off then you should turn it off whenever the bike is sitting for more than a couple of minutes (without running). Leaving it on will, at best, just waste some fuel and at worst, flood the bike and spill gas everywhere.

If you have on/prime style, then you should leave it in the on position all of the time and turn it to prime to start the bike. Switch to on after the bike is running.

If the text on the petcock is hard to read, you can usually tell the type of petcock by any extras attached to it. On/prime types will have a vacuum line running to them from somewhere in the intake (usually the end of the carbs right near the manifold). Basically, two lines from a carb with only one containing fuel means you have an on/prime type. On/off types will only have fuel lines coming out. Either one line that is split to feed each carb or one line for each carb.

For instance, the petcock on my T500 is an on/prime type and you can see in this pic, there is a vacuum-controlled diaphragm attached to the back of the petcock with four screws. As the vacuum from the carbs pulls on the diaphragm, it opens and allows more fuel to the bowls. When the bike is turned off and no vacuum is being generated, it closes and is OK to sit that way.

DSCF5857.jpg


This next pic is of an on/off style petcock that comes from my CJ360. No extra wizardry here, just a simple valve that opens and closes manually. If you leave it open, fuel is always flowing and so it must be switched off when not in use.

578293_10150965215545159_589042880_n.jpg
 
Sounds nasty, top end off and check pistons/rings, reeds.
If you catch things early its a lot cheaper to fix, may need pistons and rings, they crack down rear of skirt or, if modified, wear skirt real quick
Also, re-pack the silencers, tight as possible, makes it run a LOT better
Packing blown out of two stroke exhaust means the tuned length gets screwed up
It would probably be a good idea to check clutch basket to drive gear as well, it was a known issue, Yamaha had a repair kit at one time, I did quite a few
 
Thanks CrazyPJ, I'll do that next.

I've been told it might be piston slap and to warm it up and ride it around for 10 minutes and see if it still sounds like that.
 
If your thinking of going back to autolube pump as some have suggested make sure you have the correct pump. If I'm not mistaken there are differences 250-350 engines.
 
yikes that rd needs some tunning. Good thing its a 2 stroke since theres not as many moving parts as a 4.
 
Status update (it's been awhile, I was out of the country):

I had someone take a look at it, he said it was all good. Wiseco forged pistons are a bit loud naturally.

Adjusted the timing.

The seat came in, i'll take some pictures pre and post install.
 
Oh yeah, FYI I talked to Spec 2 about their rearsets...the price is now 299. I'm not sure why you would choose theirs over the Moto Carrera or FFtPs.
 
I finally got the shift shaft seals, engine gasket kit, oil drain plug, neutral switch o-ring seals. Those should be coming in the mail soon. While I am replacing those, I will probably have the covers powdercoated since I have them off.

Does anyone have an opinion on whether to keep running premix, or to try and get the oil pump (autolube) back up and running? It's getting to be kind of a pain, considering the bike only gets 25mpg and can only hold 2.5 gallons.

Also, when changing the seat, do you guys usually relocate the battery somewhere?

Next up: rearsets...I installed some clubmans (for now, until I can get clip-ons). Any suggestions?


Man...this is all adding up in cost...I don't even want to think about it.
 
Answers - in no particular order:

Get the pump and oil tank back on it and forget pre-mix.

Fit battery in stock place and use a side cover to match the oil tank or borrow one and take a CF skin/wrap of the shape and use that.

Engine covers I hit with a can of high heat paint every couple of years. Cheap and does the job.

I always fabricate rearsets out of whatever I can get my hands on. If you don't weld it's a bit more expensive of course. I scour ebay for deals and modify what looks like it will work - as long as it's cheap, or weld some up from scratch.
 
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