Posts
68
Joined
2/21/2019
Location
Roseville, CA
US
VoodooHusky
3/25/2019 4:29pm
3/25/2019 4:29pm
Edited Date/Time
4/11/2020 2:11pm
I just purchased a 1999 YZ250 from a friend and it hasn't been started in 12 years! My friend was the second owner and only rode the bike four times. The tank was drained but nothing else was prepped before it was stored. The bike is completely stock with the exception of a FMF silencer/SA. It even has the original tires on it! I'm going to go through the bike mechanically and keep it mostly stock and will use Jeremy McGrath graphics. I've got a bunch of questions as I've been out of dirt bikes for almost two decades and haven't totally kept on on the latest tech.
Initially I'm going to:
Rebuilt the carb
New plug
Change the motor oil
New air filter
Flush the tank
New fuel hose
New brake fluid
The bike ran fine when last run and I haven't even kicked the bike over. I'm going to put a few cc's of two stroke oil in the cylinder before I kick it over and kick it several times with the old plug installed. I'm open to any other suggestions that I should do before I fire it up.
Once running I'm going to take it out for a shakedown ride and then possible put a new ring in it and of course decarbon the PV and piston/head at the same time.
Plan is to have Race Tech upgrade the suspension and I'm open to suggestions here as well.
New tires, chain and sprockets are in the plan as well and I'll probably run a 51T on the rear.
1. First question: what 2T oil are you guys running and what ratio? The manual states 30:1 but that seems rich.
Here's a few pics of the bike in my driveway before I started cleaning it up. I don't think the left radiator was bent like that from the factory. LOL
Initially I'm going to:
Rebuilt the carb
New plug
Change the motor oil
New air filter
Flush the tank
New fuel hose
New brake fluid
The bike ran fine when last run and I haven't even kicked the bike over. I'm going to put a few cc's of two stroke oil in the cylinder before I kick it over and kick it several times with the old plug installed. I'm open to any other suggestions that I should do before I fire it up.
Once running I'm going to take it out for a shakedown ride and then possible put a new ring in it and of course decarbon the PV and piston/head at the same time.
Plan is to have Race Tech upgrade the suspension and I'm open to suggestions here as well.
New tires, chain and sprockets are in the plan as well and I'll probably run a 51T on the rear.
1. First question: what 2T oil are you guys running and what ratio? The manual states 30:1 but that seems rich.
Here's a few pics of the bike in my driveway before I started cleaning it up. I don't think the left radiator was bent like that from the factory. LOL
Anyone want to share what ratio premix you're running on their 99+ YZ250?
My friend only rode it 4 times but the original owner took it to Sand Mountain and had a paddle tire mounted on it at one point. I never like riding bikes in sand.
Great find!
It does look as though you will need to go OVER the whole Engine with a fine tooth comb, you have a great Platform to build off of with a minimum expense. Make sure you don't have ANY AIR LEAKS, this will cause all kinds of problems.
I would run Maxima K2 Oil, 40 to 1 Ratio, with a 45 Pilot, to minimize Spooge from 0 to 25% Throttle opening. IF, IF you REV the HELL out of it, only then will 32 to 1 WORK. Remember it is a Race Bike meant to REV the Hell out of.
If you have to consider a NEW PISTON, GASKETS AND RINGS, you might consider a Big Bore Cylinder Kit. A $170 outlay might get a new Yamaha 250 cc Piston, Gaskets and Rings, but a $550 to $700 additional would get you a YZ ESR 325 Big Bore, with only a change to smaller Jets.
https://www.eddie-sanders-racing.com/category-s/126.htm
The Shop
I'm leaning towards 40:1. I'm a 60 year old intermediate and not holding the throttle wide open nearly enough. I'll ride MX with it along with trail riding and desert. I'm also trying to find a ratio that will work with my 1983 Husky 250CR so i have just one gas can. But I don't really want to compromise and cause issues.
Is this your Husky?
fun.
Ideas for your bike.
I have the original side covers and rear fender along with the pipe for the Husky. I'm probably going to leave it the way it is as that's the PC look back from the early days of Pro Circuit. Their race bikes in 81 and 82 used custom side covers along with the rear fender/number plate combo. Although Andy Jefferson's 1983 250CR used the stock side covers. My friend made those side covers and I helped him. He sold them through Cycle News but only sold maybe 20-30 sets. The stock side covers make the bike very wide.
Here's some photos of the top end completely off. Stock porting and possibly the stock piston. I did not see any witness marks from the top end ever being off. The barrel was a challenge to take off with the corrosion on the studs. Note the two divots on the intake side of the piston to the left of the intake hole. There are some scratches on the barrel but nothing you can feel with your finger nail and nothing that looks alarming. I also cannot detect a lip at the top of the barrel. Note the photo of the crank and the stops on it from what appears to be moisture. There is also a lot of oil on the crank halves which can't be good. I'm taking the top end to my local Yamaha dealer tomorrow to have them inspect and measure it. Hopefully I can just put another piston in it and go.
I need new tires. Here in NorCal we have mostly hard pack and I'll be riding MX and do some trail riding. I'm looking at the Bridgestone X30 tires F & R or maybe the X40 for the rear. I'm open to suggestions so it you have any throw them my way.
Pit Row
https://www.ebay.com/itm/YAMAHA-YZ125-YZ250-1996-2001-USA-Factory-team-…
I did custom order the 1999 McGrath kit. EVOMX didn't show the tank and rad graphics so I contacted them and they are making them for me. I wanted the same graphics McGrath used in 1999 but it cost me. I should have them in a couple of weeks. I ordered number plates as well but I'm too slow for #1 so I went with #11.
https://www.evo-mx.com/shop/yamaha/mcyz32/
Update:
The Wiseco piston kit arrived today but it won't be going on anytime soon. I've determined the wet crank seal is leaking so I'm going to replace the wet and dry crank seals but not split the cases. Since the bike is 20 years old and original I'll replace the water pump seals and bearing while I have the side case off. I'm looking for someone locally to do the work but I think I'll end up doing it myself. It's been a while since I've torn into a two stroke but I'm sure I can handle it. I'm working on a parts list before I tear into it. I'd like to have all of the parts so when I do take it apart and I put it back together immediately. Wish me luck!
Any recommendations on the tires? Bridgestone Battlecross, Dunlop Geomax and Michelin Starcross all look to be good options.
Part of what I ordered and what it should look like:
I still need to buy new tires and I'm looking for suggestions.
I sent him an email regarding a fitment question I had and he was quick to respond and assured me their YZ250 covers would fit my 1999 and if not just return them with no questions asked. Luxon MX is a Vital MX vendor and he mentioned to me they have a forum discount. I purchased the covers online and I received an email shortly after that the covers were shipped and would be here within two days.
They arrived today packaged safely in some environmentally friendly packaging so I was off to my garage to install them. The quality of these covers are significantly better than the stock or Boyesen covers I have and look to be EXACT copies of the OEM pieces. From inspection they looked like they would fit with no issues and they did. I can't imagine any of the other known and expensive billet covers could be of better quality or fitment. They also offer clutch covers with some extra room for aftermarket clutches. Looking at their website they are making some very cool high quality pieces. You can check out their products here:
https://luxonmx.com/
And here are some photos before I get them dirty.
@luxon MX
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